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HandlingByJebus
Jun 21, 2009

All of a sudden, I found myself in love with the world, so there was only one thing I could do:
was ding a ding dang, my dang a long racecar.

It's a love affair. Mainly jebus, and my racecar.



Pursesnatcher posted:

Mercedeeeeeees...!

Okay, so it appears my TPS isn't really a potentiometer, it's a switch. Somehow. And to check it, you're supposed to measure resistance, not voltage. I'm decent enough with electrical and electronic stuff in general, but once you put either of those in a car, I get confused and anxious.

Problem: My manual doesn't say much at all about what values to look for when measuring said resistance, only that it's supposed to end up at zero Ohm's when throttle is fully engaged. Also, the switch itself is located at the throttle body, which is underneath the air flow sensor, which is underneath the fuel distributor octopus. That means I have to measure at the terminator. That, in turn, might be one out of two possible plugs. One looks right, but has four wires coming out of it, not three. The other's got one, not three. There are supposed to be three wires. So I'm at a loss.

Didn't get much further than that this weekend, and am seriously considering letting a trained professional handle this particular problem.

Good news though, I found out that my aux fans work! Both of them, even the one that was jammed stuck with corrosion, spin up with much gusto and excitement when fed 12 V directly. I'm positive that with both those babies running, I'll have exactly zero need for the big mechanical fan. Bad news is that they're supposed to spin up at a low setting above a certain coolant temperature, and at full blast at some higher temperature, but even after having run the engine up to 110 Celsius, I still haven't seen a hint of that low setting. So either there's a busted sensor somewhere, or there's a busted relay... so that's another thing I might want to hand over to a workshop.

Of course, a friend who came over and helped out noticed a vacuum line hanging loose, outside a connector. I have no idea what it's for, but for all I know, those power issues might have been caused by that.

Edit: It's literally 90 degrees F here now; not braining so well. Re: fans, doing some further reading, it seems they're only set to come online in the slow setting when refrigerant pressure exceeds so-and-so. As I've removed half of my AC system, and unhooked the belt from the AC compressor, that's not going to happen any time soon. Going to have to see if I can bypass that detection, I guess? Still kinda weird that they won't power up on the high setting, though, since they're supposed to do that anyway.

Your throttle position sensor is a variable resistor. You can test it right at the throttle body so long as you have access to the pins on the plug, which should be 3. One for ground, one for +5V ("sensor reference voltage"), one for output. If you measure between +5V and output pins, you should see 0 ohms or thereabouts at WOT, and something like 50k / 100k / 500k ohms fully closed, without weird spikes up or down as you open and close the throttle. The factory service manual should specify what the fully closed resistance is, the value is somewhat arbitrary but it is specific to the application.

Alternatively, with the ignition on you should be able to measure a voltage between ground and the output pin. That should be ~0V (it's around 0.26V on my car) with the throttle completely closed and ~5V (around 4.7V on my car) when fully open.

What the ECU does is feed a reference voltage (usually +5V) into one side (or the wiper) of the variable resistor. The wiper (knob) of the variable resistor is attached to the shaft of the throttle, so when the throttle moves, it turns the knob on the variable resistor, changing its value. One of the other pins (wiper if that's not where +5V goes, or one of the sides if it is) is connected to the throttle position sensor input, which sees a voltage between 0 and 5V that is relative to throttle position.

HTH.

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STR
May 12, 2006

I thought I was a nice jester


Yeah if they're meant to kick on with the AC, they'll only do so when the compressor is actually engaged and working. No idea why they're not kicking on once the engine passes 110c (that's the same setpoint, or very close to it, that GM uses if the AC isn't on, I believe).

90f is adorable though. I guess if you're not used to it, it feels like "oh god I'm gonna die". Here, it's a relatively nice day for outdoor stuff, so long as the humidity is below 60%. But driving without ac does get pretty annoying at that temp. Especially in a dark vehicle. STAY HYDRATED and keep your water out of the sun!

STR fucked around with this message at 16:26 on Jul 29, 2019

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Weather chat: July is always the hottest month of the year, but that's with an average temperature of 62įF Ė with highs and lows being ten degrees off from that. To make matters worse, I grew up further north, where you can shave another ten degrees off all of those figures. This heat is just pure torture; I much prefer a nice, chilly 10-15 degrees to this madness.

HandlingByJebus posted:

Alternatively, with the ignition on you should be able to measure a voltage between ground and the output pin. That should be ~0V (it's around 0.26V on my car) with the throttle completely closed and ~5V (around 4.7V on my car) when fully open.

What the ECU does is feed a reference voltage (usually +5V) into one side (or the wiper) of the variable resistor. The wiper (knob) of the variable resistor is attached to the shaft of the throttle, so when the throttle moves, it turns the knob on the variable resistor, changing its value. One of the other pins (wiper if that's not where +5V goes, or one of the sides if it is) is connected to the throttle position sensor input, which sees a voltage between 0 and 5V that is relative to throttle position.

This was roughly what I gathered from Youtube and wikis; both explanation and procedure. I was just thrown off by there being four wires instead of one, and my workshop manual telling me to look for "zero to infinity" Ω rather than some voltage, and without giving any other figures besides the zero at WOT. Makes sense, though Ė lowering the resistance as the throttle opens would indeed affect voltage as well. As said, I let myself get confused once electricals are installed in a car rather than in a building.

Will give it another go!

STR posted:

Yeah if they're meant to kick on with the AC, they'll only do so when the compressor is actually engaged and working. No idea why they're not kicking on once the engine passes 110c (that's the same setpoint, or very close to it, that GM uses if the AC isn't on, I believe).

From what I've been able to gather, there might be a busted relay, resistor or connection somewhere in the loop. I did come across a wiring diagram for the auxiliary fans which shows a pair of relays which, if broken, would keep them from spinning up at temperature.

What's more, it shows a "refrigerant high pressure switch" which normally would let them spin up to slow speed (4 or 6 volts, from what I could make out) once AC pressure reaches some threshold. That may or may not be critical to get them spinning up to max as well. I'm also betting that if I short that one pressure switch out, the fans will come on at low speed as soon as I turn on the ignition, since they would then assume AC pressure has reached that threshold. More testing is required.

zundfolge
Apr 11, 2007


Certain flavors of old Bosch fuel injection do in fact use throttle position switches, not sensors. All they do is tell the ECU that the throttle is closed (so that it can regulate idle speed using an auxiliary air valve) or wide open (so that it can enrich the air-fuel mixture). Everything in between is handled by whatever air flow meter the specific system uses. In your truck I think itís K-Jetronic? In any case a bad switch would probably only cause stalling at idle since the ECU doesnít realize the throttle is closed. There are almost never issues with the WOT side..

Volvos with K-Jetronic and LH-Jetronic are like this and Mercedes used the former in a bunch of cars so I figure they used a similar arrangement of controls/control logic.

STR
May 12, 2006

I thought I was a nice jester


Pursesnatcher posted:

Weather chat: July is always the hottest month of the year, but that's with an average temperature of 62įF Ė with highs and lows being ten degrees off from that. To make matters worse, I grew up further north, where you can shave another ten degrees off all of those figures. This heat is just pure torture; I much prefer a nice, chilly 10-15 degrees to this madness.

I'm insanely jealous of your summer temps, but you can keep that 10-15 degrees.

I spend a bit of time every (work) day in a -20F freezer. That's loving torture for me, even bundled up like I'm going to the arctic circle. I made the mistake of wearing shorts to work yesterday too (wasn't supposed to be working in the freezer yesterday) - my berries still haven't come out of hiding.

Charles
May 9, 2004

zoom-zoom


Toilet Rascal

I was supposed to go to Paris last Wednesday and Thursday. Really glad I backed out of that

Computer viking
May 30, 2011
Now with less breakage.

I don't know exactly where Pursesnatcher lives, but the weather over here has been ... twitchy recently.

Grakkus
Sep 4, 2011



zundfolge posted:

Certain flavors of old Bosch fuel injection do in fact use throttle position switches, not sensors. All they do is tell the ECU that the throttle is closed (so that it can regulate idle speed using an auxiliary air valve) or wide open (so that it can enrich the air-fuel mixture). Everything in between is handled by whatever air flow meter the specific system uses. In your truck I think itís K-Jetronic? In any case a bad switch would probably only cause stalling at idle since the ECU doesnít realize the throttle is closed. There are almost never issues with the WOT side..

Volvos with K-Jetronic and LH-Jetronic are like this and Mercedes used the former in a bunch of cars so I figure they used a similar arrangement of controls/control logic.

Came here to post this. Both my W124 and my BX GTi have this system, and they both have the same test.

code:
There are only three pins & on pins 1 & 2 at idle there should be no resistance, same between 2 & 3 at WOT. Anywhere inbetween these two points should give infinity.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

drat, yes! That makes sense. That makes complete sense, and a lot more of it than if it had had a potentiometer (especially since the manual keeps referring to it as a "switch" in most instances). Mine uses KE-Jetronic, I think, but it's pretty much the same thing. It also makes sense as my Idle Control Air Valve Pump thing is both ludicrously expensive and very centrally located next to the throttle. Pretty sure most of the vacuum lines eventually end up inside it as well.

I bravely went out and moved the car around a bit yesterday, with no indication that anything was off. I didn't drive it hundreds of yards along the road, which was what it took to get it acting up last time, so I can't know, but all this lends credence to the idea that the issue might have been that one vacuum tube which was just flopping around instead of being plugged into its connector.

Computer viking posted:

I don't know exactly where Pursesnatcher lives, but the weather over here has been ... twitchy recently.


poo poo, we're practically neighbors.

meltie
Nov 9, 2003

Not a sodding fridge.

The Bible: https://www.amazon.co.uk/Injection-...=gateway&sr=8-1

Grakkus
Sep 4, 2011



I guess that makes this the Satanic Bible? https://kjetkillers.pl/en_US/p/Inje...edes-V8-m117/77

Pursesnatcher
Oct 23, 2016



Grimey Drawer


I've been looking at this (and, even more lustfully, its Estonian counterpart), and if I had a second 500 GE to experiment on, I'd be all over that.

...then again, there's nothing stopping me from getting a beat-up old 500 SEC and converting that. Except money, and terrain.


And now it's on my wishlist.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

All right, my friends. I am officially puzzled, bemused and bewildered. My not-potentiometer is fine. It's beyond fine, and it turns out it's quite possibly a bit redundant.

We've got three pins, where number 2 is ground. The others start at 0 and infinite ohms, which flips to the opposite state when the throttle goes from zero to not-zero for one, and from not-WOT to WOT for the other. As far as I can tell, that's exactly what's supposed to happen.

But then: I had a friend over to help me test this out, and once we had figured out that it seemed to be all right, we took it out for a test drive. Almost a mile later, we both realize that we might have forgotten to put the plug back on, so I pulled over, and, uh, yeah. We had. And yet, the car was fine. Maaaaaybe a little rough running, but otherwise fine. So we put the plug back on, went back to the test run, and completed two full miles with no issue. No trace of power loss or weird throttle response.



So fuel pump was the next suggestion, but I don't know Ė it buzzes nicely, which evidently means it runs? Am I overly optimistic when I'm thinking perhaps fuel filter? I can't see any trace of that having been changed in my receipts, which means it's gone at least 80k miles. Or it could just be ze German vacuum system and that one hose which had come off, I don't know.

On a happier note, I can now make engine cooling! As I mentioned just a couple of posts back, I found a wiring diagram with a "refrigerant high pressure switch" in it. That, it turns out, is this:



So I just disconnected this baby here, shorted the wires, and lo Ė both auxiliary fans spin up at a respectable pace as soon as I turn on the ignition. Victory!

meltie
Nov 9, 2003

Not a sodding fridge.

Pursesnatcher posted:

All right, my friends. I am officially puzzled, bemused and bewildered. My not-potentiometer is fine. It's beyond fine, and it turns out it's quite possibly a bit redundant.

We've got three pins, where number 2 is ground. The others start at 0 and infinite ohms, which flips to the opposite state when the throttle goes from zero to not-zero for one, and from not-WOT to WOT for the other. As far as I can tell, that's exactly what's supposed to happen.

But then: I had a friend over to help me test this out, and once we had figured out that it seemed to be all right, we took it out for a test drive. Almost a mile later, we both realize that we might have forgotten to put the plug back on, so I pulled over, and, uh, yeah. We had. And yet, the car was fine. Maaaaaybe a little rough running, but otherwise fine. So we put the plug back on, went back to the test run, and completed two full miles with no issue. No trace of power loss or weird throttle response.



So fuel pump was the next suggestion, but I don't know Ė it buzzes nicely, which evidently means it runs? Am I overly optimistic when I'm thinking perhaps fuel filter? I can't see any trace of that having been changed in my receipts, which means it's gone at least 80k miles. Or it could just be ze German vacuum system and that one hose which had come off, I don't know.

On a happier note, I can now make engine cooling! As I mentioned just a couple of posts back, I found a wiring diagram with a "refrigerant high pressure switch" in it. That, it turns out, is this:



So I just disconnected this baby here, shorted the wires, and lo Ė both auxiliary fans spin up at a respectable pace as soon as I turn on the ignition. Victory!

I bet it was that hose tbh. Good hack with the fans!

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Thanks! It's just so drat weird, because the day after I plugged it back in, I still experienced a bit of the same problem Ė just not quite as bad. Fingers crossed, though!

Pursesnatcher
Oct 23, 2016



Grimey Drawer

I spoke too soon; problem is still very much there.

I can't quite tell, but I think letting my foot completely off the gas triggers it? Went a mile with no issues, stopped, and tried going back; it started getting moody as soon as I tried getting it back up from a standstill. Actually died on me once or twice, but started again with no problems. Gear selector doesn't matter one bit once it starts acting up, either.

Now this time I managed to catch it on film, sort of. Pulled off the road on an empty lot, had it die, and then filmed my instrument cluster when I started it up again. I think it's pretty helpful, because it shows what's happening far better than I can explain it.

https://www.youtube.com/watch?v=VR46B4K-bc8


So I turn the key, all fine. Rev the engine gently, all fine. Exactly 12 seconds after the engine started, RPM and oil pressure dropped first a little bit, and then a lot. Now those are linked, so I guess it's no surprise, but still nice to notice (I hadn't before seeing it here). And for some reason, the lights in the instrument panel kept dimming as well, as if there's something pulling a lot of juice somewhere. I don't get it.

STR
May 12, 2006

I thought I was a nice jester


When the RPMs get that low, the alternator stops charging. Normal running voltage of a car is 13.8 to 14.5 volts. A fully charged battery is 12.9 volts - and it won't be fully charged immediately after starting the car. That voltage difference is why the lights are dimming.

That's a really weird issue. I'd love to blame the fuel pump, but I'm out of my element on this.

PainterofCrap
Oct 17, 2002

Hey bebe





Seconding STR on the oil pressure & voltage; theyíre symptoms of very low idle.

Sounds like a vacuum leak of some kind...bad/leaking EGR, or some other component that switches at temp to open an air path to the intake manifold. Either the component, or a hose.

Do you have functioning A/C? Is there a fast-idle solenoid attached to the throttle via a cable or linkage? Itís a stretch...

Pursesnatcher
Oct 23, 2016



Grimey Drawer

All right, yeah! I was twisting my brain trying to think of something pulling too much power and causing the fuel pump to stop pumping, but this is a much better explanation. I sort of expected oil pressure to just be a symptom of low idle as well Ė my owners manual warns of it dropping unexpectedly, but I've assumed that's only an issue if engine RPM's are high (or even normal) if that should happen. I mean it drops to 2 just on regular slow idle, so.

I've got to do some research into what an EGR is and does, but vacuum leaks wouldn't surprise me. The rubber in this thing is, as someone said real early on, pretty much just junk. And there's so drat much of it, too, but I'm working my way through replacing it all.

There's no functioning A/C at the moment, since I unhooked the compressor belt and clipped off the condenser... but as for that last part about solenoids, I've, uh, got no idea what any of that means. How would I go about looking for it?

Anyway, I take it my hypothesis about a clogged fuel filter was a bit optimistic?

angryrobots
Mar 31, 2005



Oven Wrangler

A fuel restriction bad enough to affect idle would almost certainly prevent the engine from reaching higher RPMs, and it's actually running pretty well if you keep the throttle open, yeah?

In the video it seems like it's running so rich with the throttle closed that it's flooding the plugs. How does this engine management system handle idle control? Is there an IACV that could be clogged or stuck?

Pursesnatcher
Oct 23, 2016



Grimey Drawer

angryrobots posted:

Is there an IACV that could be clogged or stuck?

There is! Funny you should mention it; I've been looking into what an EGR does, and going through youtube on what issues a bad one might yield, and IACV issues keep popping up as suggested videos next to them. The engine is running great with wide open throttle, but once I let off, it dies. But it also seems to be mostly fine when it's cold Ė problems only really manifest on a warmed-up engine. All of this seem to be indicative of either one of those things.

Now my IACV has two short hoses running out of it, with a thin vacuum line between them. I've got new hoses ready, and as soon I get the new vacuum line, I'll get in there and pry it all out. Hopefully I can just clean the old one with some contact spray, then put it back together with new rubber all around. Since I want to replace as much rubber as possible anyway I'll do that first, and then move on to the EGR if it doesn't help. Really hope I don't need a new IACV though; that's a nearly $700 outlay which I really can't afford right now. Fingers crossed!

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Quick update; tubes have arrived, so time to get that IACV sorted.



This is the thing. Easy enough to get out, just have to unplug this plug right here:



Then unscrew the nut holding the retaining bracket in place, and wiggle it free. The wiggling was actually the most difficult bit, because the old tubes are stuck firmly to the engine. They're also hard as steel, so they flat out refused to bend.



Additionally, there didn't seem to be much of a seal of any kind between the IACV and these things, so I'm happy to get them replaced.



The IACV itself doesn't look too bad, I guess, at least from this angle. There does appear to be some dirt inside the other hole, though:



So yeah. I'm thinking I'll just fill this thing up with Coleman fuel, leave it for a couple of hours, and then... flush it out with more Coleman fuel.

But of course there's more.



My passenger side footwell was just soaked with water, which I have no idea how got in. This is after just a few days of heavy rain, and everything was firmly shut and sealed. People say the mounting holes for the windshield wipers are a weak spot, so I guess I'll just have to take a long hard look there.

Bah. Well, nobody said it was going to be easy!

Raluek
Nov 3, 2006

WUT.


Pursesnatcher posted:

But of course there's more.



My passenger side footwell was just soaked with water, which I have no idea how got in. This is after just a few days of heavy rain, and everything was firmly shut and sealed. People say the mounting holes for the windshield wipers are a weak spot, so I guess I'll just have to take a long hard look there.

Bah. Well, nobody said it was going to be easy!

Do you have a sunroof?

Pursesnatcher
Oct 23, 2016



Grimey Drawer

That I do, but it's nice and tight. Plus, the water is concentrated along the doors on the passenger side, and nowhere else. I've got a feeling there's a small, rusted hole in the firewall, but I'll just put a tarp over the car when it rains for now. I can't really prioritize anything outside the engine at this point.

As for the engine, I broke out the old digital caliper and had a go. The old seriously-rock-hard tubes (they sound like they're made of plastic when you clack them together) have really shrunk over these past 26 years, it turns out. One of them mounts to where the IACV measures 22.00 mm, and the new tube is 20.61 mm wide where they mate (but flexible). The old one is 22.04 mm in the same hole. For the other tube, those figures are 19.00 mm at the IACV, a 17.55 mm wide new hole, and a 18.47 mm wide old hole. That's a roughly 5 percent expansion over time, while the overall length of the tubes has decreased with about the same percentage.

Then there's the tiny hole which connects the two tubes with a 6 mm plastic vacuum line (which is weird as poo poo in itself, but I'll get to that). The new tubes have 4.94 and 5.12 mm holes for this, versus 5.91 and 6.16 mm ones, respectively. That's an expansion of some 20 percent. All in all, yeah, I think I have vacuum leaks.

Not much dirt in the IACV itself, by the way Ė apart from the first flush, the Coleman fuel came out pretty clear every time. Letting it dry properly until tomorrow, before lubing the new tubes up with silicone grease, and see if things will perhaps improve just a bit.

Oh yeah and that plastic vacuum line? It looks like this:



...what?

It's hollow on one end, and then just terminates in a flat, sealed... nothing?

Raluek
Nov 3, 2006

WUT.


Pursesnatcher posted:

That I do, but it's nice and tight. Plus, the water is concentrated along the doors on the passenger side, and nowhere else. I've got a feeling there's a small, rusted hole in the firewall, but I'll just put a tarp over the car when it rains for now.

There are probably drain tubes for the sunroof that go somewhere, and if they get blocked the water gets where it's not supposed to. Might run along where you're seeing water. Cleaning them out so they drain properly might be worth looking into, as a potentially free fix.

I guess that thing is just a plug for an unused port or something, but IDK why it's such a large thing to accomplish that. Why even have the vacuum line.

meltie
Nov 9, 2003

Not a sodding fridge.

Raluek posted:

There are probably drain tubes for the sunroof that go somewhere, and if they get blocked the water gets where it's not supposed to. Might run along where you're seeing water. Cleaning them out so they drain properly might be worth looking into, as a potentially free fix.

I guess that thing is just a plug for an unused port or something, but IDK why it's such a large thing to accomplish that. Why even have the vacuum line.

Yes, it'll be blocked sunroof drain tubes. You need to clean them out.

I used a cheap wire from inside a bicycle brake cable to poke them clean, until the cable came out the other side.

Although if they're completely and utterly blocked solid then you might end up pushing so hard that you disconnect the internal pipes, and that is very much not fun to reattach.

If it's not the sunroof then there may be "body drains" that you need to clean too. In my W201's case, there were two behind the engine, under the bottom edge of the windscreen. They too were blocked with leaf debris, and were making standing water pool up in the engine bay before it overflowed into the cabin.

If you don't clean them, it'll all rust through quickly and be hell to weld up again!

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Oh, those are solid tips. I just assumped the sunroof is sealed all around, but maybe not? This is the problem with having a very tall car, I guess. There's a stupendous amount of birch seeds floating around absolutely everywhere these days, so that might well have gotten in and clogged stuff up. Will check it out! My engine bay drainage is nice and open though, I did check that out already.

meltie
Nov 9, 2003

Not a sodding fridge.

Pursesnatcher posted:

Oh, those are solid tips. I just assumped the sunroof is sealed all around, but maybe not? This is the problem with having a very tall car, I guess. There's a stupendous amount of birch seeds floating around absolutely everywhere these days, so that might well have gotten in and clogged stuff up. Will check it out! My engine bay drainage is nice and open though, I did check that out already.

Ahhh yeah, because nothing ever seals properly on a car, everything has drains. The sunroof will have a gutter on each side, that goes back to a PVC drain tube, that goes down inside the roof pillars to the ground. Check a generic G-wagen manual, there should be a diagram in there somewhere. There will be 2 or 4 🙂

meltie fucked around with this message at 17:11 on Aug 25, 2019

PainterofCrap
Oct 17, 2002

Hey bebe





Pursesnatcher posted:

Oh, those are solid tips. I just assumped the sunroof is sealed all around, but maybe not? This is the problem with having a very tall car, I guess.

Itís at least a Mercedes thing; I had an e320 sedan that did this. That, and the special sunroof unicorn lube

meltie
Nov 9, 2003

Not a sodding fridge.

PainterofCrap posted:

Itís at least a Mercedes thing; I had an e320 sedan that did this. That, and the special sunroof unicorn lube

Oh, god, yeah. I think I ended up using some bike grease that had a very high teflon content or something. It held up for a year anyway.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

All right, thanks! Just looking in there it doesn't seem clogged, but I'll definitely need some kind of wire to poke around with. Very tight spaces! But with a 48-hour rain storm coming this way, I decided to go for a more surefire way of preventing more leaks, at least until I can get around to proper troubleshooting.



Poncho car!

So anyway, I did get around to fixing up my IACV this weekend.



That white plastic nipple was an absolute nightmare to dislodge from the old, petrified tube, but with a knife, willpower and just a few minor injuries, I got it transplanted. Blood, sweat and tears always does the trick. I couldn't find my silicone grease anywhere, though, so I went with PTFE grease for lubrication and sealing all around. It's ultra-non-reactive with everything, and can handle temperatures fairly well, so I supposed it's better than nothing.



Voilŗ! Since the strange, one-side-blinded vacuum line was... well, strange and blinded on one side, I had to reuse that instead of installing the new line I got. Should be good though; that's plastic, so it's kept its general shape and dimensions over the years.



I also located my EGR. No way of testing it without taking it off the car, so for now I just pushed the (suspiciously loose-fitting) rubber sleeve tighter onto the nipple on the back of it. I then stuck my camera down to get a look inside it.



Looks dramatic, but from what I understand, these things usually do? Anyway, I'm going to have to take it off and test it.

I did get a perfect 2 mile test run after putting the IACV back in, but not immediately. I let it idle for 12 minutes first, to get it up to operating temps. Had a couple of minor glitches in that time (I videotaped the whole thing; thinking I'll shorten the video to show only glitches when I have time), but nothing major. Then I put it in reverse, and it immediately started stalling on me while still standing still... whereupon I shut it off, started it again, and all my troubles were gone. So there's something up.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Alright, here's the video:

https://www.youtube.com/watch?v=5bem279KHHk

So that's immediately after starting the engine, right after I put the IACV back in. Stumbles properly in the beginning, but gets back up again by itself. It seemed mostly okay? I'm very curious as to what might be causing the odd variations in idle speed about a minute into this clip, though.

STR
May 12, 2006

I thought I was a nice jester


Wait.

It has a ~700-800 RPM idle while stone cold? That seems really low for anything that's not drive by wire.

Which one of you knows what the cold idle circuit is like with whatever version of Jetronic this has?

Charles
May 9, 2004

zoom-zoom


Toilet Rascal

Yeah DBW or not cold start should be over 1000 I'd guess. I don't have much V8 experience but shouldn't it be the same as a 4-banger? (my Mazda's been doing the same thing so I might learn something here too). Also that dip at 1 minute in looked more like something electronic?

STR
May 12, 2006

I thought I was a nice jester


FWIW my DBW car doesn't idle above 1k unless it's below freezing out - at which point it gets slightly above 1k (maybe 1100). That's an 06 GM. When the engine coolant temp sensor got unplugged, it would idle at ~1250 and the PCM was reporting arctic temps (far below 0F).

GF's 05 Toyota, which is also a 4 cylinder DBW, idles at ~2k when cold, up to 2500 in winter, but drops quickly to ~750 (over a couple of minutes).

But I've never seen a non-DBW car idle below 2k when cold. And agreed that the dips are something hiccuping in the fuel injection, but that could also be caused by the PCM not expecting it to be idling so low with a cold engine... maybe? I know most traditional setups used a FITV, but I know Bosch is its own special breed.

STR fucked around with this message at 03:59 on Aug 29, 2019

meltie
Nov 9, 2003

Not a sodding fridge.

Pursesnatcher posted:

Alright, here's the video:

https://www.youtube.com/watch?v=5bem279KHHk

So that's immediately after starting the engine, right after I put the IACV back in. Stumbles properly in the beginning, but gets back up again by itself. It seemed mostly okay? I'm very curious as to what might be causing the odd variations in idle speed about a minute into this clip, though.

That's a low idle from cold, it should be about twice that. (edit: wrong, see zundfolge below)

My gut feel is that the random glitching is misfires and is probably to do with ignition.

I'd refer you to Kent Bergma at Mercedessource; he's got lots of videos and guides for keeping mercs of our vintage going: https://www.youtube.com/user/Merced...edessource+idle

His main site is: https://mercedessource.com

meltie fucked around with this message at 18:48 on Aug 29, 2019

zundfolge
Apr 11, 2007


None of the various Jetronic cars Iíve worked on have had any facility for a higher idle when the engine is cold. They deal with cold starts by running a dedicated cold start injector that enriches the mixture until the engine starts to warm up. In cars with the more basic versions of CIS/K-jet, once the cold start injector cuts off thereís another component called the warmup regulator that takes over - it controls a fuel pressure circuit that allows it to gradually lean out the mixture as the engine warms up. I found this explanation of the components and behaviors of KE-Jetronic, which the OPís truck has - it has a few electronic wrinkles that Iím not familiar with. Hopefully this is of some assistance with troubleshooting.

https://www.benzworld.org/threads/b...erview.1553096/

meltie
Nov 9, 2003

Not a sodding fridge.

zundfolge posted:

None of the various Jetronic cars Iíve worked on have had any facility for a higher idle when the engine is cold. They deal with cold starts by running a dedicated cold start injector that enriches the mixture until the engine starts to warm up

Huh, that explains a lot 🤦‍♀️

charliemonster42
Sep 14, 2005
VW: Ze Official Kar Ov Ze Sird Reich

zundfolge posted:

None of the various Jetronic cars Iíve worked on have had any facility for a higher idle when the engine is cold. They deal with cold starts by running a dedicated cold start injector that enriches the mixture until the engine starts to warm up. In cars with the more basic versions of CIS/K-jet, once the cold start injector cuts off thereís another component called the warmup regulator that takes over - it controls a fuel pressure circuit that allows it to gradually lean out the mixture as the engine warms up. I found this explanation of the components and behaviors of KE-Jetronic, which the OPís truck has - it has a few electronic wrinkles that Iím not familiar with. Hopefully this is of some assistance with troubleshooting.

https://www.benzworld.org/threads/b...erview.1553096/

My rabbit GTI did. It had a small thermocouple actuated valve that bypassed the throttle. Whether or not it actually did anything, Iím not sure. It definitely didnít get over 1,000rpm when cold, though. Only ever ran at normal idle speed. Sometimes you need the extra air just to keep it running when cold, at least thatís how my megasquirted e30 is. It didnít go over 800rpm cold on the stock ecu, though.

Edit: it looked like this:

https://www.ebay.com/itm/VW-Auxilia...9YAAOSwnWpcCvce

charliemonster42 fucked around with this message at 01:10 on Aug 30, 2019

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Pursesnatcher
Oct 23, 2016



Grimey Drawer

Yeah, I don't think it's too low either Ė if anything, the warmed-up or post-throttle idle strikes me as a bit high. My daily (a 2003 1.8 liter M271 engine) goes straight to 1400 when cold, drops to 1200 within a couple of seconds, and once warmed up stabilizes at 850. I've always figured that something with more and bigger cylinders would always idle slower than that little four-pot.

Since we're looking at cold idling though, I went out and recorded those few seconds missing from the start of the previous video. This is just a non-gas-pedal-assisted ignition (starts a bit slow again these days), and the eight seconds or so before RPM's stabilize at the level shown before.

https://www.youtube.com/watch?v=4Z1cexeRiKw

I've always thought that seemed pretty normal? Except for the hard start, anyway.

meltie posted:

I'd refer you to Kent Bergma at Mercedessource; he's got lots of videos and guides for keeping mercs of our vintage going: https://www.youtube.com/user/Merced...edessource+idle

His main site is: https://mercedessource.com

Yeah, he's a great guy Ė I've been coming across a bunch of his videos, but never actually stopped to look at the full breadth of what he's covered. Hope there aren't any more ignition problems though, the only things not replaced there yet are the coil and most of the wires. And the actual distributor itself, if that counts, but that's apparently an unobtainium AMG part (since I was told timing adjustment is impossible on these AMG variants).

But! After looking at the picture I took from below my EGR valve, I realized I might be able to jam some fingers in there Ė and I was right! I was able to push the valve up a little bit using my pinkies, and then covered the hole for the vacuum tube with a finger. It did drop a millimeter or three before stopping, but as it sucked my skin in a fair bit in doing so, I'd say that thing holds vacuum very well. I also cautiously sprayed some starter spray around it with the engine running, with no obvious RPM change. Then again, unplugging the vacuum line and spraying some directly towards the opening didn't do much either, so... Į\_(ツ)_/Į

Rain storm has passed, too. It's kind of hard to explain how bad it was, so I just did this:



That's the surface of my road, after these rains. In the middle of it is the key to my daily, placed directly underneath that twig. It is that deep, and it is that wide. It's also running most of the length of the road, and further down there are more running in parallell. QED, moving water will carve the living poo poo out of pretty much anything. But my car poncho worked, as there was no new moisture inside the car!

The best news came in the mail, however.



A benefactor from this thread sent me what feels like it may perhaps be the greatest care package in the history of mankind, and I am forever grateful. You can remain anonymous if you want, but as I told you, this made my month. I've just been skimming through it for a little while, but this might just be the most amazing, comprehensive and understandable guide to these fuel systems there is. It covers everything I could think of, and with the added power of Google, I can pretty easily figure out what all the new and exciting things it talks about are. Morale has been running a bit low lately, but this really gave me a new hope. Now, to reading!

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