Intermittent stalling, idling/driving: possible ECU problem?

[Bartek]

Hello to all.
First of all - leggy '92, turbo, vos chip
Second: movie http://www.youtube.com/watch?v=LJNDVDKx ... 93tiuwGOmX_

Problem - intermittent stalling while driving/idling, engine hot or cold. Restart possible sometimes after 1 minute, sometimes 15, sometimes it takes half a day. IMPORTANT - stalling connected with complete lack of CEL with ignition on.

For a few months got CEL from TPS, which could be visible in the end of the movie. It dissapears after pushing accelerator slightly. At idling it comes back.

Replaced main relay (brown). Perhaps someone has any thoughts? In this case (movie) car was hot, after 40 minutes of idling.
Can't say what all those clicking tell me about culrpit. Shot ECU or bad ground?

[Bartek]

All right. One idea that came to me.

So far only one thing gave me symptoms similar to this mysterious stalling. There's quite a big plug (one out of two)almost under battery - close to windshield washer tank. After unplugging it check engine was gone, but oil and alt were still there. I think I have to follow this part of harness. I think this is - beyond other things - direct power to ECU. Maybe now someone could help me?

[jefferson]

I would look at your fuel pump first. Check out the car randomly dies thread.
Jeff

[Bartek]

No. It's not this. It's not like one element of injection system fails. It's like there is no present ECU at all. NO CEL means it disappear and it's gone - even if you turn ignition on and off. Then, after some time, it's back again.

[BSOD2600]

What are all the stored CELs? http://legacycentral.org/library/literature/codes.htm clear them and then see what comes back.

Stalling while driving/accelerating sounds like possible MAF and/or air leak post-MAF -- assuming the car is stock.

Whats a VOS chip? link?

[Bartek]

OK. One by one. Vos chip is a chip with new ignition map etc, that is put INSIDE the ECU. There's a empty spare socket and you put it there cutting one resistor - for ECU to know what to read from. I didn't hear anyone complaints about it, so I suppose it's not this.

CEL gives me wrong TPS voltage, but CEL goes off whena I put my foot on the accelerator. I tried to adjust it but it was almost impossible. I honestly doubt it has anything to do with ECU shutting off.

Next thing - I ruled out fuel/air system. For now. Why? Imagine you have voltage to your ECU with a switch. And when you drive your car you turn the switch off. Just cut power to ECU while driving. RPM and speedometer goes off, oil and alt light are on and car stops driving. ECU is off, engine is off. No spark, no fuel, nothing - because of ECU.

When I was unplugging various plugs, there was only one that gave me that specific effect - no CEL, but oil and alt. It was E1 (pic)



Then I went through schematics and it appeared E1 gives earth to 6 pins in ECU : A11, B14, B15, B22, B24 and B25:



Now I just need to find GE ground point (anyone knows where exactly?) and check 4 wires going from E1 plug to ground. Let someone tell me I'm thinking right pleaseee...

[Bartek]

I'm keeping my fingers crossed. It could be my problem is fixed. Don't know why but I suppose my gremlins have been coming from bad battery. I'm not sure about it but after 1 hour test drive car didn't stall even once. My mech told my there was some smell of sulphur-sometingh from the battery which might pointed to dead short cell but I didn't see a connection between stalling and dead battery. Still don't see but for now it works.
Lesson learned - always check your battery first. Or second - just after alt.
We'll see how things are in next few days.

[Legacy777]

Just an FYI, you can adjust the TPS using this procedure:

http://www.main.experiencetherave.com/s ... sting3.jpg

I know it sounds like the problem is fixed, but the symptoms you mention sound possibly like a MAF sensor.

The engine ground is on the back of the intake manifold on the driver's side.

[Bartek]

Everybody who has classic leggy uses your stuff, Josh .
Few days ago I've found thickness gauge in my toolbox and until now I couldn't remember what for I needed it.

Yup, I've tried. I couldn't get desired voltage at idling. No matter how hard I've tried. Now, when car is not so unreliable as it used to be I'll take another shot. Full throttle voltage is ok, moreover - I've got no problem with car idling. Just CEL lit.

[Bartek]

Wait Josh...I just noticed you mentioned MAF.

Is it possible for MAF to interfere with ECU in a way, that switches ECU off?
I can see this particular ground point, but I can't reach it without a special tool.
Tried to dismount chargecooler but also I failed

[Legacy777]

The MAF won't necessarily switch the ECU, but it can make the engine die. I had an intermittant issue a couple years back where I would lose all power when cruising. Most of the time if I put it in neutral and revved the engine I could bring it back. Other times if the rpm was low the car would just die. Turned out to be a MAF sensor that was causing the problem.

[Bartek]

You're right, but I guess - not with my symptoms. Disappearing CEL, dying speedo and rpms - even with car still rolling. This is not just losing power - this is complete death of ECU. If I am smart enaough to clarify it

[Legacy777]

The speedometer is not driven by the ECU, it's mechanical. I honestly don't know how you would see a dying speedo on with a mechanically driven setup unless the speedo driven gear/cable locked up.

I took a gauge cluster apart (need to get the pictures up) to see about converting to an electronic speedo setup. The existing setup is 100% mechanical.

[Bartek]

You sure? I guess I've got electronic speedo. Anyway that is what's written there. Got no cable behind - only 3 plugs: 2 on the sides, and one smallest in the center.

[Legacy777]

Can you take some pictures? I'd like to see what you're talking about. It's possible the cable is just not plugged in.

The mechanical speedo outputs an electrical signal to the ECU. These are pictures of the combination meter torn down.

http://www.main.experiencetherave.com/s ... combmeter/

[Bartek]

Of course. Need to dismount it first. But even now I can say at photo #3 you've got a round hole for cable. And I cannot say right now if I have this hole - don't remember. But I'm 100% sure there's nothing that goes into that hole. like I said - just three plugs - left, right and upper center. No cable and speedo runs, so it means this particular speedo doesn't need a cable...or am I wrong?

Of course it could mean I haven't understood you well because I know speedo inside is mechanical thing. I'm just saying there is no mechanical way of transferring speed into gauges.

[Legacy777]

I'm assuming your speedo works correct?

Is this a US or non-US based Legacy? If you have an electronic driven speedo I would be very interested in trying to get one of those combination meters/speedos.

Thanks

[Bartek]

Checked visually from outside. Definitely 'electronic' written on device.
I assume it's non-us, came from Italy to me.
Josh, don't understand last sentence - what should I do for you?

[Bartek]

Yes - speedo works correct

[Legacy777]

Checked visually from outside. Definitely 'electronic' written on device.
I assume it's non-us, came from Italy to me.
Josh, don't understand last sentence - what should I do for you?

I was just kind of rambling to myself. I would like to convert my mechanical speedo to electronic so if I can find an electronic combination meter that would make things much easier. If you had a spare, that'd be great, but I can try finding one.

Thanks

[Legacy777]

Ok....well back to your issue at hand, when the problem occurs it does sound like the ECU is cutting out. This points to either a problem with the ECU or a problem with its power supply. I would start with the power supply to the ECU since that's easier to test. If you take out the ECU, I'd look at the solder connections in the ECU to see if there are any cracks. Maybe there's an issue like this: http://bbs.legacycentral.org/viewtopic.php?f=10&t=1142

[Legacy777]

Any chance you could take some pictures of your combination meter for me? I'm curious if it's the same as the US. Also, I'm assuming your speedometer is in km/hr correct?

[Bartek]

Sure, Josh. I'm sorry fo my silence. I've been out of my town for 2 last days. I promise I'll try my best to rip off combination meter over the weekend and take some shots for you. Speedo is km/h and no spare sorry about that.

Now I'm unpacking and go to sleep. I'm almost unconcious so I definitely check your link out when my brain is working at least a little.

[Legacy777]

No worries....whenever you get time.

[Bartek]

Josh, I am so sorry it took so long . If you need some more specific pix pls let me know.
Once again I'm sorry