3.2 Chugging/Stalling

[Wish76]

Hi all -
My '85, once it warms up, will start to lose power (see video). Initially, it's just split-second blips, but will progress into longer power losses and sometimes stalls (sometimes unrecoverable stalls until it cools down).

This problem started last March; mechanic worked on it for two weeks, then had to stop as it was shipping with me from US to Portugal. The car shipped and sat until October, when my shop over here was able to work on it. Finally got the car in January (delays on registration). Drove fine for a while, but started chugging again two weeks ago. Shop thought it was the DME and is sending it out for repair. Lent me another DME so I can drive while waiting; same problem started once the car warmed up - returned it to the shop.

Here's what's been done to date:

US:
- ECU: Tested good
- Idle Speed stabilizer: replaced
- Air flow meter: Tested good
- Crankshaft Position Sensor: replaced
- Idle Air Control Solenoid: replaced
- DME Relay: Tested good
- DEM Connection points: Tested good
- Ground points: Tested good

Portugal:
- Ignition Coil: Tested good
- Rotor: Replaced
- Spark Plug Wires: Replaced
The MAF was originally believed to be the issue: Cleaned

Videos:
https://youtu.be/2wg_YYvyOMM
https://youtu.be/69YW7eJzGuA

Appreciate any thoughts. Thanks!

[Poopwink]

I just dealt with a very similar issue on my '85. The issue seemed to present itself once I got the engine up to operating temp. I'd start to lose power, the idle would drop, and it would take some effort to keep it from cutting out. My mechanic was able to blip the throttle through it and then it would be fine for the remainder of the drive; the first time it happened to me it was very difficult to restart the car because the idle was so low and applying throttle seemed to kill the engine.

The mechanic's suspicion was that it was one of the three sensors on the left of the engine (temperature, cylinder head temperature, and top dead center reference if I'm not mistaken). Oddly enough, everything tested within spec when he took a multimeter to it. In the end, we replaced the temperature sensor and I haven't been able to replicate the issue since. I hope this helps and that your fix is a quick one!

[proporsche]

i see your alt. light is flickering when the miss has happened....
Ivan

[pmax]

Yeah, I would check for loose wiring and the voltage regulator. Stick a voltmeter on the cigarette lighter and see if the voltage's fluctuating.
Battery could be kaput as a result. Any funny smells from the battery ?

[Wish76]

Originally Posted by pmax

Yeah, I would check for loose wiring and the voltage regulator. Stick a voltmeter on the cigarette lighter and see if the voltage's fluctuating.
Battery could be kaput as a result. Any funny smells from the battery ?

Proporsche and Pmax - yes, the battery light came on as it was just about to stall; doesn't usually occur. Battery is brand new and alternator was replaced a few years ago (not saying that either still can't be the problem). Will stick the cigarette voltmeter in next time I get the car back.

[Wish76]

Originally Posted by Poopwink

I just dealt with a very similar issue on my '85. The issue seemed to present itself once I got the engine up to operating temp. I'd start to lose power, the idle would drop, and it would take some effort to keep it from cutting out. My mechanic was able to blip the throttle through it and then it would be fine for the remainder of the drive; the first time it happened to me it was very difficult to restart the car because the idle was so low and applying throttle seemed to kill the engine.

The mechanic's suspicion was that it was one of the three sensors on the left of the engine (temperature, cylinder head temperature, and top dead center reference if I'm not mistaken). Oddly enough, everything tested within spec when he took a multimeter to it. In the end, we replaced the temperature sensor and I haven't been able to replicate the issue since. I hope this helps and that your fix is a quick one!

I believe the temperature sensor has been looked at too, but will suggest that either way. Thanks!

What sucks is I've had some extremely competent Porsche mechanics on this and nothing yet...

[Wish76]

End result: The shop swapped out the ignition coil from another 3.2 and it ran fine; thought that was the problem until they put the original coil back and it ran fine with that. Only thought was maybe the connection was bad, and unscrewing/screwing was enough to clean the contact and resolve the issue.

None of us are 100% on that answer, but it's running strong for now...

[pmax]

Congrats.

Thanks for updating.

[Wish76]

Well... problem NOT solved! Took the car overnight about 3 hours South - ran great. Next day - about 45 minutes into the drive heading home - same issue. Started loosing power for a second or two, then 5 to 10 seconds, then eventually died. Wasn't able to restart it immediately; restarted after cooling down. Had it towed back to my shop.

BTW - we noticed a burning smell when it died, but weren't able to identify it.

It's gotten worst at the shop. The engine no longer needs to be warmed up for the problem to occur again. The car runs fine at idle, but starts to choke when the throttle is pressed. If they lay off before it dies, it will return back to idle. My shop doesn't have an easy answer... they are solid classic Porsche specialists and haven't seen this before.

Next step is to start best-guess replacing parts, which is not going to be cheap, otherwise I'm left with a Porsche paperweight.

[FA-18C]

Curious if you have checked your fuel pump?

[mikedsilva]

A friend had a car with slightly similar issues... we thought it was the dme relay...
But it turned out to be the fuse for the fuel pump... the connections had corroded partially reducing the power flowing through...
Rotating the fuse to "clean" the connections got the car running again. After cleaning all fuse terminals, it's run fine since.

Who knows.. maybe something similar for you?

[Wish76]

Originally Posted by FA-18C

Curious if you have checked your fuel pump?

The shop is pretty positive that the fuel pump is not the issue. I actually have one arriving Monday; a pre-problem order I placed as spare parts for an upcoming rally.

[Wish76]

Originally Posted by mikedsilva

A friend had a car with slightly similar issues... we thought it was the dme relay...
But it turned out to be the fuse for the fuel pump... the connections had corroded partially reducing the power flowing through...
Rotating the fuse to "clean" the connections got the car running again. After cleaning all fuse terminals, it's run fine since.

Who knows.. maybe something similar for you?

Appreciate the suggestion.

The fuse panel was replaced with an Adapt Motorsport mini-blade fuse panel. It has LED indicators for fuse status; green is good, red is bad. All showing green.

[proporsche]

how about fuel press.regulators? have you look at them?
ivan

[Wish76]

Originally Posted by proporsche

how about fuel press.regulators? have you look at them?
ivan

Thanks - will ask the shop tomorrow.

[brianlay]

I would find another shop that knows how to troubleshoot

[Wish76]

Originally Posted by brianlay

I would find another shop that knows how to troubleshoot

I'm asking as I'm still learning on this car; how should they be troubleshooting differently?

Thanks!

[Mixed76]

Looks like you're mostly looking at controls and electrical, have you changed the fuel filter(s), checked fuel pump/ wiring/ fuse, looked in the fuel tank?

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[Wish76]

Originally Posted by Mixed76

Looks like you're mostly looking at controls and electrical, have you changed the fuel filter(s), checked fuel pump/ wiring/ fuse, looked in the fuel tank?

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Yes on fuel filter, fuel pump, wiring, and fuse. Not sure if the shop looked at the tank - will ask. It's been through a lot of fuel since the problem first started (understanding that doesn't necessarily make a difference).

I hate to be the guy that suggests things to a shop that works on 60's to 80's Porsches every single day, but at the end of the day it's my money.

[proporsche]

Originally Posted by Wish76

Yes on fuel filter, fuel pump, wiring, and fuse. Not sure if the shop looked at the tank - will ask. It's been through a lot of fuel since the problem first started (understanding that doesn't necessarily make a difference).

I hate to be the guy that suggests things to a shop that works on 60's to 80's Porsches every single day, but at the end of the day it's my money.

Just ask the shop to test the f.press.regulators....do not start replacing parts until you know what is the problem....
Ivan

once you know if that is the problem, ..ask Tony-boyt911 here he just went through this ,last year ,i think and he got the reg for MBZ for much less money since the 911 is 420 euros...