At Wit's End w/ Dad's 3.2

[wholio94112]

Hello gentlemen,
Never thought I could say this, but right about now, I love my CIS-equipped 1986 930!
I have my dad's 1988 Carrera 3.2, all stock, trying to figure out a peculiar issue that has, in hindsight, been a potential progression to its current state:
1. Couple months ago, on freeway, just exceeding 80 mph, there was a studder, rpms fell towards zero, engine just died. Popped the clutch while coasting, engine fired up, kept on as if nothing happened. I stayed under 80, and came to forget about the event.
2. Since, car runs like a dream - until it reaches temp, that is. When temp is reached, engine will sputter if cruising, and die while coming to a stop with clutch in - rpm's drop like a rock.
Here's what I've done thus far.
Replaced DME relay under seat.
Replaced o2 sensor, both position sensors, CHT sensor, plugs, cap, rotor.
I've played musical red relays up front, rotating them around into different positions.
Per Bentley, tested most of the accessible sensors for Voltage, Continuity, etc.
Now, I'm guessing there's something just precariously loose in its fitment, and the slightest bump jars it out of its seating and pffft!!!

Thanks for your time guys. It sure would be nice to get this thing going for dad again.

[MrBonus]

It sounds like it could be a bad ground somewhere?

I had that issue on my old 2012 Mustang. It would hit a bump and the entire vehicle would die then fire back up. Turns out one of the grounds was not hooked up from the factory.

[pmax]

I would replace the CPS sensors. They are almost a maintenance item.

[wholio94112]

If by CPS sensors, you mean the 2 neighborly sensors down behind the left rear wheel by the CHT sensor, then those have been done...The fuel filter was replaced as well, just forgot to mention earlier...

[RLJett]

Originally Posted by pmax

I would replace the CPS sensors. They are almost a maintenance item.

Sounds like he did that already, as well as the CHT and O2 sensors.

If only happens once warmed up, what about a vacuum leak? The CHT would create a rich condition at cold startup which could mask it. Then, once operating temps are reached, the DME will lean the mixture out, which if there is a vacuum leak, then you'll be too lean?

I had a problem similar to yours, but mine ended up being deteriorated ref sensors. But you said you've replaced those.

[Tippy]

I feel your pain. 6 months of hell on my 3.2 never figuring out why mine cut out, backfired, and stuttered at random times and random RPM's. Nothing was repeatable except the cutting out itself.

Ripped all the DME parts out and went MegaSquirt.

You can read my misfortunes to make you feel better under the search phrase as "pushing my Carrera 3.2 off a cliff", or something to that effect.

GL!

[wholio94112]

I have read that, Tippy, through the times of confusion...I am unfamiliar with the 3.2 Motronics - it seems so hi-tech compared to CIS!
Any particular areas for common vacuum leaks?
I do have a couple concerns but need to post pics for ya'll. That way I don't need to get to wordy...
Be right back.

[Pedro '84 Coupe]

Have the spark plug wires been replaced? What brand DME relay did you use?

[pmax]

Originally Posted by wholio94112

I have read that, Tippy, through the times of confusion...I am unfamiliar with the 3.2 Motronics - it seems so hi-tech compared to CIS!
Any particular areas for common vacuum leaks?

OK, CPS already done.

It sounds electrical.

Agree with checking the ground straps. Also, check every connection in the harness. Clean them out with contact cleaner.
Swap in a known working ECU.

[brighton911]

It sounds like you have addressed many of the usual suspects with no change. My money is the DME itself, perhaps a component on the way out or a solder joint that opens when warmed up. Any chance you have a buddy that you can play swap the DME game? Otherwise there are some fine people on the forum that can inspect and repair your DME. ischmitz is the user name (on this forum) of one that has a good reputation.

[Flat6pac]

Check the ground for tight on the #1 intake runner.
Bruce

[Fairview]

I concur with max, sounds electrical. If it shuts off suddenly at speed after getting warmed up, then starts up from cold like nothing happened, could be the ignition coil. That happened to us in our VW Westfalia last fall, but we had a good place to sit along the interstate while it cooled back down!

[4flyboy]

Years ago my 2.7 Carrera displayed the same symptoms on a weekend trip to Las Vegas.

Friday afternoon at 4:40pm it gave up the ghost and I coasted into an independent VW mechanics shop in Baker.

I was desperate, the old mechanic listened intently for 10 seconds and disappeared to the field out behind the shop, pulled the coil wire off a Bug. He plugged it into my coil and distributor cap.

Saved me a weekend in Baker California, an expensive tow and hundreds in diagnostics......wouldn't let me pay for the old coil wire.

Hope it's this simple, Scott

[RSTarga]

Sounds like coil issues to me too

[pmax]

Originally Posted by Tippy

I feel your pain. 6 months of hell on my 3.2 never figuring out why mine cut out, backfired, and stuttered at random times and random RPM's. Nothing was repeatable except the cutting out itself.

Ripped all the DME parts out and went MegaSquirt.

You can read my misfortunes to make you feel better under the search phrase as "pushing my Carrera 3.2 off a cliff", or something to that effect.

GL!

OK, I'll bite. Browsing thru your thread(s), I stopped after reading this ...

"w/turbo (T60-1) 447whp"

Might wanna mention that little detail in your next rant.

[techman1]

I recall a past issue with the DME itself getting hot and needing work. Any local pcar friends able to loan you their DME to test?

[wholio94112]

I'll try anything...All suggestions are considered...Except posting pics...I've failed 5 times now, each time losing everything I typed up...
So, w/o pics, does anyone know the vacuum line coming off the oil related unit above the oil filter?
Where does it go, or does it float around?
Another new development - In removing the air filter half-housing to replace air filter, I noticed the rear bottom clips - the PITA one - isn't able to clamp that corner down as tightly as designed. Could this be the culprit? It looks as though I will have to replace the removeable half, as the plastic tab has busted off. Thanks again...

[RedCoupe]

The air filter box clips shouldn't make a difference in the cars running, just that some unfiltered air could sneak in where the lid isn't fastened down. My 964 developed a nasty intermittent running problem, and the problem turned out to be a bad main battery ground wire, so electrically testing all the ground straps and wires would be wise.

[KNS]

Originally Posted by 4flyboy

Years ago my 2.7 Carrera displayed the same symptoms on a weekend trip to Las Vegas.

Friday afternoon at 4:40pm it gave up the ghost and I coasted into an independent VW mechanics shop in Baker.

I was desperate, the old mechanic listened intently for 10 seconds and disappeared to the field out behind the shop, pulled the coil wire off a Bug. He plugged it into my coil and distributor cap.

Saved me a weekend in Baker California, an expensive tow and hundreds in diagnostics......wouldn't let me pay for the old coil wire.

Hope it's this simple, Scott

Cool story - Baker of all places!

[Tippy]

Originally Posted by pmax

OK, I'll bite. Browsing thru your thread(s), I stopped after reading this ...

"w/turbo (T60-1) 447whp"

Might wanna mention that little detail in your next rant.

Why? It was ran with 100% stock DME and associated bits minus larger injectors and chip.