John_AZ

PET does not show a dipstick "O" ring for the early 944- 85/1

The late 944s use part number 900 174 0440
Size is 13mm x 9mm inside x 2mm thick.

About $2.50 -$3 each. Not a cheap rubber "O" ring.



http://www.autohausaz.com/search/pro...%20174%2004440

J_AZ

konakat

Wanted to give an update. I installed new position sensors yesterday and drove the car for the first time this morning. No hiccups so far, though only time will tell if the surging and dying are definitely gone. The engine does seem to run significantly smoother now. Vibration at idle is greatly reduced. It also fixed a weird issue I was having where the voltage would fluctuate wildly if I was below 2k rpm, the needle would just flap between 12V and 14V. Now my voltage is nice and stable.

I also did a reseal kit on my throttle body, though I can't say that I noticed much difference from that. In addition I picked up a turbo dipstick tube so that I could put an o-ring down at the block and that fit fine. I haven't gotten around to doing another vacuum test to see how much pressure I hold, so stay tuned.

konakat

I have finally gotten to drive the car again after this endless winter. Last Sunday I went for a spirited 30 minute drive on back roads and the car was wonderful. It was my first fun drive I've been able to take since getting the car, and it is amazing how well the car handles. Today I used the car to run errands around town and ran into my dreaded stumbling and dying issue again. So, a recap:

Car starts stumbling after driving in stop-and-go and slow traffic. It is always fully warmed up with the radiator fan having already turned on and off a few times. It does not matter if I am idling or revving. Eventually the stumbles are big enough that the engine dies. When I try to restart, the engine starts momentarily, surges up to 2k or so RPM, then dies. It is definitely starting for just a second or two, so I have spark and fuel.

I have never seen this happen idling in my garage or while cruising. This makes me think it is heat related and that just enough extra heat builds up in stop and go traffic that the stumbling starts. I can let the car idle in my garage for an hour, going through many radiator fan on/off cycles, without it ever stumbling. (I know it is bad to do this)

Things I've done: replaced reference sensors, disconnected TPS, raised idle, inspected and touched-up DME

Current thoughts: DME temp sensor goes crazy when hot and DME shuts down the car (not sure if the DME even has a thermal shutdown feature)? I have tested it using the Clark's procedure and it seemed fine, but maybe it just gets crazy at higher temps. Bad DME?

Someone please help. I ordered a DME temp sensor but have little faith that it is the solution. I don't know what to check next.

gtroth

If it were mine I'd be focused on the AFM until I knew that was good.

Speeddemon944

^ Agreed - Grab a Multimeter and meter the AFM and the TPS just to be safe.

The New DME temp sensor can be a nasty bugger when it fails/is failing. Swapping that is a good idea.

ramius665

+1 on checking the AFM. All sorts of bad running issues can come out of a failing AFM. Luckily they're not too hard to recondition yourself if it's not too far gone.

konakat

Well, now I'm really stuck.

I have replaced my DME temp sensor and disconnected the TPS since last update, just so you know my starting point.

A couple weeks ago it occurred to me that maybe my ignition coil might be the culprit, since some reading revealed that they can have a failure mode much like mine. I picked one up at the junkyard, verified that it worked, then put it in the car to carry around for the next time my car died.

Last night it died again just around the corner from my house. I tried changing the ignition coil, but that had no effect, so that idea was shot down. I got into the fuse box and jumpered the DME relay just to make sure I didn't have an intermittent issue with the relay, but after doing that the engine wouldn't start up at all when I tried starting it. I took off the jumper and tried again, but no change. In the past, the engine would fire and start up, then die within a second or two, now the starter cranks but the engine doesn't fire at all. I pulled out the DME to inspect and verify that nothing had burned up but everything looks good and there are no suspect solder connections. This leads me to believe I either have a wiring harness issue or whatever has been failing finally gave up completely. I tried to start her again this morning and it wouldn't fire, in the past a few hours of sitting always made the problem go away. I do get tach bounce while cranking, so I think the DME inputs are okay.

Current theories:
1. Bad DME (anyone in central MD have an early DME I can borrow?)
2. Fuel system failure (I can hear the fuel pump whirring and flowing through the fuel rail when the DME relay is jumpered. Maybe the FPR is stuck open and I don't have good fuel pressure? Test by spraying some starter fluid?)
3. Ignition issue (cap/rotor failure? I don't think my earlier issues sound like a cap/rotor problem, but who knows. Test this by pulling out a plug and look for spark while cranking?)
4. Injector wiring issue (how to test this?)

Any other thoughts? I am not really enjoying my first foray into having a project car, this issue is killing me.

ZR8ED

Maybe check your fuel pressure? If your regulator or dampner are leaking, you can get fuel spikes which will cause the car to stall. It will also cause it to die after running for a few seconds. I put a guage on mine and watched it. It would spike 100psi and stall the car. I'd let it sit a while before restarting it, and it would start fine and run for a few seconds and then the fuel pressure would spike again and the car would die. It did it once or twice and I managed to get it home, where it finally failed completely and when I replaced the dampner, it fixed it right away.

konakat

Wow, that sounds promising. That is how it has always behaved for me before this time. Thanks for the tip.

konakat

So I finally got a fuel pressure gauge attached and everything looks perfect according to the Clark's procedure. My car doesn't normally die until it has been running for ~45 minutes, but I'm not sure I'm comfortable with driving around with a fuel pressure gauge hanging off the fuel rail from hand-tapped threads. I also can't attach the gauge once the car dies since messing with gas around a hot engine is bad news. Should I drive around with the gauge attached, or do I need to continue my search elsewhere since everything looks okay?

konakat

I decided to just go for it. No fires, and she started stumbling for me so I could see what was going on. The fuel pressure needle was waving around like crazy, but just in the 20-40 psi range, so I don't know if that is the issue or not. At the very least it looks like my fuel damper is dying. Any thoughts?

msalvatore

How about the coil? Have you tried a different one? Had a similar issue in an old jeep where it would run like crap after a bit. Turned out the coil would break-up after it got hot.

Ben951S

I have an electronic sender. It shouldn't be wavering at all. It should be steady. It shouldn't really dip below 29 when running (I think it's 30 +/- 2psi, Clarksgarage has the spec). Spike should be under 50, but again, this is smooth, and when running at full boost.

Sounds like you found part of the problem!

konakat

I did already try a different coil, but now that I think about it I should probably try again because I was having fuse issues when I tried it.


So this sounds like a dampener problem, not FPR, correct?

mel_t_vin

Have you pulled the vacuum lines off your FPD/FPR?

Any moisture in/around the line/nipple?