Awwww geez. Lookout. This is the next rust/patina trend. :laugh: Seriously, though, hunt down that gremlin! Unrelated because I'm an oil burner but I fought hell and high water to figure out why my new tach wouldn't register. I tracked it down to a factory wire that looked new. Bulletproof electrical systems these cars have.
OP, second on the grounds and ecu. Having done everything else that you listed, the management was the next thing I thought of. I tend to not suspect the ecu and lean more toward brittle/broken wiring, but give it all the diagnostics to isolate the cause. Don't send that to a yard if you decide to let it go, sell it to someone else or part it. Hate to see a good one waste away in the boneyard.
this is exactly what i'm not a fan of cis-motronic (though my audi 5k runs perfectly *knock on wood*)
here are a few of my ideas (some may be far fetched)
vacuum leak (like everyone else said)
dead spot in your air box's potentiometer
tweaked hall sender window in dizzy
bad signal to ecu, bad signal to coil stage
since you mentioned bumping the harness and a few seconds of decent idle... i'd not only trace the harness for continuity, but also measure resistance. most likely there's an issue with the wires between the fuel distributor and the ecu.
it's a huge pain in the ass, because it's tedious work, but the one thing i've learned is to never trust a harness (even if you've built it yourself).
years and years ago i had an 88 digi car (split year) that didn't match ANY wiring diagrams anywhere, and had some mysterious gremlin that i just couldn't track down for months. i replaced this and that and nothing made any difference.
finally, while at my wit's end, i took a day and rebuilt the entire engine harness, reusing connectors, but rerunning and repining everything, and the gremlins were gone.
EDIT:you can also bring it up to me in brooklyn for a few days and i'll get it sorted for you.
I would suggest pulling the entire harness from your bay and go wire by wire. Replace and re-pin as needed.
~25 year old copper wiring loses a lot of conductivity due to oxidation. It MAY have started out as oxygen-free copper (kind of doubt it..) but I highly doubt it is now.
It will be replaced. Then once I get the new one in there I can hunt through that one. My back can't really handle leaning over the hood for a long time anymore. :banghead:
not knocking you just can't believe it. as many people's problem that you have solved over the years. tell me it is you back pain talking.
Mr Knappy the man give up? no way.
Well I guess that's what happens when you get older, grumpy, and aren't stupid enough to be in the car business anymore.
I took the harness out. Cut most of the covering off around where I tapped it and it ran better. Didn't really see any issues with the wiring. The coil power stage harness was fixed when I installed that harness many years ago. Still all holding together. The DPR wires however are split at the connector. It is still connected and resistance isn't too bad. I have a feeling that this will be the end of it. Unless somebody has a good fuel distributor laying around that they want to sell cheap?
not knocking you just can't believe it. as many people's problem that you have solved over the years. tell me it is you back pain talking.
Mr Knappy the man give up? no way.
Have you checked the codes? Like how it tells you in the Bentley?
I built a small black box with a light and button. Had very similar issues with mine and the code was always the hall effect sensor.
Don't give up though.
My other sisters old golf did that exact thing. The bearings in the air fuel mixture flapper were sticky and there was some goop on top that was also making it sticky. Dad cleaned it all up and the problem was gone. He always told me if it bounced more than once or did not bounce at all when you picked it up and dropped it, then the car would not idle properly.
I am not sure this would help an old pro like you, but just thought I would say it anyway. Maybe someone did already, but used short form and I missed it.
I must admit that my fuel distributor was kind of sticky. I cleaned it up real good and adjusted the height of the plate the other day. Nothing changed. I just bought a new fuel distributor yesterday since whoever drilled the plug out of the adjustment hole ****ed it all up and it is next to impossible to adjust the mixture.
Have you checked the codes? Like how it tells you in the Bentley?
I built a small black box with a light and button. Had very similar issues with mine and the code was always the hall effect sensor.
Don't give up though.
My other sisters old golf did that exact thing. The bearings in the air fuel mixture flapper were sticky and there was some goop on top that was also making it sticky. Dad cleaned it all up and the problem was gone. He always told me if it bounced more than once or did not bounce at all when you picked it up and dropped it, then the car would not idle properly.
I am not sure this would help an old pro like you, but just thought I would say it anyway. Maybe someone did already, but used short form and I missed it.
BIG thanks to Richard (cyclops594) for going out of his way when at the yard to pull the harness, send me photos of ALL the connectors while he was there, boxing it up and getting it here in 2 days from California! All for a GREAT price. :thumbup:
BIG thanks to Richard (cyclops594) for going out of his way when at the yard to pull the harness, send me photos of ALL the connectors while he was there, boxing it up and getting it here in 2 days from California! All for a GREAT price. :thumbup:
I'll eventually check the comtinuity and resistance of all the wires and find out what was actually causing that. My guess is either the CTS, O2 sensor or the potentiometer on the fuel distributor. It wasnt the DPR since the idle went to like 2500 when i disconnected it and i was able to get a reading with the test harness. It would be nearly impossible for a knock sensor wire to go bad since those are so damn thick. These things are technically complexly simple. Not very much that controls the engine. I'm still going to replace the fuel distributor when it gets here and then do a final tune on it. Then we might start on the body and the rest of the interior. Headliner was jus done.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Ask a question
Ask a question
VW Vortex - Volkswagen Forum
84.4M posts
1.5M members
Since 2001
A forum community dedicated to all Volkswagen owners and enthusiasts. Come join the discussion about performance, builds, modifications, classifieds, troubleshooting, maintenance, new releases, and more!