Replaced a cracked head on my buddy's 1986 5000S about two years ago. Engine ran fine for about three months, sat for 6 months. When starting cold, it starts but needs to have the gas pedal depressed to keep it running. So, won't idle. At high revolutions engine sounds great. After car has been run for 10+ minutes the thing will NOT start, the engine must cool down before starting again cold as described above. Compression is good, plugs good, cap and rotor good, getting fuel to distribution manifold. When he comes to a stop he can slowly let off the gas and it will idle with trouble. If we touch the throttle arm under the hood at all to give it gas, it will die immediately. He is throwing an OXY code on the cluster gauge. But he was throwing that before we did the rebuild. O2 sensor is stripped and only 3/4 way in the intermediate piping to muffler. Has anyone had these problems with these cars. I usually work on Hondas and well, dealing with this doesn't come up much. Thanks in advance for anyone that can lend some info. Happy New Year to all.

Brian

 

There should be an unit called "idle stabilizer"-works at idle and does the transition to driving rpms.
On top of the engine, rubber-metal cylinder, with pipings and wires. Makes noise when working.

 

Brian,

Attempting warm start-up: Is there a fuel coming in or not?
Faulty cold start injector would cause flooding (should work 6-8 seconds only).

Have you check the fuel pressure? There are 2 links with related discussions:
https://www.audiforums.com/archive/t...-433300-1.html http://www.audi-forums.com/audi-5000...-will-not.html
"audi-forums.com"

Good fuel system purge is always beneficial for CIS.
I use Lubro Moly – Jectron Cleaner + Ventil Sauber. At least one can each in a gallon of gas, run for 10 min, live it to soak (the distributer gets well cleaned), run for 10 min. (I had dead cylinders come back fully operational after).

Check the CTS; if there are any DTC – let us know.

Should use the factory manual as test procedures are described there. (Amazon might have the lowest prices).

 

NEMOHM:

Thank you for the advice. I have worked on many Hondas and Toyotas but not so much on Audi. I did do the rebuild with him and yes we DEFINITELY have the Bently book. I will check the things that you have mentioned. Would you mind letting me know what the acronyms stand for like CIS, CTSand the like....Seems know that every manufacturer has their own abreviations for like sensors and control modules. I really appreciate your help, my buddy is at his wits end. Please, if you will, keep checking this and I will keep you updated. Or I will just send a message to you directly. Thanks so much.

Brian

 

CIS-Continues Injection System CTS-coolant temperature sensor Hardly any Bentley manual is 100% accurate.

 

I had this same problem with my 88 A5TQ, that is the warm restart problem I mean. In my case it was that i had to get a whole "new" (yah it was used but i saved 200 bucks) distributor assembly becuase the old one was crap from 20 yrs of beatings. Anyway i dont know if your year car will have this but there is a bimetalic strip that reacts to the heat of the engine to send a signal to your ecu that the timing is correct and whatnot so that it will allow it to restart. The problem for me was not that the bimetalic strip had lost its magnetic properties, which they do over many years of use, but that the wiring within the distributor cap was loose at the wiring harness. This caused the "45 minutes to restart" scenario for me when the car was up to heat. Sometimes its the wiring in the cap and sometimes it is the bimetalic strip has lost its magnetic properties from the trials of time. hope this helps and good luck man.