2002tii

Vehicle in seemingly good visual and mechanical condition, clean engine compartment. Starts and runs AOK in all respects for 1 minute (until it comes out of cold-start mode?) and then will not hold idle unless the gas pedal is fluttered vigorously and even then, barely stays running and w/some oil burning. 2 temp sensors and fuel filter replaced, spark plugs & wires ok, fuel pressure ok, vacuum lines ok, electrical wiring & connectors ok. Not familiar with peculiarities of the fuel injection regulation or what the typically weak components or design are. Fault codes do not read out. Help!!

V8BOB

When you say that the fault codes do not read out, have you actually tried to blink out the codes? Here's a site the will explain how that is done.

http://www.sjmautotechnik.com/troubl...ng/ecufv8.html

2002tii

hi Bob: Our blink code read has not worked; I'll try this procedure, it may be different in some crucial fashion. I'll let you know.. Mucho thanx! Stephen

2002tii

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2002tii

OK, thanx for the excellent Audi V8 Motronic ECU Tests info. That info trumps AllData's so now we have a blink code of 4431 which is Idle Stabilizer Valve and/or ISV wiring. We have previously removed the ISV from the engine and jumped it to ck operation and it opens and closes almost completely. (We are assuming that the ISV is the same as any Idle Control Valve [ICV]; its the item top front and center on the engine just above the throttle ***'y - ??) So it will work if signaled correctly. As mentioned previously, both water temp sensors have been replaced. Next step would seem to be to check the integrity of the wiring and find out where it comes from and where the tail end connector is. Unfortunately the wiring seems pristine and the sheaths have never been cut open and we are reluctant to cut where it doesn't need cutting.

Does your data source include wiring diagrams, even schematics for a pin-out on the ECU? That would be most helpful!! Local dealer is AWOL on this.

One last question : is there a typically helpful dealer out there for these or other older Audis?

All Best Regards, Stephen

V8BOB

Here is the wiring diagram, from the same site. Check the plug-in connectors I've heard that sometimes the pins can get pushed back into the connectors and not make contact.

How many miles are on the car? and what did it come in for?

Here's a link to the WIKI V8 knowledge base, it got started but never completed. There's a how to clean the throttle body that shows the ISV a part.

Category:V8 - Knowledgebase

It's good to see you are trying to diagnose instead of throwing parts at it.

Most of the Audi dealers across the country if asked about a V8 will answer with a V8 what?

Bob

2002tii

Bob: No wiring diagram attached . . .? But it may be a moot point since the V8 database you cite also has an entry under "No Start . . ." which is not my problem but I ck'd it out anyway and guess what, it sez: "Have you ever had a problem where your V8 is driving along just fine, but when it warms up the engine dies? If you let it cool down it fires right back up and then dies again after you drive a few miles? You have a failing Ignition Timing Sensor"
Well ITSs (CPSs: Crank Position Sensors) usually don't fail so consistently and repeatedly in such a fashion but then I don't know how these Audi sensors are constructed and it certainly makes sense that if they do fail, it will take down the engine operation. I think I will throw this part at the problem, cleaning the old part's tip and connector first, thank you very much!!!

2002tii

Bob: OK; got the ECU pin-out info from that smj site - it was listed but didn't print out with the rest of it, needed to be selected separately. oops. 38k mi., pretty dayum clean overall.

V8BOB

Nice, 38k miles is very low. The 2 sensors usually fail over time from heat cycling. That's why the car starts and runs fine but when it gets hot from the exhaust it fails. So it could test out good when cold and then fail when you go to re-start it hot. 38k is kind of early for them to fail. You should replace both since they are so hard to get to. Check this out also Take note that the 2 sensors are the same except the length of wire and color of the connector. Read the Audiworld post below for more information.

https://www.audiworld.com/forums/aud...ickly-2200941/

[V8] Hard Start When Warm

[V8] Replacing the Speed Position Sensor

[V8] Sensor Removal

toml99

You said you replaced 2 temp sensors...was one the white connector Motronic sensor on rear passenger head below distributor? Also, that ISV connector can have a cracked wire in boot due to how it's bent there. Since that was the code you got, I'd check those wires...38K would likely make yours the lowest mileage V8 out there....Awesome.