Cold Start/Idle issue update
02-23-2008, 02:11 PM
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Cold Start/Idle issue update
Well, I did some serious searching on the forums and amongst hundreds of postings, finally stumbled across this posting from 4 years back by JSFFive. He mentions all the same issues I am having, due to a grounded wire from the fuel pump relay to 5 components.
I figure "Great, problem solved". But before simply diving in and rewiring, I decided to see what the Bentley might have to say about this wire.
I started flipping through the Bentley, and found a page on a fuel pump relay output test, where by bridging the fuse slot in the relay five different times, the five components will switch on (CS Valve, Wastegate Solenoid, Decel Valve, Charcoal Canister, and OXS Heating element).
I did the test, waiting to see that none of them worked and for sure this was my problem. Completed test: All five components worked exactly as specified in the manual. Needless to say, I am confused.
I am terrible with electrical, so I wanted to ask: Is there any way this single wire to the 5 components could be grounded yet the components still run in the output test? All my symptoms are EXACTLY as JSFFive mentions in the post below. Any feedback is greatly appreciated.<ul><li><a href="https://forums.audiworld.com/v8/msgs/65457.phtml">Cold start, hard starting, low boost, uneven running, sluggish</a></li></ul>
I figure "Great, problem solved". But before simply diving in and rewiring, I decided to see what the Bentley might have to say about this wire.
I started flipping through the Bentley, and found a page on a fuel pump relay output test, where by bridging the fuse slot in the relay five different times, the five components will switch on (CS Valve, Wastegate Solenoid, Decel Valve, Charcoal Canister, and OXS Heating element).
I did the test, waiting to see that none of them worked and for sure this was my problem. Completed test: All five components worked exactly as specified in the manual. Needless to say, I am confused.
I am terrible with electrical, so I wanted to ask: Is there any way this single wire to the 5 components could be grounded yet the components still run in the output test? All my symptoms are EXACTLY as JSFFive mentions in the post below. Any feedback is greatly appreciated.<ul><li><a href="https://forums.audiworld.com/v8/msgs/65457.phtml">Cold start, hard starting, low boost, uneven running, sluggish</a></li></ul>
02-23-2008, 04:36 PM
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No..
If the person in your linked thread had run the tests similar as to you running them, they would have all failed for him.
I'm not sure if it's clear in his post, but what happens is the fuel pump relay has two 'outputs' as it were.
One output running the pump, and the other output running things that don't need power unless the motor is running.
So..If the output tests all pass, and the motor does run, but you are convinced that that IS your problem, maybe you have a 'transient' problem that only occurs when the motor is running, or weirder? (After all, it *is* an Audi! :-)
Look at the wiring diagram, and figure where that power should be live when the motor IS running on those 5 devices, and not just in the output test mode.
FOr example:
With the motor actually running, pull the connector to the wastgate frequency valve, and see if the pin that is supposd to have power actually HAS power.
WIth that information, perhpas you can figure out what's going on..?
I'm not sure if it's clear in his post, but what happens is the fuel pump relay has two 'outputs' as it were.
One output running the pump, and the other output running things that don't need power unless the motor is running.
So..If the output tests all pass, and the motor does run, but you are convinced that that IS your problem, maybe you have a 'transient' problem that only occurs when the motor is running, or weirder? (After all, it *is* an Audi! :-)
Look at the wiring diagram, and figure where that power should be live when the motor IS running on those 5 devices, and not just in the output test mode.
FOr example:
With the motor actually running, pull the connector to the wastgate frequency valve, and see if the pin that is supposd to have power actually HAS power.
WIth that information, perhpas you can figure out what's going on..?
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