Author Topic: 90 coupe quattro bogging problem  (Read 2213 times)

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audichick

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90 coupe quattro bogging problem
« on: June 06, 2006, 05:22:08 AM »
I have a 90 coupe quattro that bogs badly during warm up and it cuts out pretty bad.  When it gets warmed up, it doesnt cut out, but still bogs constanly.  When i 1st start up the car, it runs beautiful....for about 2 mins, then it starts.  Ive done so far what ive thought was the main problems.  REplaced the plugs, plug wires, cap, rotor, fuel filter, and O2 sensor, and even done a coolant and fuel injection flush.  All that helped, but still isnt working properly.

Quattrophile457

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Re: 90 coupe quattro bogging problem
« Reply #1 on: June 06, 2006, 05:25:42 AM »
Yes this is my car, not hers, her's runs well, but my just doesnt want to work right!   :(

Rocky Mountain Club B5

Re: 90 coupe quattro bogging problem
« Reply #1 on: June 06, 2006, 05:25:42 AM »

ianacole

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Re: 90 coupe quattro bogging problem
« Reply #2 on: June 06, 2006, 06:15:15 AM »
Is there a choke system on these cars?
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jfrahm

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Re: 90 coupe quattro bogging problem
« Reply #3 on: June 06, 2006, 12:15:05 PM »
Check the air and coolant temp sensors for the fuel injection.  It might also be a bad fuel pressure regulator, can you test the fuel pressure and/or vacuum test the regulator?

-Joel.
2001 Audi A8 Quattro 4.2l

Quattrophile457

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Re: 90 coupe quattro bogging problem
« Reply #4 on: June 06, 2006, 01:44:28 PM »
havent done either, but trying to.  Im thinking fuel pump, but not sure, but it is making noise.  But i dont want to go drop $300 if thats not the problem.  I will try both and let you know.

gragravar

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Re: 90 coupe quattro bogging problem
« Reply #5 on: June 06, 2006, 01:54:13 PM »
before you go too far replacing components, I'd run a can of BG 44K through it with a tank of gas.  could just be a gunked up fuel system and the 44K should take care of that.

I have found it to work miracles for me, but don't use it too often.

Any man who can drive safely while kissing a pretty girl is simply not giving the kiss the attention it deserves.  ~Albert Einstein

Quattrophile457

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Re: 90 coupe quattro bogging problem
« Reply #6 on: June 06, 2006, 10:05:43 PM »
I went to a shop and paid the $100 to do the complete fuel system flush in my car, so i know that is not the problem.

jfrahm

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Re: 90 coupe quattro bogging problem
« Reply #7 on: June 06, 2006, 10:24:43 PM »
Heh, you never 'know' it's not the problem.

How do the plugs look?  Check all of them for signs of running rich.  Since they are relatively new that will help identify the problem.  Run the car cold, let it bog, then plug the plugs right away after a good bog.  See if any or all are wet with fuel.  You might have a leaky FPR, a leaking injector, or a confused EFI running rich (possibly a bad temp sensor.)  

It's too bad you are not handy so I can take a quick look and see if it's running too rich or lean or what.

The fact that it runs good for two minutes is interesting, as if maybe it runs well in open loop but when it goes to closed loop it freaks out.  You could try disconnecting the O2 sensor, which will keep it in open loop, and see if it runs better.

However the first thing I'd do is let it bog down good and then whip out the plugs and get back to us.   Check to see if any are wet with gas, if they are all grungy or if any are different, etc.

-Joel.
2001 Audi A8 Quattro 4.2l

Quattrophile457

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Re: 90 coupe quattro bogging problem
« Reply #8 on: June 07, 2006, 11:22:18 AM »
OK i did, and none of them are soaked w/ gas.  It is running a little rich, but not enought to make the plug wet.  After the car warms up, it doesnt bog down as bad, and just runs like it only has about 130hp, instead of its normal 160.  The plugs look prety good tho.  I know that it isnt a leaky injector, i pulled them all out and had them tested, and they are all OK.  Im kind of leaning toward a fuel pump or something of that sort.  Stil waiting to test the regulator and the pump.  Dont have to tools to do it.

jfrahm

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Re: 90 coupe quattro bogging problem
« Reply #9 on: June 07, 2006, 12:10:52 PM »
Hmmm.  Well if it's running a bit rich I would not suspect the fuel pump.
I would be thinking a leaking FPR or more likely an engine management problem (bad sensor or bad wiring.)  Disconnecting the vacuum signal to the FPR will also keep it from leaking gas into the vacuum system (if it is leaking)  the downside of this is that it might leak gas on your motor.

If it is running rich that gas is coming from somewhere.  Either leaking into the vacuum system or too much is being delivered by the fuel system.

Have you checked out 20v.org?  One thing they talk about is cleaning the big black harness connector at the front of the motor, and an electrical connector at the FPR as well:

http://www.20v.org/engprob.htm#limphome

-Joel.
2001 Audi A8 Quattro 4.2l

Quattrophile457

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Re: 90 coupe quattro bogging problem
« Reply #10 on: June 07, 2006, 07:22:37 PM »
The fuel pump is making ALOT of noise, and i will check the FPR and unplug ti to see if that changes anything.