Audi A4 (1995 - 2000) - 1998 1.8T Quattro misfiring under load.

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Sat 12 Apr 2008 19:22
1998 1.8T Quattro misfiring under load. - vancitiboy
Ok so the deal with my car

IT's a 1.8T 1998.5 AEB motor quattro

PLS help

Had a misfire the other month cel came on. Show misfire and then drove like crap for a day got it VAG'd and found a ignition control module was done. **note, car ran fine before this. BOOST level was at 12+ psi and levelled out at about 10 psi. NOW after we replaced that (same part number) new module the car does not go into boost past 4psi. It starts to bog out and misfire past 4 psi or more than70% on the accelerator pedal.

So if showed some cel lights for misfire also had a throttle body not operating properly so swapped out the throttle body with a new one and resolved the 17953-p1545 Throttle Valve Controller: Malfunction

During all this in Neutral the car can rev no problem, no misfires. This problem only in drive or underload

I thought that since it only acted up while driving regular. And the engine seemed to not be breathing well so decided to try changing out the Catalytic Converter to high flow one.

STILL SAME PROBLEM

If i keep my foot floor to the ground and let the car bog out and misifire car it will shoot out a cel. This is only if i try to floor the pedal and hold it. otherwise daily driving and no boost the car drives perfect but not power:( Like driving a 1.8 that wishes it could hahaa

ONLY codes now are

>>Cyl.3 Misfire Detected
>>Cyl.2 Misfire Detected
>>also have 18014-P1606 Rough Road Spec Engine Torque ABS-ECU Electrical Malfunction

NOW my question is could Rough Road Spec Engine Torque ABS-ECU Electrical Malfunction make my car do this? I'm in this fix for a good $1200 now and really don't think it's the ABS unit that could make my car act this way.

A fresh diagnostic would be helpful

Edited by Pugugly on 12/04/2008 at 20:04

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Sat 12 Apr 2008 19:34
1998 1.8T Qua Audi 1.8T misfiring underload cannot - Screwloose

What codes are stored in the ABS module? The rough road mode cuts the power to prevent excessive wheel-spin on rocky surfaces.

Misfire codes will drop it into limited operation strategy - low boost is a feature of that too. Have you tried a different amplifier - or was it a different cause? What were the original codes?
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Sat 12 Apr 2008 20:11
1998 1.8T Qua Audi 1.8T misfiring underload cannot - vancitiboy
original codes after "first" CEL light came on

18010 P1602 Power Supply (B+) Terminal 30 Low Voltage
16684 P0300 Random/Multiple Cylinder Misfire Detected
18014 P1606 Rough Road Spec Engine Torque ABS-ECU Electrical Malfunction
16684 P0300 Random/Multiple Cylinder Misfire Detected
16686 P0302 Cyl.2 Misfire Detected
16686 P0302 Cyl.2 Misfire Detected
17953 P1545 Throttle Pos.Contr Malfunction



NOW JUST CEL LIGHT IS JUST

16684 P0300 Random/Multiple Cylinder Misfire Detected
16686 P0302 Cyl.2 Misfire Detected
16687 P0303Cyl.3 Misfire Detected
16686 P0302 Cyl.2 Misfire Detected
16687 P0303Cyl.3 Misfire Detected
16686 P0302 Cyl.2 Misfire Detected
16687 P0303Cyl.3 Misfire Detected
18014 P1606 Rough Road Spec Engine Torque ABS-ECU Electrical Malfunction

but i don't have a engine light on only if i floor the car with the light flash then go solid
I try not to set it off. I don't like being in limp mode

Edited by vancitiboy on 12/04/2008 at 20:13

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Sat 12 Apr 2008 20:18
1998 1.8T Qua Audi 1.8T misfiring underload cannot - Screwloose

What made you think that the amplifier was defective? Changing it doesn't seem to have helped and you've still got misfire codes? Have you moved the coils around to see if the code changes?

Are the MAF sensor readings to spec?
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Sat 12 Apr 2008 23:21
1998 1.8T Qua Audi 1.8T misfiring underload cannot - vancitiboy
Not sure what you mean by amplifier? but Reason for changing the amplifier if your talking about the Ignition module is because the car first hardly ran. Now it actually runs. BUT seems to have brought on a new problem ....ie hardely any boost and no power.

If your talking about the CAT converter well seemed as though the exhuast didn't have alot of flow out the tail pipe so just did it to see if it helped , more flow after changing to new one.

but yes i know didn't correct the problem.

Tried moving the coils around to all locations but does not change the misfiring :(

MAF is reading to spec. So i'm lost
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Sat 12 Apr 2008 23:37
1998 1.8T Qua Audi 1.8T misfiring underload cannot - elekie&a/c doctor
Multiple missfires are often caused by a faulty maf sensor even though they do not flag a fault and appear to be working within spec.A common failure on a lot of models in VAG models and are cheap to replace,even from main dealer.hth
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Sat 12 Apr 2008 23:38
1998 1.8T Qua Audi 1.8T misfiring underload cannot - Screwloose

Ignition amplifier is the correct term for the coil driver module. Does the code change when you swap the coils - if you've got a faulty coil, then it will still miss, just on a different cylinder. Have you changed the plugs?

Have you read the ABS for codes? Work on the cause of the misfire; start with a compression test.
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Mon 14 Apr 2008 02:05
1998 1.8T Qua Audi 1.8T misfiring underload cannot - vancitiboy
I'll be working on all this in the following week prob get the coils done just I'll update in a little bit

Thanks for the input guys let yah know how it goes

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Sun 20 Apr 2008 21:12
1998 1.8T Qua Audi 1.8T misfiring underload cannot - vancitiboy
Ok sooo funny that all it was the old culprit..... coilpacks and plugs. Next time that's the first thing i'll be changing hahaha Thanks for all the input guys
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Sun 20 Apr 2008 21:37
1998 1.8T Qua Audi 1.8T misfiring underload cannot - Screwloose

Glad to hear that you got it sorted. It's very easy to take a wrong turn and head off into headache territory.
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