A4 1.8Tq Stumble, WOT when Cold
07-19-2011, 09:57 AM
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A4 1.8Tq Stumble, WOT when Cold
Car is a '99 1.8T, APR Stage 1, no other mods whatsoever. My girlfriend, the driver, reports:
In the last two days, shortly after starting in the morning, the car has stumbled when floored. Oil and Trunk lights both flickered, no other lights came on. Everything went back to normal after lifting foot from the throttle, and was fine for flooring seconds later.
We'll have a chat later about being rough with a turbo when it's cold, but any ideas what might cause something like this? Car runs perfectly otherwise, all maintenance is up to date (and then some). I'll check for vacuum leaks this weekend - it's the only thing that comes to mind, although the fact that it fixes itself within seconds makes it not seem much like a vacuum problem but an electronics issue. Maybe MAF?
In the last two days, shortly after starting in the morning, the car has stumbled when floored. Oil and Trunk lights both flickered, no other lights came on. Everything went back to normal after lifting foot from the throttle, and was fine for flooring seconds later.
We'll have a chat later about being rough with a turbo when it's cold, but any ideas what might cause something like this? Car runs perfectly otherwise, all maintenance is up to date (and then some). I'll check for vacuum leaks this weekend - it's the only thing that comes to mind, although the fact that it fixes itself within seconds makes it not seem much like a vacuum problem but an electronics issue. Maybe MAF?
07-20-2011, 10:26 AM
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I am going to keep replying to my thread.
Drove the car last night, it's clear ignition is breaking up at high speed/high boost. It's fine at low/mid RPM even at reasonably high boost.
What is certainly odd is that when the ignition is freaking out, random warning lights come on. The girl reported the Oil and Trunk light lit up... last night, I got the Brake and Gas lights. WTF?
Anyone ever seen something like this before?
Drove the car last night, it's clear ignition is breaking up at high speed/high boost. It's fine at low/mid RPM even at reasonably high boost.
What is certainly odd is that when the ignition is freaking out, random warning lights come on. The girl reported the Oil and Trunk light lit up... last night, I got the Brake and Gas lights. WTF?
Anyone ever seen something like this before?
07-20-2011, 12:47 PM
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I still haven't mustered up the will to buy a VAG-COM.
I need to, because the *other* issue this car has is that the alarm will occasionally and randomly go off.
I could definitely see how this is all a bad ground issue, but the question is what ground could possibly have all these systems in common? The main battery ground?
I need to, because the *other* issue this car has is that the alarm will occasionally and randomly go off.
I could definitely see how this is all a bad ground issue, but the question is what ground could possibly have all these systems in common? The main battery ground?
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07-22-2011, 09:52 AM
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It was replaced a few months ago - the car had an occasional CEL for CTS, so I replaced it with one from ECS.
I am going to replace the plugs tonight or tomrrow AM. It's running Denso Iridiums since January-ish without an issue. Maybe they suck, maybe the high boost killed them. I imagine I cannot get anything good in Sacramento on a day's notice, so chances are it'll be some NGK Platinums from Kragen. They'll either make it worse or better, or wag a finger at the coils.
They have 130k on them, I wouldn't be sad if they needed to be replaced. Rather spend the two bills on booze & hookers, but you do what you gotta do.
I am going to replace the plugs tonight or tomrrow AM. It's running Denso Iridiums since January-ish without an issue. Maybe they suck, maybe the high boost killed them. I imagine I cannot get anything good in Sacramento on a day's notice, so chances are it'll be some NGK Platinums from Kragen. They'll either make it worse or better, or wag a finger at the coils.
They have 130k on them, I wouldn't be sad if they needed to be replaced. Rather spend the two bills on booze & hookers, but you do what you gotta do.
09-02-2011, 11:24 AM
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FWIW, new plugs did not cure the issue. Even after a few weeks of additional driving I couldn't get a code, so I replaced the coil packs with new, and that solved the problem. I am shocked no code was ever set - maybe a side effect of the APR chip?
I COMPLETELY cheaped out and bought no-name coil packs. $75, including shipping, for a set of four from FCP Groton. They're $100 on their website, but $75 through their ebay store. That is frighteningly cheap. They do the job, though - we'll see for how long.
I COMPLETELY cheaped out and bought no-name coil packs. $75, including shipping, for a set of four from FCP Groton. They're $100 on their website, but $75 through their ebay store. That is frighteningly cheap. They do the job, though - we'll see for how long.