>>> URGENT HELP: A4 3.0 Quattro - Suddenly Rough Idle / Bad Pulley ???

[Detonator]

URGENT HELP NEEDED HERE !!

My 2003 A4 3.0 QT MT6 has suddenly developed this really rough idle/drive and I can't seem to find what is causing it.

Car has 74k miles (timing belt has NOT been replaced yet).

I took it today to get an oil change & Flush at a local Audi/VW shop hoping the new oil would make the issue go away but no luck.

They checked out the car and could not find the problem, they checked for codes - and not a single error. That is when my gut started to tie into a knot (fearing the possible worst) as their only guess could be a malfunctioning pulley causing the rough idle. Could this be ?? Has anyone had an issue like this ??

A little more about the problem - this is not the FIRST time this rough idle shows up, it has happened a 2 times before and the car would rough idle for like 2 days and THEN go back to NORMAL. Also about all 3 times the issue has occurred it has showed up after spirited driving on the highway at 80-90mph - once I would get OFF I would notice the idle had changed ... It has been more than 8 days now and it still persist, now Im fearing the worst.

Again the car gives NO CODES, also the ENGINE MOUNTS checked out ok.

WTF could it be ??

[kaizr]

coil pack perhaps? had a similar problem in a 1.8

[Grenade]

coilpack, fuel filter, vacum leak, spark plug

[Detonator]

That was the first thing i thought, but no they are all fine ... no misfire codes.

I have had a coilpack GO before and the rough idle is very similar - slightly less though, maybe 50-70% of the bad coilpack shake.

[int2str]

I've had the same issue recently.

A4 3.0 Quattro with 92k miles.

The cause were indeed misfires. But in my case it was the spark plugs boots as well as some coil packs. The cause was a slight leak in the valve cover gasket which caused some oil to leak into the spark plug holes over time and short the connectors and coil packs.

It had no check-engine light on or anything.

At the same time the shop checked the timing belt and found 8 teeth gone. On a subsequent test-drive they got a code that the timing was off on one cylinder bank - the belt had slipped (!!).

~$2900 later it's all well again

Hope you'll fare better.

[Detonator]

I've had the same issue recently.

A4 3.0 Quattro with 92k miles.

The cause were indeed misfires. But in my case it was the spark plugs boots as well as some coil packs. The cause was a slight leak in the valve cover gasket which caused some oil to leak into the spark plug holes over time and short the connectors and coil packs.

It had no check-engine light on or anything.

At the same time the shop checked the timing belt and found 8 teeth gone. On a subsequent test-drive they got a code that the timing was off on one cylinder bank - the belt had slipped (!!).

~$2900 later it's all well again

Hope you'll fare better.

Did the rough idle begin and then fade as in my case ?? Also it gave no codes ?

Was $2900 what they charged you for the timing belt ??

[Detonator]

BUMP

Spoke to the mechanic and they mention it could be a damaged FLYWHEEL ??

Would it cause this shake ??

[chrised007]

I'm seeing the same problem on my 2003 3.0L A4 Quattro. After running at highway speeds for about 30mins to an hour, the engine would rough. A day or two of city driving and it stopped. A couple days later same thing. My mechanic was stumped by it and took it to an Audi mechanic friend. He too was stumped. No engine lamp or codes. Problem stopped again. I went for about 2 months then the same thing happened again, back to a rough engine and a stumped mechanic.

[john_gonzo]

Any unusual temperature gauge activity after you drop back to slower speeds?

[-Audi_tuning-]

- Start small, physically look at each port on the coil, then the wires then each plug.

- also what about the MAF going bad, if you re-calibrate the throttle body you may get it to go away (if it is going bad this may help to throw the code for you).

- You could also check under the oil cap to see if you have a sludged motor, its very common in our motors.

- If all is good then move on to the idea of timing, but on the 3.0 if the car was off timing it would be destroying the engine, and if it is still running with good power(for a 3.0) I wouldn't think its off timing (just my .02)

Just some suggestions to help isolate the issues. Hope this helps in some way/shape or form.

[walky_talky20]

I'm wondering if there could be any trouble with the VVT. You say it runs rough after high-rpm activity. I'm wondering if perhaps the VVT is actuating and then not "releasing" the camshaft back to the home (idle) position properly. That would certainly cause a rough idle - the same symptoms you would get if the engine were mechanically out-of-time (incorrect t-belt installation or t-belt jumped). I've seen this problem on Toyota 1MZ-FE with VVT-i where the camshaft actuator solenoid (which controls the cam advance with respect to it's sprocket) and/or sprocket actuator itself was slightly gummed up with some sludge. Unplugging the VVT actuator would prevent the problem, but with the loss of the VVT feature (loss of top end horsepower). After unplugging the unit and driving it a bit, it would finally release back to the zero-position. Leaving it unplugged would prevent it from advancing and thus jamming in the advanced position.

Just an idea as you 3.0 guys have 4 VVT actuators as I recall. Not sure if there any common problems with them, though.

The only problem with this hypothesis is that it should almost certainly throw a code for cam advancement setpoint not reached - "over-advanced" or some such. It may indeed be an intermittent code such that it might not throw a CEL unless it faulted on several drive cycles in a row. Such a code might be missed by a generic scan tool.

[Tahoe3.0]

Necro bump...


Began exhibiting the same symptoms as OP last weekend, went away after sitting for two days. Today my girlfriend had the car and she said the same thing happened. I drove it around the block and am definitely misfiring. No codes, no lights. I’m overdue for a valve cover gasket and have a minimal amount of oil residue on the block so perhaps that is it. Bumping for ideas because it’s 10 degrees out and dark and I can’t take a look until morning

[SJorge3442]

No codes means its gotta be something external, IMO. Have you had a look at the crank pulley? With extreme cold I could see this having issues since its rubber dampened. If you can (when its not so damn cold) pull the accessory belt off and see if it idles smoother. Thats what I'd do as step one.

You could also have an issue with engine vacuum too because of the valve covers. Could also be part (or the whole) of the problem.

[Tahoe3.0]

No codes means its gotta be something external, IMO. Have you had a look at the crank pulley? With extreme cold I could see this having issues since its rubber dampened. If you can (when its not so damn cold) pull the accessory belt off and see if it idles smoother. Thats what I'd do as step one.

You could also have an issue with engine vacuum too because of the valve covers. Could also be part (or the whole) of the problem.

going to have the opportunity to look at it tomorrow in a heated shop. Going to take a look at what you've suggested as well as pull the coil packs and plugs to see if any are bad. I have one of those android head units that has torque installed and have the vacuum gauge on the main dash. It reads normal with no flutters so I think I am ok there. To elaborate, it's definitely missing a cylinder as opposed to just a rough idle. It sounds like a subaru with a custom exhaust (that awful boxer engine blubblubblubblub noise). Will update with more info after I get the chance to tinker a bit. Really wishing it wasn't zero degrees right now

I guess my Saturday is going to be spent angry wrenching lol

[SJorge3442]

going to have the opportunity to look at it tomorrow in a heated shop. Going to take a look at what you've suggested as well as pull the coil packs and plugs to see if any are bad. I have one of those android head units that has torque installed and have the vacuum gauge on the main dash. It reads normal with no flutters so I think I am ok there. To elaborate, it's definitely missing a cylinder as opposed to just a rough idle. It sounds like a subaru with a custom exhaust (that awful boxer engine blubblubblubblub noise). Will update with more info after I get the chance to tinker a bit. Really wishing it wasn't zero degrees right now

I guess my Saturday is going to be spent angry wrenching lol

Yeah I know what you mean when you mentioned the boxer engine noise. Is it a manual or auto? When my dual mass flywheel failed I was getting a rotational noise similar to that. That would change when I pressed the clutch (pressure against the pressure plate).

With what youve told us, id start with pulling the accessory belt and seeing if it goes away.

Sent from my LG-H871 using Tapatalk

[j-rod144]

I really don't think it's a pulley issue if it is an intermittent problem, I live in Alberta Canada where it is regularly polar cold and yes the engine can seem to vibrate a little more but not shake like you're describing. I would say it's a coil pack or spark plug, especially since you said it's leaking somewhat already. Also the OP did mention that he didn't have any codes for a misfire which is odd but it can happen.

[Tahoe3.0]

I finally got a chance to pull things apart today. VCG job is very necessary, there is oil present in the spark plug wells. Coils and plugs had oil all over them so I wiped them down and reapplied dielectric grease and put them back in. I FINALLY got it to throw a code P0302 so I swapped the pack on #2 to #1 to see if it would then give me P0301. No dice, back to not throwing codes. I am headed to get a new coilpack in hopes that that's it. Next thought if that doesn't resolve my situation is either the harness or injector. My hope is obviously that the new coilpack will fix it. The fact that I am back to not getting codes again is really bugging me.

edit: vacuum reading has been very steady at -25, is that the normal "window"? I visually inspected most of the lines today and have until now ruled this out because the symptoms went away for about a week after they first started and then returned.

[Tahoe3.0]

swapped all spark plugs for new.

swapped cylinder 2 coil pack for new.

still not fixed, no codes showing up

I am stumped.

[Tahoe3.0]

I ended up towing the car to a new-to-me shop over the weekend and spoke with the owner this morning, who gave me some excellent news.

Much like the OP my problem seems to have been blown valve cover gaskets due to me putting off the timing belt job for FAR too long. Oil was making its way into the spark plug wells and shorting out the plugs/coils is what we arrived at. His VAG-COM pulled misfire codes on cylinders 2 and 4 but he said that it was running beautifully this morning. Car is currently under the knife getting its much needed tbelt done which will include some shiny new gaskets.

Basically my "calculated negligence" (not having my finances together to get the job done on schedule) caused my problems. I dodged a big ass bullet on the tbelt and definitely know better. Never again. I think a small part of me wants the 3.0 to explode so I can justify dropping in a 2.7...

thanks for chiming in all, hopefully this thread can help other idiots like myself in the future.


edit: this was the condition my belt was in

[SJorge3442]

I ended up towing the car to a new-to-me shop over the weekend and spoke with the owner this morning, who gave me some excellent news.

Much like the OP my problem seems to have been blown valve cover gaskets due to me putting off the timing belt job for FAR too long. Oil was making its way into the spark plug wells and shorting out the plugs/coils is what we arrived at. His VAG-COM pulled misfire codes on cylinders 2 and 4 but he said that it was running beautifully this morning. Car is currently under the knife getting its much needed tbelt done which will include some shiny new gaskets.

Basically my "calculated negligence" (not having my finances together to get the job done on schedule) caused my problems. I dodged a big ass bullet on the tbelt and definitely know better. Never again. I think a small part of me wants the 3.0 to explode so I can justify dropping in a 2.7...

thanks for chiming in all, hopefully this thread can help other idiots like myself in the future.


edit: this was the condition my belt was in

I'd say you got your monies worth out of that belt! Glad to hear you're running good again. I too need to change my VCG before they start causing issues. They are already leaking oil on the passenger side. Putting it off till the spring and I'll just keep topping off the oil every other tank when needed until then.

[john_gonzo]

...Oil was making its way into the spark plug wells and shorting out the plugs/coils...

Along with leaky valve cover gaskets there is another source of oil around spark plugs. One level below the valve cover is the guide frame. Bad sealer between the guide frame and the head can allow oil to seep into the spark plug wells. This mating surface is the lower ring visible in the plug wells when the coils are removed.

A plugged or poorly operating PCV system can cause VG leaks too. The PCV hoses get brittle and crack which allows air into the system (instead of sucking fumes out the back of the valve covers). Gunk then builds up in the valve covers and eventually can block the PCV port. Gaskets start to leak due to overpressurization.

And holy shit, that belt!

[Tahoe3.0]

BUMP

Spoke to the mechanic and they mention it could be a damaged FLYWHEEL ??

Would it cause this shake ??

The answer to this question is yes. What actually happened was flywheel failed and shook the engine so bad it felt like a misfiring cylinder. I clearly needed to do my tbelt anyway but when I got it back today realized that something else was way messed up, turns out it has been a bad dual mass all along.

Cheers to doing timing and a clutch job at the same time, fml and my bank account.