Recently my car has been stuttering and shaking really bad when accelerating, it's in pretty much every gear and seems to be somewhat random, but it's typically only when accelerating.

(1998 2.8QM, 140k miles)

When I start accelerating, it'll be fine then all of a sudden it'll just bog down and hesitate and stutter a few times, then I'll switch gears, fine again for a second, then hesitate and shake a few times again. I believe this to be a misfiring engine but I am not an expert by any means

I haven't done a tune up but am planning on it when I get the time (and figure out how to get under my car to change the oil) --

I also know you guys are going to want codes but I don't have a code reader or VAG, if anyone is in the Seattle area it would be awesome if someone could scan my car as it's never been done since I owned it (no CEL surprisingly)

I plan on changing my spark plugs and doing an oil change ASAP, the car sat for like four years before I bought it so I'm assuming the plugs and oil are along the lines of THAT old...

I've read a bit on here about bad coil packs or something cause misfires a lot in the B5? not sure what those are but I hope it's nothing too expensive I am broke

Is it safe to drive the car if it's misfiring somewhat bad like this? I have another car but it's got bad tabs as of this month (need to get them haha poor Audi always has something to fix, knew it would be this way when I bought it though )

 

If your misfiring that often the check engine light may be blinking instead of solid. The coils are on top of each cylinder on my 1.8 and you need to remove them to even get the spark plugs out. Im not sure about the 2.8 but if the packs not on top of each cylinder follow the wires from the top of each cylinder and youll find it. Replace packs and plugs may solve all your problems. But the codes would help to be more acurate.

 

Thanks man, yeah I read about the blinking CEL and I haven't seen it blink at all which was weird to me too... yeah I know codes would be great I wish I could scan it, my uncle has an OBDII scanner that'd work right?

I am planning on changing my plugs asap, along with the oil, and coils if they're not too expensive, do you know how much those are? they sound easy enough to change too huh

How unhealthy for the car is it to drive while misfiring?

 

It could be something simple like plugs and coils or something more serious. A scanner will help you out a bit more. If you have a misfire these are some things that could cause it, but the best place to start is at the plugs.

Air Intake System leaking
Fuel Supply faulty
Injector(s) faulty
Ignition Cable(s) and/or Spark Plug(s) faulty
Ignition Coil(s) faulty
Exhaust Gas Recirculation (EGR) Valve (N18) stuck/open
Camshaft Position Sensor (G40) faulty

Possible Solutions
Check Misfire Recognition
Check Air Intake System
Check Fuel Supply
Check Injector(s) and Injector Sealing
Check Ignition Cable(s) and Spark Plug(s)
Check Ignition Coil(s)
Check Exhaust Gas Recirculation (EGR) Valve (N18)
Check Camshaft Position Sensor (G40)

 

Did you flush the old gas out before driving it? If you are running the 4 year old gas through it that could be the problem right there.

It does sound like it's misfiring, but misfires are usually accompanied by a flashing CEL. It would be best to get the car scanned for codes to see what the problem is before throwing money at the car. The coil packs for the 2.8 are more expensive than the 1.8, and are less likely to die.

If the car only misfires while accelerating, just try to avoid hard accelerations until you fix the problem. It shouldn't really hurt the motor, but it's still not something to do regularly.

 

thanks a lot guys, i didn't flush the fuel but I think it was driven a bit before I bought it, I'm just going off of the carfax, between 2008-2012 it was only driven like 4,000 miles, it had one owner so I'm assuming they purchased a new vehicle and rarely drove it until they finally decided to sell it.

The misfiring is much worse when it's humid and raining out, no idea why that would be, like today it's not raining and it's hardly misfiring at all.

I'm going to start with the plugs and go from there... I also think my valve cover gaskets are leaking, oil level is constantly low so I'll check the end of my plug wires when I do my spark plugs (to see if there's oil on them i believe?)

thanks again you guys rock

 

So, any update? All fixxed?

 

if the misfire gets worse when its humid/raining out then its most likely ignition related. if theres even the smallest crack/tear in a plug wire or coil-pack housing somewhere the moisture in the air will draw out your spark and ground it. most commonly you will see cars not starting in the rain because of faulty coil/plug wires. But i would throw some plugs and wires at it and see what happens, my .02

If you want to test it, run the car in the garage or when its not raining out. get a spray bottle with water in it, and spray/mist the plug wires and ignition components while its running. just listen for any hesitation/stutter/change in idle speed. If its dark enough when you do it, you may even be able to see the electricity arc around the faulty component when you spray it as the water draws it out. kinda cool sometimes.

 

I noticed mine would stutter or hesitate under heavy acceleration. It was a broken vacuum line to the fuel pressure regulator. Basically, the engine was thirsty for fuel when it needed it. No fuel, no power and it would stutter until I would let the accelerator off a bit.

 

Haha thanks guys, yeah I changed the spark plugs and haven't had a single misfire since, didn't even change the wires... it hasn't rained since I changed them and this was over two weeks ago so knock on wood, next time it rains I'm bound to get some misfires

Especially because when I changed the plugs I ended up tearing one of the plug wires at the base (where you grab to pull it out, the knobby part) tore the rubber a bit so it's exposing some wire I believe... It would not pop out for some reason, was suctioned in there extremely tight so it tore before it would ever come out

I plan on replacing all the vacuum lines soon, it's on my agenda, I have soo much maintenance to do still ahh **** i don't like thinking about it.