Major bucking/jerking

[A4 Lemon]

I wrote a thread yesterday but it never showed up anywhere. Basically, it feels like fuel enrichment isn't working when applying throttle. I have to give slow, gradual gas or it bucks and jerks like a horse from severe misfires. I changed the plugs, used 1 new coil from cylinder to cylinder to rule out a bad coil. I unplugged the MAF to see if it would go into limp mode and improve driveability.. Would've told me if that was the issue. I unplugged the MAP sensor and it was improved dramatically. It still misfires on the highway if I apply throttle in drive (if I throw it in S and get the rpms up, it's OK...just gutless. Had it improved completely, that would tell me MAP, but its only improved, not fixed. I'm thinking unplugging the MAP maybe richened it up and offset a lean misfire being caused by something else? Only codes were misfires...300, 301, 302 and 303, and the 238 from unplugging the MAP. I'm broke so I can't afford to just replace everything till I find the issue. Does it sound like a bad o2? What are your guys' thoughts?

[A4 Lemon]

I also don't see and cracked or broken vacuum lines. Are there areas where they're prone to crack?

[Okedokey]

codes?

[A4 Lemon]

I said the codes in my post

[thenofjboy]

what did you use to scan for codes? Id would find someone with a VAGCOM and do a full scan on your car...

sounds like your coils are good but what did you gap the plugs at? How long has this been going on?

[80sGuy]

I wrote a thread yesterday but it never showed up anywhere. Basically, it feels like fuel enrichment isn't working when applying throttle. I have to give slow, gradual gas or it bucks and jerks like a horse from severe misfires. I changed the plugs, used 1 new coil from cylinder to cylinder to rule out a bad coil. I unplugged the MAF to see if it would go into limp mode and improve driveability.. Would've told me if that was the issue. I unplugged the MAP sensor and it was improved dramatically. It still misfires on the highway if I apply throttle in drive (if I throw it in S and get the rpms up, it's OK...just gutless. Had it improved completely, that would tell me MAP, but its only improved, not fixed. I'm thinking unplugging the MAP maybe richened it up and offset a lean misfire being caused by something else? Only codes were misfires...300, 301, 302 and 303, and the 238 from unplugging the MAP. I'm broke so I can't afford to just replace everything till I find the issue. Does it sound like a bad o2? What are your guys' thoughts?

Could you tell us a little bit about your ride? Year, model, mileage, transmission?

[A4 Lemon]

They're pre-gapped and the fact that it improved when unplugging the MAP tells me it has nothing to do with the plugs. I had 113k on the plugs and it ran fine. I thought it may be plugs so I changed them and no change. It's an 07 a4, bone stock, at almost 114k miles. If I weren't so broke i'd just buy a new MAF and o2 but these Audi parts are ridiculously expensive :-(

[Denio24]

You need to log! Now

You drive an Audi, and it sounds like you care about the performance of your vehicle. Vagcom is not a bad investment.

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[thenofjboy]

They're pre-gapped and the fact that it improved when unplugging the MAP tells me it has nothing to do with the plugs. I had 113k on the plugs and it ran fine. I thought it may be plugs so I changed them and no change. It's an 07 a4, bone stock, at almost 114k miles. If I weren't so broke i'd just buy a new MAF and o2 but these Audi parts are ridiculously expensive :-(

got a buddy with the same car, maybe you can throw in his MAF and see if its better? you can always get a can of CRC MAF cleaner...

post in the regional section for someone locally that has a VAGCOM. people do that all the time. GL

[A4 Lemon]

got a buddy with the same car, maybe you can throw in his MAF and see if its better? you can always get a can of CRC MAF cleaner...

post in the regional section for someone locally that has a VAGCOM. people do that all the time. GL

That sounds great..thanks!...but the fact I pulled the MAF connector and it didn't improve at all tells me it's not the MAF...even though the bucking when applying throttle sure seems like a MAF issue. Shouldn't it go into limp mode and stop the bucking? Where's your buddy with the MAF live?

[Okedokey]

Yeah O2 sensor can do that and also the rpm sensor. I don't know what those codes are. Only recognise VAGCOM sorry.

[thenofjboy]

That sounds great..thanks!...but the fact I pulled the MAF connector and it didn't improve at all tells me it's not the MAF...even though the bucking when applying throttle sure seems like a MAF issue. Shouldn't it go into limp mode and stop the bucking? Where's your buddy with the MAF live?

LOL sorry.....I left out the question mark DOH! ha. Maybe YOU got a buddy with the same car. also, call around local junkyards too, you might be able to get a MAF for cheap

[SLOPOKA4]

Sounds like my car did about a year ago, is the car tuned? Turned out to be my fuel filter was clogged......

[Sanjman]

Do you mean your codes are P0238, P0300, P0301, P302, P0303? If so you are over boosting and there are procedures on how to figure it out firther.... Google "P0238 b7 a4" is,a good start

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[A4 Lemon]

Do you mean your codes are P0238, P0300, P0301, P302, P0303? If so you are over boosting and there are procedures on how to figure it out firther.... Google "P0238 b7 a4" is,a good start

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I e been refreshing this thread for days and nothing new ever showed up till ibwent to the main forum page... Anyway, thanks! I thought 301, 302, 303 just means misfires on those cylinders? It's definitely misfiring. I'll look into what you said...thanks

[A4 Lemon]

And that day I had looked up po238 and it said it was the MAP... Which is unplugged (runs way better like that)

[A4 Lemon]

Well, thanks to dirtyaudi for using VAGCOM on my car. He found the high fuel pressure to be flatlined when I'd try and put a load on the motor. The low pressure pump was working a little harder than it should, which makes me think my fuel filter with 114k on it. But I'm wondering if low and high use the same fuel line? Could the clogged filter be jamming the whole thing up?

[Okedokey]

Yes, and its a cheap fix to try.

[1killera4]

Mine is doing the exact same thing. I replaced all coils and am still getting cyl. misfire codes and the flashing check engine light. I'm taking it to my mechanic on Saturday. I am done working on this...:lol:

[A4 Lemon]

Mine is doing the exact same thing. I replaced all coils and am still getting cyl. misfire codes and the flashing check engine light. I'm taking it to my mechanic on Saturday. I am done working on this...:lol:

Please let me know what they find

[Denio24]

I had an issue like this long ago; when i replaced the cam follower the symptoms miraculously disappeared. Not sure if it was directly related, but no more issues like that since.

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[1killera4]

Please let me know what they find

Will do.

[A4 Lemon]

Well it's not the fuel filter. Just did my timing belt and fuel filter and the issue is still there. I had noticed the intake was splitting slightly at the seam and listened with a hose..it was leaking. I sealed it all up with high temp U.V. adhesive and it still has the issue. Only thing I haven't checked is the cam follower.

[80sGuy]

^^

Could you tell us a little bit about your ride? Year, model, mileage, transmission?

You still hasn't answer the question - what kind of transmission???

[A4 Lemon]

Don't know...it had the PRNDS and manual gears 1-7 if you move the shifter to the right. My codes are for misfires. Po300, 301, 302, 303. VAGCOM confirmed. High pressure fuel wasn't coming on according to the guy who scanned it, but the engine never got to a point where it would need high fuel pressure...can't get past the stumbling, missing and popping...not a tranny issue unless there's some ridiculous connection between the two.

[1killera4]

Is it Quattro or FWD?

[80sGuy]

Don't know...it had the PRNDS and manual gears 1-7 if you move the shifter to the right. My codes are for misfires. Po300, 301, 302, 303. VAGCOM confirmed. High pressure fuel wasn't coming on according to the guy who scanned it, but the engine never got to a point where it would need high fuel pressure...can't get past the stumbling, missing and popping...not a tranny issue unless there's some ridiculous connection between the two.

If it's 1-7 gears and FWD, I can guarantee you it's the CVT transmission. So stop wasting your time and money on other things that won't remedy the problem. Could of caught the culprit earlier if you'll just let us know from my earlier post. Just a note, these are major symptoms of CVT failure as I've had the same major bucking, jerking, hesitating issues with mine and ended up replacing the whole box. Smooth as silk to this day...and hopefully ever. You can try one last thing: is to change the fluid. The only cost would be a few hundred bucks ($300-$400 and get it done only from the dealer!!). It might or might not cure the problem, but some here claimed to have remedied the issues after fresh fluids.

[A4 Lemon]

I had a feeling you were going to say that, and I did think of the tranny, until I saw the misfire codes. Erase the codes and it comes back again. Dont the misfire codes pretty much rule that out? And unplugging the MAP sensor made it way more tolerable. That's another thing not pointing to tranny.... :-(

[80sGuy]

Those codes (or issues) are not uncommon for our cars with this kind of mileage. They are in addition to your main problem. I hope I'm wrong but I don't see it any other way. When my CVT was acting up, my car has zero codes displayed nor recorded whatsoever. It was a perfect car except for the bucking and jerking.

[jpjmustang]

I had two items which caused my bucking/jerking

(1) the 1 inch (rubber hose) line with came off the upper engine (passenger side front of engine) and turned into a metal flex was cracked

and

(2) coil packs 3 and 4 were misfiring

After replacing both - idles great and accelerated well

JPJM

[Okedokey]

Change the fluid yourself. Its pretty simple, did it on Thursday night.

[A4 Lemon]

It's fixed! I had thought about how I had gotten pO300, 301, 302 and 303. It hadn't been missing on 4 which happened to be where I had a new coil. I had bought 1 coil a few weeks back and went cylinder to cylinder to rule out another bad coil. No difference. And it would always get worse and worse with time and heat. I said what the hell and spent 75 bucks on 3 new cheapo coils at autozone, and it's fixed. I've never seen 3 coils go bad at once. And jpjmustang...I hadn't seen your post until right now. Looks like we both had the same crap happen. Can't believe I stressed out over something so simple, but thanks everyone!

[80sGuy]

Well I'm glad it is just the coils.

[A4 Lemon]

Well I'm glad it is just the coils.

Thanks for your help :-)

[teddybear]

2008 a6 quattro 3.2 same isue bucks and jerks no check engine light

[Jeevan]

coils usually go bad due to heat, I pretty sure that your spark plugs are either of bad quality or the gap is too wide for the spark to jump. This creates heat and wears out the coil. if my guess is true, you coils will go bad in few months again.

spark plugs are like 4 to 5$ each doesnt hurt to change them all asap.