misfiring/ignition coil problems

[richieb138]

Hi Guys,

I'm having a problem with an irritating misfire with the throttle floored, usually around 4k and especially in the higher gears.

I had the problem when I first got the car, and a new ignition coil from the free recall fixed it...... for a few months or so. Slowly, it came back, and gradually got worse until it happened almost every time under certain conditions. I tried swapping each coil for a new one to find the bad one but it didn't show itself so I replaced all four coils and it 'almost' went away, i.e. it didn't happen too often and was much less severe when it did happen. Slowly it got worse again until it was happening all the time again and quite badly, so i figured that I must be killing my coils somehow.

I noticed that the insulation around the wiring across the top of the engine to the coils was a bit knackered so i replaced it all and got all new connectors and four new coils again, hoping that all would be cured, but no, i'm back to it being much less frequent and not too severe again.

Any ideas on where to look next would be much appreciated, although i'm pretty sure it's got something to do with the ignition coils because I get a very obvious improvement (even a complete fix the first time) when I replace them.

 

[<tuffty/>]

If its doing it under boost then it could be a lean misfire... tired fuel pumps are the culprit in that case typically... from your previous posts I believe you have an AMK S3? in which case you can log block 031 in VCDS and see what the fuel is doing when this happens... or you need to get it on a dyno and checked... I wouldn't take it to a dealer as they will throw parts at it and not actually fix anything..

Have seen this kinda misfire a few times..

<tuffty/>

 

[marrick92]

I've had this problem before, i had it diagnosed at an auto electricians as a ignition amplifier.. its the sensor that is attatched to your air box. I'm not saying it is this for definate but its a possibility.. i was charged £110 for the part but there is one on ebay for £35..

Audi A8 A6 A4 A3 Ignition Amplifier | eBay

 

[s3dave]

No ign amp on his car...

 

[g60leigh]

I have a problem with exactly the same symptoms. I have replaced the coils with the tfsi ones and fitted new ngk plugs. The problem is less but still there every now and then.
It is exactly the same as in it happens at about 4k rpm when throttle wide open.

The only thing that regularly shows up on vcds is a lambda error. Could this be linked?

 

[<tuffty/>]

I have a problem with exactly the same symptoms. I have replaced the coils with the tfsi ones and fitted new ngk plugs. The problem is less but still there every now and then.
It is exactly the same as in it happens at about 4k rpm when throttle wide open.

The only thing that regularly shows up on vcds is a lambda error. Could this be linked?

Plausible... if lambda is iffy it will affect fuelling and could be rich/lean and cause a misfire... get it sorted

<tuffty/>

 

[richieb138]

Cheers for the replies fellas, I haven't got access to VCDS but any idea if I can log block 031 if I get a trial version and a cheap ebay lead?

 

[g60leigh]

Plausible... if lambda is iffy it will affect fuelling and could be rich/lean and cause a misfire... get it sorted

<tuffty/>

Cheers Tuffty.
I am planning on getting it ordered soon as the rain stops so I can try and get under the car an get a part no for the lambda.
Unless anyone on here can tell me the part no for AMK? Or is it possible to get it through a vcds read?

Thanks all.

 

[g60leigh]

Cheers Tuffty.
I am planning on getting it ordered soon as the rain stops so I can try and get under the car an get a part no for the lambda.
Unless anyone on here can tell me the part no for AMK? Or is it possible to get it through a vcds read?

Thanks all.

I have just rechecked my logs and it is not a lambda fault showing. It is Exhaust gas temperature sensor. Fault code
P1453
AUDI-Exhaust gas temperature sensor 1 open/short to B+

Is this likely to be a wiring problem or component?

Thanks again.

Richieb sorry for hijacking your thread a bit, but hopefully this will help you with your problem too.

 

[s3dave]

sounds like a wiring fault...

 

[<tuffty/>]

I have just rechecked my logs and it is not a lambda fault showing. It is Exhaust gas temperature sensor. Fault code
P1453
AUDI-Exhaust gas temperature sensor 1 open/short to B+

Is this likely to be a wiring problem or component?

Thanks again.

Richieb sorry for hijacking your thread a bit, but hopefully this will help you with your problem too.

If the EGT sensor is playing up the ECU will run rich all the time and that could well be the reason you get misfires....

Based on that code I can assume its not VCDS you are checking with? open circuit suggests its unplugged or the wiring is damaged somewhere... short to B+ could also be wiring also but looks like a generic code... VAG extended the P codes for OBD II to make it a bit more granular but in this case it suggests a wiring issue of some description...

This is a fault you need to sort soon as the ECU will pour fuel in and you will end up with rubbish fuel consumption and the unburnt fuel will kill the CATs, mix with the oil thinning it and wash the bores increasing engine wear...

<tuffty/>

 

[g60leigh]

Just a quick update.
I have sorted out the wiring on the EGT over the weekend and it has completely resolved the holding back at 4k revs.

Tuffty - Thanks for the advice.

Richieb - I hope this helps resolve your problem.

 

[richieb138]

cheers g60leigh, much appreciated, i'll look into this. And thanks to Tuffty too!