So I got a misfire code the other day and cleared it with my Durametric. I was logging it to count misfires on the fly and it seems to only be at idle, mostly in Cylinder 4. Cylinder 1 will do it ever so often.

The spark plugs have recently been changed less than 1000 miles ago. The car is a EVOMS gt700 w/Giac flash at 36k on the odometer.

I'm guessing Coil packs, any other suggestions is much appreciated.

MT

 

Had a misfire cylinder 3. Changed the plugs, misfire cylinder 1... Crap.. One of the new plugs I put in was bad. Changed them the next day with a new set problem went away. I had it down to 2 hours for the second change out.

 

Thanks,

I had a shop put in the plugs when the car got a PPI, I was wondering what is the correct amp/voltage for the coilpacks to be tested?

 

You are very lucky to have a code that tells you what cylinder is having the problem... If it says Cyl 4 - change the plug and coil for that cylinder only. If the code stays, keep the plug and coil for next time and continue to troubleshoot, but I think you will find the problem is gone.

 

Bringing this back to life, I changed the coil packs for cylinder 4. The misfire is still there at idle not under load also I'm reading a 1.1 bar at wot. The car is a older style evoms gt 700 with Giac flash.

Could a vacuum leak be the cause? When I start the car the idle dips and catches again.

Any other suggestions is much appreciated.

 

Are you getting a code for a specific cylinder or just a general misfire code or no code at all?

 

I'm getting both, the general misfire code and Cylinder 4.

The codes are P0300 and P0304.

I'm assuming the the P0300 code will go away when I find out why Cylinder 4 is misfiring.

Again this only happens at idle and the misfire is only on #4. I'm stumped, the worst it can be anything from a burnt valve to faulty injector which I can't diagnose easily. I already changed the coil packs and plugs.

I'm thinking a vacuum leak at idle?

 

i get a missfire on cylinder 4 on start up every so often. It happens more when it is cold out. I change the plugs and swapped a coil pack on to cylinder 4. Still the same situation missfire at idle every once in a while when its cold out. Thing is i have this odd feeling i put the same coil pack back on 4 when i thought i actually swapped it....DOH!! Either way they were pretty new beru units, Don't recal if they were 997 coil packs though.....

 

It certainly wouldn't hurt to make sure you don't have leaks. These cars can be really hard to diagnose - the codes are often not directly related to the problem. If you are not sure about changing the coil pack, I would go back and do it again. I have a couple of spares that I use for diagnostics. If I swap it out and that wasn't the problem, I keep it for next time. If it fixes it, I throw out the bad coil pack.

 

Slider, thanks for the quick responses. I changed the coil packs with brand new ones from Beru and I am sure I put the new ones in with new plugs. I will do a pressure leak with a DIY from my local hardware store and compressor.

I was just wondering if there is anything else it could be? It is certainly cylinder 4 as indicated from my durametric at idle only.

 

I had the exact same thing on cyl # 4 - changing plugs and coil packs made no difference. It turned out to be a fuel injector.

 

Ria was this only at Idle or did you get a misfire when driving?

 

Thats not fun, I heard injectors are a huge pita to instal. I have relatively new 72lbs injectors ( i bought ttboost's car) I can't imagine they would be bad this quickly. I have 60lbs on my B5 S4 for well over 4 years with no issues.....

 

Yep - only at idle, and only on cyl #4.

I had 60lb injectors that were only a year or so old when I developed the problem.

 

Thanks Ria, I was hoping it would just be a boost leak but I think problem is being the injector.

Is there anyway to diagnose the problem via Durametric to be sure it is the injector that is the problem?