Misfire, no codes

[alm001]

Originally Posted by Smallblock454

So i have some questions:
When did you clean the sparks the last time? / How many miles ago?

Plugs have less than 700 miles on them

is your car a daily driver or a seasonal car or did it sit for a longer time in the past?

The car sat from January 5th to about April 4th. Gas was purchased on Dec 25th, refilled April 14th

If is had sit for a longer time, did you use a fuel stabilizer before you got it to sleep?

No

Did you use an injection cleaner in the near past?

No

Was the engine really warmed up before you pulled the sparks? Because they should look a bit more brownish.

I haven't driven it since 4/27, except in and out of the garage

Replies above

[Smallblock454]

Hello alm001,

first thanks for answering my questions.

So it seems that the sparks are pretty new and that the car didn't sit for a longer time.

Why did i ask for sitting for a longer time: i had a motorcyle with carburettors that was sitting for 8 years. I started it and it run well, but had some problems with upper revs. I dismatled the carburettors and found a kind of gumming (Verharzung is the german term for that) all over. It looked like a breaking up clear code on a car. This harnish clogged everything and that is why the bike didn't run well at higher revs.

So if the car has sit for a longer time in the past that could cause problems by gumming.

So there are 3 ways fuel injectors can fail.
1. they can fail completely, but that would give us a dtc.
2. they can be clogged
3. they can leak

If they are clogged than the clyinder would run lean but in general you won't get misfire.
If they are leaking you will get missfire, because there is too much fuel in the cylinder or fuel in the cylinder when it had not to be there.

So, because you don't get a dtc and because you have misfire and because of the way the spark looks like i would say some of your fuel injectors are leaking.

And because that you only have driven 700 miles on the sparks i would say act fast and don't drive too much with the car.

My recommendation is to uninstall all fuel injectors and bring them to specialized workshop. They can check if the fuel amount is OK, if the way the injectors spray is correct (german term = Spritzbild) and if one or more of them are leaking. Maybe the bad ones can be rapaired, maybe they had to be replaced.

Hope that helps.

Regards
Markus

[JayG]

Originally Posted by alm001

I think that will be my plan, but if I'm going under there, I may just swap in new coils anyway. at 98k miles, it could probably use them anyway.

The part number on my coils is 996 602 102 00
Does it make sense to use the same ones, or the updated 99760210700?

If you are going to buy new coil packs, get the newer ones

best price I found was warehouse33auto.com
put rennlist in the coupon code and you get 10% off

[911monty]

I would think you should get your fuel pressure before going too much further.

[Smallblock454]

@911monty:

Good idea, but if he would have a low fuel pressure i think all cylinders/sparks would be affected the same way. Please take a look at the picture of the sparks (i know you did): Misfire, no codes

But maybe it's a good idea to check the fuel pressure too, because fuel pumps on these cars tends to get fatigue and the sparks look more black and white than brown.

Just my 2 cents.

Regards, Markus

[911monty]

Originally Posted by Smallblock454

@911monty:

Good idea, but if he would have a low fuel pressure i think all cylinders/sparks would be affected the same way. Please take a look at the picture of the sparks (i know you did): Misfire, no codes

But maybe it's a good idea to check the fuel pressure too, because fuel pumps on these cars tends to get fatigue and the sparks look more black and white than brown.

Just my 2 cents.

Regards, Markus

Marcus your expert advice is most appreciated! In your previous reply you mentioned leaky injectors, I also think this is possible. This would cause some cylinders to run rich, confuse the 02 sensors causing other cylinders to run lean correct? There appears to be soot on the electrode also pictured indicating possible rich/misfire.

[alm001]

Thanks everyone for the suggestions. I'll keep plugging at this when I have spare time.

[alm001]

Took it around the block, and got it to misfire - 4th gear up hill, 2500rpm,light throttle

Thursday,05,May,2016,17:59:57:42003
VCDS Release 15.7.4 (x64): Generic OBD2
Mode 07: Pending emission related fault codes

Address 11 (Engine): 1 Fault Found:
P0302 - Cylinder 2: Misfire Detected


So the #6 misfire must have been a fluke (or a sympathetic symptom). I'm going to swap 2 & 3 when I get a chance and retest.

[alm001]

Well this is embarrassing.

Went to take apart passenger side, got the wheel off, got the fender liner off.
Tugged on the #2 electrical connection... and I was able to pull it off. I must have not "clicked" it in when I did plugs 700 miles ago.

So, double check that the plug is set. Get that stupid rubber boot out of the way. CLICK it in, then push the boot down.