PDA

View Full Version : Cooler weather = misfiring issues return...



Quattrocket
09-19-2006, 04:36 PM
Well, I did a lot of work and thought I had fixed my misfires but no such luck [:(]
After 4 months of no misfiring It did it again this morning.
It seems when the outside temps drop dramatically overnight its causing my car to misfire in the morning until the engine warms up.
I had the car vagged and it showed only cyl 3, 1 and 4 misfire and a random multiple code. no o2 sensor fault or anything like that. I noticed I have been losing a bit of oil lately as well, but no evidence of a leak.
As long as the car is revving it wont miss but at idle the engine will struggle to keep running. the rpms will hit 800 the misfire and jump back up to 1300 then back down til it misfires again. could the temp drop be causing the coilpacks to act up? i dont wanna drop $200 on coilpacks if it might not be my prob, cuz I wanna sell the car soon.

Some things i have doen include:

new oil pump
-cam chain
-cam chain tensioner
-valve cover and tensioner gaskets changed as well of course
-spark plugs
-oil change
-coolant flush/change
-EFK install (heard faulty fan clutch can cause boost issues)
The engine is pretty noisy since the misfiring started as well. Several times when i left the car to run in the driveway to warm up before a trip, I came out to hear a knocking sound coming from the front of the engine while it was idleing. Even My mech doesnt know what to tell me. i might have him give it a really hard look over next week if hes not crazy busy. Any ideas boys? this prob is getting VERY old and tiresome for me.

Quattrocket
09-20-2006, 12:03 PM
BIGGITYBUMP

mike-2ptzero
09-20-2006, 12:10 PM
It sounds like a fuel/timing issue during cold weather temps. If you have an adjustable fpr you can always try lowering the pressure a little bit to see if the misfire at cold idle goes away.

marcini
09-20-2006, 12:12 PM
i think it is the coil packs, i had the same problem

mike-2ptzero
09-20-2006, 12:14 PM
Just odd that it only happens during cold idle and goes away when the car is warm and again when the temps get warmer.

bitterchild
09-20-2006, 12:15 PM
what brand and heat range are the plugs?

Quattrocket
09-20-2006, 01:08 PM
Originally posted by bitterchild
what brand and heat range are the plugs?

Right now I have the OEM Pfr6q (bosche i beleive)
but I tried NGK bkr6e and 7e both fouled and misfired within days. the pfr6q was the best one so far. As for longevity anyhow.

pac1085
09-20-2006, 01:09 PM
always had that problem with pc-16...

mike-2ptzero
09-20-2006, 01:16 PM
Originally posted by Quattrocket
Right now I have the OEM Pfr6q (bosche i beleive)
but I tried NGK bkr6e and 7e both fouled and misfired within days. the pfr6q was the best one so far. As for longevity anyhow.


Isn't that doing it backwards? Wouldn't you want to go with a hotter plug vs going with a colder one which would misfire even more. Might want to try a 5 heat range NGK plug.

bitterchild
09-20-2006, 02:37 PM
you running the correct injector/fpr?

Quattrocket
09-20-2006, 04:24 PM
Originally posted by bitterchild
you running the correct injector/fpr?

yup, bosche redtops and adj FPR set from 36-44 psi with misfiring occuring at all pessures. I thought I had the wrong injectors before but these are the correct ones as per the GIAC website's FAQ section.

Quattrocket
09-21-2006, 12:19 PM
Well, this morning I threw a solid CEL instead of the usual flashing ones for misfires, so hopefully whatever was going on the car is now gone and I can find out what it is...

Rosati
09-21-2006, 03:38 PM
how about dropping 80 at the VW dealer for coilpacks then?

b00st
09-21-2006, 11:40 PM
i found when i was setting my fuel pressure....that i had to actually disconnect the battery for 2hrs before the actual adjusted pressure would take place.

i was running lean with pc16....plugs were stark white....i kept bumping the fuel pressure but the ECU kept adapting and pulling it off. i was only disconnecting the battery for 20min or so....i had the fuel pressure up to 51psi and they were still white.

finally i disconnected the battery for 2hrs and set the fuel pressure back to the appropriate 2.8bar and the car runs great. i wish i would have set it right before i went to the dyno. i was running really lean then.

Quattrocket
09-22-2006, 01:13 PM
Originally posted by Rosati
how about dropping 80 at the VW dealer for coilpacks then?

AEB coilpacks are super expensive. I think they are closer to 80 bucks each.

Quattrocket
09-22-2006, 01:14 PM
Originally posted by b00st
i found when i was setting my fuel pressure....that i had to actually disconnect the battery for 2hrs before the actual adjusted pressure would take place.

i was running lean with pc16....plugs were stark white....i kept bumping the fuel pressure but the ECU kept adapting and pulling it off. i was only disconnecting the battery for 20min or so....i had the fuel pressure up to 51psi and they were still white.

finally i disconnected the battery for 2hrs and set the fuel pressure back to the appropriate 2.8bar and the car runs great. i wish i would have set it right before i went to the dyno. i was running really lean then.

I got the opposite prob. mine are black. I'll try your idea though thanks.

Quattrocket
09-22-2006, 01:15 PM
Originally posted by marcini
i think it is the coil packs, i had the same problem

How much did the coilpacks cost you?