Barnes
Well-known member
I've got a misfire I cannot figure out. Pretty much desperate at this point.
Symptoms: Car had a code44 off and on for a long time. Misfire is severe at cold idle, sometimes the car stalls. Warm idle the misfire clearly happens, but the engine can barely hang in there. I'm pretty sure it happens at all ranges as my on boost performance doesn't seem to be right.
It appears (and the code 44 would indicate this) that and entire coil is simply not getting the fire signal. This misfire can go for several seconds! Not just a single spark missed, long stretches of seemly no spark.
I'll try to get a video to post.
Config:
Stock coils (*WAS* a COP setup.)
3g MAF
660 denso injectors
Evo3-16g
AFRP set @ 38psi
Stock long block except for a cyclone intake.
Walbro 255 pump
Eprom ecu w/keydiver ecu (CAPS have been replaced)
Diagnostics and adjustments so far:
Boost leak checked
TPS adjusted to 0.5v/10%
Set base idle and timing as best as possible
6-7 ground locations cleaned down to bare metal
FSM check of transpack wiring(except pins 2 and 7, because I'm not sure how to do it.)
FSM check of coil pack wiring
Cleaned the connectors for the coil, CAS, transpack thoroughly.
Listened to the injectors with a stethoscope and they sound good.
Injector resistor pack checked out.
Items swapped with no change
2x stock coil packs
1x trans pack
New Spark plugs (NGK BPR6ES) @ 0.028" (dielectric grease used for sealy)
New Spark plug wires (NGK)(dielectric grease used for sealy)
1x green top CAS
1x socketed ECU with my chip installed (thanks CarRacer)
Per some old posts by BluFalcon (Ed) who had a similar problem, he found a short in his wiring harness. So just to completely isolate that possibility, I used some parts from an old wiring harness, and built some jumpers between the ECU and various parts.
Stock wiring completely bypassed at this point:
ECU to transpack (Pin 54 to 7, and 55 to 2)
Transpack to coil (1 to 1, 8 to 1)
Coil directly to battery positive.
Transpack ground straight to ground.
I've also added several grounding jumpers between the ECU, battery, engine, and chassis.
So after ALL this, I still get the same exact symptoms. The code 44 isn't back, but I haven't done more than idle the car in the garage. There are a few remaining things that have been constant through the whole process, and some other things I can't explain.
1)Keydiver chip (although I swear the car did this on the stock ecu)
2)ECU voltage supply i.e. MFI relay. I haven't checked it.
3)O2 doesn't cycle at idle, runs in the mid to upper 0.9v range. Although I think this is normal if you are rich, indicating spark misfire.
4)Gas is kinda old, BUT I'm pretty sure I put stabilizer in there. Also, that shouldn't affect a code 44 misfire.
5)Right as the misfire starts, I can see the injector pulse-width on the logger jump from ~1.5ms to 3ms. Now, I'm not sure which comes first, the misfire and idle drop, or the IPW jump. My guess is the former because it's dumping in fuel to try and bring the RPMs back up.
One of my last options is to buy/borrow an oscilloscope which would help give a more positive diagnosis. Trying to avoid that however.
I'm going to try and gap the plugs down further. It's an unlikely 'fix', but it's easy and quick. Any other ideas? I'm ready to throw in the towel. /ubbthreads/images/graemlins/frown.gif
Symptoms: Car had a code44 off and on for a long time. Misfire is severe at cold idle, sometimes the car stalls. Warm idle the misfire clearly happens, but the engine can barely hang in there. I'm pretty sure it happens at all ranges as my on boost performance doesn't seem to be right.
It appears (and the code 44 would indicate this) that and entire coil is simply not getting the fire signal. This misfire can go for several seconds! Not just a single spark missed, long stretches of seemly no spark.
I'll try to get a video to post.
Config:
Stock coils (*WAS* a COP setup.)
3g MAF
660 denso injectors
Evo3-16g
AFRP set @ 38psi
Stock long block except for a cyclone intake.
Walbro 255 pump
Eprom ecu w/keydiver ecu (CAPS have been replaced)
Diagnostics and adjustments so far:
Boost leak checked
TPS adjusted to 0.5v/10%
Set base idle and timing as best as possible
6-7 ground locations cleaned down to bare metal
FSM check of transpack wiring(except pins 2 and 7, because I'm not sure how to do it.)
FSM check of coil pack wiring
Cleaned the connectors for the coil, CAS, transpack thoroughly.
Listened to the injectors with a stethoscope and they sound good.
Injector resistor pack checked out.
Items swapped with no change
2x stock coil packs
1x trans pack
New Spark plugs (NGK BPR6ES) @ 0.028" (dielectric grease used for sealy)
New Spark plug wires (NGK)(dielectric grease used for sealy)
1x green top CAS
1x socketed ECU with my chip installed (thanks CarRacer)
Per some old posts by BluFalcon (Ed) who had a similar problem, he found a short in his wiring harness. So just to completely isolate that possibility, I used some parts from an old wiring harness, and built some jumpers between the ECU and various parts.
Stock wiring completely bypassed at this point:
ECU to transpack (Pin 54 to 7, and 55 to 2)
Transpack to coil (1 to 1, 8 to 1)
Coil directly to battery positive.
Transpack ground straight to ground.
I've also added several grounding jumpers between the ECU, battery, engine, and chassis.
So after ALL this, I still get the same exact symptoms. The code 44 isn't back, but I haven't done more than idle the car in the garage. There are a few remaining things that have been constant through the whole process, and some other things I can't explain.
1)Keydiver chip (although I swear the car did this on the stock ecu)
2)ECU voltage supply i.e. MFI relay. I haven't checked it.
3)O2 doesn't cycle at idle, runs in the mid to upper 0.9v range. Although I think this is normal if you are rich, indicating spark misfire.
4)Gas is kinda old, BUT I'm pretty sure I put stabilizer in there. Also, that shouldn't affect a code 44 misfire.
5)Right as the misfire starts, I can see the injector pulse-width on the logger jump from ~1.5ms to 3ms. Now, I'm not sure which comes first, the misfire and idle drop, or the IPW jump. My guess is the former because it's dumping in fuel to try and bring the RPMs back up.
One of my last options is to buy/borrow an oscilloscope which would help give a more positive diagnosis. Trying to avoid that however.
I'm going to try and gap the plugs down further. It's an unlikely 'fix', but it's easy and quick. Any other ideas? I'm ready to throw in the towel. /ubbthreads/images/graemlins/frown.gif
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