i'm getting mixed reviews from people here, and now i need to ask the J tuning community what you all think i should do next to try to diag my issues.
my motor build is in my profile... 2000 Z24 N/A Build
the first issue is that i am forever throwing a P0300 code. It hits pending DTC within minutes of startup, and sets a MIL after 3 key cycles.
So far i have replaced:
--Plugs
--boots
--coils
--coilhousings
--ICM (from junkyard)
--Engine Wiring harness (with new harness)
i am running LSJ Injectors
My Tuner, Joe Rutledge, has put a base tune on the car. He has set the injector constant for the LSJs, and done some basic fuel and timing tuning.
I am running out of ideas... So far, it has been suggested to me that the .430 cams and lack of CPS are the cause, others say the ECM is bad, and others stay the Tune is incomplete and this can be tuned out. My real question here is what else could cause 24/7 random misfires?
When are you getting the misfires? Idle? Driving, WOT?
Any logs?
FU Tuning
i've recorded freeze frames at idle, in motion, at WOT ... and cool intake temps and warm intake temps... in open and closed loop... seems like its all the time... the only time i notice it while driving is when i am in stop and go traffic and the car hesitates going in to gear when im going on and off the clutch a lot
we' ve checked timing twice when the motor was dropped in 15,000 miles ago. i even put a brand new timing chain on. timing is right
Have you gone over ALL of your grounds?
P&P Tuning
420.5whp / 359.8wtq
yes... while the motor became quieter when we replaced the wiring harness, the misfire problem did not change in the slightest. the new harness came new from Vintage parts.
im starting to think i have a bad ECM... this past weekend i pressure washed the engine... (something ive done a thousand times before)... usually i have IAC issues for a couple hours until the water dries out, in this case, the IAC issues are computer related, which is a first, and the car is having major runability issues for the first time. The IAC is holding 2500 - 3000 RPM while slowing down until i reach 3 miles an hour to which it drops to normal. After the motor warms up and after i come to a stop, when i give it gas to go in to first gear, the car hesitates, revs, backfires and stalls. once i restart it, the car engages first and moves. when i attempt to feather the gas above 5 MPH out of gear, the car acts normal, it seems to only want to do this when stopped (but it got to the point today where it did it every time i stopped)
i also noticed that although the majority of the time while cruising the Wideband hung around 14.7, there were times where it would jump from 10 to "---" (which is above 17) and mostly stay at the "---" though the car didn't act like it was leaned out.
so i wonder if water has been getting in the ECM and jacking it up worse and worse...
Joe told me that i'll have to repurchase credits if i want to reload my tune on another PCM, while a couple of my co-workers said when they had to swap an ECM out, as long as the VIN is the same in the ECM, HPT will write to the new ECM without additional credits... can anyone tell me which one of these statements is correct.
The VIN/OS has to pair up. If they don't, and Joe does not have a model/year license, you will have to purchase more credits. I', honestly not sold on the PCM being your issue.
P&P Tuning
420.5whp / 359.8wtq
i know he doesn't have the model/year license... thats what i thought was the case... but i'd figure i'd ask...
if you don't think the PCM is the issue, do you have any other ideas for things i can check for to be causing this?
UPDATE: driving it this morning. The car acted normal for the first 25 minutes of driving. I put about 23 miles on it before it started to act up... when it did i noticed the wideband start flicking from 10 to ---, then i pushed in the clutch and every time i'd pull out of gear to slow down to a stop, the car would rev and hold between 2500 and 3000 RPM until 5 MPH to which it would drop to idle... finally as i was pulling in to work, the car started to do the stall out thing trying to give it gas going in to gear... i'll hook the scanner up later on today and see if any new codes have popped up.
I had to slot the tps to run the pre 95 TB ... However on a scan tool it still reads 0 closed and 100 at WOT ... I've also had the rev issue periodically in the past with the 95 TB I had .... But I wonder if water got in the connector and is hanging out causing my current problems.
Mystic02VA (GME Chat) wrote:I had to slot the tps to run the pre 95 TB ... However on a scan tool it still reads 0 closed and 100 at WOT ... I've also had the rev issue periodically in the past with the 95 TB I had .... But I wonder if water got in the connector and is hanging out causing my current problems.
I have had TPS show fine on the scanner and still be bad. Seen quite a few of them acutally....
P&P Tuning
420.5whp / 359.8wtq
Ill run next door to Chevy and order another tps today ... but even if that is the cause of my rev/stall issue, that wouldn't be the cause of the random misfires, would it
It's almost acting like my Eco did when my map sensor recently went bad. It was randomly making the car jerk while driving and causing the afr to do just like yours.
I've replaced the map sensor recently ... No changes.
When my TPS on the vert went up the car would buck and stutter, rev at crazy rpms then try and die, act like it had no power when I took off and damn near stall when I let my foot off the gas. I hope it fixes your problems. If it is causing the engine to run lean or rich at any given time that explains the random misfire code. It however did not have the damned annoying 5mph issue. My battery died on the Z btw and now its doing the 2500-3000 thing again it had tamed down to like 1800 for a while.
I now have a tps low input code ... So that would explain my recent symptoms. It does not explain my misfires since I've had them since the first start up on this motor and I have since replaced the TB and all the components ... Still misfires ... Md suggested that its probably all in the tune while Joe said my tune is in the ball park.
I would send a copy to some others and let them look over it just to be sure.
Have joe send the tune to all of us to look over. right now we are just chasing our tails.
I'm sure Ryan or John could give it a quick look over.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
Ryan and Joe know of each other... so if Ryan is willing to look it over, i'll ask Joe to send it his way.
as for now, im putting my 95 TB back in, as it has known good tps and IAC valve. i have no clue what year quad 4 my current 60 MM Mantapart TB is from, so it'll be nice to have sensor in hand trying to find a replacement.
Mystic02VA (GME Chat) wrote:Ryan and Joe know of each other... so if Ryan is willing to look it over, i'll ask Joe to send it his way.
as for now, im putting my 95 TB back in, as it has known good tps and IAC valve. i have no clue what year quad 4 my current 60 MM Mantapart TB is from, so it'll be nice to have sensor in hand trying to find a replacement.
If Joe wants to send it to me, I'll take a look at it. He has my email.
P&P Tuning
420.5whp / 359.8wtq
i'll shoot him an email tonight
UPDATE: I put in my old 95 Quad4 TB, the car is acting worlds better... still misfiring, but runs smoother... i reckon the TPS was going bad on the Pre95 Quad 4 TB for a while now.
i did notice some things on the scan tool though, after putting on the 95 TB.
The wideband would bounce back and forth from about 14ish to --- while the short term fuel trim would be in the negatives while the wideband was at --- and would be in the positives at 14.7 or lower
im not sure if that means anything though.
Edited 1 time(s). Last edited Wednesday, March 23, 2011 6:15 PM
So my car drove completely normal yesterday home from work...
today it decided to pull the exact opposite issue. Anytime i put my foot on the clutch or pull out of gear, the car stalls... if i turn the AC/Defrost on, the car idles normal...
on my way home down the interstate, i turned the defrost off and cruised with no issues, but once i got in town, it kept wanting to stall, and then i hit the gas and nothing happened, so i down shifted to second (at about 45 MPH) and floored it, and it sounded like i lost a cyl. I flipped the defrost back on, and after 3 or 4 seconds, the power came back and instantly revved to where it should have been at... i drove the rest of the way home with the defrost on, and it drove normal... parked in the driveway and shut the defrost off and the car stalled...
FML its like one thing after another
