this has been an on going issue and after working on my own and doing a ton of reading to get it resolved I've had limited or no success. I keep getting a lot of misfires according to HPT scanner. Its hard to tell if its a real misfire or not with all the vibes in the car. I have raised the Idle speed to smooth things out, so now it feels like one of those hand massagers on a low setting. I get a surge feeling from time to time that I suspect is the auto trans not liking the higher idle because I don't get it at lower idle speeds.
Everything in the ignition system engine side has been changed out. I had a completely stock set up to now having an MSD set up, with the 2200 coils, MSD wires, CAM SYNC GEN, and of course the DIS BOX. My mods are the usual suspects INTAKE, COMPCAMS STG 1, 2.25 EXHAUST, 4-2-1 HEADER. TTR UPPER MOUNT, TTR AUTO TRANS MOUNT, RKSPORT DOGBONE. I'll get a fresh scan in today to post up, I noticed that somehow my scanner was logging the AEM WB that comes with the HPT instead of the custom one I had set up with the offset corrected. still not sure how that got switched on me.
also how can i post up a log here, on HPT I can just do it right in the post from my computer. pictures are easy, not sure how to do a scan file here.
What is your AFR when this is happening?
GM allows a lot of misfires in a certain time frame before tripping a code. I have found the Eco does not like to run righ, or safe rich, or it throws misfires.
FU Tuning
I scrolled through the chart and it goes from 14.37 to 15.15 AFR thats w/o the offset, go busy this AM so I don't have a new scan, but I think its close enough that it shouldn't matter too much. heres also a picture of the chart so you can see more of whats going on. the misfires seems to go in waves.
FYI: I just reread this and realized I left out I have the LSJ injectors too, constant is set to 0.11866
That AFR it should be good, but when I have seen this kind of misfires on a Eco, it usually stays consistent, or waves as you said.
Does it feel likes it misfiring? Does the fan come on?
Different motor but I had misfires showing on my LD9. Not at idle, but during a pull. It would come in waves like that. You could not feel it misfire. Made good numbers like that. Anyone who rode in the car was like this thing is not misfiring. I tried different plug gaps, switched to a 2200 coil and wires, then MSD coils. No difference. Went back to stock, and it still gets it, but is not really affecting the performance.
FU Tuning
to me it doesn't feel like a misfire, or a stumble and I can live with it being there, I'm just wondering if its be detrimental to tuning. in other words is the PCM adding timing on me thinking its a real mis, and if it is can I filter it out? the timing advance is all over the place, and since I didn't start tuning until I got the cams in I don't know what normal really looks like.
I have also seen cams do this. more so at idle. If you idle the car up wiht the gas pedal slowly does it go away? or feel smoother?
FU Tuning
Sorry I didn't post back sooner, my day seems to have disappeared on me. not sure on the question of the higher RPMs. I'll test it out tomorrow and post back.
Mine does the exact same thing. But I know why mine does lol. I fuel fauled my plugs this winter. Since we have no control over the iat part of fueling I was pig rich at start up all winter long. Now I gotta retune and change plugs.
SLO CAV (autocrossing dude) wrote:Mine does the exact same thing. But I know why mine does lol. I fuel fauled my plugs this winter. Since we have no control over the iat part of fueling I was pig rich at start up all winter long. Now I gotta retune and change plugs.
You just dont drive hard enough, lol. With boost those babys should clean right up.
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Is it picking up KR at the time its doing this?
P&P Tuning
420.5whp / 359.8wtq
Mine does not. but I'm sure your talking to the op. Sorry to thread jack guys didn't mean to.
sorry I didn't get back sooner life got in the way.I don't know what it is but this week has been a total cluster &*$%.
the misfires go away at about 15-1600rpm below that its there. the Kr I have it a random 0.2-.0.4 and one spike of 0.8 but it never recured.
Cinny wrote:sorry I didn't get back sooner life got in the way.I don't know what it is but this week has been a total cluster &*$%.
the misfires go away at about 15-1600rpm below that its there. the Kr I have it a random 0.2-.0.4 and one spike of 0.8 but it never recured.
So just to verify. These misfires are at idle, below 1500-1600 RPM's?
The KR you mentioned was this also during the same time as the misfires?
FU Tuning
your gonna hate this most of them are, but there are a couple that show up right after the misfires drop off and then start a few cycles later. you want me to send you my log so you can look for yourself?
Cinny wrote:your gonna hate this most of them are, but there are a couple that show up right after the misfires drop off and then start a few cycles later. you want me to send you my log so you can look for yourself?
You can email me your log, need your config file also. Email in profile is fine.
I think the cams are the reason behind the misfires.
FU Tuning
sent, the fun part is I'm going to have to go through this again when I switch everything over to the 2.4 harness and computer
Screaming for Mercy!! wrote:That AFR it should be good, but when I have seen this kind of misfires on a Eco, it usually stays consistent, or waves as you said.
Does it feel likes it misfiring? Does the fan come on?
Different motor but I had misfires showing on my LD9. Not at idle, but during a pull. It would come in waves like that. You could not feel it misfire. Made good numbers like that. Anyone who rode in the car was like this thing is not misfiring. I tried different plug gaps, switched to a 2200 coil and wires, then MSD coils. No difference. Went back to stock, and it still gets it, but is not really affecting the performance.
I'm glad to hear that... my Ecotec does the same : Random Misfires on idle, especially on #3 Cylindrer. In low throttle, cruise and WOT i have no Misfire and Kr if that can reassure you.
Boost Lover
John after looking at stuff any thoughts on this?
Cinny wrote:John after looking at stuff any thoughts on this?
Only thing I really see out of place is the TPS reading 10% at idle.
Which plugs are you running?
FU Tuning
right now I'm running some Autolite double platinum, I have been running AC Delco Iridiums that are supposed to be in there. I changed them just to see if it would make a difference. nothing really changed, and the MSD may be happier with the platinum plugs. I remember when I had the MSD on the old 2200 it was drilling a hole on the ground electrode with the Iridiums.
I forgot to ask, isn't there a way to correct the TPS thing, I remember something about this, but couldn't find anything in my book other than the basic replacement stuff.
I would try some NGK's. I hate Autolites in GM motors, but that is me.
FU Tuning
thats like me with Bocsh plugs, I have the old ACDelco/NGKs I'll double check the gap and put 'em back in
thanks for your help, I've been chasing my tail
