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I was doing some data logging looking for a possible falty sensor and I noticed if I hold the rpm at a steady 1500 I get 2 codes for multi misfire, and random misfire. Doesn't show on the check engine light till I get up to around 2500 rpm the it lights up n starts flashing. Any idea what could cause this? I swaped plug wires and that didn fix it
What are we working on, what code numbers, any mods, how many miles, can you identify which cylinders are misfiring?
If your pcm is spitting out a code, then there is a cylinder misfiring enough that you'd be able to scan and see which cylinder is misfiring.
Add all the cylinder misfires to the table display and drive around while keeping an eye on which cylinder is showing the most counts.
Most counts: some cylinders will pick up false misfires from a cylinder that is actually misfiring.
P300 is the code.
I'm not able to see which 1s r misfiring I'm just logging off my I phone lol, but I'm fixing to send my PCM back to u this week and was trin to get some info for some fine tuning. Bank 1 LTFS is running at -3 which I belive is ok. -2 is wat we want right? Bank 2 is -10 so that's to much fuel right? It's in closed loop I had just cleared the codes. Also my MAF is stayin at 1lb I think it is ill have to recheck but 1 something and if u rev it hard I'm lucky if it jumps up to 10. But it does very fast and back to 1 Evan if u hold rpm steady day 3000 it's at 1, does this seem right? I have the screen removed and just clean it and the filter last week
It's reading lb/min on the MAF I'm using gopoint from Palmer performance to read it. I have a friend that has the hp tuner program, can he data log for u with out me havin to buy credits?
It's a 2000 Z71 new body, 5.3, bout 120,000 miles on 05 avalanche motor. Only mods is spectra cold air, screen removed on MAF, exhaust, and mid grade tune from Nelson. I can't tell which is misfiring. That's all it says I deleated the codes but ill make it doit tomarrow n get them. It has done it b4 with the old stock computer I had diablo sport on it then. But hasn't done it in a long time since the tune. But I can make it do it anytime now, seems like as long as there's no load on the motor it will do it from 2000 rpm upQuote:
Originally Posted by 96/chevy/pu
pull the plugs and read them, they will tell you which are misfiring
Get me a good long scan with various driving. No need to save multiple scans, just one big one. Save it as .hpt format so i can view it with the scanner.
No, not rich. ltrims indicate how much fuel the pcm is trimming or adding to maintain stoich. -25 and a rich code would mean it's running too rich because the pcm can't pull enough fuel to satisfy commanded.
Using hptuners, you'll be able to see individual misfires.
Ok so he can hook up to it and log with out me payin for more credits?
I'm betting your misfires are on the bank two side just going off the LTFT you gave us, misfire = fuel unburned which would explain why computer is taking away more fuel on that bank. You could have something else going on, just makes since in my head. Guessing HPtuner will give you those individual cylinder misfire as Allen suggested, I don't presently have HPtuner but than hear comes Christmas!
The front o2s r new, could falty coil packs maybe the cause? I don't have anyway to check individual cylinders. But I do need to pull my comp so I can send it in n get it back n time when I get my trans built. So I guess I'll have to hold off till then
I wouldn't send computer in to be retuned with reading your having with a misfire this will give false reading. Fix misfire than do some datalogging
Ok. So back to my original problem, shift is harsh in to second. I'm not getting any codes and its not the trans, this is the second trans it's done this with. There saying it's not the line pressure in the tune. But that's what it feels like and been like that since I put the computer on. But what do I need to look for as far as locating the faulty sensor? Front o2s r new dealer part, there reading correctly. Only 1 that sticks out to me is the MAF wat kind of read should it be puting out during operation?
Ok I have a bad MAF guess my PCM don't mind since there's no code lol. Can this cause random misfire and ltfs to be out of wack? I havnt replaced it yet to know myself. But wanted to know if I need to keep looking