jrob56

iTrader: (39)

Swapped in another ls1, car had 200k on it that the engine came from but awesome oil pressue and it looked good so we threw it in. New tr55 wires, msd plugs, 17/8 headers and Y(no cats), single exaust into magnaflow 4x9. Ls6 intake, ls6 injectors, slp lid. Stock maf and sensors on stock tune.

After the swap we put in the old speed density tuned pcm and it had the misfire/hesitation and threw the 2 maf codes oviously and the AIR code.

Because I thought it might run better I swapped in the 02 stock PCM so it could use the MAF and make adjustments. It does run better but misfire is still there somewhat at idle, hesitation on take off a lot better but get it once in awhile. Itll throw an o2 code and AIR code.

Could these issues just be because it needs tuned?

smokeshow72

Are you sure about the injectors? Accidentally put a 26lb tune back in my car with 42lb injectors and it displayed the same issues you described until we fixed it; car idled rough and fell on its face every time the throttle opened because it was pouring fuel in the cylinders with the wrong injector constant.

C

jrob56

iTrader: (39)

I bought them from a member with 80k miles and I think I checked the number on each individually, but I will check those first thing tonight to make sure. I have some truck coils laying around to so I think Im gonna swap those in just to rule the coils out.

It seems a little intermittent as well, and runs smooth as can be once it gets some rpm. Havent gone full WOT as I dont think its safe untuned, especially with the misfire at idle.

jrob56

iTrader: (39)

Update: All injectors are the same part number, and for sure ls6's. Swapped coil packs with another set with no change. Swapped msd wires because they felt a little loose when all the way down with some Oreilley ones and no change. Plugs is the last thing I know of to try, PITA but worth a shot for 20 bucks.

When started cold after work today it didnt do it at all, but after it got hot at the first stop light I stopped at it started doing it at idle.

Any other ideas? It will not throw a code for misfire, wish it would... Just P0140 o2 no activity bank 1 sensor 2 which I believe is the rear so no biggie there. And its throwing the air injection code since the system is gone..

BLK02WS6

iTrader: (2)

Log misfires and figure out which cylinder it is. Was the car it came from an M6? could be a bent pushrod from a missed shift... or a broken valve spring...

jrob56

iTrader: (39)

I wish I could log it, trying to find someone who can. It was from another auto B4C, dont know if you can hit the rev limiter hard enough in an auto to do that? Valve springs are good, checked them when it was going in the car.

Can a car be a lil rough and it just be the tune or be normal? Im just baffled as to why it wont throw a misfire code

BLK02WS6

iTrader: (2)

With all those miles, could just be in need of a valve job... hard to say. You need to get someone to log it to see how far off the tune is - but with the few mods you have, I would think hard parts are the problem, not the tune.

jrob56

iTrader: (39)

Thanks for the quick replies, I left it to sit today in the garage so I can swap the plugs when I get home and it wont be hot. If that doesnt do it, we will def be finding someone to log it before we tear into it.

jrob56

iTrader: (39)

Swapped the plugs out, and even though they looked good, must be a small crack or something somewhere. So far no misses since swapped out, Ill keep driving it and report back.

I also gapped a little tighter. Went with .055 the first time, stepped down to .045 closer to the new GM spec.

This is a pic of #7 was the whitest of the bunch, all looked a tad lean but were a tanish white, 7 was a little whiter. Is this acceptable for stock tune? Going to get it verified with a wideband through a friend tomorrow I think.