Conv_z28_camaro

I have a 1998 z28 camaro that's swapped with a lq4 and I cannot seem to track down a misfire and it's driving me crazy. My setup is 102mm lsxr intake, nw trottle body, 85mm MAF, slp lid, long tube headers, 42lb Bosch green giant injectors, and a tune by tuned by frost. So this is where it began prior to tune it threw code random misfires in multiple cylinders. After tune I'd get voltage to high in bank 1. So pulled O2 sensors they were brand new. Had them replaced under warranty and local parts store, put new ones in same thing. Talked to Steve Williams turned out we had a miscommunication and he tuned for 78mm MAF. Well I then swapped my 78mm MAF back on to car. Same issue. I spoke with him about this. He says since it on one bank look for crams in intake or leaks anywhere. So i pulled the intake turns out a oring wasn't in all the way or some how popped out. Well I ordered fast brand orings and swapped the ls1 intake back on with the felpro orings in it. No more rich code. Long story short I also went through three brand new sets of plugs. Currently running ac delco iridiums. Now I'm no longer running rich. I overnighted the ecu to frost and he reimbursed me that back ( he is AWESOME!) and re tuned for 85mm MAF. I got my ecu back and put it in. Thinking maybe the miss would be gone. Well it wasn't. So I ordered Taylor 10.4mm wires thinking it was the wires. It needed them any ways. Got them, same problem. Well I read on some forum truck coils need a common ground or something along them lines. Well I swapped my stock ls1 coils on. Just zip tied them up and tried it. No change. Pulled them back off and hooked up the other coils. I pulled plugs today 1,6 looked to be running optimum-lean and 3,5,7,2,4,8 all looked rich. Had suet all over them. Cleaned them up and put them back in. Drove it, still misses but improved. Pulled plugs 1,3 after my drive just to see if the color improved. Both had a light brown color. So now Ive checked tps voltage again. It was setting at .64 I'm lost on how to set these. So I googled it and from what I've gathered .55 is where I need to be at and adjusting it I'm lost. I can't really turn it. I loosened the two screws and tried to twist and had no luck. So I just backed out the idle screw. Got it to .55v took it for a ride. Same thing but how ever I did this: 1st gear 1300rmp and hit throttle and it backfired into exhaust, same scenario again just moments later and backfires in intake, and once more try it again same way and roasted tires... So I kept trying this. 10 times in a row runs like a raped ape and then pow sluggish and gutless until it gets over 2k rpm. So shoot some ideas at me please. I'm lost? I've noticed the crank position sensor wire harness is close to headers. They don't look melted but has me wondering if this has anything to do with it. Like it hitting headers every so often. And makes me wonder if it's a wiring issue. Or tps working sometimes. Also another part that was replaced was water temp sensor.

Conv_z28_camaro

1,3,5,7





2,4,6, hadn't got to 8 till later.

Rob WS6

iTrader: (16)

TPS shouldn't need to be adjusted, the PCM should zero out what every voltage it sees when its first turned on, effectively adjusting itself. The old pre-1990 TPI cars had a fixed TPS voltage requirement but that went away long ago.

As far as the misfire issue, have you done a CASE relearn since putting the new engine in? If not, I suggest making that your first priority. When I swapped my LQ4 in, it ran fine but had a severe misfire code where the SES would flash on the highway. I knew there was no misfire but this was caused by the PCM not knowing the exact location of the crank. If yours is even farther off, it can throw off timing and fueling. Its worth a shot.

Conv_z28_camaro

CASE relearn? What and how? Never heard of it..?

Conv_z28_camaro

Anybody???

Rob WS6

iTrader: (16)

After some more research, its more for diagnostic purposes only, so no, unfortunately it probably wouldnt cure your problem.

Conv_z28_camaro

Ok. Any ideas?

CAMSTER

iTrader: (10)

I didn't read the whole thread or the entire first post but I'm sure I know what your problem is.

If your trouble seem to have both banks misfiring then you may have to swap the coil harness around on both banks.

The coil harness are the same, so no need to swap across.

Just flip front to rear on each side, what is not the same is the wiring.

The misfiring comes from number one cylinder been fed number eight cylinder spark and so on.

I hope this helps and if it does come back to the thread and say so that others may benefit if having same problem.

Conv_z28_camaro

So try taking coil harness and swap from rear coil to front coil? Does any ones have a pin out on this harness?

CAMSTER

iTrader: (10)

Please don't undo any pins, here's what to do; disconnect the injector wires on the misfiring bank, with all four injectors wires disconnected flip the harness bar so the injectors will get the proper firing order.

To flip meaning the wire that was at front will now be going to the back and the rest of the wires will plug to the injector in front of it.

Hope this helps.

CAMSTER

iTrader: (10)

Problem solved, OP called to let me know he is happy all cylinder firing no back fire.

Reason for this last post is to let others having similar problems how to fix it yourself sense even the stealership ship maybe at a lost in such situation.

Conv_z28_camaro

Problem not solved yet. I still have misfire. I blew a fuse, (engine sensor) and replaced it, MAF sensor was the code that was being thrown. Used multimeter to test wires. Pink wire had no power. Found the fuse causing it. Coil packs being swapped did help but didn't solve the problem. I would say it helped be truthfully it's hard to tell. Sometimes it runs good other times it runs like crap. Only under 2,000 Rpm's but now it's getting worse and have felt occasional mis as far as 3500 Rpm's. Under a load it seems to preform better, almost no miss at all. No load, like a quick rev misses like crazy under 2k. No Ses light or codes. I've swapped MAF sensors than realized it was the fuse not the MAF.

Conv_z28_camaro

I swapped entire bracket from one side to the other side. No change, swapped just like you said here from end to end, it would not idle at all. Bad back fires in intake. So I swapped back. Car is drivable I guess just has a lot of hesitation under 2k and once over 2k pulls hard. Car idles all day long no issue there. Surges when driving sometimes. I'm about to give up hope and just drive it. Just sounds like poop taking off!

Josh Whygle

im having this same problem, I dont understang what to do with the injectors and coils? Do I flip all injector wires or do they stay in the same place

Dirty dave !!!!!

Dirty dave !!!!!