1Bad93Z

Long story short, car was dyno tuned, made close to 400 rwhp. ran excellent for 2 days then developed a miss. Took it back to the tuner to have him find a dead cylinder from a sticking injector.

Replaced injectors/retuned the ecm, car then developed a miss/intake backfires/bucking...tuner looks into it and cannot find the cause. He looked at it closer to find some pinched wires in the engine harness and fixed them which cleared up the miss/intake backfires/bucking. He also doesnt think its a mechanical problem. He checked compression, spring pressure, and valves.

However the car now has no power on acceleration, it cruises good/smooth, idles good but when it goes WOT he describes it as "having less power than a stock lt1" He looked over the air/fuel/knock values and he says everything shows good. I just dont see how it doesnt have some tell tale numbers when he is accelerating.

He says the 93 is kind of a bastard year to watch things as they run and is suggesting that something in the harness may be culprit and thinks a new one will clear it up.

Are 93s really that hard to diagnose on wot pulls? I dont understand why it was fine for 2 days and then went down hill after it was retuned on the new injectors.

Should I just grab a new harness being the factory one is 20 years old...Should be be able to read the cars values when the power drops and see when certain things get out of line? If hes saying the mixtures and voltages seem good shouldnt the car also be running fine?

Ive hit a 6 month brick wall with this car and Im frustrated beyond belief that the "f body specialist" in my area cannot figure it out knowing that if he cant figure it out how the hell am I suppose to?

Car is 93 m6, cammed, heads, 2 new optis, o2s deleted, new 36lb injectors with tune, tried 3 sets of plugs, new coil, new prom slot soldered in, checked springs, valves, compression, leak down test. various other tests...no power at WOT

96capricemgr

iTrader: (1)

O2 delete is kind of scary, makes me question the knowledge of anyone/everyone involved.

That said ICM, two friends have had similar issues that went away with ICM swaps.

Ed Wright

iTrader: (1)

I have people ask me to tune their cars with "the O2s shut off". That is almost to stupid to consider. I usually just tell them "I'm sorry, I'm afraid I can 't help you right now." Have to wonder who they have been talking to. LOL

One of the "voltages" your tuner could have been looking at when it goes flat is your O2 sensor voltage. Would be a very handy thing to know. :-)

quik95lt1

iTrader: (7)

^what they both said.......the O2 voltage should be floating around 750-800mV at WOT, do you know what the AFR is at WOT? is there a wideband in the car? also whats the spark advance at?

1Bad93Z

The car does in fact have a wide band, and he even pulled it and tried another to make sure it was reading properly. I don't know the exact numbers atm, I do know he tuned the car out for what he calls for "proper" afr numbers at idle and wot. He orginally shut down the o2s because he told me a 93 with long tubes will never let the o2s function properly. Perhaps ill tell him to turn them on and see what e can make out of it. Cprmgr, the icm was replaced with 3 working units...ill have to check the spark adv numbers. Thanks guys

Ed Wright

iTrader: (1)

The '93s need converted to a heated O2, so he is correct about that.
If he had a wide band in it , that eliminates fueling. Going to be interesting to hear what you find.

1Bad93Z

So since the car doesn't have heated o2s and didn't really plan on the converstion asking him to turn them back on to check numbers again won't really do anything for troubleshooting?

englundjd

just because the o2 sensors arent heated doesnt mean they wont work. you just gotta give them plenty of time to warm up before they read reliably. it would probably help to turn them back on.

1Bad93Z

First off thanks for the replies, I'll have to give him a call and talk with him on the o2's. One thing I would like to do mainly because my 93 harness has cracks and splits and just old in general Id like to get a new harness. And if I do that Id like to swap to a 94 ecm/harness. I hear the tunability/trouibleshooting is a tad easier on the 94 compared to the 93, was I correct in reading that? Is it a straight forward swap?