z28mccrory

iTrader: (7)

Hey guys,

Im still trying to chase down this problem im having with my TA i bought.

It still just feels like it falls on its face from about 3k to 5k or so, then picks back up. Its almost like you just backed your foot off the peddal a little. Its seems like it mainly only does it if you stay WOT for a bit... like if im going along at 3k in first gear and just mash it, its doesn't do as bad as if say im at a stop and launch it and stay WOT through a couple gears. It feels like it has power on short bursts, but falls off under 4-5 second WOT pulls.

So far items i have replaced:
New Plugs and Wires
New Fuel Filter
New Fuel Pump (walbro 255 in tank)
New Oxygen Sensors
Deleted EGR
Had someone look at the tune and everything is in check in there they said.

Before i changed anything, i ran a tank of gas through it with sea foam.

Its just bugging the crap out of me. I have let a few other guys drive it, and everyone agrees, its the slowest LS1 they have ever driven and definitely falls off. One would almost think its valve float, but it picks back up from about 5-5500 to when i shift at 6100-6200.

The car is a 98 with 148k miles. It doesnt use oil, it doesn't smoke, etc. It purrs like a kitten at idle, mechanically it seems like everything is in check.

Since i got it, i put on an aftermarket air lid, smooth bellows, and a k&n. Otherwise its just has the catback and gears that were in it when i purchased it.

I swapped out the MAF off my 99 Camaro just to make sure it wasn't the MAF, and it changed nothing.

I have been told that if it were the cam or crank sensor, that it would be extremely noticable.

I pretty much have it eliminated down to maybe being a bad fuel injector or possibly a bad coil pack?

Its throwing two codes, which are low voltage on the front two o2 sensors. I replaced them and the same code came back up after a day or so.

I have a dry nitrous kit sitting here for it, but i dont want to put it on untill this is figured out.

I appreciate any and all help.

usaf_hess

iTrader: (8)

Try cleaning your sensors in the MAF with some cleaner, my car seemed to run good at idle but then it wanted to run crappy till about 70 then it picked up like nothing was wrong. I never looked at the RPM's but might be worth a try.

Ok i just saw that you said you switched MAF's but did you try cleaning it? I saw you said you have a K&N filter, mine did this after installing my FIPK cause it gunked up the sensors in the MAF.

Also my car threw the same codes and i could never figure out why, it stoped after i cleaned it with MAF cleaner.

sreve

iTrader: (3)

i'm thinking the front O2s are telling the truth it's too lean.

Dan Stewart

Having someone look at the tune isn't as valuable as having them log live data.

Do that. You'll be surprised what it tells you.

wht01ws6ta

iTrader: (45)

You could try disabling (unplugging) the MAF to put it in SD and see if that makes any difference. I guess you don't have access to a wideband anywhere?

Old Geezer

iTrader: (3)

And, the fuel pressure is, when this is happening??
Also, as Dan Stewart said.. Datalog it. And, do it while you are driving, not just idle.