'02 s-10 blazer, ls, 4 door, 4wd, 4.3, 86,000 miles.
so here is the problem, in park or neutral truck runs fine, revs up and idles fine. Put it in drive, any gear, it won't go past 2,000 rpm and might hit 5 mph if that. I've acquired this truck because of this issue... Here is a list of what has been done so far. New plugs, wires, cap and rotor, distributor, coil, spider injector, IAT, IAC, MAP, MAF, TPS, PCM, fuel pump, fuel filter, engine and transmission. I might be missing a couple of things as well... Same problem exists.. checked brakes. On jack stands, everything works as it should. What could I be missing here?

 

Partially plugged cat or pre-cats would be my bet.

 

The exhaust has also been replaced, cats removed, even ran open and no change.

 

Do you have any codes?

Can you monitor live data? If so what are your fuel trims at idle (4 numbers) and when the truck is crapping out under load?

George

 

​​​​​​At idle STFT B1: 0 to -.8%
LTFT B1: 4.7%
STFT B2: 0 to -.8%
LTFT B2: 1.6%

Under load

​​​​​​STFT B1: 0 to -6.3%
LTFT B1: .8%
STFT B2: 12.5 to 16.3%
LTFT B2: 11.7%

 

You have a bank 2 problem (pass side), the computer is trying to add fuel on that side.. This likely to be either the fuel injectors or the O2 sensor on that side. You need to do the fuel pressure test and graph your o2 sensors at idle and under a load. Did the O2 sensors all get re-installed when you gutted the cats? Did you have to modify any of them?


George

 

Regardless of fuel trim, pressure or any of that, if I have the truck in neutral and hold it at 3,000 to 3,500 rpm and drop it into drive it still just gradually bogs down and goes nowhere... I'm by no means a professional mechanic but I've worked on hundreds of vehicles in my life and this one has me baffled..

 

I did fuel pressure tests. It holds 55-60 psi. All O2 sensors were reinstalled and new.

 

Fuel trims are way out of whack under load and look like you have either an air leak on that bank or possibly bad injector(s) not supplying enough fuel (or a stuck poppet if you didn't switch to individual injector setup) and its trying to play catchup. That's IF the new O2 sensors are working as they should. The lack of forward momentum odd though, it should idle in drive on a flat surface over 5mph, are you 100% positive you have a 99+ transmission with (from what I've read at least) a longer input shaft to match up? I read that's something I have to deal with for my 99 Blazer since they changed things to be LS block compatible. Not getting the power through the converter to the transmission properly could cause havoc as well. Separate issue from the LTFT, but still potentially an issue, especially if you bought both separately and/or used.

 

There is an echo in here.

Pull the plugs to see if bank one looks different from bank 2. If bank 2 looks rich then the injectors are working and the O2 sensor likely has a problem or there is an exhaust or intake leak. If the bank 2 plugs look lean then its likely an injector problem.

George