Rough Running - No Power (1 Viewer)

[MattMud]

1997 1FZFE w 350k except for recent work listed below:
New OEM shortblock
New head job
New Wits End Turbo
New O2 sensors
TPS swapped to check if cause (from good running donor)
New IAC to. check if cause (from good running donor)
New fuel pressure reg to check if cause (from good running donor)
New MAF to check if cause (from good running donor)
New coil to check if cause (from good running donor)
New OEM fuel pump

Symptoms: acts just like when the air hose between MAF and throttle body is cracked. Rough idle, no power or rev above 2000rpm when in drive. But, I don’t have that hose and instead have all new intake with the turbo.

Drove 2000 miles cross country 3 weeks ago and was fine. Splashed through water and symptoms happened. Splashed through water earlier this week and happened again. Any solve it after three days of swapping parts noted above.

Ultra gauge shows fuel trim adding up to -30 between short and long. Fuel pressure regulator swapped and fine. Pulled plugs and all equally showing rich running. Thought of injectors but all refreshed with new engine 3000 miles ago and would they all go bad together? They all look similar rich.

Thinking of water in harness somewhere but dried all plugs at O2, dissy, coil, TPS, IAC, MAF and problem remains.

Super frustrated. Thanks for any ideas.
@NLXTACY
@landtank
@Malleus

 

[Malleus]

Random thought: use a fine mist while parked in the driveway with someone holding the rpms @ 2000. If you can recreate the stutter, it might point to an area to check at least. Beyond that, nothing comes immediately to mind.

 

[MattMud]

There is not issue creating the stutter. It idles rough, revs on its own to 2000 and crack down to 400 for a bit, struggles and goes back up to 2000, etc. It will sometimes idle well enough to make me think I fixed something, then drive up the block and acts just like the air intake hose is cracked - super low power and will not rev past 2000.

 

[Fj80oregon]

Injector? Injector wiring clips I had similar symptoms after a complete rebuild and found the new injector wiring clips I installed one of them had a bad connection. Easiest way to find this issue is pull the plug wire one by one and see if idle changes if you pull one and nothing changes that would be your dead cylinder. Maybe a shot in the dark but only takes 10 min and is free.

 

[landtank]

You stated fuel trim adding -30, is it adding 30% or subtracting 30% ?

If subtracting 30% you probably have a short in the engine harness.

 

[mudgudgeon]

Splashed through water and symptoms happened. Splashed through water

There's your problem.

Water in an EFI connection somewhere.

I've had it happen after degreasing the engine bay and getting a bit too excited with a hose.

I never found my problem, but once everything dried out, it was good as gold again

 

[MattMud]

Thanks very much. I suspected water messing things up somewhere. Swapping new OEM harness in right now. Will report back with findings and praying it is the solution. If not, at 350k on the clock I don’t think the harness is wasted effort.

 

[landtank]

My money is on it will fix it

 

[cruiserdan]

The distributors get wet in spite of the sealing. Then they run like crap.

 

[MattMud]

As George Castanza’s father famously said, “I’m back baby!!”
Took me 10 hours but it’s done except for adjusting the TPS/idle. Idling about 1000. Super smooth. The other item for tomorrow is to swap the knock sensor from my donor motor. Coupling is broken off and glue didn’t hold. That’s keeping it in open loop too. But, victory lap with ice cream tonight. Do I adjust the idle with the screw to the right of the TPS or twist the TPS itself?

Million thanks!!