Weird hesitations

[RckyMtnLegacy]

I just a few months ago I rebuilt my engine (1993 EJ22T) all new gaskets, bearings, rebuilt heads,new pumps, new plugs, new wires, new belts, Perrin crank pulley, and so one. The pistons and rods were fine and within spec. I replaced knock sensor, oil sensor, and temp sensors. I am now having a weird hesitation when I start the car. When its cold and I tap the gas it bogs and when I try and go faster it will stumble and pop a bit. When it warms up it won't stumble but it will quickly respond when I press the gas. On the highway I can push it WOT and it will rise to about 3k or 4k and just stop there almost like it cant breath. I have codes about O2 sensor and 3 out of 4 injectors. I think the injector codes are just from the connectors being swapped but I can't find the green 'T' connector to help me erase the codes. Any ideas on my hesitation? Maybe O2 sensor?

[Legacy777]

Check your MAF sensor. If you have a spare you can swap in that'd be an easy test.

How long has this hesitation been occurring?

[RckyMtnLegacy]

Used to have spare MAFs but now I have only one subie. Ill try to see what I can find. not many in TX.

Couple months. Kinda since engine was put in.

[Legacy777]

Is this on an AT or MT turbo legacy?

You may have better luck finding a Hitachi MAF from a non-turbo 90-91 MT Legacy.

[RckyMtnLegacy]

its an automatic

[Legacy777]

The reason I ask about the AT/MT is that when my car was AT, I had a weird stumble/hesitation upon startup. It didn't happen all the time, but primarily when the engine was cold. If I started the car and put the car in gear and touched the gas, the rpms would drop and stumble, and then pick back up. If I let the car warm up a minute or two, I didn't have the problem.

I can't say for sure what exactly fixed the problem because I don't recall whether it went away when I replaced the MAF or if I was still having problems after that. What I do know is that I never had the problem when I swapped to a MT. I really think the problem went away when I swapped the MAF, but can't confirm that.....it's been 10+ years.

[RckyMtnLegacy]

Ah thanks. Maybe its my excuse for my MT swap

O2 sensor?

And I cannot find the green T plug under the dash at all.

[Legacy777]

I doubt it's the O2 sensor, but if you know it's bad, may not be a bad idea to replace it.

As for the green T plug, check on the right side of the steering wheel column.

[RckyMtnLegacy]

Only thing telling me that its bad is the code.

I have been under the entire dash with a flashlight upside down searching every wire and connector

[Legacy777]

It's there, but it's likely taped up on something, so you may want to try one of those mirrors which may help in locating it.

[RckyMtnLegacy]

Ya ill try that I have some other wires I need to feed anyway

[jefferson]

I am kind of thinking maf also as you said everything was covered in oil when the piston went. Oil and maf equal bad.

Jeff

[RckyMtnLegacy]

Ya I think you may be right Ill check soon

[RckyMtnLegacy]

Took MAF our and there was oil burn onto it. After spraying it with cleaner and in my eyes I got it cleared up and start up hesitations and pop are all gone!! I can punch it and it will go. I still have a feeling like its being helD back when I get around 3k feels like it can't breath or not enough fuel. I may make a video of it since it there is like a humming or some kind of noise when I accelerate which could just be normal. Thanks for the help though I can't believe I didnt clean it before since my STI would kill itself all the time when the MAF got dirty

[Legacy777]

Glad that helped. If you can find a cheap MAF, you may want to pick one up and swap it with the one you have.