high rpm stumble issue.......stumped (blue top)

[4agshoob]

okay, so aquired this car in a trade, and really came out on top (5th ae86 =]) i got it for a steal, because it had sat since 2004-ish with almost a half of tank of gas. early 2013, the owner, started it up, and decided to try and drive it around..............

need i say more?

anyway, they attempted a new fuel pump, thought the sending unit was the pump port, seen that it wasnt and gave up. at this point they drained the 2001 fuel out of the tank, filled it with new fuel, and tried again........

no go.

so, i managed to get the car onto a trailer under its own power to bring it home. ive dropped the tank, poured in 2 gallons of alchohol, and a 5 lbs. bag of river rock, and shook, and shimmied, and slushed until my arms fell off. (works kinda like a washing agent against the rust pitts in the tank) so i removed all the river rock, followed thru with another alchohol flush of about 4 gallons to ensure it was rinsed thoroughly. i then allowed it to dry in the sun for about 2 days before re-installation.

i also, changed the fuel pump at this time, and installed a sending unit, since the original was no where to be found.

ive removed the old fuel filter and let about 1 gallon of fuel pump freely through the line to clean out any debris. upon removing the fuel filter, it was full of what looked like concrete dust. i found that the fuel line was kinked, right before the fuel filter. so using a small screwdriver, i drove it into the line, and opened up the kink, (like a swedge) to where a screw driver almost the same i.d. as the fuel line, passed freely through the kink.

installed a new fuel filter.

so, i start the car, let it warm, rev it a few times, etc. then proceed to test drive it. low rpm, great, mid rpm, great. if your above 6k rpm for longer than about a sec. the engine hesitates, and falls flat on its face till i let off the throttle. then it picks right back up for about another sec.

timing is spot on, car runs and revs really good (127k miles =]) i know these cars pretty damn well, but this.....this has me absolutely stumped. any insight? suggestions, etc?

[allencr]

Test the fuel pressure when it's happening or just pinch off the FPR's return line to see if its creating a low pressure/volume problem.
What's the compression? Any codes?
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Also, was there actually rust in the tank or only that horrible sh.i.t from the ethanol??????

[yoshimitsuspeed]

I would send the injectors out for professional cleaning. Something like witchhunter.com

[4agshoob]

no codes, comp is 180 give or take across the board. its only got 127k miles on it. ill trythe fuel line issue. yes there was rust in the tank.

[Jeonsah]

Try unplugging the TVIS and seeing if that makes a difference. If the engine still feels boggy, then this may be your issue. I agree with cleaning out the injectors. Id just take them to napa for a cleaning. After that, rent a kit from a general auto parts store and ensure that your fuel pressure on the rail is within spec. I think its between 30 - 35 psi. Once you eliminate that fuel is not the problem, you can move onto AIR or SPARK. Lastly, I would swap out the AFM and air filter and check to see if that makes a difference. The range of which the potentionmeter works inside could be bad. Let me know what happens.

[4agshoob]

Try unplugging the TVIS and seeing if that makes a difference. If the engine still feels boggy, then this may be your issue. I agree with cleaning out the injectors. Id just take them to napa for a cleaning. After that, rent a kit from a general auto parts store and ensure that your fuel pressure on the rail is within spec. I think its between 30 - 35 psi. Once you eliminate that fuel is not the problem, you can move onto AIR or SPARK. Lastly, I would swap out the AFM and air filter and check to see if that makes a difference. The range of which the potentionmeter works inside could be bad. Let me know what happens.

yes, new plugs, gapped .044, new ngk wires, new cap, rotor, new dizzy. and new coil. no filter at the moment. im running 2 layers of aluminum screen over the AFM opening.

edit* found a ripped vacuum line going to tvis, going to sort that out today, ill report back. not only is it a vacuum leak, but its leaving tvis disabled.