Strange fuel or elecitrical problem

[einherjar]

Hi,

I've been having sparatic trouble with my car. A few months ago my car started to act really weird. It would rev up then all of a sudden it felt like there was no fuel entering the engine, the engine would not die, but would go quite, if i pushed harder on the throttle i could see the boost gauge go from vacuum to 0 psi, and if i let off the throttle eventually the engine would start firing again (is this the ECU is fail safe mode?, i have no tach so i estimate it was around 2500 rpm). I was sitting with the car, and 45min later i started it up again and it ran fine. The problem seemed to be gone, but i changed the MAFS anyways.
This problem started again yesterday, same symptoms, so this morning i reset the ECU via disconnecting the negative terminal of the battery, and the car is running fine, no problems again. But just to be certain, today i replaced the fuel filter, and checked the wiring around the MAFS and TPS, all the wiring was fine. And the car is running normally.

Anyone have any idea what it could be? Its hard because the problem goes away, could it have been a clogged fuel filter? could it be bad gas?

Any help would be great. Thanks

`Nik

[ace240sx]

Maybe try checking the codes.

[einherjar]

I checked the code and got 43: TPS ... but that doesnt really make sense because i unplugged the TPS, and the car had the same problem, just worse, and i plugged it back in drove a bit, and got the ECU reading ...

[Flybert]

This kind of sounds like a problem I'm having. Whenever I hit a harsh bump when cruising down the road, it feels like I hit a fuel cut and I lose all power for a second. I think that I notice it more when there is less fuel in the tank. I'm gonna be checking my fuel pump wiring. When I installed my walboro, I was lazy and crimped it. I'm not throwing any codes.

[einherjar]

This kind of sounds like a problem I'm having. Whenever I hit a harsh bump when cruising down the road, it feels like I hit a fuel cut and I lose all power for a second. I think that I notice it more when there is less fuel in the tank. I'm gonna be checking my fuel pump wiring. When I installed my walboro, I was lazy and crimped it. I'm not throwing any codes.

Yeah im about to check my fuel pump wiring too ... i also crimped mine.

FUCK, its hailing out ...

[einherjar]

Alright the wiring was fine ... shit.

Could really bad grounds cause this problem? im debating grounding my car, the battery ground is pretty shitty on my car ... but its never given me this problem before.

[einherjar]

I grounded my car all over, i can not get my car to run properly, it keeps sputtering and then it stops accerelerating like its getting no fuel ... AHHH!!! SOMEONE PLEASE HELP, ... this is my daily driver.

[llteddy4playll]

try checking the voltage off the tps it should read 4.5 or sumin forgot. Or just mess with your tps untill you fix it and tighten it back so it wont come loose on you. My car was like that it accelerate then stop then accelerate then stops.

[einherjar]

Well i changed my plugs, ... i was thinking maybe i was getting sparkplug blowout, .... well if you look at the attachment, ... i think my plugs were pretty fouled :tweak: . I took the car out ... it hicupped a few times, but nothing like before.

[einherjar]

FACK! so the problem wasnt fouled plugs, ... becuase the problem came back. ... is there anyone out there who can help? do i have a problem that is beyond zilvia members abilities?

Here is the problem again.

The car idles fine, but once its driving ... normally after a min or so, it starts sputtering really bad, then it will stop accelerating and the engine goes quiet like there is no fuel, or, no spark, then once i let off the gas it goes away, or if i hold the throttle, it may come back. Latey, the car feels less powerful, something is not right. Also, when i had this problem before, warmer weather made a large improvement.

What ive done.

Changed the plugs, re gapped them to .031"
Checked the wiring to the fuel pump
Checked the ECU code, its reading 43, TPS, but the car should run without the TPS, so i unplugged it and the car had the same problem ... so i plugged it back in.
Changed the MAFS
Checked MAFS wiring, and TPS wiring
Checked for vacuum leaks
Added new grounds and cleaned up the old ones.
Changed the fuel filter
Unplugged MAFS, can ran even worse ... so plugged back in

What i plan to do
Check the MAFS wiring completely, from MAFS to the ECU.
Check the timing on the car ... but i dont understand why the timing would be off, unless shit happened internally ... :O


... anyone have at least ideas?

[Flybert]

I believe that the gap should be .028 but it's been a while since I've checked the FSM.

[einherjar]

Well, i was outside ... in like 40 F weather, with my multimeter, i was checking all sorts of things, i rewired the MAFS connector, but the conection was good already, i just redid it except with solder, tested it while the car was running, got .09V and .43V depending on pins, which is right. So i played around with the TPS again, checked it while it was running, got very small fluctuations of current while i was playing with the throttle, so i unplugged it again ... car starting running well ... so i clean up take it for a spin ... the car ran like a dream, so smooth, not fluctuations at all not even a hiccup. Took it for a long cruise, 160kmph on the highway, slid a few turns, car took it like a champ.

So i guess the car needed the TPS unplugged and the new plugs i installed yeaterday, that were gapped small ....

the real test is if it will take me 30kms to work tomorrow. I'll update then.

[F3600]

did you try another ignitor .. ? sometime when the ignitor is bad .. when its cold its start good but after 5 min of driving It start to cause trouble

ohm you winring harness between the ignitor and the coilpack subharnes ..i was having a similar problem and there were a short.. 2 coilpack signal wire we tocuhing each other.. cross check every pin to see if there a short with the other wire

good luck

[einherjar]

Thanks, ill try that tonight because .... the problem came back ... the car goes into safemode sparatically, then will go out, then in .... dammit .... would the TPS unplugged cause this problem?

[einherjar]

Would running with the TPS unplugged cause the ECU to go into failsafe mode after about 10min of driving? I was under the impression that it can run no problem with it unplugged.

[Flybert]

I think you should try a cheaper plug with a fatter tip. I have some lying around and I'm going to try switching mine out this week to see if it makes a difference. When your crap bogs, does it let you boost but you just don't go anywhere? That's what's going on with me right now. It pisses me off but doesn't seem to happen as often as you.

[einherjar]

It lets me go from vac to 0 psi, not actually making pressure, but because im opening the throttle body i can vary within that range.
I'm going to do some testing on the TPS tonight, i got the FSM and will follow that procdure, maybe clean it up a bit too, i figure mine aswell, it is what the ECU is saying is wrong, probably check some more for short or open circuits.