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Thread: having an issue with gtir swap

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Posts: 1-10 of 22
2009-08-09 10:51:05
having an issue with gtir swap
its been finished for a little while, but sitting while i did my brake install....ever since my big turbo install, its been like this. when you start it up, and rev it, it hesitates if you give it wot. if its anything less than wot, then its fine sounds good. i thought it was due to no o2 sensor. then, once the car warms up, it would start idling erratically. this has gotten worse, to the point it will now stall. if you try to drive it, its NOT fast at all, bucks a bit, and loads up with fuel, and normally stalls when the throttle plate closes. im trying to figure out what it could be. thought it could be the maf getting overwhelemed by the turbo, its a t3/t4 57 trim on a stock gtir maf, running a stock gtir ecu(for now). I bypassed the turbo, and hooked the maf to the manifold directly, but it didnt change. i DID have to use a de o2 sensor and am using it now, could that maybe be enough to do all this? its a complet gtir swap, with a t3/t4 turbonetics. i did a boost test, and it held pressur perfectly.
2009-08-09 15:49:49
power and groungs

check the groungs on the intake make shure wires are not broken or hanging on by a thread

add a ground to the maf ground if it already has this check circut for crosion.

clean all grounds

batt cable to block and body
ecm grounds on intake
alternator ground

its kinda hard but ck power and ground to ecm
wirring diagram or connector pin out will tell you what pins have what

also a good idea to ck major sensor voltages at ecm and at sensor
like tps if you have .4 under the hood and .1 at the ecm then your harness is junk

my b13 harness had cancer i had to replace several wires

it really sounds like a garbage in garbage out problem

have a timming light? get one and check base timing and make shure timing goes up when you rev it
if it stays still or only moves 5 deg then car is in timing mode or limp mode

check switch on ecm idk if gtir has the diag dial on side of ecm but if it is in the wrong spot timing will be fukd
2009-08-09 16:26:11
I have a similiar problem with mine, sometimes when I crank it..it takes it minute, I finally figured out that if I press the the gas when I crank it and let off it fires right up. There is still this thing where I press the gas after I crank it and it doesnt wanna fire, rpms drop and wants to stall. So If I ease the gas down and drive it for just a bit it starts working fine. It bucks like you said at first like when I go to press the gas after I shift. did it with stock turbo, now doing it with 2871r
2009-08-09 16:31:05
I run no o2 sensors no knock sensor and my car is just fine
2009-08-09 19:33:26
ok....so i bypassed the turbo and charge pipe as said above. i figured id check the maf that way, so i started it up. i have good voltage on the constant wire, and it looked like 1.2 volts at the signal at idle. anyways, it started runnning pretty good that way! usually when i rev it up, it will stall stutter, and run like crap. well, it didnt with the turbo/charge pipe bypassed. ran pretty good actually. so i GUESS it could be a boost leak. but ive done a boost test! very weird. at any event it seems like the electrical is fine. anything besides a boost leak that could cause a issue like this?
2009-08-10 01:35:21
Your maf and ecu are garbage for a big turbo like that. Stock injectors on a bigger turbo setup prob isn't that smart.
2009-08-10 02:22:21
Alex, the MAF/ECU/Injector issue is null if the car doesn't even want to idle correctly at operating temps.


Do you even have a wideband?
2009-08-10 03:58:22
lol, I running stock gtir maf and stock injectors on my setup as well but I don't boost over 10 psi.not until I get a wideband at least
2009-08-10 11:57:40
ok....so i rehooked up the maf to the charge pipe......crappy again. so, i checked the maf voltage...full 12 volts getting to the maf, and the signal wire reads 1.2 volts at idle. isnt that a bit low? on top of that, i checked the tps....i found a wire with 4.9 volts, but thats it. the other 2 wires were dead. is that right? i dont think so, but i dont know. on top of that, when i disconnect the tps, nothing chages.....SO maybe i wired the tps up wrong? ideas here? when i opened the throttle plate, the tps voltage did not change either.
2009-08-10 12:47:06
The TPS should have constant 12v for power, 0-5V signal, and ground. You should be able to see the 0-5V signal by opening the throttle plate more or less, as it acts as a potentiometer. Without that, the car will definitely run crappy, as the ECU won't know what you're attempting to do, but will see extra air coming in via MAF and will throw fuel at the car.
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