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s4 t2 hesitation. did almost everything!

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Old 10-20-11, 07:44 PM
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s4 t2 hesitation. did almost everything!

after installing my ported waste gate, i took it out for a drive. freaking car still hesitates! it seems like the secondaries isnt kicking in. it also bogs around 3000+rpm

its rebuilt, new 55o injectors, changed the maf, adjusted the tps (reading 4.5ohms so its still good), cleaned all ALL of the grounds, new vac lines, changed n332 ecu, has a fd fuel pump, fcd, swapped out the pressure sensor for a different one, removed acv, twin scroll, and all off the emissions solenoids.

so the only vac lines attached are the brake master, pressure sensor, and bov.

i was told that the engine harness was swapped out with an unknown one. it doesnt have a plug for the 02 sensor. could that be the problem?

thanks!
Old 10-20-11, 09:15 PM
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If your're in the driveway and you free rev the engine does it hesitate at all?

You can check to see if the secondary injectors are wired up properly by first checking to see if the Light Green/White wire and the Light Green/Red wire in the smallest ECU plug has 12 volts w/key to on.

You could also disconnect the TPS plug along w/disconnecting the vacuum hose to the Boost sensor and capping it. Doing these two things will trick the car in to thinking it is under load so when the engine is free reved the secondary injectors will fire. If the ECU is pulsing a ground signal to the secondaries it would show up by the 12 volts on the Light Green wires dropping down to about 8 volts or so. If it stays at 12 volts then they won't fire.

You could also add a temporary ground by selecting the ground wire at either the TPS or Boost sensor for example and shoving a jumper wire into the back of the respective sensor plug and bolt the other end of the jumper wire to the engine and see if this changes anything worth a darn.
Old 10-20-11, 10:23 PM
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i havent tried reving it on my driveway because the car keeps leaning out when i drive it on the street.

so i checked the voltage of the secondary injectors w/key on, which is the green/white and green/red wire on the smallest plug in the cpu, and it didnt even go up to 1 volt. i guess ill change the harness.

does having the 02 sensor unplugged effect anything too?
Old 10-21-11, 04:42 AM
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Replacing the harness seems pricey and unnecessary.

How do you know that the car is leaning out? Do you have an AFR gauge?
Old 10-24-11, 10:29 PM
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Originally Posted by dwb87
Replacing the harness seems pricey and unnecessary.

How do you know that the car is leaning out? Do you have an AFR gauge?
no afr gauge but it bogs down after 3.5k and it seems like its not getting enough fuel.

ok i checked the voltage of the pins on the primaries and secondaries with the key on but it didnt give me a reading past 1v but when i check it battery its at 12volts so my multimeter isnt broken lol.

if the 02 sensor isnt plugged in will the injectors max out at a certain rpm or add more fuel/air than normal?

thanks guys!

Last edited by NatAsRex7; 10-24-11 at 10:37 PM.
Old 10-25-11, 12:02 AM
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Your low voltage on the ECU secondary wires could be a function of the injector plug not being secure or the wire(s) being pulled back in the injector plug and this would prevent these injectors from firing. Check for both possibilities. The voltage sent to the injector does not come from the ECU but the voltage received at the injector plug gets passed on to the Light Green wires and shows up at the ECU w/key to on so check the possibilities as mentioned above. This is likely your problem and should be a rather easy fix.
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