Ok guys, new z owner, just got a jdm swap, was running fine in the beginning but now wont rev above 2500-2600rpm, pulled the codes off the ecu and they are 12,13, forty something (detonation sensor) and 51. when the engine is on and idling the check engine light goes off, if i press the gas half way it comes back on, if i barely press the gas right when it hits 2500, the check engine light comes back on. Once i hit about 2500-2600rpm it cuts and goes back and forth.

 

well 2500 sounds like a bad MAS sensor i had one go bad and it alows the car to run to get it home but not rev above 2500

 

also, if you are throwing a det sensor code, you will be running in safety boost. if you dont fix the det sensor, even after you fix the main problem, the car wont run at full boost.

 

it's a MAS or fuel delivery problem (might be CAS as well, but not as likely). Since it's cutting out around 2500 rpm, I would guess that it's likely a bad fuel pump (the TT fuel pump runs on 3 settings, respectively, low, medium, and high. A single speed of the pump can die, and I think around 2500 is when it kicks into medium, so if your medium and high settings on your pump are not functioning, it'd have a rev limiter-type effect on the engine. I know this from experience, my high setting died on me and I'd hit a wall closer to 3500-4000rpms under boost).

Here's my writeup on fuel system diagnostics from another forum....

If BOTH your fuel pressure regulator and dampener are fine, it's probably your MAS or fuel pump. You'll have to search on how to diagnose those, because I don't remember off the top of my head. I expect it'll either be your FPR or pump though.

good luck

 

Please read this link, it may get you to where you need to be without question. There are too many factors involved. Eliminate the codes you read and then diagnos your car based on these things.


http://zhome.com/ZCMnL/PICS/hesitation/hesitation.html


Here is a table of the codes with their meanings :

11: Crankshaft position sensor circuit
12: Mass air flow sensor circuit
13: Engine coolant temperature sensor circuit
14: Vehicle speed sensor circuit
21: Ignition signal circuit
31: ECM/ECU
*32: EGR function
33: Heated oxygen sensor circuit (Left side)
34: Knock sensor circuit
*35: EGR temperature sensor circuit
42: Fuel temperature sensor circuit
43: Throttle position sensor circuit
*45: Injector leak
*51: Injector circuit
53: Heated osygen sensor circuit (Right side)
54: Signal circuit from A/T control unit to ECM/ECU (A/T only)
55: No malfunctions in the above circuits

* : Not available for non-california models.

A little more meaning :

11 - crank angle sensor circuit, 1 deg or 120 deg signal is not received for the first few seconds during engine cranking or not often enough at high RPM- check harness, connectors and the crank angle sensor.
12 - Air flow meter circuit, open or short circuit is detected- check harness, connectors and the air flow meter.
13- engine temperature circuit, open or short circuit is detected- check harness, connectors and sensor.
21 - ignition signal circuit, the ECU is not detecting ignition signal from the transistor ignition unit- check harness, connectors and power transistor unit.
33- Oxygen sensor, - check harness, connectors and sensor.
34 - detonation sensor circuit , open or short circuit is detected- check harness, connectors and sensor.
42 - Fuel temperature sensor circuit, open or short circuit is detected- check harness, connectors and sensor.
43 - throttle sensor circuit, open or short circuit is detected- check harness, connectors and sensor.
54 - signal circuit from the auto transmission computer is open or short circuit check harness & connector. (Auto only)

 

jsut a thought... have you checked the ecu connector? I'd go through my connectors starting with that and make sure they are well connected

 

I agree with Zlover. MAS or fuel pump.

 

Close To The Same Thing Happend To My Car And Found Out I Had No Mass Air Flow Meter! Hope You Find The Problem

 

You had no MAF? Was this a Z32? I'm afraid to ask how or why.

 

I bought a new maf and i installed it. It solfed my problem and it ran strong. Thanks for the answers

 

glad you figured it out