kdxzx

Hi,

This car has been giving me hell. Currently the car wont go past 1700rpm. The car will run normal below this, the car feels like the car is in limp mode. From reading and research the MAF is usually the culprit, this item was replaced(new). The car ran fine. Then it sat for a month, when it was time to start up, the car continued to not rev past 1700 again, let it cool down, performed this cycle 3 times and the car acted how it should. Drove the car for a week. Then let the car sit for another month, same issue happened when it was time to drive again, performed the same cycle the car worked properly. Now after this startup the car will not get out of limp mode?

The MAF connection was pulled, the car sputtered and died as you would expect.

This has utterly confused me, I am thinking a lose wire, but not sure what direction to look at?

This car was a 2+2 NA to Turbo

zxguy1986

Great Z you have~ You have your FSM, right? XenonZ31 Reference

I have some questions first. The more info you give, the better our guys can respond.

How many miles on the motor?

Has this been happening since the conversion from na to T - or did it run great and then start doing this?

Does the engine do the same thing whether it's cold or hot?

Is your ECU putting out any trouble codes?

Thanks

kdxzx

Thank you for the welcome.

The car has 130k miles, the motor worked properly then was swapped into the NA body

I have pulled the codes on the comp, there's a lot.

Codes Pulled after the comp was rest:
12-AFM
13-Cylinder Head Temp
14-Car Speed Cen
21-Ignition Signal
23-Idle Switch
24-Neutral Switch (Auto Trans swapped with 5 speed)
31-Air Con
41-Fuel Temp Sen

The car the same thing hot or cold 1700 max rpm

The car never really ran the best after the swap. The car was taken to a Mechanic specializing in Z's and got the car running smoothly. Then it sat for a while and now I am back to square one..............

rogerz

what ecu are you using? what is your fuel pressure? Is the 02 sensor compatible with the ecu you are using. forget the codes they are usually useless. especially since you did a transplant. but the car speed sensor might be your problem. the turbo cars were limited by a speed sensor in the speedometer module. look on the fsm schematic for a turbo and check out purple wire to pin 26 if I remember things anymore. clip that and see if it solves your problem. fuel temp sensor doesn't do a damn thing that I have discovered after wasting the bucks to get one.

zxguy1986

You can check your current ECU's part number against resources:z31_ecu_list [Z31.com]

kdxzx

yes the ECU was checked and this is the proper one

PredatorZ

it could be the TPS, if it is adjusted wrong you will have a very narrow useful band of power, almost un drive-able. Your manual will cover the basics on testing and setting it, very simple really, it has 2 switches, one that monitors if the engine is at idle, the other looks for FOT, if it is confused it will try and adjust randomly and run like crap. You might check it. Also the contacts in the connector are prone to corrosion, and it is easy for the switch to get wet, or to have water sitting in the connector and shorting it out.

kdxzx

Update from today, I changed out the MAF and nothing changed in the cars running

zxguy1986

OK, check out throttle position sensor next, like PredZ says above. Sounds like one or more sensors are sending your ECU wrong/part-time/or NO information. Your ECU does the best it can with that - which is run the motor bad. Please report back

FlyingT

What about the MAF harness? This car is 28 years old, the copper in the wires is getting brittle. Just moving them can break them. Corrosion on the connector?