TwinTurbo.NET: Nissan 300ZX forum - Another TPS, MAF, IAC issue
People Seeking Info
 
   


     
Subject Another TPS, MAF, IAC issue
     
Posted by cm1wrx on September 09, 2023 at 10:58 PM
  This message has been viewed 217 times.
     
     
Message I haven't posted in a while. Decided to stop trying to figure out why the car wouldn't run correctly and get it painted. Now that I am done with that, its time to drive.... but I can't. : (

So I finally bought an ecu talk cable and got it hooked up to the car. I've been getting a lot of MAF (Code 12) faults. The car has been idling EXTREMELY rich and has been totally undriveable. If you try to rev, it just misfires and pops. The TPS and MAF from Autozone (this is after two other MAF sensors (the original, another OEM and now this one). That being said, the Autozone one has worked the best so far but it doesn't read signal voltage (key on no start) correctly. It's at approximately .031V on my Fluke multimeter. Something to note, I have replaced all the connectors on this car so don't say, corrosion because there isn't any. I have also traced all the injector wires and the MAF wires back to the ECU and all test good. All 6 plugs look the same and I have done other checks so no issues there (all 6 coils firing, all 6 injectors firing). It idles pretty smooth for the most part once I play with the TPS a little (duralast one). The TPS is also out of resistance per z32 wiki process (1300 ohms as opposed to 9000) and I still need to make more adjustments because the throttle shows very slightly open (ECUtalk) even though I know its closed but I think it might work.

Both throttle bodies were cleaned and regasketed when I did the plenum coolant line delete. I also did an EGR delete, not that it should matter.
I can't find any vacuum leaks but I might be missing something. The grounds are all good, tight and tested so I know they are good. The ECU could be the issue but I don't think its bad based on how it responds and outputs data (again, ECUtalk answers so many questions). I am going to set the TPS as accurate as I can tomorrow and see where that takes me but am looking for other ideas?

Any thoughts as to what I should be looking for?

Some more notes:
Injectors-new but cheap ones (amazon phase 2) but they seem to be working fine and ohm out ok.
Both coolant sensors are new (gage and ECU).
Timing belt, tensioner, pulleys, etc. are all new
02s are new
Has the knock sensor resistor setup from Z1 but the wires from the harness (not the not sensor harness but the main harness are a little damaged but its not throwing codes so.....)
MAF- Duralast now... the last OEM was showing really high voltage (like 3.4 on the signal wire (key on no start). The duralast is low as mentioned before but is working well and the car is not running as rich (verified by the O2's, which are also new and were not cycling before I added this MAF.
The plugs are new Denso Iridium.
When I got the car, it didn't have the little damper unit that is normally connected in line with the Idle air control on the back side of the plenum but it ran fine. Not totally sure what that part does. I've heard it can be deleted and just assumed it was ok with out it. From what I have read, its part of idle air control system but its only active when the engine is warm (it has been running bad enough for me to never let it get warm because of all the fuel washing down the cylinders). I am totally stumped at this point. Anything else I should check? Timing is at 16 degrees according to ECUtalk. I took it off to check some stuff and just put it back on to the mark I made, might be a little off but no big deal. I understand they will run and make a bit more power at 17 degrees but that's another discussion. I just want it to work! Help!

     
Follow Ups  
     
Post a
Followup

You cannot reply to this message because you are not logged in.