yo2001 Posted July 6, 2003 Share Posted July 6, 2003 OK, I've been making progress on the Z31 ECU conversion. I can now crank the car and i idles. but in Limp mode. It runs rich and won't rev any higher than 2000rpm. I keep getting MAF code and fuel pump code in Mode III OBD and MAF code on Mode V OBD. I've tried two MAF's and have check the power comming into the MAF connector and resistance between pin C&D and it came out good. Also, my MAF is lead up with power on. My only guess is I've two bad MAF. Any idea? I also need more info too. which way the MAF go on to the intake? the arrow pointing toward the turbo (intake) right? Another. I've one yellow wire coming out from an unknow connector. It's labeled (ignition +). Anyone know where this wire suppose to go. My harness is modified 280zxt. Anyone with a clue, I need help. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted July 6, 2003 Share Posted July 6, 2003 I had the same problem when I first did mine. I had wired the maf connector wrong. Check your mail for a pinout sheet. Does the maf voltage change with the rpm? (pin 31 at the ecu) It should be about 2.6 or so volts at idle. Bernard Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 6, 2003 Author Share Posted July 6, 2003 How would I check that? I have no clue how to check voltage without taking the connector off. What do I need other than a voltmeter? Quote Link to comment Share on other sites More sharing options...
Bernardd Posted July 6, 2003 Share Posted July 6, 2003 Use lead with a paper clip into pin 31 at ecu and the also connect to chassis for ground. Or the B pin (I think) to ground at the maf. At key up the output of the maf should be the one that reads 1.6 volts or so to ground. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 7, 2003 Author Share Posted July 7, 2003 OK. not getting 2.6V. I had .02v or something So could it be bad ground?? Quote Link to comment Share on other sites More sharing options...
jeffp Posted July 7, 2003 Share Posted July 7, 2003 Ok since you are running the 280 harness you will need to add a wire to the harness for the MAF sensor. There is a wire to the MAF that applies 12 volts to the filament to burn off the junk that may have gotten on it. This is important as the filament is what is metering the air intake to the engine so having junk on it will mess up the metering. The MAF from Nissan is set to 2.2 volts @ 750 rpm. If you get a lower voltage then 2.2 volts the ECU will not be able to read the MAF output. This is critical also. Since you dont have any voltage at the output pin for the MAF at the ECU, I would suggest that you get the schematic and verify the wiring, if you need a schematic I can email you it. So atart there and see how it goes, I am not sure of your setup, but there are also other sensors that the 300 used that were not used in the 280 like the fuel temp sensor. Also you may find you have a parblem with the knock sensor in the 280 because they are a different sensor, but more importantly, the 280 inline engine is much more noiser then the VG30 engine, so that may be getting turned on when there is no problem with knocks, something to keep in mind when you get the car running correctly. The other thing that comes to mind is that you need to swap two of the fuel injector wires as they are incorrect for the inline six engine, not a real noticable problem, but none the less it is a fact. anyway check out that stuff and see how it goes. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 7, 2003 Author Share Posted July 7, 2003 I got my MAF burn off hooked up Jeffp. It lights up now. I'm getting little to no power from pin 31. So I started to see and follow the wire. Then I found the wire connected to shielded grey wire and black wire. WTF? either of the wire is getting solid voltage. I got like 0.1v out of one. Do you guys know how these two wires hook up to pin 31? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 7, 2003 Author Share Posted July 7, 2003 Ok, I worked on some more. I reconnect the grey shielded wire to pin 31 and took the black wire off. (I assume it's some sort of ground) With MAF not hooked up, it's getting .1v and with MAF hooked up and key on, Getting little over 4v. It's that right or close? Quote Link to comment Share on other sites More sharing options...
jeffp Posted July 7, 2003 Share Posted July 7, 2003 You may want to double check that wire. Typically the black wire with the shield and grey cover is for the O2 sensor. So at the ECU, the shield stranded wire around the black wire goes to ground in the harness. The black wire goes to the O2 sensor. The shield wire strand ONLY gets hooked up to the harness at the ECU end and the other end is left open. The shielded stranded wire is there ONLY as a noise suppressor. I cant remember to clearly, but I can tell you one thing, that gray shield and wire is not an active component in the harness, it is ONLY a noise suppressor so if you hooked it up you need to reconnect it to ground, and leave the other end open, making sure that it does not make contact with the other wire it is covering. I have the pinout to the ECU from the MAF, you really needto check to make sure the wiring is correct as I think you have miswired the MAF. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 7, 2003 Author Share Posted July 7, 2003 Thanks jeffp. Send me a pinout and I'll go through it again. I do remember a shielded wire with black ground use as O2 sensor wire from my A/F ratio gauge. I think the sheild is to protect the small voltage signal from getting interference with other power source. Since the MAF signal is small (up to 5v right? ) may be shielded wire is needed for accurate reading? Well, I'm going to run a single wire from pin31 to B terminal on the MAF and see if I can get te car to run right today. Thanks Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 8, 2003 Author Share Posted July 8, 2003 I worked on some more. Now I'm getting voltage to pin 31. But I think I'm getting too much. at idle, it was pass 5v. Any idea? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 8, 2003 Author Share Posted July 8, 2003 Got up today and I fiddle some more. Now I got it running off limp mode and no more MAF code and CAS code. hoohoo Now when I rev up, the car misses some like it's running out of fuel (but fuel pressure good) It must be something to do with the fuel pump control. Well, Thanks guys. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted July 11, 2003 Share Posted July 11, 2003 If you're getting more than 5vdc at idle your maf is shot or it needs adjustment. Is the adjustment screw beside the connector exposed? Or has it been tampered with? On second thought I'm not sure if the idle mixture screw can adjust that much. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted July 11, 2003 Author Share Posted July 11, 2003 I found the reason why my MAF was getting more than 5v. I had the self cleaning circuit opened. I got it fixed now, it's sweet. Thanks for your guys help. Quote Link to comment Share on other sites More sharing options...
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