Problems with my car

[gixxer750]

I've got issues. When I start my car(warm) the AFR starts out @ 14.5 or so, and after 30/40 seconds the AFRs start slowly working leaner and leaner, until 18:1...

The car did throw code 31&51 @ one point. When the CEL came on, the AFR went 10.0... check engine light off, 18:1..

So, I have to attempt to drive home @ 30 mph... the car runs fine at some points, and then jerks and bucks with AFR's bouncing everywhere.

Emanage throws a code when the check engine light comes on too. Air flow meter

Car has Brand new wiring harness, with maybe 5000 miles on it. Swapped Air flow meters to a known working one. It made the car run worse. So I reset the ECU. The Car ran fine upon being restarted, and I drove it 3 miles down the road. It ran perfect, boosted good and the tune was still perfect.

Then it went back to running like shit again, no codes until it went rich. 31 & 51 then reappeared.

I would guess the ECU, but the emanage is throwing the AFM code too!

 

[Nick M]

Bad connection between the AFM and ECU.

 

[gixxer750]

Thats what I was kinda thinking too... but its a new harness I guess I'll be tearing into it.

 

[Nick M]

I didn't turn to the DTC explination page but, if your Hz goes high, you set 34. I don't know if it sets for low. I think it is just another open or short electrically code.

 

[gixxer750]

Well, got a clamp on the high HZ with the emanage. So, no FC for me.

I haven't hooked the laptop up and checked out the HZ yet, but I will, and get more info. I'll watch what it's doing and report back

 

[Nick M]

Also the 51. Set the contacts closed.

 

[gixxer750]

Car has no A/C system at all, could that be it? Always had a code 51 even with stock TB...

It now has a q45 and nissan TPS on it. It was factory calibrated still?

I'll check it

 

[Nick M]

51 is when the A/C is on. Make sure the harness isn't shorted.

 

[jetjock]

I don't know if it sets for low. I think it is just another open or short electrically code.

Set above 4.8 volts and below 100 mv. Anything in between is judged valid even if it's not calibrated. Same with the analog sensors.

 

[staticpat]

The TPS code probably isn't causing all that but it only takes 5 minutes to fix. I found out my base timing had been 5 degrees retarded after fixing the contacts. This may have more severe results for you than what I was experiencing.

Of course if the nissan TPS doesn't use the IDL contacts, not much you can do except make your own throttle stop switch and input that into the ECU.

 

[jetjock]

Good post staticpat. If his car always had a 51 it makes me wonder about his timing because doing it with IDL possibly open is bad news. I wonder how many people just stick the diag jumper in and time away. Timing should never be set without first verifying the MIL is flashing a normal code because it proves IDL is closed.

 

[Nick M]

Set above 4.8 volts and below 100 mv. Anything in between is judged valid even if it's not calibrated. Same with the analog sensors.

Good to know, thanks. Now I have a Hz value.

 

[gixxer750]

The nissan sensor has an idle validation switch in it, but according to my ohm meter, it is closed with the TB closed. Anyhow, my car is fixed. Broken wire around 10 inches from the afm. Green wire/red stripe. signal wire.