Massive overfuelling at idle

[zrated]

I've got a problem with a 180sx with an SR20DET....

At idle, the TP is huge and the injectors are running between 12-14ms...... I've swapped out CAS, ECU's, Wiring Harness, AFM and TPS and nothing changes.... I don't understand why it keeps running so bloody rich....

Any suggestions?

[Matt]

the injection time is huge for idling. should be about 4ms-ish from memory when i was looking at my car idling

what size injectors / MAF is it running?

injector time also looks very shaky. how does your battery voltage graph here? something definately not right, should be smoother than that

[zrated]

the injection time is huge for idling. should be about 4ms-ish from memory when i was looking at my car idling

what size injectors / MAF is it running?

injector time also looks very shaky. how does your battery voltage graph here? something definately not right, should be smoother than that

Yeah I know, I just can't put my finger on what is wrong.....

The MAF looks like it's running a little too high for idling too?

Stock MAF and stock injectors.... We didn't put them in though, but they all look stock... SR AFM & grey injectors

Also, battery voltage is 11.8V on idle

[Fusion Ed]

Maf voltage looks way to high. What maf and where is it in the pipework in relation to the turbo, and do you have a dump valve or similar that is not a dual valve type that may be open at idle?

[PL]

Yeah, you should be seeing a bit over 1V AFM voltage at idle. I suspect 2.6V would be enough to take the map trace about halfway across the fule maps and this on its own would probably account for your overfuelling. You'll be wanting around 2ms at idle.

I'm tuning an SR tonight with std injectors and AFM so I'll take note of the AFM voltage and injection time at idle. But from memory AFM voltage at idle is around the 1 to 1.2V mark.

PL

[Fusion Ed]

Just also thought check that the maf voltage engine off is about 0.5v or so.

[Fordy]

i can confirm both mine and a friends sr's mafs idle at 1.180-1.250volts

k constant, ttp min and also maf translation are the ones i know will affect idle afr

[PL]

I checked that car that I was tuning last night and at idle the AFM voltage was 1.2V and inj pulsewidth was just a smidge under 2ms. This was an S14 but I'd expect an S13 to be pretty close to those figures too.

Incidentally we cranked some boost into this one (15psi) and std injectors went to 100% at 5200rpm. AFM still had some headroom but it was all over for the injectors. They still held AFR's at richer than 12:1 up to 7000 but far from ideal...

PL