Really Rich Idle, Lean on Throttle

[nissanman04]

Some background info: '91 KA24DE, Garrett T3/T04E, JGS starter kit, 740cc injectors, 255lph fuel pump, Z32 MAF, nistune ECU

I've been trying to troubleshoot this problem for the past few days. I originally installed some brand new nismo 740cc injectors and 255lph fuel pump for my new turbo setup. I have not been able to get the car to run right since doing this. The car idles between 9 and 10 AFR but really leans out under throttle (18:1+). I can move the injector latency way down in nistune to get a 14.7:1 idle, but it is really rough and falls on its face even worse on throttle. The rich idle is actually pretty smooth, only missing every 5 seconds or so. I have since changed all components back to stock and I'm still getting this problem (Injectors, fuel pump, MAF, turbo stuff is still there, though this problem was happening before those parts were installed). There are no fuel leaks at the rail, as I have removed the rail and primed the fuel pump without a drop of fuel anywhere. I did discover a torn injector insulator on the manifold, could this be causing the problem? I have already ordered 4 new ones since they could obviously use replacing. I'm just looking for suggestions as where to look next...thanks.

[biggie]

If air was leaking in at injector insulator at higher RPMs that would explain being lean.

Other major leaks after the MAF or on the intake mani?
O2 sensor working properly?
All MAF connections right?

Otherwise has to be something in the Nistune setup.

[nissanman04]

If air was leaking in at injector insulator at higher RPMs that would explain being lean.

Other major leaks after the MAF or on the intake mani?
O2 sensor working properly?
All MAF connections right?

Otherwise has to be something in the Nistune setup.

It does this with both stock and z32 mafs, voltages are in spec for both. I guess I could put the stock intake back on to bypass my ic piping, but I did a boost leak test and fixed the leaks I found. I've turned off o2 feedback in nistune, so it's not doing anything. I'm going to try a stock ecu to see if that makes a difference.

[Chris28]

Could it be a faulty o2 sensor? Maybe you can find someone with a different wideband system and verify that those readings are correct.

When my duaghterboard fell out and I was running on basemap with 370cc injectors, my AFR's were right around 10. This gave me a horrible idle and the exhaust smelled strongly of fuel, and the idle wasn't very smooth at all.

[nissanman04]

Could it be a faulty o2 sensor? Maybe you can find someone with a different wideband system and verify that those readings are correct.

When my duaghterboard fell out and I was running on basemap with 370cc injectors, my AFR's were right around 10. This gave me a horrible idle and the exhaust smelled strongly of fuel, and the idle wasn't very smooth at all.

Could be, I actually have another wideband sensor that I'm going to try tomorrow. I may take it up to my tuner's shop to verify as well, assuming the car can make the 45 minute drive.

[nissanman04]

So I loaded my maps for the n62/740cc setup and threw those parts back on. It still idles between 9.5 and 10.5 AFR (cruising is around 11), but under load the AFRs are pretty much dead on. Moving the K constant around changes the AFR very little, if at all. My current narrowband o2 sensor seems to be no good (0.33V most of the time), so I'm guessing the ECU thinks the AFRs are withing spec, thus not adjusting accordingly at idle and cruise (even though i've turned o2 flags off in nistune, which is weird). I may try and hook up my LC-1 to emulate the narrowband signal and see how that goes.

I currently have my BOV vented to the atmosphere (waiting on recirc tube to arrive). This, along with a super rich idle, makes it a pain to drive since it is always stalling going into neutral unless I heel-toe to keep the revs up. I'll probably also do another boost leak test just to be safe. Hopefully the BOV recirculation will make it better...

[WDRacing]

Be careful how long you let the motor run that rich. You'll flood the oil with fuel which will eventually eat bearings. It also washes the oil off of the cylinder walls pretty quickly especially under load where you get the most blow by.

WD