ca18det idle's great, under load studders (lean)

[keechusmc]

So i just picked up this problem recently with my ca18det.

Car will start up and idle perfectly and even rev great while the car is not under load. My problem is once i am moving the car starts to run really lean 17+ and starts to studder (hickup). As soon as i pop the clutch the afr is back down to 12.1-14.

The only thing i recently did to it was change the coil grounding point to the intake manifold instead of that corner end screw (kept breaking). And change from stock plugs to heat range 7's. Does it really matter where the ground goes for this?

Car also run like crap is boost before which ended up being #1 cyl spark plug ceramic cracked

IACV/air reg has been deleted (ran great with these unplugged before)

Running
s15 t28
z32 afm
444 inj
full exhaust
fmic

tuned via nistune and made 278whp/245 tq at 16lbs

[float_6969]

It could matter if that's causing noise the ECU can't filter out. Try moving the ground again, but keep it on the head somewhere.

[boost_boy]

So i just picked up this problem recently with my ca18det.

Car will start up and idle perfectly and even rev great while the car is not under load. My problem is once i am moving the car starts to run really lean 17+ and starts to studder (hickup). As soon as i pop the clutch the afr is back down to 12.1-14.

The only thing i recently did to it was change the coil grounding point to the intake manifold instead of that corner end screw (kept breaking). And change from stock plugs to heat range 7's. Does it really matter where the ground goes for this?

Car also run like crap is boost before which ended up being #1 cyl spark plug ceramic cracked

IACV/air reg has been deleted (ran great with these unplugged before)

Running
s15 t28
z32 afm
444 inj
full exhaust
fmic

tuned via nistune and made 278whp/245 tq at 16lbs

There is no need to run such a cold plug on the CA18DET and with your modification list. Change back to the 6s and go from there as 7s are extreme and will cause fouling issues as well as other weird things. Trust me on this one

[keechusmc]

Pulled the old 7 plugs and found that they were running hot (lean). Installed new oem v power ngks and the car still runs like crap. (Could it be bad gas? One website mentioned if the grounding strap appears as though its been spray painted white it could be high ethanol content.

[keechusmc]

Here are the plugs I pulled out while it was running decent (oem ngk v powers)


Here are the ngk 7's (like one mile if that of travel)


I also moved the igniter coil pack ground back to the oem position. No difference.

Car idles at 14.6-14.8 Afr

So obviously everything is working. As soon as I blip the throttle the car goes off the charts lean 17+, I have also noticed my ecu lights have stopped flashing.

If it was a vacuum leak the car would be running rich right?

Fuel pressure is 2.2 bar. It increases with the blip of the throttle as well. I even tried to increase fuel pressure to 3 bar and afr's at idle remained the same.

I am thinking its gotta be my z32 afm is s*** out or I got bad fuel/fuel filter/fuel pump and last but not least my ecu is toasty.

[float_6969]

A vac leak will be lean below boost, but the ECU can often compensate for the extra air with it's closed loop adjustments, so you won't see it. It will be rich under boost.

I can't think of any reason why bad gas would make it show up as lean. A bad fuel filter is possible, but you'd see a drop in fuel pressure and it would happen as the engine got load on it, not just blipping the throttle. A bad fuel pump would show low fuel pressure as well. A bad ECU is possible as well. Have you checked the maps on your Nistune and make sure it all looks right?

[keechusmc]

I don't have access to the files, I would have to get my tuner to access my ecu.

[keechusmc]

I think I found the problem lol





Metal n62 housing on the way

[float_6969]

Hmm, that could cause some issues, LOL

[keechusmc]

Changed the maf housing with an all metal one. Put some new gas in. Still runs lean at idle. It's able to rev but backfires. Could my tune be off?

[float_6969]

Yea, this sounds like a tune issue at this point. I'm not familiar with Nistune, but I've been noticing that the latency is an often overlooked tuning parameter with the Nissan ROM.