Stumble off idle

[rindoze]

I have an issue where my car stumbles off idle. If I put the car in neutral and rev it, it stumbles when I rev it under ~2k rpm. If I roll into the throttle it is fine.
Car is a turbo 6 clyinder, with an E67, and probably a very oversized throttle body. I tried adding timing, removing timing, adding fuel, removing fuel. The stumble wont go away and doesnt noticeably change with anything I've tried. I don't know what other thing to try to adjust. Any ideas what I can try? As a last resort I could increase the idle rpm to maybe 1200, but that feels bad.

idle revs more timing.hpl
L28SDSpark.hpt

[GHuggins]

Are those factory inj timing tables? They don't look it but your base file shows they are. Since your dc is so low you can try advancing the inj timing in your trouble area. Your throttle appears to open slow in general, but I assume that isn't the stumble you're referring to.

[edcmat-l1]

What injectors are in it? You might want to try dialing it in first before you try stomping on the pedal repeatedly. It's overly rich and the trims are bottomed out around -9%. You need to dial everything else in before you focus on WOMP WOMP WOMP.

That being said, once everything is dialed in properly, if it still feels like that it's either injector timing and/or transients.

[gtstorey]

https://forum.hptuners.com/showthrea...l=1#post757947

"Yeah its an I6, the I6 forums were pretty dead so posted in here. Whats been done is this is an Nissan L28 engine with ALL the EMS of a vortec 4200 attached to it (sensors, injectors, throttle body, pedal, everything). I'm not worried about fuel pressure, I have a camaro Zl1 pump feeding this and expect around 350whp when deep in boost.
I'm using the original MPV1, non pro, so can't hookup a wideband. Only running the precat O2, wiring harness I got had the second one chopped off and I'm used to deleting them on V8s. I'll try to get the wiring for one and see. I also ordered another O2 bung, I am running the O2 ~1.5ft after the collector merge and 1ft before the turbo. I'm going to add a bung in the collector to see what it says.
mafFailed less VVE.hpl is the log for tune L28SD2.hpt. The logs of mafFailed less VVE+10.hpl mafFailed less VVE+10+10.hpl are L28SD2.hpt with whole VVE x1.1 and then x1.1 again. So VVE+10+10.hpl is a log with 21% more fuel than mafFailed less VVE.hpl.
If you look at mafFailed less VVE+10+10.hpl I'm idling for about the first minute. At ~24-52 seconds with the car sitting idling the O2 is oscillating between full rich and full lean when nothing else is changing so my guess is the O2 reading is wrong."

[rindoze]

Yep I got all those issues sorted in that post, VEs adjusted pretty good. They are not as rich when the engine is under load, and most of those high negatives at low KPA are in part from DFCO not working very well since there is no VSS sensor attached. Injectors and timings are stock, the injector flows are adjusted to match the higher fuel pressure I run. I can try adjusting injector timings, but my cam has no overlap so I wouldn't expect much to happen. The stumble is at first a pause, then a bum.....bum.....bum....bum...bum...vrooom. You should be able to make out the slight dip in RPM (the pause) right after I hit the gas and as the MAP kPa spike immediately.

[rindoze]

This is solved. Fix was to change spark plugs, I went to a projected tip one. Factory was non-projected tip for this engine, but everyone with a turbo online were running projected tip. I had also tried the injection boundary timing, but no change was noticed.