LQ4 stroker idle problems

I'm looking for advice getting a stable idle. The engine starts when cold (not smoothly, but it doesn't die). Around 80-90*F ECT the motor dies everytime. at that point it will only restart with some pedal and will die as soon as you let off the pedal.

Engine is 403ci w/ new heads and 236/244 cam, 102mm TB DBC.

I am attempting to tune SD - I have the MAF failed.

I've messed around with spark and Fuel quite a bit and haven't had any luck. I don't fully understand the ETC area scalar value, mine is the decimal version (stock value .0255) - I have tried moving it both up and down and neither one really seemed to change anything. I've also messed with the injector timing, it seems a little better where It's at right now but it still dies at the same ECT.

I am running out of ideas to try on this one. any help would be appreciated.

Attachment 127664Attachment 127665

What injectors are they?

deatschwerk 60lbs

The ETC Scaler is for Electronic Throttle Control. It's not applicable for your combo.

Once you get your engine up to operating temp, Adjust your throttle body minimum air screw to get the IAC in the 30-50 range on your combo. You will have to make the adjustment with engine off/key off. That will help considerably.

oh okay That makes sense now. I guess I had it in my head that the IAC vs effective area table worked in conjunction with the etc area scalar. Thank you for clearing that up.

This might be a stupid question, but you have to be at idle to adjust the IAC right? because right now the only way to get it to start/run at all above about 70*F ECT is to give it some pedal. Should I just keep adjusting the set screw until I can get it to start warmer?

Quote:

---

Originally Posted by MHK5

oh okay That makes sense now. I guess I had it in my head that the IAC vs effective area table worked in conjunction with the etc area scalar. Thank you for clearing that up.

This might be a stupid question, but you have to be at idle to adjust the IAC right? because right now the only way to get it to start/run at all above about 70*F ECT is to give it some pedal. Should I just keep adjusting the set screw until I can get it to start warmer?

---

Just adjust the set screw until you get the IAC in the 30-50 range at a warm idle. That'll help the warm start issue.

I opened the throttle blade until it would start, the IAC goes to 0 in order to slow the idle. I tried less Base airflow but didn?t seem to make a difference. Also tried adding/removing spark. The IAC starts to close, the motor surges hard about 2 times and dies. It happens within about 20 seconds of startup.

I did find that I had missed a short pulse adder limit value when changing injector data. I?ll get that fixed and try again.

Load this one when you get a chance. It'll get you moving in the right direction.

Attachment 127830

well fixing the injectors seemed to help a lot. it still dies though. This is about the best i've done so far. I can't figure out what is causing it.
Attachment 127885

Attachment 127929
Try that and see if it helps at all

I got it to run from cold start all the way to operating temperature before the motor died. Thank you to everyone for the help so far. The tune is definitely getting better.

Something is changing in the airflow or fuel calculation during warm up. See picture below(before you ask, it is commanding 14.68 PRIOR to the drop, so it's not the base open loop table). my afr% error is relatively steady except for one spot, where it transitions from being steadily lean to approximately stoich. As far as I can tell the engine runs more smoothly a little lean at idle (you can see the spark and RPM line become very jagged after the afr% error transition). I want to know what could cause the change in the fueling calculation. Right now If I lower the VE at idle, my cold start gets TOO lean but operating temp is slightly lean like I want it to be. If I don't change VE the engine dies at operating temp, but will cold start and warm up pretty successfully.

Attachment 128203Attachment 128204Attachment 128205