Please help, high idle after restart randomly...???

[lsx523]

Hi Gents, been a while since I've been on. Please look @ this tune. Am trying to diagnose why the car will jump to 2200 ish RPM & hang during the entire trip of that car's start. It happens randomly, but, only after car has warmed up & on a second or third time starting for that day.

Have tried...

-ECT spark table mods to subtract spark under certain ECT conditions
-idle air airflow mods
-engine overspeed spark reduction
-IAT mods
-start up mods

Am pretty sure that it's IAT/ECT related, but can't pin it down. Should also note that if the car is started a number of time immediately after the initial high speed hang (2200 ish), I can get it to stop doing it. If the car is driven without restarting to eliminate the hang, it will hang for that entire trip.

Thanks for looking

08-02-10 Master.tun

[WeathermanShawn]

Wow..

You have definitely made a lot of modifications from stock. A lot of the changes you have made..make it very challenging to narrow down.

I take it you are running MAF-only (Rpm Threshold-200 Rpm)..but I can't tell from your tune if indeed it is running Open or Closed-loop (Temps vary..are you in and out of Open-Loop).

What is the 'Stall Saver' doing? Where did you get the values for your Leaned Airflow Corrections?

Normally I would suspect the IAC contribution to be incorrect..This still happens when the car is moving, correct? Like the TC or TF, but I see your TC is zeroed out.

I guess I might try taking as many Airflow Values as possible back to stock to eliminate confusion. Yours is one of the more complex tunes I have seen as far as modifications. Perhaps the culprit will jump out from another Tuner checking it over..right now there are too many variables to eliminate from tune alone..

[lsx523]

Thanks for the reply. Yes, OL-MAF. Will look into stock airflow. However, the start up & idle is pretty uncontrollable when I go back to stock airflow settings. The leaned airflow corrections are all wide band verified & it is set up to run lean under normal driving conditions in order to save fuel. Yes, it still happen when the car is moving, but, it only happens when the start up yields a 2200 ish hanging idle. Does not happen w/ normal idle.

[mr.prick]

B3605 is a bit lean, how is fueling when this occurs?
What are your logged RAFIG values?

[WeathermanShawn]

Right..

What I do not understand is Table B4205 Closed-Loop Temp Enable. Your car starts in OL-MAF, then goes back to Closed-Loop when your ECt hits 90C (Scan Label-IAT inaccurate?..believe that should be ECT?).

Since you have LTFT Trims disabled, how is it learning the Airflow Correction when you 'go-back' to Closed-Loop?

Anyhow, in all reality unless you have modified the Start-up Airflow Corrections, then I would still assume it is the TF..perhaps the decay rate(s), since that looks like it has been modified. When you are moving the Idle Airflow Corrections are not commanding anyway..

All I can think of is that one of the many Airflow parameters is not properly decaying..

Anybody else got any ideas..

[joecar]

Ok, I merged threads, deleted duplicates, and moved to GenIII.

[lsx523]

Right..

What I do not understand is Table B4205 Closed-Loop Temp Enable. Your car starts in OL-MAF, then goes back to Closed-Loop when your ECt hits 90C (Scan Label-IAT inaccurate?..believe that should be ECT?).

Since you have LTFT Trims disabled, how is it learning the Airflow Correction when you 'go-back' to Closed-Loop?

Anyhow, in all reality unless you have modified the Start-up Airflow Corrections, then I would still assume it is the TF..perhaps the decay rate(s), since that looks like it has been modified. When you are moving the Idle Airflow Corrections are not commanding anyway..

All I can think of is that one of the many Airflow parameters is not properly decaying..

Anybody else got any ideas..

To reply to the post above this one regarding B3605. That is the lean, "normal driving," table. I have no cats. So, the A/F does not need to dither around stoich in order to keep them healthy. My lean cruise is 16-17:1 A/F ratio.

In response to this reply, I don't understand either. It is programmed based on IAT, not ECT. So, if the sofware means ECT where it states IAT, the program will go back to closed loop & it is not supposed to. Are you able to confirm that this is a software miss-nomenclature? If so, the value will be changed so that it does not go into CL. I stopped the 120 there thinking that it wouldn't reach 90 IAT. There is true RAM air & the IAT sensor is in a location where it reads ambient temps., not ambient + underhood.

Will look @ TF first & then decay rates. Also, would like to clarify the B4205 IAT or ECT labeling.

Thank-you for the replies.

[lsx523]

Joecar,

Thanks, I couldn't figure out how to delete one & was in a hurry.

[WeathermanShawn]

In response to this reply, I don't understand either. It is programmed based on IAT, not ECT. So, if the sofware means ECT where it states IAT, the program will go back to closed loop & it is not supposed to. Are you able to confirm that this is a software miss-nomenclature? If so, the value will be changed so that it does not go into CL. I stopped the 120 there thinking that it wouldn't reach 90 IAT. There is true RAM air & the IAT sensor is in a location where it reads ambient temps., not ambient + underhood.

Thank-you for the replies.

OP, in all honesty I always assumed Closed-Loop was dictated by ECT Temperatures. I always put those temps to the Max if I was utilizing Open-Loop to make sure. Perhaps the IAT nomenclature is correct..it just struck me as odd. I agree 90C on IAT would be pretty high.

Did you modify the IAC Effective Area or the Start-Up Idle Airflow Correction and/or Multipliers? I wonder if that is not decaying?

[joecar]

My understanding:
B4205 is ECT vs IAT... if IAT is some value x, then ECT must exceed the y value at x for CL to activate.


What is the question again...?