Cold Start Tuning Help

[muttley383]

Other issue is if the engine stalls at idle the IAC increases to approx 110 but fails to stop the stall. On restart the idle stays very high and the IAC steps will only drop to 80 or so and no further even though the TPS is at 0%. Is this related to above parameters?

I forgot to add that the only way I have found to reset the IAC back to normal is to rewrite the calibration to the ecu.

[VL400]

Only having a quick look, but no speed sensor might not be helping idle learn so the base steps are always really high. Part of driving around is learning the base idle steps (and storing in RAM for next time idle is entered) along with IAC reset above 2000RPM so it knows where it is. Yours looks to have a very low number of steps (around 6 in that hot idle log) so might need to close the throttle plate up a little.

Will check it out more later.

[muttley383]

What is wierd is the fact that my logs whilst driving do have the speed showing and is accurate.
The no speed signal may be left over from when it was reving high at about 110 steps on the IAC.

I set the throttle at roughly 13 steps with headlights and cooling fans running, this drops to 6 steps when engine load is removed. I read somewhere that it should be set at about 10 steps, I dont know if this is too low.

[Holden202T]

genereally i try to run mine about 20-30 steps at idle ....

[delcowizzid]

yeah 20 steps hot idle no load

[muttley383]

Will check it out more later.

Hi Ryan, did you get a chance to have a look at the logs?

[VL400]

I think just adding some more steps by closing the throtle plate will help it a bit to start with, idle is way high and is even to the point of resetting the IAC in one part of the log.

I think your right about the VSS fault too, if you have a VSS it will be from the high RPM and high vacuum - it looks for a VSS fail during decel.

[muttley383]

I adjusted the throttle stop to allow approx 20 steps when hot.
Attached is a log of a cold start and hot run, idle was hunting under some circumstances and below are some observations.

- Idle at first start when cold not that bad.
- @ approx 2.55m in the log the idle starts to hunt quite a bit.
- @ approx 5.22m idle start to even out.
- @ approx 5.42m idle starts to hunt again until 6.13m when it evens out.
- @ approx 8.17m idle hunts for a bit after stopping at traffic lights.

anyone recommend any changes to the .bin I can make to improve the situation.

Also I noticed that I have DTC 24 and 36 up. The VSS fault should not be there as I pulled the fuse for 30 seconds to reset the ecu and at no stage was the engine reving above 1500rpm for any period unless the car was running along the road. As can be seen in the log, the speed signal is working.
Should I mask DTC24 ? . I dont know whats up with DTC36 as I dont think I have a vac leak. Will any of these DTC's contribute to the idle quality problem I have.

See attached log.

[Holden202T]

it doesn't really look like there is anything specifically in the log that shows whey its hunting .... but i must say there are still alot of places in the tune that are way rich .....

[muttley383]

Yeah, I know it is rich.
I wanted to try and sort out the idle problem before moving on to the next issue.
I have to sort out the ve table properly and then move to spark.

What confuses me a little is that other 383cui tunes I have seen is that they seem to have a ve of approx 43 with an afr of 14.0:1, whilst I have the ve set for about 25 and still am too rich.