Idle surge to 2,000 rpm when shifting to neutral from a cruise.

[jpb1972]

Shifting from any gear to neutral while cruising, idle will spike to 2,000 rpm's or so and hang there for a while. Will drop back to idle once I come to a stop. Idle at any other time is fine.

Read several posts that say this is a normal condition.

Has anyone figured out a way to tune it out.

Mods are Centri, Cam, and ported heads.

Thinking a vacuum leak is pretty much ruled out. I don't experience any other symptoms that would suggest otherwise.

[Area47]

could be a number of things. just need the tune file.

[jpb1972]

Here is the tune file.

Appreciate the help.

[Area47]

id take the 1st gear settings and put them in all the tables as a test. {final idle airflow} watch the commanded timing and run that against what the ecm is doing. That would be where i would start. assuming the cam is not super aggressive. your knock sensor settings on the other hand. they seem a bit dumbed down a lot farther than I personally would do.

[jpb1972]

id take the 1st gear settings and put them in all the tables as a test. {final idle airflow} watch the commanded timing and run that against what the ecm is doing. That would be where i would start. assuming the cam is not super aggressive. your knock sensor settings on the other hand. they seem a bit dumbed down a lot farther than I personally would do.

Thanks. I will try that.

As far as the knock sensors I've never messed with them. How would you change them?

[Area47]

i wouldn't without a dyno to run it against to be certain. If the air flow is in check, you can also tweak the under/overspeed coast settings under the spark tab to gain a bit more control over it.

[jpb1972]

i wouldn't without a dyno to run it against to be certain. If the air flow is in check, you can also tweak the under/overspeed coast settings under the spark tab to gain a bit more control over it.

Thanks!

[jpb1972]

i wouldn't without a dyno to run it against to be certain. If the air flow is in check, you can also tweak the under/overspeed coast settings under the spark tab to gain a bit more control over it.

Changing base airflow only made things worse. Not to mention I think doing the TB relearn also contributed to that.

Still surging, put the table back the way it was.

[GHuggins]

Go back to factory idle advance and idle coastdown advance - should take care of the worst of it... As for the surge that's going to be a combo of things from proportional and integral airflow settings, idle spark corrections and most importantly the VE table which looks off pretty bad.

[jpb1972]

Go back to factory idle advance and idle coastdown advance - should take care of the worst of it... As for the surge that's going to be a combo of things from proportional and integral airflow settings, idle spark corrections and most importantly the VE table which looks off pretty bad.

I will take another look at it.

[espinjt]

Turn on Adaptive Idle RPM.

[jpb1972]

Turn on Adaptive Idle RPM.

I have this set to 20 sec. Still nothing has worked in correcting this issue.

If I hold the clutch in for about a minute before letting it out the idle stays normal. It's only when I shift to neutral and let clutch out right away.

So it appears it does have something to do with elapsed time.

[jpb1972]

Anyone else have any ideas, just started driving car again and this issue is really driving me nuts.

Again, the following has to occur to duplicate condition:

Driving car, depress clutch, shift to neutral, let clutch out, idle revs to about 2k rpm. Push clutch back in idle lowers to normal.

If I hold clutch in for about a minute and let clutch out in neutral, idle does not rev.

Thanks in advance

[lukearmstrong1990]

you're using proportional idle airflow corrections when you let the clutch back out.

clutch in according the DFCO spark will drop the timing to 0 then when you shift to N and let the clutch out it will revert to coast down spark table. if that's at 1400rpm you're going from 0-28* spark instantly.

either enable CFCO and set the spark value to something suitable.

you can also cheat by setting adaptive idle to work at the speed youre having issues. it wont work with clutch in but itll work when its out and TPS pedal is 0%

[jpb1972]

you're using proportional idle airflow corrections when you let the clutch back out.

clutch in according the DFCO spark will drop the timing to 0 then when you shift to N and let the clutch out it will revert to coast down spark table. if that's at 1400rpm you're going from 0-28* spark instantly.

either enable CFCO and set the spark value to something suitable.

you can also cheat by setting adaptive idle to work at the speed youre having issues. it wont work with clutch in but itll work when its out and TPS pedal is 0%

Sounds so simple when you understand exactly how the system works! lol Thank you for your explanation, it makes complete sense.
I will give this a shot.

Thanks for your time,
Jeff

[jpb1972]

you're using proportional idle airflow corrections when you let the clutch back out.

clutch in according the DFCO spark will drop the timing to 0 then when you shift to N and let the clutch out it will revert to coast down spark table. if that's at 1400rpm you're going from 0-28* spark instantly.

either enable CFCO and set the spark value to something suitable.

you can also cheat by setting adaptive idle to work at the speed youre having issues. it wont work with clutch in but itll work when its out and TPS pedal is 0%

Just took a look at my tune. I have the DCFO disabled by temp. My CFCO and DCFO spark tables are stock. Should I lower the main timing table in the idle areas?

[Area47]

For a quick and easy test. Take the 1st gear air flow numbers and paste them in all of the tables.

Raise the up the idle areas from 15 to 20 degrees, and same with the coast down from 18 to 20.

[Dwill83]

Just took a look at my tune. I have the DCFO disabled by temp. My CFCO and DCFO spark tables are stock. Should I lower the main timing table in the idle areas?