High Idle and Engine Misfire problems

[Isaiah48]

Ok guys, I've tried to get this idle thing down on multiple occasions and it just doesn't respond like others who have successfully saught help on Idle problems on here before. Most of the problems started after doing a major drivetrain overhaul this past winter, I upgraded the clutch to 900# Zoom dual disk with an Aluminum fywheel. (I know the Aluminum fylywheel is probably making it a bit more tricky since it allows the rpms to drop and recover so fast due to less inertia that it can easily start chasing itself in Timing and fuel causing a lot of surging and bucking. I dealt with this by fixing the Timing to not adjust automatically when at idle, not gone but much better than witht the spark bouncing around) I upgraded the Trans to a fully race prepped Z06 close ratio, I know that shouldn't be a factor and the rear to a fully built 3:90 setup, which again should not be a factor.

I can get it to idle but it is much higher than I want, about 1200rpm but it still wont let me use the AC or it will lug it down and either start surging or it will stall abruptly. I've tried finessing the Base Air up and down to get the idle to work with AC but if I put it where it wants to be it causes an extremely high idle without AC and even then it will still have Stalling or idle surging issues with the AC on.

I haven't been actively working on this issue for awhile now, I felt I needed to step and just drive it and rethink everything. I drove it into work this morning and realized that I'm getting a consistent Misfire code getting set, hmmmm... I wonder if it is missing at idle and I just dont hear it or really feel it, not sure that was possible since I've always been pretty good with being able to pick out even the slightest burp in the past and this exhaust definitley is loud enough to hear anything going on. To me it sounds fine but the ECM says otherwise.

Do you all think the Misfire is an issue, I didn't use to get them?
Do you think I might have a vacuum leak, it isn't pulling any lean codes?
Do you think the Gremlins are just messing with me?

Oh, I also got an Immature Crank Position Sensor code, not sure if that could be related since it was only immature but worth mentioning.

Things tried:
Adjusting the Base Air Minimum, the Baro and ECT as well
disabling DFCO and CFCO
Manually set the spark to be static in the idle range.
The AC Airflow Ramp in and Ramp out
Went to MAF only tuning and went away from VE.
Checked for vacuum leaks. This still maybe possible the Fast I have may need to be repaired but if it is leaking it is very small.

I attached a tune and Log form my drive in, all build details are in my Signature. Any insight would be appreciated...

[angrygoat]

is the misfire on one cylinder or is it a multiple misfire i.e. p0300 code

no log or tune posted

[Isaiah48]

is the misfire on one cylinder or is it a multiple misfire i.e. p0300 code

no log or tune posted

Good question, I didn't take note of the code #, just the code description...

Sorry I forgot to post the Log and tune I'll go back and edit my post...

[Isaiah48]

The misfire code is the p0300 code, what does that signify?

Also does anyone know why the idle keeps raising to 1,100 to 1,200 when I have it set to 850? It idles down just fine if I push in the clutch and while rolling but as soon as I come to a stop it goes up again, I dont see what is causing it in the tune...

[EC_Tune]

First off, what are your actual fuel injectors? If you do not have complete information about them, you can't tune the car properly. Injector offset and short pulse adders as well as minimum pulse width are critical, especially for idle. You NEED this info to tune your car properly.

I made some changes for you. Check them out and report back.

[Isaiah48]

I was unable to open he file you posted, it gives me a message that says: "Index was outside the bounds of the array"

The injectors I used are:

http://www.thunderracing.com/catalog...oduct&pid=3645

The only thing I changed when setting up these injectors was the Flow Rate vs KPA. I used the spreadsheet to calculate the input. The injectors were 42# at I belive 42 psi, so there are 48# at 56psi, not positive but I know they calculated to 48#.

[Joe_G]

I was unable to open he file you posted, it gives me a message that says: "Index was outside the bounds of the array"

The injectors I used are:

http://www.thunderracing.com/catalog...oduct&pid=3645

The only thing I changed when setting up these injectors was the Flow Rate vs KPA. I used the spreadsheet to calculate the input. The injectors were 42# at I belive 42 psi, so there are 48# at 56psi, not positive but I know they calculated to 48#.

You need to update to the 2.23 beta - it will give you access to the throttle rate table too which is a nice change, gives the car a snappy feel. 05's are tuned to have sluggish throttle from the factory.

[LSxpwrdZ]

I need to get this update myself.

[Joe_G]

I need to get this update myself.

Email support for HP Tuners and they'll put it on your customer login page.

[Isaiah48]

I'll send support the request but does anyone have any idea why my idle goes up when I come to a stop? It seems to be tied to the speed somehow since it hovers around 850 as commanded whe coating down until I get to about 5 mph and then it goes up to 1,100 or so... If I back off my Base Idle Airflow anymore I'll stall when I coast down, I did back it off in the Nuetral area since I posted the tune and it now matches what I had in each gear, it seemed to help a little bringing it from 1150 down to 1100.

Could the Idle Proportional Air table have something to do with, it currently is set to stock where it is zeroed out in the negative rpm range in Coastdown but has multipliers in the Transition? I was thinking of trying to zero out my Transition in the negative rpm area to see what happens, not sure what this will do since I really dont fully understand the Proportional and Intergral Idle Air tables...

[Joe_G]

Tom I've attached my tune - I don't have these idle issues, why don't you compare my tune to yours and see what's different? Maybe the answer will pop out.

In a LS1 there are tables to do what you are describing...but I don't think we have all those idle tables.

If you see anything funny in my tune let me know! Always like learning something new.

Oh you'll need the latest beta to open my tune.

[Isaiah48]

Tom I've attached my tune - I don't have these idle issues, why don't you compare my tune to yours and see what's different? Maybe the answer will pop out.

In a LS1 there are tables to do what you are describing...but I don't think we have all those idle tables.

If you see anything funny in my tune let me know! Always like learning something new.

Oh you'll need the latest beta to open my tune.

Thanks Joe, I'll check it out when I get the beta installed.

[Isaiah48]

I got the idle to come down at a stop now, the problem was in my Idle Adaptive Spark table. At coastdown it was at 10 degrees and idle was at 16 degrees. I had previously made changes in the table to force the rpm to stay stable and had forgotten all about it.

Now I just need the AC to work without stalling, any ideas? I played with AC ramp in and it didn't seem to do anything...

[Isaiah48]

Ok, I got the AC idle working now, I just need to keep the rpms from bouncing when the AC is on... Any ideas?