Tuning with PRP- IAC issue.... maybe?

[CJK440]

I'm just starting to tweak my base tune using PRP. The car is an 04 GT with a saleen/eaton blower. I am attempting to dial in the MAF at idle and free revs before I put a load on it. At idle as soon as the throttle is tapped off the stop the engine flares to ~2000 or so for 5 seconds.

Dataloging ISC integrator shows -.35 at idle and then jumps to zero when the throttle is touched and then after the 5 seconds it quickly stairsteps back to -.35.

The issue its causing is I am trying to dial in the MAF with free revs it is just that I can only get data for idle and 2500+ because of this.

 

[txcharlie]

ISC is like a STFT for idle. You need to subtract .35 from the cell at the corresponding rpm in ISC Neutral Idle Air. You should be in closed loop and let it idle for 3-4 minutes while logging ISC.

 

[CJK440]

ISC is like a STFT for idle. You need to subtract .35 from the cell at the corresponding rpm in ISC Neutral Idle Air. You should be in closed loop and let it idle for 3-4 minutes while logging ISC.

That makes sense. I am forcing open loop now but will be allowing closed loop to verify my MAF curve adjustments by way of the STFT's.

On my datalog I was able to creep RPM up to about 1200 RPM before the -.35 immediately went to 0. But this was forced open loop.

If it does the same in closed loop I would want to subtract .35 from all cells from 1200 and below?? (highlighted)

 

[txcharlie]

That makes sense. I am forcing open loop now but will be allowing closed loop to verify my MAF curve adjustments by way of the STFT's.

On my datalog I was able to creep RPM up to about 1200 RPM before the -.35 immediately went to 0. But this was forced open loop.

If it does the same in closed loop I would want to subtract .35 from all cells from 1200 and below?? (highlighted)

View attachment 44814

As always, check for the dreaded vacuum leak first.

 

[CJK440]

Not seeing any air leaks.

I logged again with closed loop and same issue. I modified neutral idle air by subtracting .35 from 1200 rpm and down and although the integrator reads close to 0 at idle, I'm still getting that 1000 rpm flare for 5 sec. once I rev past 1200.

I took if for a quick spin around the block and it doesn't affect drive ability. Maybe its no big deal. I never paid attention if it did the same when the car was stock.

 

[Mach828]

You can check the dashpot settings to see if that helps. It controls how fast the rpms fall back to idle. If its too slow then you tend to get flares. I set mine so it falls immediately to idle after you let off the gas.