E40 Idle Speed with M6

[5_Liter_Eater]

Try zeroing out your final airflow minimum table just to test. That sounds like what is keeping it elevated.

[Boilermaker GTO]

Thanks, I'll give it a try when I get off work tonight.

[StarCaller]

nope. same thing.

[Chris@HPTuners]

hmm.......
flashed it, but the result's not perfect...
(it's WAY better than before, so I'm not gonna complain... if there's nothing one can do about it, I'm happy like it is right now!)

I set both tables to 500.
now, first thing: I have to drive the car a couple hundred yards after each shutting off, to get the lower idling. otherwise it can sit there for 10 minutes & idle at 800...
next thing: once the idle gets lower, the lowest I can get (by a commanded 500) while the car is in a standstill, is 650.
once the car is moving & I push the clutch or put it in neutral (no matter what speed), the idle goes down to 550.

what does your Desired Idle RPM PID say?

[Boilermaker GTO]

Mine does the same thing as StarCaller's. On a hot start the Desired Idle RPM stays at 800 for ~1 minute then will drop down to what it is set at. However for some reason the lowest it will idle is 650 when stopped, though the Desiried Idle RPM PID reads 550. It will idle at 550 during coastdown though. I'll attach a log so you can see what I'm talking about.

[LazMan]

Indeed. I have the same phenomenon on my 07 Monte Carlo SS. I set the idle from stock 600 to 550 on both tables.

On coastdown, I hit 550, but it bumps back to 600 when I fully stop. If the AC is on, there is some hidden-adder that adds to idle RPM, probably because the electric fan for LOW comes on. Its just about 50rpm at this point. Ditto when the electric fan for HIGH turns on (amperage pull!) except now its well over 100 RPM over stock, and I'm idling at 700-750 at this point.

I feel confident that there is some logic somewhere (that we dont have access to) that determines minimum idle vs alternator amperage when stopped.

(5LiterEater, played with the new O2 voltage settings yet?)

[5_Liter_Eater]

(5LiterEater, played with the new O2 voltage settings yet?)

Just started this morning. I have been in open loop since I got my Paxton running. Enabled STFTs this morning, I need to look at the logs to see where the average AFR is. It seemed lower than before. I did use some exhaust repair goop around the WB O2 bung. Perhaps air leaks were the problem.

[5_Liter_Eater]

I guess I'm happy with the RPM thing now. Before I couldn't get it to go below 800 and that was problematic but I can't see wanting to idle below 650. You guys are really trying to save gas any way you can.

[Boilermaker GTO]

I'd much rather burn it while moving

[LazMan]

I changed my crossovers from 300 / 675 to 300 / 500. I also set the 'cold skew' to zero from 180F on. Seems to have helped at highway cruising speeds, particularly when I don't run the AC. I'm seeing highway cruise numbers in the 30 to 34mpg range if i stay between 60 and 70ish w/out AC. Very happy ... and I've not really logged anything yet. No time to really fiddle this week so far so I'm not really running 'lean' either.

Although, I do have DOD and I've significantly changed how it works (more timing, easier 'in' settings) as well as V8 mode part-throttle timing, so I have an advantage over stock to begin with.

Now, it beats that A4 GTO which got 24mpg when I ran OL lean.

As for fuel-savings ... you bet! I always thought my GTO could have idled at 500-520. I dont mind the slight rough-ness. My old 86 Camaro Berlinetta would idle at 450.

Ahh ... I miss those days. 18 years old with a rochester 4-barrel carburator and a hacksaw in my bedroom ... and a less-than-happy mother outside ...

[5_Liter_Eater]

Did some testing tonight and learned something.

http://www.hptuners.com/forum/showth...t=15564&page=5

If you're having trouble with not being able to get down to a commanded idle RPM, lower your idle spark table.