What's holding my Idle high?

[eboggs_jkvl]

Here is my current tune. After the car is hot, the idle is running around 950. Not bad, but I have it set for 850. Something is screwing with me and holding my idle up an extra 100 RPM. Any observations that might "set me free"?

My scan file shows that my temp is well up into the operating range but the idle is averaging 950 or so.

tun file http://www.ls2.com/boggs/efilive/102306testtuneac.tun


Elmer

[eboggs_jkvl]

Ok, what the hell am I doing wrong? I can't get the lnk to work on the tun file. Does the site restrict this from happening?

[SSpdDmon]

The link downloaded fine for me. Why is your desired idle airflow so high? Did you log the RAFIG and adjust? Also, why is your learned airflow table zero'd out? The short term correctors look to be adjusting you as best they can. But, there's no learning going on with that table zero'd out I believe.

Try changing the Learned Airflow table (under Idle>Learning) and nothing else. I'd put .007813 in for 40.0rpm, .014648 for 60.0rpm, and .019531 for 80.0rpm on down in both drive tables. See if that helps...

[eboggs_jkvl]

Did what you recommended and the idle is back to 850. However, the stupid surge is back too.

Cold start? Absolutely perfect. Hits and holds rock steady.....

PArk the car, wait about 75 minutes, get in and restart the car... Instant start AND instant hunt for idle to as low as 2-300 rpm, back up to 1100, down to 500, back to 900, down to 700 back to 850 and holds steady. Crap.

[eboggs_jkvl]

Here's my adjusted tune

[TAQuickness]

I haven't looked at your files yet, but what do your AFR and Spark look like at idle? Might want to use the BiDi to optimize the two.

[eboggs_jkvl]

By the time I try the Bi-Di, the stupid thing has stopped acting stupid. It just makes the surge at initial startup and 10 seconds later it knocks the crap off and behaves! It acts like a kid! It just wants to push my buttons!

[SSpdDmon]

Did what you recommended and the idle is back to 850.

So, we're making progress....


However, the stupid surge is back too.

Cold start? Absolutely perfect. Hits and holds rock steady.....

PArk the car, wait about 75 minutes, get in and restart the car... Instant start AND instant hunt for idle to as low as 2-300 rpm, back up to 1100, down to 500, back to 900, down to 700 back to 850 and holds steady. Crap.
Ok, so you made the changes I suggested and only those changes, right? Now, you have a warm hunt for idle after restarts? Ok, keep the changes I suggested and zero out anything you have in your RAM stored values under Idle>Learn>Parameters (B4322, B4323, B4324, B4325, B4328, B4329, B4330, & B4331). I think what's happening on restart is, the PCM is remembering what happened the last time it was running and is using that to guess a starting point. If there's nothing to remember from, that might solve the issue since prior to the change you had idle learning [essentially] disabled. LMK how it works out and if it doesn't, there's one other thing we can try.

[eboggs_jkvl]

4322 = 0
4323 = 0
4324 = 3, now 0
4325 = -3, now 0
4328, 4329, 4330, and 4331 do not exist in my tune.

Elmer

[TAQuickness]

Elmer - Not sure if you've seen this thread before, but it may be what you need to get past the lean cold starts http://www.forum.efilive.com/showthread.php?t=3170 (http://www.forum.efilive.com/showthread.php?t=3170)

[SSpdDmon]

So, is it better??

[eboggs_jkvl]

OK, here's the status. I think It's fixed. I set the 3632, 3628, and 3650 tables to the stock settings that I found for a Z06. After that, the IACs went down to 0. Spent about 10 minutes twisting the set screw and got the IACs at idle back to 35-40 (It seems to like that range) and I let it sit for an hour and a half. Cranked it up and the idle held as advertised for the full start to warm. We'll give it the acid test on Monday when I have total control of conditions that I know cause the surge.

Bottom line? I think it will work. I'll let you know on Monday.

Thanks,

Elmer

[eboggs_jkvl]

OK, update....

Still swung looking for idle at a "warm" (sorta) start. Car driven 15 miles, parked in garage, allowed to cool for 1 hour and 30 minutes. Started immediately and did a really Deeeeeeeeeep drop in RPM to almost stall and then recovered back to 1100 and then quickly lowered to 850 and held there. The deep swing is what I'm chasing. Cold starts are perfect.

E:)

[joecar]

Elmer,

Do you have an chart image showing your startup and RPM drop/recovery...?

Joe

[eboggs_jkvl]

No, I missed it this time. What I'll do is take my laptop with me and get it running before I start the car. My next "optimum" condition is Wednesday AM. I'll make sure to get a good recording of it and post it up along with the current tune.

[eboggs_jkvl]

Right now the idle is behaving but it is still pressing the high side of what I'd like. It is 900-950 and it is VERY slow to drop down as I come to a stop and idle. I recorded tonight and did get that. I didn't get the big swing tonight but I may have let it sit too long. I'll post it up in a minute after the laptop boots up.

Elmer

[eboggs_jkvl]

OK here is my current tune, my latest scan chart image with NO dip in the idle at start up but where the "marker" is placed shows the slow idle fall at stop. My idle is supposed to be 850. The scan file is attached too.


I really appreciate the help guys. I'm ready to smack the damn engine for insubordination to a geezer.

Frame 208 is stopped but the idle just keeps creeping down and never really gets to 850 ubtil frame 219.
Elmer

[SSpdDmon]

Try changing the Learned Airflow table (under Idle>Learning) and nothing else. I'd put .007813 in for 40.0rpm, .014648 for 60.0rpm, and .019531 for 80.0rpm on down in both drive tables. See if that helps...

This is the table to bring the idle down faster when you come to a stop. Try increasing the values on the column for high rpm (in gear since you have an M6). Icrease it by small amounts [i.e. - .007813~.014648] at a time to avoid overshooting and creating a new problem. Try to keep the lower RPM numbers small and have it ramp upwards for the higher RPMs. This should help it come down faster without overshooting the target. As for the surge on starts, I was thinking you could extend your Startup Airflow Decay {B4340} by reducing the value or increasing the S/U A/F Delay {B4342} by a second or two in the trouble spots. But, only if it's not gone.

If it were me, I'd work on the idle issue first. Then, after the flash has been through a handful of restarts without any issues, check for the mild-ECT dip on startup.

[eboggs_jkvl]

OK, added .014648 to all fields under P/N columns. I think that is what I read out of your instructions.

Elmer

[SSpdDmon]

OK, added .014648 to all fields under P/N columns. I think that is what I read out of your instructions.

Elmer

Sorry...it was a little fuzzy and I corrected it. I don't think the PCM uses the P/N tables in an M6. Mine were zero'd from the factory. Just adjust the "high" tables for In Gear.

[eboggs_jkvl]

Ok, back to the drawing boards.

I adjusted the high in gear. The dots are what I changed & the lower red "line" was where the dots were sitting.

[eboggs_jkvl]

Hmmmmm...



Vehicles fitted with a manual gear box are assumed to be in gear unless the clutch is depressed
From the "Description" tab of the B4514 table

So Column 1 and 3 should be alike while 2 & 4 should match?


I'm not touching anything until further review. :D

[SSpdDmon]

The link downloaded fine for me. Why is your desired idle airflow so high? Did you log the RAFIG and adjust? Also, why is your learned airflow table zero'd out? The short term correctors look to be adjusting you as best they can. But, there's no learning going on with that table zero'd out I believe.

Try changing the Learned Airflow table (under Idle>Learning) and nothing else. I'd put .007813 in for 40.0rpm, .014648 for 60.0rpm, and .019531 for 80.0rpm on down in both drive tables. See if that helps...


You can put values in the P/N tables if you want. But, I'm pretty sure they don't do anything. If they did, I find it odd that they were zero'd out from the factory for all of the M6 tunes I have. If you have what I think you should have based on what I've suggested, it should look like this:

High (Drive):
40RPM ~ .015626
60RPM ~ .022461
80RPM ~ .027344
.........all the way down.......


Low (Drive):
40RPM ~ .007813
60RPM ~ .014648
80RPM ~ .019531
.........all the way down.......

If this is making improvements, continue to play with this table based on your logs. Just make small changes until you get it where you want it. Just for reference, here's what mine looks like. By keeping the high higher than the low, it'll force it to learn from the bottom up. But, these are still a lot less agressive than stock to prevent surging.

[eboggs_jkvl]

OK, we're loaded. Time to drive it around a bit and see how it acts.

TTylater...

Elmer

[eboggs_jkvl]

Man, this is a can of worms. I did your recommendations and the darn IAC went and smacked 0. So burn the knuckles on the hot engine parts and tweak the darn IAC back up to the high 40s. adjust this, readjust that! Aargh!

Idling at 850. It gets there but still takes it's sweet assed time doin' it! :D Better than it was. I need to drive it around some to make sure it has settled it.

I have the "warm" start test in the AM and then I need to go and get some fuel lines replumbed. I'll give you a report tomorrow evening.

Thanks,

Elmer

[eboggs_jkvl]

OK, Wednesday and the acid test. The idle is coming down but it could be quicker. The big swoop for "warm" start is still there and I caught the blighter ths time.

2 files attached. One is the cold start in the AM and what it did. 2nd file is the warm start and the big swoop.

In the warm file, recording going prior to engine start.
Frame 2 engine start
Frame 3 1167 RPM
Frame 5 241 RPM
Frame 6 1320 RPM
Frame 7 1003 RPM
Frame 15 850 RPM

Idle hunting over and engine is holding idle.

Frame 21 slight stumble as I pull out of parking place.

Car drives well behaved for the rest of the trip to the Shop.

Looks like IE had a headache. Mozilla transferred tham fine.


Elmer

[SSpdDmon]

attachments aren't there...

[eboggs_jkvl]

There ya go. IE7 burped.

[SSpdDmon]

It's hard to see what's really happening since it's only over a few frames. But, I would guess it's in your startup airflow tables. You could try setting {B4343} to 4 grams/second from 133 on up. Also, you could add 2 grams/second to the {B4304} table from 140 on up. The first table hangs around a lot longer than the second. So if it's too much, take a little back out of the first table where you made the changes.

[eboggs_jkvl]

Thanks, I'll play with it in the AM. Right after I get done with Goodyear and my tires.

Elmer