E38 Idle tuning help needed

[bikewiz]

Hey guys,

I've got an E38 computer setup for a 2010 Camaro SS LS3 installed in a Mustang engine swapped drag car. It's tuned as a manual trans setup because it has a TH350 behind it. I just had it dyno tuned to finish off the majority of the tuning on the car. However, this car has a idle stalling condition when I move the car around in the driveway or on/off the trailer. I can't seem to figure out what the deal is. As soon as I accelerate and let off, the car will stall. I'm thinking the idle airflow is off, but not sure how to tackle this.

Can you guys take a look at my logs and point me in the right direction? Trying to make its first track day on Sunday and I would love to have this figured out before then.

Thanks in advance.

[bikewiz]

I should add more details:

416ci stroker
12.3:1
E85
85 lb FAST injectors
Ported heads, stock intake, 87mm truck throttle body
242/252 cam
Tuned in speed density with MAF failed

[mowton]

Matt,

When looking at the latest files/logs you sent me you appear to have little or no vacuum (pretty big cam) at idle and when you hit the pedal even a little, you enter into PE (15kPa/30%pedal) which creates an over rich condition. First make sure your VE at the low rpm/load area's is tuned correctly. Next, look for a vacuum leak (with a propane cylinder/hose) and if you can't find one than you could change the PE values for the low RPM area's to stoich (1.0) and say at 4K and up go to your 1.15 enrichment for WOT. Let the cylinder charge value/knock be your guide.

Ed M

[bikewiz]

Ed,

The camshaft is 242/252 .629”/.629” 114 LSA +2 advance.

I'll follow your recommendations and come back with my results.

[bikewiz]

Matt,

When looking at the latest files/logs you sent me you appear to have little or no vacuum (pretty big cam) at idle and when you hit the pedal even a little, you enter into PE (15kPa/30%pedal) which creates an over rich condition. First make sure your VE at the low rpm/load area's is tuned correctly. Next, look for a vacuum leak (with a propane cylinder/hose) and if you can't find one than you could change the PE values for the low RPM area's to stoich (1.0) and say at 4K and up go to your 1.15 enrichment for WOT. Let the cylinder charge value/knock be your guide.

Ed M

Looking at log #2:
Okay, so you are saying that when I touch the throttle (ETC 15%) and the TPS goes above 30% (TPS 32%), this is entering into PE mode? Changing the PE values to 1.0 would effectively disable PE until you reach the rpm where the values are back at 1.15?

[mowton]

Yes....

[bikewiz]

Okay great. Just wanted to make sure I understood. I prefer to learn rather than just make changes because I was told to.

[mowton]

Okay great. Just wanted to make sure I understood. I prefer to learn rather than just make changes because I was told to.

Just as a side note, what brakes/system are you using. With that little vacuum, I would think there would be an issue with the stock vacuum assist setup. Most of the times we need to add a separate vacuum pump on cams that don't generate a lot of vacuum.

Thanks,

Ed M

[bikewiz]

Upgraded disc/drum setup with a 93 cobra booster and master.

4th of July got in the way of loading the new tune, will do it this morning and update.

[bikewiz]

Just got the tune loaded and then i get a phone call that i need to go help out with a family plumbing emergency :-(

Here is a log of the new tune and me moving back and forth in the garage. Didn't die out.

As far as vacuum goes, I think you are right, there isn't any. I just felt the brake pedal and there is minimal assist and also checked for obvious vacuum leaks, but didn't find any. I'll revisit this later.

[bikewiz]

Took the car to the track today and did very well. The engine didn't stall once. I also tweaked the PE enable for low RPM to bump up to 39% TPS just so I stayed out of PE.

Thanks again Ed!

[mowton]

My pleasure. Glad you have a great running setup. Tuning it yourself is a great challenge and the more you can think outside the box, the better you can get at it.