gta324

Trying to get a good idle on my car. I have a good and stable idle in D but not in N/P.

I've been working on (at idle)
- Des. speed 775 rpm
- spark advance ( currently at 22 deg )
- Idle dead target rpm (+/-25 rpm in D used to be 50)
- IAC keep Alive learning temp. adjusted.

BLM are at 126
steps 10-15
load is 70-80 at idle
vacuum is around 14-16
TPS 0,58

and my two middle headers (SLP) start to glow a litte on both sides at idle...( you can only see it if its really dark and look direct at the headers......)

any hints/comments.......

/N.

Morley

Base timing? Checked for Vacuum leaks?

gta324

Base timing - OK!
Leaks- No.............

Going to burn some new proms now and try them out............

/N.

Grumpy

Might raise the idle some.
Sounds like you set up just likes being under a load.

Might look really close in the MAF tables to see if you can find a difference in the gm/sec used at idle between D and N and see if you can richen it a little in the N area.

Sign line shows a blower and cam. They may be working against each other at idle. You might be in an area where the self EGR'ing of the cam, and blower speed at idle artificially lowers the vac a little, and worsens the EGR'ing.

gta324

Grumpy:

thanks, i'll try to raise the idle some and look ar the MAF tables...

I have not the belt on the blower yet, I want to make a PROM that is working without the blower before I put on boost....

Can runned lika H*ll until I burned a Ign.wire......damn headers

87_TA

Thats pretty funny,having the same problem with the glowing on my canfield headed,slp headered car.
I have been running my car lean by forcing open loop to eliminate problem.

89 Iroc Z

I looked at some pics of your engine on your website. It looks like you have the MAF sensor after the supercharger so the MAF is under boost. Aren’t you suppose to put the MAF before the supercharger.

3.8TransAM

lol now that depends on if your name is Grumpy or not. Check out www.gnttype.org to see what i mean :-) Theoretically speaking and having been proved by a few people a MAF indirectly measures the amount of incoming air(it is figured thru a calculation not a dircet measurement) so where it lies in the intake tract should not ahve a beargin on it as long as it will see any air that will make its way into the engine....................

But general rule fo thumb on most production applications the MAF is before the turbo or SC

Later
Jeremy
Hope that made sense i been sick since fri uggghhh

Grumpy

It depends.

In the higher boost applications you can blow the plastic type apart, or so it's been reported.

Depending on the MAF having the MAF post charger may have some good gualities, in so far as the MAF correct the air flow based on the actual intake air temp rather then IAT. At a prolonged idle ie like waiting to stage the MATs can climb and during that condition the motor is alot more prone to detaonation.

Then also mounting the IAT sensor so that it is a MAT sensor might be an advantage if you can correct the MAF AND timing based on MAT. In my car, I use MAT to make a 4d timing correction. That's 4d more everywhere other then the MAT is high. That's enough to matter.

Again, depends on what code your running, and what lenghts you want to tinker.