Camaroholic

iTrader: (1)

I've been helping Travis (Formula 1) get his GTP-headed, PIG-cammed (226/226 .591/.591 112) '00 A4 tuned. His car runs well, but was having trouble idling. A LOT of trouble idling.

First, we have the idle set at 900 RPMs. The motor does seem to smooth out at 875-900. Below that, it's unstable.

Next, we used AutoTap (DOS version), and watched the IAC counts at warm idle. Before we drilled the TB hole, they were in the 100-110 area. We drilled 2 sizes higher, and the IAC counts went down to about 40. Perfect. Stop drilling.

Next, I added 1-2 degrees of timing in the idle portion of the spark map. DO NOT ADD TOO MUCH. I played around with this on my '98Z once, and got 'marbles in a can' pinging once. It's easy to over do it.

Finally, what did the most improvement - modifying the IAC Park Position table, the Idle Air in Gear table, the Decay Value in Gear table, and the P/N Airflow Decay table

Here's the changes I've made:

IAC Park Position table: 40c and up, set all values to 25.

Idle Air in Gear: 80c and up is 9, 60c is 10, 40c is 13.8 (both rows).

Throttle Follower Airflow Decay in Neutral - changes from 0-6 MPH (multiply by 200%).

The Decay Value in Gear table, I scaled everything from 66mph and down scaled by about 160% in places, 130% in other places.

The only issues he's still having is it dies while braking and turning. It was dying at nearly every stoplight, just running badly. It's no longer dying as much, so we have a little more to do. However, I know it's in these IAC tables where the problem will be fixed - it's just a matter of getting the time to do it.

Has anyone else taken this approach? It's very time consuming, but it's working.

There is another post in this section that gave us the start on the IAC tables.

-Andrew

Raven

Great info Camaroholic, thanks for sharing! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" /> I too have been struggling with my car dying when stopping &/or turning for weeks now after recent torque converter install <img border="0" title="" alt="[Frown]" src="gr_sad.gif" /> <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

Please continue to post any new findings regarding a resolution to this fairly widespread problem <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

DailyAluminumBlock

Excellent info. I will be trying some of these fixes in the near future.

ChrisB

Did adding in the timing help at all? If it didn't help you might try putting it back to stock/pulling out some timing.

Also try putting the car in PE mode at 1600 and below or so and then richen up the mixture a bit there to see if that helps out with the idle stability/quality.


Chris Bennight

gojo

iTrader: (12)

I have not put in the cam yet. But, I installed a Vararam and P&P TB, hoping to resolve these kinds of problems one at a time.
I found that scaling the tables worked better for me. It's like setting a choke. You might have the throttle blade set too long. Also, you lowered one table and raised the other. Mine also worked better when I used somewhat the same %, on both tables, in the same direction. In your case, I believe the numbers should be higher at colder temps. your right it is tedious, but real easy and a lot of fun. You see the results right away. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

eallanboggs

iTrader: (1)

Man you need to charge for that kind of information. That's what LS1Tech is all about.

XAntivenomX

iTrader: (5)

That is great info, I will be trying some of those things soon. It kinda sucks having a 98, the IAC park position is not implemented for my year. <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />