CactusCat

First, my apologies for the couple of months absence from the forum. Work, two week vacation and then having the car in the shop has kept me away. Things are starting to smooth out again and looking forward to mucho time visiting here and contributing. Secondly, I'm not sure if I should be asking this here or in the Scan and Tune section. So here goes...... (I'm going to include some details as that might possibly clarify some things).

Just had the 98 A4 updated. Complete new top end which includes cam (230/236 .591/.601 114+4), 243 heads (milled to 11-1 compression, professional porting done, dual springs, trunion upgrade), ported Fast 102, ported 90mm TB, XS headers, 3200 stall converter, etc. Had it all done at a professional shop that has tons of Corvette experience. The car dynos at 430 rwhp and runs terrific. Only item giving the tuner a bit of trouble is the idle tables for the A4. Car starts instantly and idles at 950. Put into reverse and motors spins up to about 1500rpm then engages and drops to about 600rpm and then comes back up to 950. Then putting into drive, car revs to about 1600 rpm before engaging and again drops to about 600-700rpm then idles correctly at about 950. The tuner told me it was tough to tune the idle for P,R,N,D..... If I remember correctly, he said there are tables for each but he hasn't nailed it yet. He's not giving me any flak on working on it, but he's gone until next week with his wife due to a family medical thing. Just thought I'd ask in here and see if someone can drop a little advise on tuning the idle tables. Not sure of his software, but its on his laptop. Maybe EF? Car sounds like a beast and runs like it too. Really liking all we've had done but would like to get these idle tables under control.

On a side note, at the 950rpm idle, I can shift into drive, never touching the gas pedal, and simply remove my foot from the brake and the car will start moving on its own, get up to about 10-12 mph, then shift into 2nd where it'll continue to pick up speed to about 20-22mph then shift into 3rd. Is that normal for it to have that much pull or is the idle too high? Any and all advice would be appreciated.

RonSSNova

There are 2 different tables to tweak.

Base Idle RPM (target idle RPM vs coolant temp both in and out of gear, AC on and AC off)

Base Running Airflow (Idle Airflow vs coolant temp both in and out of gear)

You get to choose the RPM, best set at 950 or so to start the process.
Then do BRAF (base running airflow)

Requires a cold start, coolant from cold to 235 or so hood closed, no touching the throttle.

This all takes time and is an iterative process.....

Your tuner should know all of this....this is where the tune starts.

ron

CactusCat

Ron, thanks for the reply. Since I've never tuned a computer controlled car, I was somewhat unfamiliar with the process. All knowledge on the subject has come from studying and reading, no actual hands on experience. Maybe I didn't make clear what I was asking in my first post. The tuner has the car idling ok. It idles in Park just fine, once I get it in any gear, its also ok. Sits there sounding real nice at about 950rpm. My question was in regards to the (to me anyway) somewhat excessive high jump in rpms (I tested this last night) to about 2000rpm when I shift out of park into reverse and then from reverse to drive. Each time I shift into the gear, the motor revs to about 2000rpm, then shifts into gear where it idles just fine. I'd like to have almost no gain in rpms when I shift into gear. Is this something that will have to be done by the tuner or could it be re-learned (as per this link - http://s2performance.net/relearn.html ).

RonSSNova

I didn't do any TPS reset.
I'd have to see those tables I mentioned. Do you have the AC on or OFF?

A data log while it's doing this might tell you what is happening.
Have you checked for vacuum hose off?

Maybe CTD will chime in.

Ron

tblu92

When the coolant is cold below 140* the ECM is in Open loop mode---The fueling is set by the "open loop normal table" After the ECT reaches 140* it switches to closed loop
On a warm start above 140* it switches to a timer before going from open to closed loop usually between 10-20 seconds---
In open loop there is NO fuel correction via your fuel trims
In EFILIVE the most common table to make starting easier and correct idle issues is the
"desired airflow table"
However to me it sound like you are having what they call a "hanging idle"
This is corrected with another table called the "throttle Follower" there is one for P/N and one for in gear
To make the car idle down faster you would ADD a % to the entire table in P/N and if its doing it in gear--same thing applys in that table--- IF you add to much--It will do the opposite and will try to die---Then simply back them off some--