A/A LS2 with A/A Vortech. When OFF the throttle and coasting to stop with clutch engaged at 2000RPM and again at 1500 RPM there is a very noticeable sensation that feels just like an automatic trans downshifting. It's brief but driving me crazy. With clutch disengaged it's not noticed at all. Does not do it on acceleration. My tuner has told me that I just may have to "live with it". I should not have to. I need to add that it began to do this when the car still had the original LS1 and SC, leading me to believe it is somewhere in the tuning software/computer and NOT the motors. Also, when the original LS1 left A/A with the SC it had no such problem but began after the home tuner began making adjustments.
Anyone have any suggestions? I get NO codes from this.
I recently replaced the PCM, and as it was brand new needed a base tune for my SCd LS2. A&A did a mail tune to get me started which worked very well......but the sensation at 2000 and 1500 is still very much there. Give me some ideas.

 

I wish I could help.
Out of all the things that I do,, I will admit that TUNING is not one of them.

Funny thing, I under stand all the stuff and how it works, just not all the IN's and OUT's of making the adjustments (The correct way)

Sounds like a Deceleration fuel table issue.. There are tables that control that value. Do you have or have access to EFI Live or HP Tuners?

You can data log with either one of those and send the data log file to a vast number of forum members who SPEAK TUNE.



Bill

 

From what I understand about DFCO the sensation you are feeling is the fuel coming back on. Definitely a tuning issue.

 

To answer your ? is it a tuning issue ABSOLUTLY. I love when the tuners say live with it that means they suck and don't want to put the time in to tune it right. Had the same problem with my tuner. So i instead of paying him for nothing i got hptuner pro and with tons and tons of reading on line and asking ? i fix it. Was well worth the money to prushace HPTuners. Your tuner suks. Almost all tuners can tune wot but to get the driveablty down is a whole different ballgame.

 

Why would the old tune that worked have not been copied & flashed into the new puter?

You can also use a feature called compare to see the differences if there is a copy of the previous tune.

If you can post up a data log or a screen shot of the problem I'm sure it is a simple solution.

 

Let me clarify a few things:

1) I unfortunately don't have HP Tuners or other tuning software. I have AutoTap which allowed looking but no adjusting but the computer I used died and it won't run on Windows 7/8/etc. I bought it 10 years ago.

2) while I love tinkering, messing with the programming scares me to death. Helga, you ARE bolder than I and I applaud your accomplishment but I think I would just make a mess. But your right, the tuner didn't want to deal with it.........part of why he no longer works on it.

3) The "old" tune began with the issue in question....simply copying and flashing would bring whatever software issue was there into the new PCM. So, when I bought the new PCM I had it mail tuned to start me off. It would start me off fresh. So, I suspect the mail tune (a close, but not perfect tune designed to at least get me running) may be programmed that way, and then needs fine tuning in the decel table......something the local tuner can't figure out? Part of my issue is I prefer Andy at A&A begin and fine tune the car but I live too far to do that easily, and there are not many tuners in the area. Might have to take Helga's advice and learn how myself.

I'll see what I can do to get a freeze frame of the tables.

 

HPT and I assume EFI LIVE too, are much more than a tuning tool. They are also excellent diagnostic tools.

There is a LOT to learn.

Mine paid for itself within a couple of weeks of owning my car when I used it to discover that the previous owner added an 85mm MAF but didn't change the tune. It's paid for itself many times since as well.

Ron

 

Ron,
Take a gander at my post from yesterday.....The Gremlin King is Dead......there are some electrical questions I need help with.

 

I did, and sent you a PM.

Ron