terry02

I have an 02 Z28 with headers newly installed. After the install I had a buddy put on an HP tuner program, to eliminate my AIR/EGR/SES light and things of that nature. While tuning my friend said that he bumped up the timing by 2 or 4 degrees, I can't remember which, but the end result is me running down the road at 64-65mph at 2000rpm as opposed to running at 68-69mph at 2000rpm like I used to. Is this normal? I just know that this, accompanied by him raising my idle for no apparent reason other than he said he thinks that the car runs better at 800-850rpm idle, has resulted in what seems to me significant gas mileage loss. Any help would be appreciated.

TheBlurLS1

iTrader: (8)

Put the idle back to stock lol. Sounds like your friend doesn't know what he's talking about. Not sure about the timing affecting the rpm/speed (I'm assuming you're an A4 car though).

The 02's only come with 19* of timing or so at WOT, so you're pretty safe with adding some though.

VinceTrifecta

Sounds like your torque converter lockup has been disabled, which will wreak havoc on your gas mileage.

SSpdDmon

iTrader: (10)

The upper part of the table is limited to 19*. However, the part of the table where they actually operate has them running between 22* & 23* of timing. On my '02 A4 w/ longtubes, I couldn't run much more than 24* of timing before I'd start seeing KR. But, it does sound like he made some changes that didn't make much sense.

terry02

Thanks, guys I appreciate the help. I do have an A4 car. One thing that I have noticed and what led me to believe that the torque converter is locking up, is when I take my foot out of the throttle after getting up to 90-95mph, the car tends to just keep coasting at high speed and takes a while to deacelerate. Part of this I attributed to aerodynamics, but it just seemed like a little much to all be in it's bullet shape. Please jump in and stop me at any point if I have the wrong idea.

thanks, terry

ZL1Killa

iTrader: (17)

get homeboy to lower your car back to what it was. he raised more than just timing to affect the idle and drivieability of the car.

you can bump timing up all over the board on the stock cars by about 4 degrees and pick up power everywhere, that won't change your idle or running RPM, it will just take more advantage of the power. your friend is dicking around tooo much, run as much as 26 degrees WOT in the top cells and my idle is at 22 degrees

VinceTrifecta

Maybe your friend changed the timing at non-WOT conditions too? If so, that would affect your mileage, but the biggest hint I got on the TCC lockup is what you said about the change in RPM and mileage. Disabling TCC lockup (or delaying it to higher speeds) will destroy your fuel economy.

AINT SKEERED

iTrader: (2)

to see if your converter is locking up , drive at cruise speed and while holding your peddle steady take your other foot and touch the brake. it should jump the revs up some when it unlocks.

terry02

I talked to my friend and we went back through the tune. We found that stock tq converter lock up was at 40mph across the board, and the tune that was on the car had raised it to 47 mph. I thought that I was pulling too much timing at wot somewhere around 41 degrees, but we changed the TCC settings and tried to clean up the tune and reset the idle a little lower. I will get the program flashed at the end of the week.
Thanks again guys.

VinceTrifecta

Fuel economy is ALL about the TCC lockup. Thanks to skyrocketing fuel prices, I am thinking about developing some custom programming that uses a more aggressive lockup strategy to improve fuel economy. I'm not very optimistic I can do a better job then the factory did, but then again I would have thought the same about WOT air/fuel mixture. Lol.