Michael V

I have a H/C 02 Vette and I want to see if I can make it more consistent. I know the PCM pulls timing when the outside air and water temps reach a certain criteria. Has anyone tried to reset these settings. I have already removed TM. Any ideas would be helpful.

Mike

Ed Wright

iTrader: (1)

Mike, zero the IAT spark correction table up to 150 or so degrees F. Then in the next column put -1, next column -2, next -3, etc. I would not fill the table with zeros if you drive it every day in hot weather. If it is a track only car, just zero the whole table.

It helps some to open the hood in the staging lanes in hot weather to allow hot air out.

Michael V

Thanks Ed. So if I understand you, this will reduce the chance of KR but only up until 150 degrees? The problem with
Vettes is the sensor is built into the MAF and can't be moved to a better location.
Thats the kind of info I was hoping for. I do open the hood and I turn on both fans at the end of the run all the way back to the pits. Thanks
Ed.

Mike V

RonSSNova

iTrader: (3)

You can of course log the IAT and see what you are getting during a run. I hava a VaraRam onmy car, MAF in the stock location, and I see within 1 degree or so of ambient during a run. You can adjust the table accordingly. The factory setting is very conservative. And designed to combat heat soak. The VR helps greatly there.

Ron

flame

iTrader: (13)

If you wanted to relocate the IAT then just cut the wires off the maf plug and get the 2 wire sensor and plug the fbody runs.

Ed Wright

iTrader: (1)

If you log temps higher than 150, move those numbers to the second row higher than that. If you don't drive it on the street in hot weather with the AC on just zero that table out like we do NA race cars.

Alvin@PCMofNC

Being consistent with the car will do quite a bit. Beyond that keeping the car away from spark knock and knock retard would be my next recommendation. Do this by running a slightly richer AFR (mid 12's) and back the timing off a couple degrees from where you find max power. Doing both should only cost you 3-8 rwhp and make the car much more consistent.

Ed Wright

iTrader: (1)

Actually, guys I race tend to run them on the lean side in "bracket mode". When it cools the car picks up less because colder air of course likes richer mixtures, and when it gets hit out it slows less than it would if rich. When running heads up situations when you need to run as quick as possible we fatten them up. I use a FAST XFI ECU, which can hold four calibrations. I just use two, one bracket mode calibration, just flip a toggle switch for the faster, richer calibration. Runs quickest at 12.8-1, at 13.5-1 it doesn't mind hot air, doesn't pick as much when cool. As the day warms up, or when evenings cool, it varies much less than the richer calibrations. Lots of guys doing that. I take out 2 degrees in the lean one just to be safe.
Trying to keep coolant temps consistent helps iron block engines repeat closer. All aluminum LS engines don't care about that as much. Most repeat very well between 180 & 210. LT1s like 90 to 110 on the starting line. They fall off pretty good above that.
Btw, any Texans coming to the NHRA points race at Ennis this weekend look me up. Parked there right now. Got tech inspection today. First round of qualifying tomorrow morning. Come by and look me up.

Michael V

Thanks everyone for your help. I have some experimenting to do!

Mike V