JFH

I got my new set up running and got a tune. Motor feels strong it has a 230 234 602 605 cam fast 92 intake and a nick Williams 92 throttle body with a 85 mm mas air it made 406 hp on a dyno jet. It will sit there and idle then all of a sudden it will start to surge from like 1600 or 1700 down to 400 or 500 and it will shut off sometimes from the surge... Does anyone have any ideas on this? And the cam is a eps and is rated to 6700 and the hp stops and starts to fall at 6100 to 6200, is it possible for it to be running out of fuel at higher r's I am still running the stock pump the guy that tuned the car didn't say anything about it being lean but when it falls there is no plato or flat, it just goes off like it is out of fuel or something.. Any ideas that will help.

Thanks for any help you can give
Frankie

WhiteHawk

In my limited tuning experience, when it hunts idle, it needs the base idle airlow in the PCM bumped up. Go back to your tuner - they should be able to fix it. Do you have dyno graphs?

-Geoff

gearslammer

Dude I had the same problem with the LS1 edit program. Bugged the **** out of me. I looked stupid as I pulled up to the light and had to hit the clutch or feather the gas. My problem was associated with the air conditioner or the rear defrost turned on. Apparently the guy who wrote the program didn't figure those things in. My tuner called and was given some generic advice. He changed some air-fuel ratios and got some of it to go away. I wouldn't let them mess with trimming the idle externally. Get someone who can get into the PCM and figure it out that way. The engine will sense the ratio being off and will self correct it back to the tuners numbers so all you are doing is making the engine go round and round trying to fix a problem that is in the program itself. My .02 hope this helps

JFH

I have some graphs but my scanner is down I will post them as soon as I get it back up... I talked with the guy that tuned it with the other set up and he is going to tune it again... I did put a set of 255 50 drag radials on it it still spinning all the way thru first but when I rolled on the gas and hit it around 25 mph or so it ran a 12.07 at 115.9 by 1 of the lil gtechs , when I get this other tune I am going to the track and try both of them to see which 1 is better and maybe combine parts out of each to make it better. Not sure I hope that I am not just throwing money away but the guy that tuned it is a 2 hr. drive to get there.

WhiteHawk

It sounds like he has the full throttle stuff dead on. You just need him to tweak the driveability a little bit. There is a table for base idle airflow as a funtion of temperature. It is a single columns and about ten boxes of data. I just bump it a half gram of air at a time until the car idles smooth.

-Geoff