jimbo98z

iTrader: (3)

I've got a 98 Z28 with 243 heads, a 230/230 cam, LS6 intake, long tubes, stock TB drilled out a small amount (can't remember how much), stock MAF and when I went to get the car tuned today the car will start and then immediately bog down to about 400-500 rpm, pull itself back up to 1200 rpm, then fall into a 900 rpm idle. During tuning, we also found the kPa numbers were erratic up top, jumping 5 or 6 and then going right back.

Came home and did a quick check for vacuum leaks with the old brake cleaner method and couldn't find anything. Then, just for ***** and giggles, decided to unplug the MAF. The car fires right up and settles into a 900 rpm idle in maybe 3 seconds. Is this telling me there is a MAF issue, or is this just making the car ignore the issue at hand?

Will be running a more thorough vacuum leak test tomorrow, and probably a leak down test just to make sure.

Any help would be much appreciated

BIG_MIKE2005

iTrader: (116)

put a fuel pressure gauge & check it at idle. I'm fighting a similar issue & just put one on mine, was only getting 25psi to the rail instead of 58-62. Before that I replaced a ton of stuff & mine is doin the same in reguards to the MAF. I got a Racetronics pump on the way & a new stock FPR for the bucket too.

jimbo98z

iTrader: (3)

It's got the racetronix kit with the hotwire kit on it right now.

I'm starting to lean towards a vacuum leak at this point. After thinking about it, I realized that if I unplugged the maf it was just going on a set amount of fuel, so it was just ignoring the vacuum leak (assuming there is one). Going out to check all of this stuff now, including compression/leakdown and now fuel pressure...