Engine stalls at idle

[mrviper99]

Here's the problem. 1996 GTS. Lost harmonic balancer in Nashville last year, that messed up the end of crank. So this winter I decided to have Arrow engine replace the crank and put better pistons and rods in, while I was so deep into it. :flag. Arrow finishes engine engine runs great. Engine before Arrow worked on it ran great also. Engine has street perforance cam, heads, headers,and roller rockers. Arrow put on new stock throttle bodies, I had 65mm throttle bodies before Arrow. Now viper tech puts engine back in car, runs great except it won't idle, stalls when ever you come to stop. Viper tech measured the vaccuum on only gets 8 inches of mercury reading. Tricks the computer, creates vaccuum with pump to 12 inches, car runs fine at idle. On Monday they are going to try my old TB's to see if that works to solve problem. However if that doesn't work what should we do to correct the problem. Is the computer the problem? Do I need a VEC 1 or what? Please help:

 

[ceieio]

What are the specs on the new cam (lift, 0.050 duration, Lobe Displacement Angle LDA)? Longer duration and narrower LDA increase overlap which will reduce vacuum at idle.

I will assume that your cam has more overlap. Given that the 96 lumpy cams have a narrower LDA already it could be that the new cam is causing a low idle vacuum.

The good news is you get a better cylinder fill and scavenging at higher RPM, and will usually build higher HP and higher RPM.

The bad news is that your MAP sensor will get confused which means that your car will not idle correctly. Another potential problem is that you may lose the power brakes at idle / low RPM.

There are work-arounds for both problems but on a Viper it will likely take some experimenting.

 

[mrviper99]

Bump