Larry G

I had Livernois build a 4v 298 Ci strocker motor with stage 3 4V heads, Compcams XE266BH-116 and 60 lb injectors. I'm running a Vortech which I upgraded to a T trim pushing 12 PSI with intercooler. I also added Kooks long tubes and off road mid pipe with Borla exhaust.

I installed the engine in the car, started it up a couple of times to make sure everything was in place and put it on a trailer (never drove it) and took it to a mustang shop in Miami where they kept it for over 5 months and a lot of BS. THat shop added the headers, MAF, 4.10 gears and axles. After finally getting pissed off and demanding my car either be finished or give it back, the owner told me he couldn't tune the car. This after telling me for almost a month he only needed a "couple more hours" on the dyno to finish it. I actually went over with a key and "repossesed" my own car!!!

I then took it to another mustang shop in South Florida. After adding 8 rib pulleys and an attempt at tuning the motor, they advised me to put an intercooler on the car to "straighten" the air to the MAF which I had them do.

It still seemed that they had trouble tuning the car and mostly the issue is with idle. The HP numbers in my opinion are also low (460HP). Livernois told me that the motor should produce minimum 500HP with no problem at that boost level.

This tuner is telling me that the compression of the motor (8.8 to 1), along with the big cams is the problem. He said that the overlap of the exhaust and intake along with the low compression motor doesn't allow enough oxygen in the combustion chamber for a good burn at idle. I spoke with a tech at Compcams tech line and they said there should be no problem with these cams in this compression engine and that there is a -2 degree overlap between the intake and exhaust. I also trust that Livernois knows what they're doing when they built this motor.

At this point I'm just glad to have the car back and running, but I feel like something is still wrong with this setup. The car pulls great all the way to redline, but it will die at red lights and if I step on the clutch to downshift on the freeway. Since the idle issues seemed to me like a vacuum leek I asked the tuner and he told me they did a smoke test and didn't find anything.

I've only had the car back a few days and I haven't had time to try and analyze the problem. I will have time over the upcoming holidays and the first thing I will check will be the IAC, anyone have a suggestion as to what else may cause these problems?

Larry G

An update;

My son and I cleaned the IAC last night and that seems to have helped the idle issues greatly. No more stalling at red lights and while down shifting on the freeway. It also idles MUCH smoother then before. I hope that takes care of that issue. I'm surprised that it wasn't identified by the shop working on the car, but I suppose they were thinking that a new engine wouldn't experience that problem. However, I used everything from the original intake and attachements when I reassembled the motor.

We also cleaned the throttle body because it was sticking when opening from idle just enough to make it difficult to get a smooth start in first gear.

We didn't have new gaskets for the IAC and throttle body last night so I picked them up today. We will take the parts off and clean them up really well one more time with new gaskets.