Went to p/u my car from the engine builder. Stroker, ported heads, comp stage 3 cams, and they did the remove and reinstall. Car has a Vortech HO s/c.

First problem I notice on start up is what sounds like an exhaust leak on the passenger side, which irritated me. It quieted down as engine temp increased.

Knowing the existing tune was not going to cut it, we plug in the Diablo and get (3) codes right away.

1. Rear O2 sensors - Okay, the OBX headers have none, and we need to turn them off.

2. OBD - probably due to the car sitting for 6 months.

3. Fuel pump driver code - No clue what the issue is, but GT500 pumps have been in for a year w/ no trouble.

Took it for a very delicate ride around the block. Fuel tables look good as we are driving, and then it starts dropping clyinders, and then recovering. On one occassion at a light, it again drops cylinders, and I pull the car over and shut it off. No obvious problems under the hood - fire it up and it is nice and smooth.

Why would the car drop cylinders, and then recover? This does not seem like a mechanical issue.

 

When you say "dropping cylinders" do you mean not firing?
If the engine management system thinks the engine is overheating, it will shut off cylinders in alternation to protect it.
Could be just a sensor problem.

 

Engine temp was good.

I tend to agree with you. My thoughts are that when the motor got reinstalled something got pinched, missed, or not connected securely. Talk about a needle in a hay stack.

 

If you can't find it with some quick looking around, I think they (the installers) owe it to you to fix it.