I got the Jet Hot LT's installed and the engine runs very rough up to about 1800 but it's pretty smooth above that. We hooked up a scanner to it and it's throwing a code 18 indicating that the crank sensor isn't hooked up or that there's a problem with it. But there IS no crank sensor since the LT1 has a distributor! The Optipieceofcrapspark was replaced 4 years and 15K miles ago, I hope that's not the problem. Also, the O2's are reading about 4 mV, this is about a tenth of the value they should be at, indicating that the car is running extremely lean. The car ran fine before the job but now it's not. I have LE1 cam and heads. Can anyone help?

 

i'd start with checking the wires then o2s and go from there

 

The plugs and wires are 6 months old and I checked them first thing. Unfortunately that doesn't seem to be the problem.

 

What year is your car? If it is a 1996 or 97, you do have a crank position sensor. It is not used for spark delivery, though. Check your plug wire routing.

 

The car is a '94. I checked again also to make sure the plugs were routed correctly and unless I bungled it somehow, they are. The O2's are old but I had someone who knows take a look at them and he said they were alright. I've read that coated headers will destroy the O2's but I wouldn't expect it to happen after only 30 miles or so.

 

Any wires burnt? RUn the car at night and see if you can find any arch's.

 

I don't think any wires are burned or are arcing but that is a good suggestion. I heat shielded all the boots and spent many hours looking over it to make sure nothing was going to melt. I expect I'll check that though and probably also end up quadruple checking that the wires are routed correctly.

 

Its happened to me a couple times, make sure your serpantine belt isn't eating away at them also.

 

I should have looked it up-code 18 is injector circuits. I don't know how 18 translated into crank sensor.

 

Injector circuits! Funny. The scanner is a Snap-on and said code 18, something like "crank sensor disconnect or faulty." There was no code 18 listed in the troubleshooting program, nor in the Haynes book. I supposed I'll check to make none of the injector wires melted...but that is highly unlikely, also, I don't see how the injectors would be struggling to keep up at 1200 RPM's. Thanks for the help.

 

We ran the scanner with the car parked in the driveway. We're going to see now how it acts while it's being driven. Thanks again for the help, I'll post anything we find out.

 

With the car rolling the O2's are fine, they read the voltage they should. With the car parked the O2's read like it's running incredibly lean. They didn't do that with the manifolds. It also reads "A/F not learned" but that shouldn't cause the symptoms I have. It feels like it has a miss but no code of the type is coming up. Those of you with OBD II are lucky because the scanner will read misses and which cylinder is missing. OBD I doesn't read anything on misses so I'm stuck guessing.

 

sometimes cheap spark plug boot protectors can screw with the spark. i had brand new wires and somehow it was causing them to arc, inside the fire sleve. bought fiberglass ones and now no miss.

 

That could be the problem; I never would have thought of it. The shop had one pack of super high temp wire loom protectors and one pack of the fiberglass protectors which were cheaper. I got both and put them on. The stuff was so frieking expensive it was a joke so I covered other wires and one of the boots with aluminum foil. I'll yank them and see if it helps.