LT1 Miss Fire
I have a 1997 Formula with the LT4 conversion, done at 36,000 miles, and 95,000 miles. Just lately I've starting to get a quick miss.
Scenario: 70 MPH on highway with the cruise set, when the cruise starts to accelerate going over an overpass the engine will feel like its shuttering. On the flat highway it runs great but when its gets a load it bucks.
Also, I've noticed that on Mondays after it set over the weekend it starts as soon as I hit the key. Over night it cranks a few seconds before it starts.
I am thinking it might be the injectors. I am going to change the fuel filter tomorrow and add injector cleaner.
If I need injectors what size and do I need the PCM reflashed.
Thanks,
________

 

Factory Opti?

How old are the plugs/wires/Coil?

 

Check the wires.

 

If it was the wires wouldn't it do it all the time?
The opti was replaced around 30,000 miles by the dealer along with the water pump.
Original coil.
The wires are Taylor Made with about 36,000 miles and the plugs are 3 months old.

If I need wires which should I use?

Thanks,,,

 

A sticking EGR valve will do what you've described....

 

I had that problem. As long as I was cruising, the car ran just fine. I could even run through the gears and it was fine. It would only do it when it was in sixth gear and you tried to accelerate. I had a couple of burned wires. If you have an enhanced scan tool, it should pick up the cylinder(s) that are misfiring.

 

My missfire was a burned wire as well. Check there first.

 

Thanks all!!
I think it will be easer to replace the wires that to troubleshoot which wires are bad.
So, what brand of wires should I go with??
I have the LT4 conversion with the MSD 6A.

 

I fixed the plug wires at the dist. It still bucks under a light load.
Could it be my MSD? Does a MSD box usually go out gradually or does it just goes out. Like its good or its bad!!

 

Unplug the box and see if it stops misfiring.

 

under load only? sounds exactly like what I had... a burned wire shorting out on the passenger side header. it's happened twice now.