My car has recenlty had a surge as if I had a rev limiter on once I get beyond 5000rpms. I can't figure it out. I rev the car in N and I can notice the surge in the 5000 range. Under a load, it cuts out and falls on it's face, then picks up, then sruges again. Fuel pressure is 43.5 with no issues. I changed my coil, wires, plugs were brown with a little fuel on them, nothing bad. No codes. I even changed my ingition back to the stock ignition and I've got no change in my surge problem? Waht gives? Vacume is 14 inches which is normal for my car. L98 with a lpe 212/218 cam, paxton sn 2000 supercharger, exhaust, crane hi 6 s ignition.

 

What condition are the valve springs?

 

Valve springs are failry new. I think I have 15K on them, AFR heads with the springs they supplied. Maybe a compression check is in order?

 

If it is not hard to pull valve cover. I would look for a broken or weak spring. Compression check could be good with a defective spring.

It's the load/noload thing, fuel would be different but spark and springs wouldn't.

David Vizard talks about spring surge at this rpm (4500-5000), only takes 10# more of seat pressure to cure (blower boost?). Something about "initial spring relaxation". At first they added more shim, then they went to a double spring at the same pressure.

 

pandin,

Thanks for all your help. Valve springs look great! Compression test shows 180 in all cylinders. Turns out, it was my fuel injectors. I have been running 30lb injectors for a few years. I recenlty purchased a set of 24lb injectors due to poor gas milage. I used to have a set of 24lb injectors and my car ran fine with the 24's. I never had an issue with the 24's till I recenlty put them in my car. They were used but reconditioned. Im gonna call the company and talk to them this week. Sorry I did not mention the new injectors till now, but I wanted to find other possible causes of the surge @ high rpms. I was kind of thinking ignition module...or rather hoping. My 30lb injectors get terrible gas milage! When my foot is in it, it gets 4mpg! I'm sure it's running pig rich, so a tune with the 30's in order as soon as I find time. Thanks again!