Alright i know this post has been seen before because its plagues almost all lt1's but right between 4500 and 5200 the car feels like somethings holding it back. It started last year when my waterpump was going (anti-freeze on the wires) and i just did a tuneup on my car so it is probably gone but havent had it running yet. I wanted to hear if other guys have successfully fixed this problem. ive heard 02 sensors map sensor all that but is there a conclusion? Hit me with some ideas, car keeps revving but feels like im pulling a house...... THANKS
CHRIS

 

First, check to your spark plugs wires and make sure none have come off. A few people have already experienced this problem. Then rule out any type of problem with the fuel system (injectors or pump) and air intake (loose clamp or hose). If those are okay, it's most likely your Optispark system. If water gets in there, it's as good as toast. A hesitation problem due to the Optispark will usually be noticed in certain RPM range. Most commonly, it is in the upper range (3500 - 5000 RPM). But it can certainly develop in the lower or mid ranges as well. You might even get some back-firing.

 

check your catalytic converter

 

Time for some new valve springs.

 

this might sound lame but im not sure what the opti spark is. the ignition system? the optical distributor? i just changed the cap and rotor of the "optical distributor" and will let you guys know how it is once i am driving it again. spark plugs and wires are new along with fuel pump. most of the stuff that could be effected is now changed so hopefully this problem is gone. WELL SEE!! please give me some more input and btw?? MY VALVE SPRINGS ARE BAD?? that hopefully isnt the case, do you know anyone else whos had that problem LMK

 

any other responses??

 

One in the same.

Good luck...hope at least one of those issues you've addressed was the culprit!

 

Check your fuel system....

 

Check air filter, cat and insure throttle body is opening completely I lost that feeling when I changed to catback system

 

It is generally a good idea to replace the entire OptiSpark distributor, not just the cap and rotor. The bearing can wear out, rust can block/interfere with the optical sensor, the harness connector seal can leak, etc., all in the back 1/2 of the unit. When my car had a flat spot from 5,000rpm up, it was showing DTC 16 for a fault (loss of low resolution pulse) in the optical section. Replacing the Opti cured the problem.

A lot of people seem to get into problems with knock retard at high rpm levels... .a result of "noisy" mods, poor fuel quality, excessive carbon buildup in the heads, etc.

 

I agree on the fuel system. You might also consider the coil and/or coil wire.