Luckluster LT1

[N20LT4]

Got something going on with my '93 Z28. During part throttle acceleration, the car is very sluggish. I mean, it's as if it's running on less that 8 cylinders. In the the cool evening weather it gets a little better, but the is still pretty much the same. But this is the kicker -- when I go full throttle, the car comes alive and delivers full power and throttle response as if the problem never existed. A friend of mine suggested bad spark plug wires. I've changed the spark plugs, but not the wires. The wires are the original ones, and have 123,000 miles on them. Can anyone help?

[BlackLT1Z28]

Probably the opti. I had the same sort of problem. It would miss in the lower RPM's, but at WOT, it would run like a champ. I think its time for a new opti, or at least cap and rotor.

[N20LT4]

Probably the opti. I had the same sort of problem. It would miss in the lower RPM's, but at WOT, it would run like a champ. I think its time for a new opti, or at least cap and rotor.

Figured so, but I was hoping it would be a much less expensive problem. If it happens to be, i'm going with the Accel unit. It's better than stock, and cheaper than the MSD. Thanks for the info!

[BlackLT1Z28]

If you are tired of the opti units, you could go with the Delteq setup. Its kind of similar to the LS1 coil conversion, but its a complete plug-and-play install. Its about $650 or so, but doesn't rely on spark generated from under the waterpump. Other than that, good luck on replacing it.

[N20LT4]

If you are tired of the opti units, you could go with the Delteq setup. Its kind of similar to the LS1 coil conversion, but its a complete plug-and-play install. Its about $650 or so, but doesn't rely on spark generated from under the waterpump. Other than that, good luck on replacing it.

Yeah I'm very familiar with that. My buddy's 97 Z28 runs the Delteq setup. He's had an explainable problem with the unit though that no one seems to have figured out, so I never took liking to it. On my last '93, I ran a Electromotive Opti-Spark Eliminator/Super Direct Ignition system which is similar (sort of) to the Delteq and worked great. At $800, it was very expensive though.

[hotrod18_69]

I'd also look into the o2 sensors.. Sounds like they may be alittle on the slow side.. Do you have a scan tool? And can you notice any kind of missfire at ideal or mid RPM when its being slugish?

[grandkodiak]

Mine gets like that down low, had it confirmed as an opti problem... wot youd think it was dynotuned, runs amazing. below 4k or light gas, feels like its on 3 cylinders.

[chevyguy8413]

My experience ('94 Auto Z28) was coolant leaking into the optispark....caused the exact symptoms you d'scribed...
Another possibility is an input to your ECM going bad...O2, MAP, or throttle position sensor...all should "code" in your Diagnostic connection...and all will cause a "misread" in the ECM.
In my case, it sorta felt like a "cold engine" at moderate throttle openings. I still have the original Optispark, however...I don't think you need to replace it just to fix your symptoms...save your $$/..

[N20LT4]

I'd also look into the o2 sensors.. Sounds like they may be alittle on the slow side.. Do you have a scan tool? And can you notice any kind of missfire at ideal or mid RPM when its being slugish?

I was thinking of the 02's as a serious possibility. The 02's as well as the cats are old with 124k miles on the them now, and look kind crispy underneath their. The only thing is the car doesn't mis at all anywhere in the 'band', it's just simply sluggish and doesn't have the "ooomph" it did a couple thousand miles ago. I'm the second owner. The original owner was a conservative man in his mid-70's. When I got it, it was probably the first time it had seen a quarter-mile run it's it's entire life, let alone WOT. These problems I am having right now are classic for our LT1's and I can almost be sure it will be one of you guys guesses. If I can't pinpoint it, I was start replacing the usual things that need replacing anyway, like a fresh opti-spark, cat & o2's, wires, and so on.