Playdrv4me

Hi everyone,

Loving the car so far except for one annoying problem. After the car reaches operating temperature (and more as it gets hotter, especially once it goes a bit past the middle of the temp gauge) and has been driven around town for a while in 80+ temps, I start to get a bad miss, like a "dropout" at idle. If you apply the throttle it will occasionally bog for a moment and then drive fine at highway speeds (so far). Unfortunately, I am not getting a check engine light so I presume I don't have any codes to check. I had a pre-purchase inspection done by a Chevy dealer that came out with flying colors except for needing a serpentine belt, which I have done. Really love this car.

The Opti-Spark unit seems like a potential culprit for a lot of running problems on LT1s, but strangely that did not come up a lot in the searches I did for this type of problem. As I'm not a real DIY'er, just want to have some idea of what I'm talking about when I take it to someone to look at. Problem seems worse when the car is in gear (automatic) with the A/C on, but it skips just a little in Park as well. Car has around 75k

Thanks.

Dexter McCay

NGK Optispark... It is vented like the ones on 95 an 96 Vetts and comes with all vacuume hookups... Also LT1 are very picky when it comes to plugs... I have tried them all. Strange that plugs can make so much differance... A few months ago The Chevy Mech. told me about Denso Platinum TT's, WOW My Vette has never Idled and ran so smooth and the power curve in fantastic...

Playdrv4me

Thanks, one of my LT1 buddies (Roadmasters) suggested doing a tune up with fresh wires and especially plugs, and fuel filter, and if that doesn't work moving on to the Opti unit and water pump. Does this sound like a logical course of action (assuming I have no stored codes), or should I just do the Optispark right from the get go?

I also confirmed that this stumbling seems to begin almost immediately as soon as the temp gauge passes just over dead center. I see my temp gauge has a boldened hash mark exactly at 185*, but it doesn't seem to hang out there or near there unless I'm moving at a fairly rapid pace on the highway. If drive the around from stoplight to stoplight at 40-45mph, I start creeping toward, and sometimes over the middle a bit.