Incomplete LT1 Tune-up

v90hamm77 · #1 (**permalink**) 04-14-07, 06:17 PM

I hate to sound like an idiot, but on a LT1 is it smart to change just the plugs and wires without adding a cap and rotor. I did it and I can't really tell a major difference in the performance of the car. I still feel like it a little rough at idle and crusing around 45-50. Any suggestions? There are no signs of the water pump leaking on the opti-spark. The number 7 and 8 wires did have some discoloration at the opti-spark ends though. the rest were fine!

**jayoldschool** · #2 (**permalink**) 04-14-07, 06:32 PM

Change the coil wire if you haven't. Put a fresh pair of O2s (in the front if you have a 96) in - Delco, not Bosch.

96Fleetwood · #3 (**permalink**) 04-14-07, 09:47 PM

I changed my plugs & wires without touching the optispark... there is no need to change the optispark if it is in good shape.

v90hamm77 · #4 (**permalink**) 04-14-07, 10:10 PM

96 Fleetwood did you change your coil?

v90hamm77 · #5 (**permalink**) 04-14-07, 10:13 PM

Jayoldschool; If the service engine light isn't on should I change the 02 sensors? Aren't there four on here, why not change all four? Change just the coil wire, or both the coil and wire?

96Fleetwood · #6 (**permalink**) 04-14-07, 10:25 PM

Nope, did not change the coil.

And if any of your O2 sensors or heaters are bad you will get a code, especially on a 1996 OBDII car.

**jayoldschool** · #7 (**permalink**) 04-14-07, 11:47 PM

The O2s are a "wear item" - they are supposed to be replaced at tuneup time. They get "lazy" with their voltage readouts. You can check this with a scan tool, or a properly equipped laptop (special cable and software). The fronts are the ones that the PCM uses for fuel/air calibration - the rears simply tell the PCM the cats are working. A code will only be set if the 02s fail, not if they are old. Replace the front two - your mileage will go up. Next time, move the two newer fronts to the rear, and put two fresh ones in the front.

The coil should be fine. Put a new coil wire on, and check carefully for corrosion.

v90hamm77 · #8 (**permalink**) 04-15-07, 12:03 AM

Thanks. I will get on it as soon as it stops raining!

Old Fleetwood · #9 (**permalink**) 04-15-07, 12:07 AM

Maybe it was "all in my mind," but I was bugged by what seemed to be a miss - or something like it in lockup at around 70mph under load going uphill or under a slight load.
New plugs, new wires, good Optispark, no codes showing.
N0DIH mentioned something about some fuels having Techron additive.
I usually figured most such are considered mouse-milk, but I bought a bottle and tossed it into the fuel tank. Hell, I'm sold on the stuff.
One tankfull and NO MORE MISS!
So - - - could the problem at the beginning of this thread be nothing more than crap building up in the cylinders (or maybe injectors) like it was in my case?