Kloppy064

i have a 96 z28 with a LT1 with 194,000 miles on it. It seams to have enough power, but it's hard to start and it backfires on deceleration any advice on parts for the tune up and replacement for the opti spark? Thank you

Injuneer

Let's move this to "LT1 Based Engine Tech". Better chance of a response than here on "New Member Intro".

Have you ever scanned it for codes? .....checked the fuel pressure? How many miles on the plugs and wires? Original Opti? Still have cats?

Kloppy064

The opti spark is original I believe. I have had the car almost a year. The plugs are pretty old as well as the wires.

Injuneer

Have you pulled a plug to look at it?

Not knowing the age of the plugs, wires, ICM and coil, I would pull the plugs, with the idea of replacing them unless they appear to be in very good condition, examine the plug wires for cracks and burns, have the ICM tested and replace the coil. Just replace them all if not in great shape.

Pulling codes is important. You can actually pull up the misfire counts by individual cylinder. Large numbers for all cylinders can point to the cap/otor, coil or ICM. Large numbers on individual cylinders can indicate specific problems like a plug, wire, injector or compression.

The Opti has two sections - cap/rotor for high voltage distribution, and the optical cam position sensor feeding info the PCM uses to fire the injectors and coil. Problems with the cap/rotor don't set codes, other than for misfires. Problems with the cam position sensor will set specific codes.

Fuel pressure can cause power loss. And, does it still have cats? No cats, and you hear the pops in the exhaust on decel.

Kloppy064

Yes I live in Washington where my Cats are required for another two years for emissions. I have the majority of the things on order for the tune up, but was just trying to get some advice if there was anything else I needed to possibly get to make it run better. I'm gonna to put it in the shop here soon to have the rear end done, but wanted to get it running right before I have it rebuilt.

Chimera96

OP, at 194k mi with unknown service history where some parts may be original it could be a combination of things causing your symptoms.

Injuneer offers some very good advice so I would follow those steps. The Optispark is just like any distributor that has a cap & rotor. Those are wear items and do need replacing....certainly if over 100k mi on them. The MSD cap & rotor kit is considered a very good replacement. Use blue loc-tite on the small screws that hold the rotor on

If your bearing on your existing Opti is good and you still have a original AC Delco Opti I would just get a cap & rotor for it. The OEM AC Delco opti is considered better than the aftermarket brands available today

KW Baraka

I have 3 optis available.

One is new, one w/less than 1000 miles and one w/about 1200 miles.

PM me if interested.

KW

bobstoy97ss

Excuse me for jumping on this thread. I have a 97 with no problems and hope to keep it that way. How do you get at this dist ? Looks like you have to pull balancer ?

Chimera96

you remove the water pump and the damper off the hub. No need to pull the hub itself

Injuneer

Courtesy of Shoebox:

http://shbox.com/ci/water_pump.jpg

http://shbox.com/ci/balancer_hub.jpg

http://shbox.com/ci/opti_mounting.jpg

http://shbox.com/1/opti.jpg

http://shbox.com/1/93-94_opti.jpg

http://shbox.com/1/opti_back.jpg

While the crank pulley is not an interference fit, and would literally fall off the crank when the engine was new, years of rust sometimes make it necessary to use a puller to remove it from the hub:

http://shbox.com/1/pull_pulley.jpg

bobstoy97ss

Thank you, guess i wont be changing the cap and rotor