have a 94 f-body with 110k on motor, going down the road the other nite and noticed a hic-up off stop lite, than another down the road then lost all power in motor and coasted to stop. motor barely running 200-400 rpm and some exhaust popping but wont even idle. towed it home. tests so far, changed fuel filter, old one seemed okay-fuel pressure 42-45 at rails, no codes set, well maybe there was but i switched pcms for test and removed neg batt wire, have spark out of coil, out of coil wire, and out of opti to plugs, kind of stumped here, motor sounds like its not fireing in all 8 or like wrong firing order, starting to take front end apart to open up opti and see how cap and rotor look , any advise? used a scan tool for codes and restarted motor -400 rpm- but still no codes?

 

Opti doesn't always throw a code. Mine never has whenever it went out. If it does throw a code, I believe there are 3 or 4 of them that could come up.

 

The only codes for the Opti are for the signals from the optical sensor.... one (DTC 16) for loss of the low resolution pulse (shuts engine down), and one (DTC 36) for loss of the high resolution pulse (does not affect the way the engine runs). There are no codes related to the high voltage section.

Clearing the codes by pulling the PCM power before checking the codes was a mistake.

 

sounds exactly like my first opti failure....except mine ran just enough to get it to the repair shop...nothing over 2000 rpm.

 

i am having the same problem but its still doing it witha brand new gmpp opti from summit..

 

Just because you have spark out of the coil, doesn't mean it's a "hot" spark. I found this out the hard way. You local hardware store sells a spark tester for about $10, it's an adjustable gap. A good coil should be able to jump 3/4" easily. Fixed my buddy's 96 TA this way by replacing the coil after it couldn't jump the gap.

 

i would venture to say it's opti related. i wouldn't be the least bit surprised if the rotor screws have come loose causing the rotor to fire at will.
good new is it's a cheap fix. bad news is you have to take your opti off and take it apart to fix it. just some red loc-tite on the rotor screws and you should be golden. it's worth it to at least look and see.

 

spark plugs? burnt plug wires, wires fell off
just some other things i would check too
id say its your opti tho

 

Today I took some of the great advise you guys thru at me, tested coil with arc tester including coil wire, jumps 3/4 to 1 inch gaps no problem, even tested arc at plug wire ends ,still good. Put a noid lite on injector harnesses and they are lighting up, I guess my next step is to remove opti and take it apart and inspect it, i have one from a 94 carprice but its pinned in back and not splined, I took it apart , what a pita, needed to get a e-4 female torx socket, and the crappy screws that gm uses strip easy cause thier in there tight! wound up turning 2 out (barely) then had to grind heads off other 2, then slipped out cap but ended breaking the 2 i ground cause they didnt want to spin, then had to go and but a t-9 torx bit to remove rotor.So much for practice ,tomorrow i'll remove waterpump and opti so i can get parts before newyear.

 

Today I removed opti-crap, found out why my car couldnt idle or run but did stumble a bit. Took off cover hopeing it was a loose rotor, I was real close to my guess, rotor still attached but shifted about 20 degrees, looks like main opti bearing started to go and got hot from engine forcing it to keep spining and rotor connects to bearing/housing . Unfortunatly plastic went everywhere so im not going to rebuild, I kicker was that it still worked fine just way off and so no codes were set , plugs sparked and f/i worked , just not properly. Plan on getting a new gm unit for like 350.00 from a friend, this one lasted 110k so should the next.Ill let you guys know what happens, thanks much for your help, I have some pics Ill try to post soon.

 

Installed new gm non vented opti today, as well as a new gm water pump, started her before i installed water pump just in case, all is well again. I also installed a nipple in waterpump weep hole to redirect future leaks.Learned a lot from you guys ,thanks