Today when merging onto a State road I buried my foot on the throttle and wound it up. Just after it shifted to second the motion got funny and died. I coasted to the next crossroad and tried to start it. It acts like it wants to start, but doesn't. I checked the oil, which was full, checked all the fuses, they were good, and checked fuel pressure, well I mean I pushed in the shrader valve and fuel squited out. Then I started cranking it and heard I noise I hadn't heard before, kinda like something hitting the block... So, just to try to rule out the Opti, when it goes bad you get absolutely no spark, correct?

It'll be awhile before I get my tools to my new house, but I'm going to pull the valve covers first and then the oil pan, hopefully I won't see anything broken.

 

Any shiny stuff in the oil? Since you had to pull the harmonic balancer when you did the opti look for anything around it that might have loosened.

 

Total loss of spark doesn't usually happen, but more of a spit and sputter situation ( and usually in front of a crowd ). Mine did that act and would fire right back up after the show...it might not do it again for weeks, which made it a little tough to find. If your car has the original Opti and is anywhere close to 100k it probably time.

When I disassembled mine I found the bearing to be the problem, electrically it was fine. If there is ANY movement in the shaft or platter its bad.

later, tiny

 

Could be the coil or icm. The noise sounds worrisome, like it' something far worse than the opti, but it may just be one of those brain playing tricks on you things.

Find the shbox lt1 no start troubleshooting guide and go from there.

 

I don't know why you think that, I've never touched mine.

good info, thanks. I tried again yesterday and absolutely no sign of life. I assume it's original, the car does have 96k on it.

I want to check for spark, but I need my wife to come help with that. The noise isn't loud, and may not be anything to worry about. However, I did notice that when you turn the key on, the fuel pump comes on and doesn't stop like a tpi/tbi motor. There is also some noise under the hood which I hope is just fuel flowing through the regulator. I'm going to bring my pressure tester out just to see what my fuel pressure is.

 

I agree with FAUEE: Something that sounds like it's hitting the block is NOT part of the Opti. If it is the opti, the car will crank for days as long as the battery has a charge. Isolate the noise first.

 

This weekend I'll check for spark and fuel pressure since the pump seems to run non-stop and under the hood sounds like fuel whooshing through the regulator. Probably a compression test before I start pulling things apart.
The noise I mentioned isn't loud. I tried to get it on video and you can't really hear it, at least I didn't. It's probably nothing.

 

Fuel pressure is good, 54 psi but let me I said the pp just runs and runs with the key on engine stopped.
ill check codes again but last time I checked (which was right after this happened it was codes for egr and o2.

 

The PCM should shut down the fuel pump 2 seconds after it stops receiving reference pulses from the Opti ( Factory manual for 96 ) sounds like yours is getting reference pulses regardless....think maybe a part of the wiring harness got shorted ( or grounded ) when you stepped on it ?

If the car was running good beforehand, it's gotta be something simple..the noise you said you heard...maybe a motor mount ?

later, tiny

 

That's not true. Total loss of spark is the more common symptom. I've had two opti's die and both would completely "turn off"; no spark, no tach signal...none.

That's not to say Tiny totally wrong; "spit and sputter" CAN happen...but I wouldn't say that it's the more common symptom.

Did you check for spark?

 

My only experience with Opti's has been my own and a few others, all of them were original to the car and like the OP and the mileage was around 100k.

later, tiny

 

Not yet. I'm in the middle of moving to a new house and the car is at the new house while my tools and everything are at the other. I've got a week off from work so other than a couple commitments I'll be packing up my tools and moving them to the new digs. Hopefully tonight I can pull a plug and see what I've got. BTW, ether didn't do anything.

I've been reading a lot about Optispark and alternatives, and in a few cases it sounded like just the rotor disintegrated, so maybe I'll get lucky and the sensor will still work. If so, I'll look into an LTCC conversion, but at about half the cost of Torqhead (once you add the price of coils and wires) and me wanting to swap cams, why not just do the TH?

 

JMHO, but here are my reasons:

2. cost -you could buy 10 0pti's for the price of a TH...how long will10 opti's last? Longer than the car.
3. I don't mind changing opti's. Not as much as I mind paying for another system

Just some things to consider, but everyone has their own reasons.

 

Tom, the TH system does not use the opti any longer. It replaces it with a separate housing that has a genuine LS pickup sensor in it.

The LTCC on the other hand, still relies on an Opti. That is what I have.

 

Ahhh....well that eliminates one of my reasons. Thanks for pointing that out.

The other reasons still stand -for me.

 

If you are just going to run a stock LT1/LT4 then the th doesn't make sense. I wish, I really wish there was an affordable non-opti alternative. Maybe one could retrofit a small cap hei? Is there room?

 

There is room, b/c people run small cap HEI's on Gen I SBC's with a "converted" LT1 intake.

The problem is the pick up. A typical Gen I uses an 8 pole magnetic pic up...which the LT1's PCM won't read/understand or know what to do with. As we know the OPTI uses a LED and photo cell pick up, and produces 720 points of reference per revolution on the hi-res side and 8 changing length (cylinder "ID") points of reference on the low res side.

They're incompatible with each others' ECM's.

The cheapest conversion you could do would be to use a junk yard distributor that will house the OPTI's wheel and sensor, then mount those two items in the conventional distributor. Modify the LT1 intake to accept a conventional distributor, and then seal the OPTI drive hole in the timing cover....problems solved.

Now you've got an OPTI mounted out of harms (water) way, easy to access and service, and it's still compatible w/the LT1 ECM and provides the more tightly controlled angle based timing.

This is the plan I will pursue someday when I build a 400, for my LT1 car, and I was thinking about the L31 Vortec distributor, for that due to the low profile, "correct-a-cap" cleanliness and readily available in salvage yards.

 

Thanks. Now I'll have to Google L31 and learn what I can.

My big issue is the multitude of posts talking about Opti failure, and the few posts claiming aftermarket Opti longevity.

I've got a mill in my garage, so making the modifications is just a matter of buying the right tooling.

 

Cool. With a mill....you can do a LOT.

You don't hear about Opti "Successes" b/c people rarely post about that. They only post when they have issues. My stock OEM opti lasted over 150k miles; 50% longer than GM said it should. That's a success, IMO. The napa unit that I replaced it with lasted 5 years/~30k miles. That was...fair and for the price ($500) it was poor -a failure, IMO. I brought the "price-to-longevity" ratio into what I feel is an acceptable range when I bought my current one; a SAC CITY unit with a 2 year warranty. If it lasts 2 years for ~$160, that's O.K. with me.

If you get the thing mounted up in a conventional, rear mount distributor, I'd bet that it lasts indefinitely; it'll be cooler running, stay dry, and if it does get wet/contaminated, it's 5 minutes to get to it to clean it...not an hour. My wife used to have a Dodge Stealth RT/TT (remember those?) and it had an opti in it, but mounted in a regular distributor mounted/driven off one of the OHC's. It lasted indefinitely, except that I got it wet washing the engine once. I took it apart, drew kleenex tissue through it to dry/clean the lenses and it worked flawlessly after that. Same/same on a Nissan Xterra I worked on for someone, too.

So, *I* think a standard/rear mount opti converted distributor will make a great working solution.

EDIT: THE L31 distributor's internal sensor is only for cam orientation; it's a "cam sensor". The L31 has a crank sensor that provides the "Now, now, now, now..." for the ignition events and injection events. Anyway, that cam sensor wheel and pick up that are in the L21 distributor would have to go, or be cut down so that you could replace them w/the opti counterparts.


.

 

Scout, I am thinking about that fuel bypassing...its really not suppose to do that, there should be no whooshing and the pump should shut off after it builds pressure. Have you tried putting a vacuum gauge on your fuel pressure regulator? It sounds busted to me...and its easy and cheap to change. Its right on top of the motor, just a couple bolts holding it to the fuel rail. If you do change it, remember to pull your gas cap and bleed the fuel pressure down before you open it up...it makes a REAL mess if you don't.

I had a bad one on my car. The symptoms were a bit different than yours because my valve would reset itself, but a good hit to the gas would expose the tear in the diaphragm and the car would die. Once it reset, it would run again...but it sounds like yours is not resetting. Good luck...and I got nothing on the loud thing hitting the engine...