Roostmeyer

iTrader: (3)

The hotcammed lt1/t56 is out of a 96, in my GTA its running very well, when it runs. I had a bad ground with the baker vats eliminator, as well as a bad ICM, and plugs in the car, but its been doing better with one exception. The current problem is it occasionally won't start, or it'll run fine and then die and not restart.

Heres the thing, I've had the engine more or less "done" for the last month or so. It was difficult to start at first and would die alot, but I think most of that was the bad plugs, ground problem, and the cracked ICM from the enigne hanging off of the nearby ground stud... Last two weeks the car wouldn't start at all, leaving me to push it in and out of the garage to change the oil on the girlfriends car and to help a coworker put struts on his M3 (humiliation!).

Friday when I finally sat down to toubleshoot it, it ran fine after cranking for 15-20 seconds. I pulled the #1 plug after 10 seonds of cranking and they were dry. I had a timing light on it and it was NOT getting spark during that time. After pulling the plugs, the car cranked for another 3-5 seconds, started up and ran for 15 minutes, then died suddenly, I hit the trigger on the light and there was no spark as it died. No fuel and no spark seems like a clearcut Opti problem. When the car is running and it dies the tach goes dead before the car as well, so I think its safe to assume it is the Opti.

After this last time the car has started fine and ran until I turned it off, so I'm not sure what to think. I have a theory that some dust got in the opti while the motor was sitting for 9 months causing the optical sensor to go f'nuts. Has anyone ever experienced this? Makes me wonder if I should just change it now or wait until it dies for good...

Firebat

iTrader: (7)

Almost sounds like a fuel pump thats going out. Have you checked fuel pressure? Also could be a bad fuel filter, I recommend changing it if it hasn't been changed for a while.

ttypecamaro

iTrader: (2)

make sure the pin in the end of the cam was not sticking out too far. That will cause the encoder wheel to contact the optical sensors when the opti bearings start to wear/fail. or else some dirt or something could be in there like you said, causing the problem to be intermittent.

Roostmeyer

iTrader: (3)

I can check fuel pressure, but its a rigged setup, fuel filter has been a few years, but I don't think thats the problem.

It ran great yesterday, today went out to the garage and nothing, cranks forever and nothing, no spark. Pisses me off, I had planned on spending the weekend changing it out with a working used one, but it ran so well yesterday, I thought it was alright and spent the last day and half getting the rear suspension squared away.

I'll check the pin when I pull the opti out, but I think I may try to use a vacuum to pull some air through it and see if it helps. Other than that I'm out of ideas and I'm going to just pull it and replace it.

ttypecamaro

iTrader: (2)

next time it doesn't start, test the optispark with a multimeter. I've seen it done once but forget the exact procedure. It involves probing inside the gray 4 prong weather pack connector that goes over the intake manifold from the optispark.

Klortho

I would make sure you have power to the ICM and check the opti harness and make sure it's not damaged, my opti has over 150k miles on it and charged my battery yesterday and cranked up after 4 turns after sitting for a year.

Roostmeyer

iTrader: (3)

I've done the test on shbox.com, but I don't think it checks voltages/resistances on the opti itself. I'll probably try to run through that again tonight as well as check voltages at the PCM side of the harness. It very well could be an intermittant wiring or PCM problem.

One of the reason I got the motor/tranny for only 2k (rebuilt and with installed hotcam kit) was the guy had it for sale for the last 4 months with barely any bites, and it had been sitting in his grandfathers quantset shed at the farm and was very dusty. The motor was well sealed, but I can't help but think that some of the dust on it got somewhere it shouldn't. Needless to say it got an oil change after running for 5 minutes.

Roostmeyer

iTrader: (3)

Damn piggy back underdrive pulley. 25 minutes to install, @#$%ing 2 hours to remove! Didn't even realize what it was for a while, kept looking at the diagrams trying to figure out what it was. Ended up having to drill 3 5/16 holes in the car and putting a nut on the backside to use a pulley puller it. Oh the suprises with a new to you motor.

You would think they would make some way to remove this POS!

Anyway, the new used opti seems to be working great. Of course after spinning the old one for a bit it starting working too. Kinda fun hearing the injectors clck when you spin the opti!

Roostmeyer

iTrader: (3)

Update, from what I can tell I have fuel now, but no spark. I do now have 2V AC on pin B now when I didn't before ( http://shbox.com/1/4th_gen_tech2.html#opti_test ). Is it possible to install the opti off 1/3 on the dowel pin? If so what would it do?

I'm guessing I may have fried the ICM with static discharge or possibly screwed the connector up by forcing the DMM probe in. Kinda feel like I'm grasping at straws now, but I've got to be close.

chevyowner02

iTrader: (3)

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

Roostmeyer

iTrader: (3)

After doing some more research yesterday its possible to force the opti onto one of the other slots. This would cause my ignition to be severly out of time, but I would still be getting ignition. The more I think about it, I think the cap and rotor part of the opti is shot, but the optical portion is fine. I'll check if I'm getting spark from the coil to ground on cranking. If so the ICM and coil is fine and its the distributor cap. If not its the ICM or coil.

I was going to do this last night, but I decided I'd done enough wrenching in the last week and went drinking for st. patties. My cross-member shows up today and I've got an appointment on friday for the exhuast. I'm stoked to get this thing back on the road!

Klortho

The Opti has a big square slot and two that are oval, the pin goes into the square one, that way it's not out of time at all. I would check the voltage on the coil and make sure you have 12v on it which if you're not getting the full 12v to that would definatly cause it not to fire.

Roostmeyer

iTrader: (3)

I broke both of my drop lights last week. From what I could tell with a little pin light, the dowel was in the correct slot, but its tough to see in there with little light. I suppose that at 120° off that the coil could be firing and the rotor isn't even touching a terminal in the distributor at all. Either way, a coil spark test is quick to do and I'm pulling back off the opti.
I am getting 12V on pins A & D on the ICM. Looking at the wiring diagrams, both of these are getting power from the coil. Of course this is assuming they didn't change the wiring with the new coil connector style of my 96. All the wiring diagrams I've found on the net are for the 95 from shbox. I should've known better on the whole thing... I had new MSD wires I didn't want to get dirty by installing them twice so I waited to put them on until after the water pump and crank pulley was on.

Klortho

Well, to get the opti on wrong you pretty much have to force it onto one of the other slots to get it to fit, I dunno if that would be enough to possibly push the dowel pin in far enough that it's not making contact to the opti but you never know.

Roostmeyer

iTrader: (3)

And the winner is....








Bad ICM connector, apparently me probing it for the last 4 weeks loosened the prong and it wasn't connecting as intended. I put in a few drops of solder and its working fine again.