'94 Bad A Z28

A little background on the problem. This first started about two weeks ago. Was on my way home from a car meet, just driving along barely doing the speed limit, and boom... Some type of retarded backfire and the car shut off. Tried to restart while rolling and got nothing but the same popping backfire. Pulled off into a parking lot and let the car sit a couple minutes before trying to start it again, but with the same result. So I called for a tow truck to get the car home to figure out what the problem is.


While waiting for the tow truck to arrive I kept trying to start the car every now and then, all with the same result except for the last time. The last time I tried the car started, but sounded like it had a loose rocker, so I shut the car off and continued waiting for the tow truck. Tow truck gets there blah blah blah, get the car home... fast forward to the next day.


I take the driver-side valve cover off (the side that sounded like it had a loose rocker) and don't see any problems, no loose rockers or anything like that. Just for ****s and giggles I put the valve cover back on and started the car... started up like there was nothing ever wrong. No rocker chatter no nothing.


Fast forward a week. I'm on my way to my cousins for a BBQ and I get on it a little. Run first gear out to 6850 where my shift points are set and all seems well. Then second gear at about 5500 I hear the same popping backfire as before so I immediately get off the throttle, and just as before the car shut off but this time I was not just cruising. Pull in to a parking lot that is only about a quarter mile from my cousins, so thinking it is going to be similar to last time I just left the car there and walked to my cousins thinking the car would start in a couple hours or so.


Get back to the car later that day and no start. Okay, no biggie I'll check the rockers again. Check cylinder one exhaust and as soon as I touch it the poly lock breaks... hrmm... call a tow truck and get the car towed home.


So get to today, I replaced the poly lock and checked all the rockers on the driver side and the passenger side of the car. Everything seems fine, put everything back together and try to start the car. Nothing but some retarded backfiring that sounds like liquid bubbles in the exhaust.


Now I am at a loss for ideas. It seems like the car is some how 180* out. I don't know if it is at all possible for the dowel pin to have jumped out to a different slot in the opti, or if somehow my double roller timing set jumped a tooth?! The timing set probably has less than 8K on it. The car has a LTCC on it, I don't know if that can have anything to do with it but it has been fine up until now.


Uploading the videos now. Give them a couple minutes.

'94 Bad A Z28

'94 Bad A Z28

Anybody have any ideas?

MEAN LT1

WTF is goig on with your car?, Sounds like its trying to make bubbles or soemthing. Have you dont all your basic checks?. sounds like its out of time some how. Although when my car had a timing issue it would back fire out the intake and out the exaust. Not sure if this is your issue or not it does sounds like something is out of time.

grumpygreaseape

sounds like the timing chain jumped. check compression on the easiest cylinder to get at and see where you are at.

'94 Bad A Z28

It did backfire out of the intake once while trying to start, just not for the videos.



I was thinking the same thing but is it really that possible? The car has a Cloyes Double Roller Timing Set on it. The timing set has at very most 8K on it.

grumpygreaseape

i would just go ahead and check compression on one cylinder. i know that the timing set is young, but sometimes strange things happen when you dont expect it. it really does sound like ya jumped time.

'94 Bad A Z28

So decided to stop being lazy today and took the opti off the car, just for fun... no SES light, no codes, nothing. Low and behold...





Threw the opti off my other motor on and it started right up, now I just have to be everything back together.

'94 Bad A Z28

Now I just have to save up for a Dynaspark GenIII.

Dave1980

Not trying to dog on dynaspark, but what is the real difference in the dynaspark III ($525) and an opti with a rotor removed? Essentially you just want the optical portion for LTCC and Deltec. I can bet you that your rotor fell apart within the opti unit if you open it up. Usually the optical portion is ok, assuming that it has a factory type sensor IMO. This sensor is actually made by Mitsubishi. I at least found their emblem on mine.

'94 Bad A Z28

Yeah, the whole opti is Mitsubishi's doings. GM Engineers said hey we have this awesome engine, lets go to Mitsubishi and as them what to do for ignition.


Dynaspark GenIII = completely sealed unit.

Opti with rotor removed = no where near sealed.

Dave1980

I am not thinking dynaspark is anymore sealed than the reg opti. Look at the pic it has the same vent lines. Spend your money how you want, but I am not thinking that it is justified for that price. I would say go for the LS1 PCM conversion if your that concerned.