My '94 with 230k miles died suddenly. Has fuel pressure, spark at plugs, will crank and barely start. Idles violently at about 200 rpm, for about 5 seconds, and dies. Can smell unburnt fuel from the exhaust.

I've already pulled off the waterpump and Opti. Nothing obviose wrong with the opti, other than really rough bearings. It had 70k miles (Delco, I replaced at original at 160k miles)

With crank hub at TDC, opti rotor does not point to cap #1 electrode (6:30). Instead, it points to 5:30, approx. 30 degrees retarded. This leads me to belive the timing chain has jumped a tooth.

Also, the flat on the opti drive gear is at 12:00 with the crank at TDC. My Haynes manual has a picture that shows it at approx. 1:00 with crank at TDC. I've confimed TDC by pulling #1 plug, inserting a screwedriver, and rotating the hub back and fort to find the high spot - it jives with the arrows on the hub and pulley.

Can anyone confirm if this is correct? I'd like to avoid dropping the pan, pulling the hub and removing timing chain cover.

Thanks in advance!!!

 

my car does the EXACT same thing, very interested in the answer

free bump

 

The stock timing chain is junk IMO. Any high performance build up, get rid of it.
On my blown motor, the chain was so loose, I could have removed it by hand.

Don't be too afraid of dropping the oil pan. It isn't all that bad. Just reuse the existing gasket with lots of silicone in the front just below the distributor and you will be fine.

 

Yea, since your almost there(another 45min most)....Pull the hub, then I would remove all but the rear pan bolts and carefully pry the front of the pan down a little and remove the timing cover..with those kind of miles, and how loose LT1 timing chains have a tendency to get....I wouldn't be surprised if it skipped like you mentioned.....but even if it diddn't and it's not the immediate problem, I bet with those miles your chain is super loose and needs to be replaced anyway.....good luck with it .......joe

 

I pulled the cover and inspected the chain - not the problem. Timing marks on both sprockets line up, definatley did not jump a tooth. Only about 1/2 inch of chain slop, not bad for 230K miles. Starting to think its a bad coil, or opti etc.

 

Okay, so you have eliminated the chain, that's good.

I think with a stock engine the chain is okay, but start adding power and it becomes a liability.

It's probably the opti, you may as well replace it.

 

I just tore my car down...opened up the optispark and the screws that hold the rotor in place had backed themselves out. This is your problem, all you're gunna need to do is open up the opti and get those screws back in. Good luck

 

Update: I replaced the timing set, since I was in there. Original was ok, very little signs of wear or slack.

Bolted on a new opti, buttoned a few things up, and car started right up, runs great!

Opti disection didn't show any obvious problems. Suspect the a gremlin with the trigger wheel or optical pickup.

I've since thorughly cleaned the MAF, and have gotton 30MPG on my commute! Averaging about 68mph, very light throttle. Not bad for 230K miles!

 

So your chain was at 12 oclock TDC huh? So is mine, did you just pull it straight off and replace it the exact same way with the stock sprockets?