Gos2Slo

Hey guys, I finally gave up on my thread on my car's hard starting problem here but have come up with another good possibility:

Since the car is very hard to start, coughs and stumbles as it starts, and is down on power, could the timing chain have jumped a tooth? It certainly feels like the timing is WAY retarded.

It has spark and fuel, I've verified both a dozen times now. New coil, ICM, plugs and wires, and the Opti is sending a signal to the ICM.

I just dropped it off at a local mechanics shop with a lengthy explanation, but I have some questions:

1) How does timing chain jump a tooth? I mean, what causes it?
2) What would the symptoms be?
3) Is this common on a 51K mile motor?
4) Assuming the job is pretty involved, and the timing set needs replacing, what are my options?
5) I'm on a tight budget, but should I put in a bigger cam while I'm in there? If so, which one?
6) What new timing set should I use?

The water pump is new so I know that doesn't need replacing, and if I had some extra dough I'd swap out the Opti while I was in there just to be safe, but I don't think I can afford it (especially since I think it's still good.

Can the Opti be "checked over" while it's out of the car to see if it needs to be replaced?

Thanks for any help guys, sorry for all the questions.

Gos2Slo

Anybody? Shoebox or Injuneer?

grendal

I've never heard of "skipping a tooth" on a timing chain. I suggest having evidence of this being the problem before paying someone big bucks to "fix' it.

-Michael

shoebox

Skipping a tooth is not very common. If your fuel pressure is good at all times and after reading what you have replaced, I might suspect the opti. Electrical things can happen no matter how many miles are on the car. Every electrical connection in the ignition system should be carefully checked over.

If you are on a tight budget, I don't see how you could be thinking about a cam. Too many other things to buy that need to go with it. Stock replacement parts would get you by for now.

The opti can be taken apart to look for obvious problems, but if nothing obvious is seen, does not prove it's good. It's even possible that there is a problem with the cap and rotor.

Some scan data/logs would help in diagnosis.

Gos2Slo

Yeah, I'm more old school so I'm used to cam swaps being fairly inexpensive. Whew! I did some more research and priced out the parts, I think I'll hold off on that idea until I get a big commission check!

Anyway, sad to say, I'm actually glad to hear it MIGHT be the Opti now (comparitively speaking at least) but am concerned as to why or how it could be dying at 51,000 miles. Could my MSD have wiped it out when it killed my coil 6 weeks ago?

Now that I think about it, the car did hit the MSD rev limiter when the car died that day, maybe it killed the Opti instead of the coil this time?

I dunno, is it possible a dying Opti would cause a huge power loss, make it hard to start, but otherwise run pretty smoothly (and throw no codes?)

Gos2Slo

TTT

grendal

Many people say the MSD (and other) multi-spark boxes actually cause premature failure of Optis. Also, they can go bad just from moisture or age...

Friend of mine had a '95 Corvette LT1 and it needed a new opti at under 35,000 miles. Others have gone over 120,000 on the original. It's luck of the draw I guess.

-Michael

Gos2Slo

Interesting, so a dying Opti would cause all the symtopms above then? I just bought this from a dealer about 10 weeks ago, and have already had to replace the water pump. If the Opti needs replacing I'm gonna place a nasty call to the dealer who sold it to me.

atljar

The timing didnt jump. I would bet my car on it. I would point fingers to opti too. I bet it got all wet when you changed out that water pump didnt it

Gos2Slo

Just got off the phone with the mechanic, he plugged the car into the scanner and found the O2's are shot, and the car is running really lean. He said the car "sounds funny" like the exhaust is choked or something.

He recommended changing out all 4 O2 sensors, and if it still has problems he said it MIGHT be the Opti. He's testing the ignition system now to see if the coil and ICM are getting good signal.

He's also not charging me anything, nice eh?

Could I have a clogged cat? It would certainly explain the difficulty starting and lack of power, (like a potato up the tailpie) but how would I get this tested?

How does this sound so far?

Gos2Slo

God, drove it home from the shop, I can't give it more than about 1/8 throttle or it falls on it's face and tries to stall. I'll start a new thread about exhaust replacement options, but is there anything else I should check that would cause this?

I'll replace the O2 sensors this week and maybe unbolt the muffler, just to see if it was the stock muffler that blew a baffle or something. The car is VERY very quiet when it's running, even for a stock car.