I was negociating slow traffic and trying to beat out a green turning to yellow, so I floored it.

I was in 4th (manual) and the car sped up ok (I still say it's soft, I think 183k miles have caught up with something... valve seals, cam lobes... I donno which).

As I went through the intersection, I let off the gas and it backfired, then stuck at 2500 RPM for a moment until I prodded the throttle.

Backfires - the POP! in the title are timing related.

I am about sure as I can be that my intermitten failures are caused by a crap dynaspark. No codes... but I will confirm.

For the newbies, 1992 LT1/MN6, 183k miles, Dynaspark with LTCC (uses 8 GM LS2 coils for high voltage). Taylor wires, NGK plus (10k miles each), new NGK O2 sensors.

New Racetronix fuel pump and new WIX fuel fiter.

Thoughts?

Man even the good after market Opti offerings have issues.

GM should have tossed that idea out LONG before it made it into production. I mean seriously, is there an advantage to Opti over rear distributor?

technically, it is the most precice ever made, and the optical pickup is actually the good part, OEM... it's made by Mitsubishi and is known to last 250k miles in a conventional distributor.

I think that the dynaspark guy can't or isn't getting Mitsu sensors.

To think, GM had lost spark in 1992...

Did it backfire out the exhaust or sneeze through the intake?

Put an MSD on.

sneezed through the intake - good description, churchkey!

I have an entire 96 LT1 waiting to go in, I ain't buying jack for this motor. As soon as it is out, I am doing a leak down on it.

Quote:

My MSD failed as fast as my OEM.

They're hit or miss. Put on the cheapest known good part you can find.

Quote:

I thought you had an LS7 to put in?

Hell no. I have a brainstorming session thread, no engine... the LT1 is a stop gap until I can get enough parts to make a decision.

I'd find out why the throttle stuck 1st

Was it the IAC?

it was odd about the throttle. Maybe I imagined it was stuck, maybe it was. I have never had that happen, so perhaps the engine was holding revs in accordance to the gear it was in? I didn't try neutral or anything like that.

The IAC is a rather new part, GM at that. I have not had any issue with the car holding idle.

Quote:

That's why the raceshops put regular distributors in anything that has constant high revs.

The GM is junky compared to the MSD.

Probably a timing thing. Streched timing chain + according to conversation on CF the opti can be off a number of degrees internally. Being a standard shift the engine will go from load to no load instantly, cam & ignition timing will change instantly if the timing chain has stretched. It will probably happen again.

Since it sneezed (old biker & track racer term) suggest checking all vacuum hoses & caps on the intake as they tend to blow off when there is an explosion in the intake manifold.

GL

I will check the vacuum lines - again, great observation!

Stretched chain? Likely... the engine has 183k miles on it!

I am really going to need to get my act together and get this motor out. It's about done.

Speaking of Opti's...

Anyone use one of these?
http://www.ebay.com/itm/1995-1996-199 ... sh=item3a6bad337d&vxp=mtr

I'm sure this is a made in china type....
I bought one for our nova, to upgrade it to HEI, most the regular manufacturers make their economy distributors over seas anyway so I figured I'd try it.. works gread and it was only like $40... though with one of these there is quite a bit of labor envolved... but if your doing it yourself you may want to try one out and see how it works, I'm curious.. afterall it has a warranty... (which doesn't cover your time obviously.. )

-=Rick

Interesting...