Car was starting before I replaced water pump on 1992 LT-1. I was very careful to not get the Opti wet. Everything is back together now and it won't start. It has spark since it belched a flame from the throttle body. New injectors, FPR, plugs and MAP. It was suffering from a rich condition before the pump was replaced. Plugs were fouled and the carbon deposits were from this condition. Where to start to look for problem now? I have a new OPti sitting here and I can install it but I wanted to troubleshoot the no start problem first. Has anyone ever had a bad Opti cause a back fire such as this. The opinion I have read on the forums is that it just quits. Stored codes are H42 and H64. I found a bad plug wire while changing the plugs and I am waiting on a new set to arrive. I tried to start it with the injector with no wire to the plug disconnected. Not the smartest thing I guess but every V8 I have had will start and run on 7 cylinders. In the starting sequence, the coolant sensor is involved to some degree and it is new so I would like to rule it out as suspicious. Is there a way to ohm it out? Sorry this is so long but I am puzzled...Thanks!

Welcome aboard!!!

The temp sensor has little effect on the starting process.

As long as the oil and coolant are within about 10F, at cold start, the ECM considers things ok. I have read that on other forums, but haven't found supporting evidence in the FSM, so I need to confirm.

The engine should start with just about every sensor unplugged, because in closed loop, no sensor, except the TPS and IAC, are being used. O2, knock, you name it, unplug it. The computer is running the engine off of tables, not inputs.

Fire out the intake smells like timing, so I assume the opti is plugged in? I know, duh...

Most odd... my experience says even a bad opti will start... and since you never removed the unit, it should be ok. And the Gen 1 opti is impossible to install wrong - spline drive, goes only 1 way. Gen 2 opti, screwed up key way, can go on wrong... ask me how I know. grrr...

I agree, pull one bad wire and the engine should start.

Make sure the coil harness is good. They can get icky over time.

How many miles? Any mods? Which plugs did you go with?

Welcome to the site!

Sounds like 1) the Opti is put on wrong (not aligned correctly) or 2) plug wires are crossed.

http://ltxtech.com/forums/showthread. ... 620d37a390dedc9d014418fc5

it would have to be wires... the first gen opti is all but impossible to misalign. It would take effort and a hammer to get past the spline drive with the gap in it.

Well...anything is possible! I would check wires first. Could also be an internal problem with the opti cap/rotor, no?

wires, yes... opti failure? sure...

When I installed my opti with the timing off that's exactly what happened

ok... for the last time...

the Gen 1 opti uses an indexed spline drive.

the gen 2 opti uses a key drive.

The gen 1 opti CANNOT BE INSTALLED WRONG. It just can't be done.

End of discussion. Unless his car has been upgraded to Gen 2 specs, it's it and that's that.

Quote:

seen it done Bogus
the man got impatient and broke the drive in the process

Quote:

I read it has happened when people used the bolts to draw the opti to the engine block.

Anything is possible

I stated above you had to break shit to do it, and in that case, the engine ain't gonna run. It would also be rather obvious.

The Gen 1 shaft is longer than the screws... I dare you to do it.

This is one of those cases where you all will just have to take my word... Having owned my 92 for 13 years, I have seen (and done) pretty much all there is with that damned ignition system. I swear, I have a masters in Opti... ugh. And then there are always the "I have seen it done" tales, and Brian - I bet that opti was seriously messed up to force it on wrong.

The gen 2 opti uses a keyed drive, and it's REAL easy to get wrong - I did it! And it took me a week of tinkering to confirm I did it. the opti looked flush, but it sure wasn't... the chassis on the opti was off just enough - about a business card thick worth of off.

But that meant the key drive - more accurately, a pin drive - was not in the right hole.

There are three holes in the engine side drive shaft.

There are three machined out voids on the same shaft end.

The pin will fit into only 1 hole - the correct one. It will not fit in the other two holes. But the damned thing WILL fit in the God forsaken voids. Five shots at getting wrong, one shot at getting it right. I know my historic odds.

I will have to post pics.

It's not going to run even if it puts out a spark.

The timing is off

hence the backfire

yea, duh... but you are missing my point... for it to back fire out the intake means it did get a spark, but at the wrong time...

I think the two of us are missing the point

Did the OP ever get this car running?

it's all apart now... check his other thread...

Thanks for all the input gentlemen! Glad to have you all as resources! Got the opti in today. Not really all that difficult. New plugs and wires installed and such. Cleaned all the gunk out around the area since I had the chance. Water pump is ready to go in. I had a person tell me to go ahead and start the car without the pump in so I can determine that the car is running. Is this a good idea? Seems like it should be okay, but I am looking at the open coolant ports on the block right above the opti and that makes me a little nervous. Thought I would throw that out there. Another thing I saw on a thread was that there are O-rings at the front and the back of the water pump coupler. I did not see any sign of O-rings when I removed the pump. Are there supposed to be O-rings there? Doesn't seem like they would do much of anything but I am known to be wrong. Any and all advice is appreciated. Thanks again!

Orings? I can't recall orings.... anyone eles remember orings?

As for starting without the pump, perfectly fine. You have 45 seconds to 1 minute before things could scare scary.

Yep, 2 O-rings. Check your FSM.

oh, I believe you... just don't recall them... I guess mine have either always been there, or never there... take your pick!

Yes, I managed to get one stuck in my camshaft

that sucks... I am sure mine are present and accounted for... I just don't remember them...

I don't have leaks, so that's a good thing, right?

Up and running great! The O-rings are there. One was on the new pump already and the one on the shaft is a hard plastic guide. It is there to hold the coupler I guess.

yay!!!