To shorten my typing, this is an e-mail I sent to a friend. For this to make sense you should know that this is a completely new 396 stroker that we are having trouble with. It is in a 95 Z-28, please help on this one guys. We spent 13 hours yesterday and the car still doesn't run.

"Give me fuel, give me fire, give me that which I desire...." or so the
Metallica song goes. Well we seem to have fuel and we have fire, we
just seem to be lacking what we desire.

We have had no luck whatsoever today. After we put the fire out things
looked a little better (another story). We finally got the starter
working, however the car wouldn't start. We decided that it was
possible to have fouled out the plugs, they had been sitting for a while
and the car was running way rich before. New plugs later we still have
no love, only to find out that it is flooding the crap out of the
engine. If we disconnected the injectors we were able to blow flames
out of the headers for several minutes until we burned up all the fuel.

We thought it might be his injectors, he got them used at a very good
price. After trying to track down somebody with a set of injectors we
finally just took the injectors off of my car. No love. Just for the
hell of it we put his injectors in my car. Technically it should flood
the crap out of my car and make it run rich, these are 36 pound
injectors when my computer is programmed for 24's. My car fired right
up and ran like a dream. Injectors aside we now decide it must be the
fuel pressure regulator, if it is stuck open it could be making it
flood. We were able to track one down from a friend. No love.

After everything we can only figure that it acts like the timing is
off. As tight as his stuff is it would have to be exactly 180 degrees
off for it to not beat the valves with the pistons, etc. Maybe, that's
our thought anyway. (note, he didn't actually put the cam in, the guy
at Scotty's did) The only other option is his Opti which has
all of 100 miles or less on it.

Any ideas? We have fuel and fire but they don't seem to be mixing well.

BTW, he has an Ed Wright program set up for his mods, he also has a stock program, same results on either.

 

Is the Opti installed properly? I installed mine on the 95 one tooth off and the car would just backfire and not start at all. Not sure if the early opti can be put on wrong.

 

came could be exactly as you guessed, 180 degrees out of time, if the installer though both dots were supposed to face down this is what is happening. other things to check, might be opti out of aline, or forced on in an improper position, also, are the injectors wired in correctly although i doubt this would mtter much, if they are firing you will have fuel. is the spark happening at the right time? have a timing light? try removing the number one valve cover and spinning the engine with the timing light on the number one plug wire, you will be able to see if the spark is coming after the intake valve or the exhaust, this will help in identifying if cam is out of degree as previously mentioned.
(sorry this is an addition, this will not work with the opti as the opti is cam driven and factory preset, i would bet the cam is in wrong though, if all else works but no run.)

have you followed the troubleshooting flow chart in the shop manual? and tested all other sensors, although if one was out it should default to limp home mode and set a code yet still run rich. hmm, i would check timing asi described and ensure plug wires are in their perspective positions, i criss crossed two and it shot flames through the headers upon my first start up attempt, a few minutes later after retracing my routing found the problem and vroom she fired right upperhaps also try closing the gap on the plugs, if the compression is really high, it may be related, mine ran terrible with the gap at factory and continuously fouled plugs, i closed the gap to .039 and have gotten rid of the problem. what did you adjust the rockers at past zero lash? could be collapsed lifters, check all grounds for good coneections and check for voltage drop between wires. this will take some time but will lead you closer to the problem. i wish you the best of luck and post as you find the problem or run accross other tell tale symptoms that might help us to think of ideas to trouble shoot it.

you'll get it, these things happen1

chris :smash:


[Modified by ncChris, 8:59 AM 10/14/2001]

 

If we disconnected the injectors we were able to blow flames
out of the headers for several minutes until we burned up all the fuel.


Are you saying that when you diconnected the injectors the motor did run?
If so that would eliminate your timing & optispark issues.
I guess it would also point to whatever sends the signal to the injectors.
Just guessing goodluck.

 

No, it doesn't run. It just fires enough to blow flames. That's another thing that makes me think the timing is wrong. Wouldn't it have to fire with a valve open in order for that to happen???? It would seem that if the valves were closed it would actually fire the cylinder and kick it around a little faster, if it runs or not.

 

Check your timing like a normal car with timing lite...if you can...but I have heard the opti can be 180* out....just like a normal distrib....

GENE

 

Yes fire out the exhaust would indicate late timing or improper cam installation.Also you could have the plug wires mixed,but I think you guys have checked that.
I wonder ...If the cam is in 180 off ,can you make the spark 180 off by changing the plug wires to 180 off? That would be a test.

 

If the cam was installed with the dots lined up correctly, the cam is fine. The dots line up at two positions when the cam is installed correctly. One position is when the cam dot is at 6 oclock and the crank gear dot is at the 12 oclock position. The other position is when both dots are at the 12 oclock position.

The vented opti has two slots that the cam pin goes into. One is #6 which should not be used and the other is #1 which is the one you want the pin to be in. The actual position of the engine does not matter with an opti like it does with the old distributors. Make sure the plug wires are going to the correct plugs and you should be ready to go.

Before you start the car again, leave the injector rail out of the intake with the injectors installed and let the system pressurize by turning the key to start several times. Check for any fuel leaks and leaking injectors.

Put the fuel rail back in and crank over the motor. It should start. Be sure your valves are adjusted correctly also.

 

aqua,
if the opti isn't timed by the cam, what is it timed by? only 96 cars have the crank position sensor, so if not the cam then what? how does it know when to fire? and to what cylinder? i think the opti must be on the correct rotation and on the correct pin, if it fit perfectly on another pin it would be out of whack exactly like a distributor on a Gen I. am i wrong? thus if the cam is out of time, so also is the opti and they will fire in conjunction with each other but at an incorrect time of crank turn ie.. might fire at 6* before BDC which is in fact what i would guess the problem is if the rest of the checks come back with now probable cause for not starting. just a thought.

chris :cheers:

 

Your right. The opti is driven and timed by the cam.

If you look on the back of the vented opti, there are two slots on the rotor hub. One is marked with a triangle and that is the one to use. The other may have a 6 on it but I cant remember. The pin in the cam that goes through the timing gear slips into either one of the two slots. The slot with the triange is the one to use. I have no idea why GM put two slots on the opti rotor.

If the cam is installed out of phase so that the dots on the gears don't line up, the whole timing will be off. I am reasonably sure that the motor and cam were put together correctly. It sounds like wrong rotor slot was used when the distributor was installed.

 

TTT!!!!!!!!!!!!!

Alright guys this one just got a lot better. He got a new opti, no love. He pulled the timing chain cover and it is perfectly in time. We have a serious WTF situation going on and we need all the help we can get.

We have fuel, we have fire, we just apparently don't have it at the right time. It still sounds like a timing issue, but WHERE??? He has two computers, neither one works.

BTW, I think it's a timing issue because it blows flames out of the headers once the injectors have been disconnected, this would make me assume that it has to be firing with the exhaust valve open.

 

TTT

 

make sure that the timing gears are installed correctly....

This sounds stupid, but is the harness for the injectors correct? What would happen if the left injectors fire when the right ones should?

 

The timing gears only go on one way. Unfortunately it's not so simple as the injectors being mis-wired, they are labeled with the cylinder number. We have 2 4 6 8 on the passenger side, 1 3 5 7 on the driver's side.

Thanks for the thoughts though. It may be something silly that we have overlooked. Kepp chucking ideas at us, someone might stumble onto something we haven't checked.

 

Are you sure that the distributor shaft is going on the cam correctly ?
Make sure your valves are adjust correctly too.

The number one cylinder is in firing position when the cam gear alignment dot is at 12 oclock and the crankshaft gear alignment dot is at 12 oclock. Be sure you get the hub installed correctly so that the arrow inside the harmonic balancer is pointing up at #1 TDC. Put a small line on the balancer as reference too.

 

If you're getting fire out of the exhaust, it has to be either cam/crank timing or ignition timing. It sounds like it's firing a little BTDC on the exhaust stroke. So either the engine is in time and the spark is firing 180 out or the spark is firing but your crank/cam timing is 180 out...or some variable of the two.

I know you're frustrated, but its gotta be! (I think).

 

Recheck the plug wires and make sure they are installed on the right plugs on both ends. I mismatched one once and it kicked my *** trying to figure it out. I thought it was the clutch and r&r'd that bastard 3 times before I realized what my mistake was. I felt like an idiot when I found it, but then again, I found it.

 

I had the same problem. I have a 86' with a 90' 383 in it, and the first time the engine builder gave me the engine back it did the same thing. It would fire on a cylinder and then the next one and so on. It would run in the vages sence of the word never really idling just poping enough to let you know that the timing was wrong. But the timing was right. The cam was installed right. Everything was right. It got to he point were the injectors were washing down the cylinder walls and things were getting tight. I thought the motor was seised. I took the whole motor out and gave him everything so he could check all the last details. What he came up with was the cam was too big for a computor controled car. Belive it or not, I told him that in the beginning. I followed the forum and knew what combinations worked with the 383, so when he gave me the grind card on the cam I said this is a little big. Well it turns out it was a lot big and center of all the problems with the engine. He changed the cam, freshed the cylinders and now the motor runs good.
Good luck, Joe :yesnod:

 

you could have pinched the injector wiring harness or other wire which could short out the injector return path...therefore bypassing the computer for turning on the injectors. Or the computer could have gone south...among other things.

An easy way to check...get a noid light ( a small light that is designed to plug into the injector harness in place of the injector to provide visual indication of signal ), see how it lights up when you crank the engine...it should cycle on and off...if it stays on...thats the problem. You can get the lights from any tool truck ( Snap-On, Matco, etc...) or sometimes you find them at auto parts stores.

 

I dont know much about the opti but what I have seen is that you cant put it on but one way, the one I but on a LT1 would not go on but one way (I maybe wrong) and that it reads the cam, so it is hard to think that it can be the timing is off, even if you have the cam in wrong way because if you have it off one tooth it will just advance or retard the cam about 6 to 8 degress and that is not to much but the opti will still look at the cam to see when to fire, but the only thing you have to look for when you do that is if the valves are hitting the piston, I dont know what kind cam you have or how much clearance you have and then the intake valve would most likely be the one that is bent, but if you have a exhaust valve that is bent then you will most likely get fire out of the exhaust system and it will not run right because it will not have any compression to burn the fule.
I would look it to that because the opti looks at the cam to see when to fire so it is hard to see it being off that much, I think I would do a compression test and to check when the cam is opening but you have to have a degree wheel to do that, and see if it is about the same as the cam card.

this is just my 2 cents

Jay