Timing Problems

I have a 1990 Camaro Iroc-z with a 350TPI motor. Ever Since I tore the motor down and rebuilt it, i can't get the computer to quit taking over the timing and making it retard. Can anyone give me some ideas on what to look for or how to fix this. Thanks

Jess

How big of a timing retard are we talking about here? Really big and in the system couldnt possibly be working right...or normal, slight retard.
I know this sounds like a dumb Q, but did change the timing chain and tensioner?
Any trouble codes?

We did change the timing chain. The tensioner is the same. When we first fired up the motor it retarded the timing along with a couple of eingine codes. A new knock sensor seemed to fix all of that. Now when your driving it and you get on it you can feel the car get into it then back off so I'm assuming that it is the computer taking over the timing, not sure what else it could be.

Have you changed the air and fuel filters? Mabe it is being starved by one of the two.

and check to see if there i any new codes.

The fuel filter was replaced a couple of months ago as for the air filters they are probably a little dirty but not bad. If the motor was starved for air, would that cause it?

it could, just take the air filter out just to see if that is it, DO NOT RUN IT LIKE THIS. Just take it out and start it up and see if it is still doing it.

Have you checked to be shure the base timing is correct?
Any play in distributor shaft?

I haven't noticed any play in the distributor. I have jst replaced the cap and rotor though, thought that might have played a part in it. What do you mean by base timing?

When you adjust the timing(need timing light) that is the base timing, then the computer makes changes as necessary.

Got ya. The base timing is correct. I have it set about 8 degrees advanced.

And you are shure the problem isnt something simple like air filter, vacuum leaks, spark plugs, or dirty injectors?

The plugs were just changed a couple of weeks ago. I ran some injector cleaner through the system a couple of weeks ago also. Any other suggestions.

Vacuum hoses, plug wires, or any trouble codes?

No trouble codes. I did have a wire burn on my headers so i had to replace it with a lesser quality wire. Haven't had the money to pick up a new one yet. I have ACCEL 8.0 on there right now and the one i had to replace is just a cheapy. As for the vacuum hoses, i think everything is good there.

Have you had your tranny serviced? (should be done every 10-12k mi anyway)
Have you noticed anything else since you rebuilt the engine? It doesnt need to seem related...like running hot, hard start when hot or cold, gas consumption,...

The tranny was serviced about 8K miles ago. I just remembered there is a ticking under the hood. You can hear it more on acceleration. What do ya think?

could be a lifter,or roler.

What is the easiest way to determine that it might be a lifter or roller.

I would check for exhaust leaks first.
Probably an exhaust leak at one or both of the donuts because you probably would have knoticed a leaky exhaust manifold. Did you change the engine mounts when you did the rebuild? When the rubber in the mounts breaks down, it allows the engine to move more and that causes the donuts to get chewed up. But if the donuts are the origionals, then you could probably get away with just changing them, but you should really change the mounts first so the donuts last longer...it will also reduce how much you car vibrates.

start the engine up, and listen next to the valve cover and see if the noise is comming fromt here, or you can take the valve cover off and start it up and see if you can here it, or you may be able to see the lifter not lifting right.

ya, could very well be an exhaust leak. I would check that first.

Or mabe just not proberly tightened

When we rebuilt the motor I had planned on changing the motor mounts but the way they are mounted to the frame it is next to impossible to change so i left them alone. They weren't too bad but they weren't great either. What do you mean by donut.

On the ticking sound, it seemed to start when i gave it a good tune up, distributor cap, rotor, plugs, plug wire(1), fuel filter.

Donuts are like a gasket between the exhaust maniforlds and the exhaust pipes.

That does give me an idea. I never rechecked the header flanges to the y pipe to make sure they were tight. I will add that to my list of things to check.

They are a pain in the ass but they can be changed. I changed mine, well one of them anyway. By the time I finished changing one of them, I was too tired to do the other one. It would have been a lot easier if the engine was out of the car at the time :grinyes: Il get the other one soon, and then Il have to change the donuts again because they got kind of chewed up since I replaced them long before I even thought about changing the engine mounts.

Sounds like i have a lot of fun to look forward to. Actually i think i am gonna wait. I am fixin to put a whole new flowmaster exhaust on. I can knock out two birds with one stone. Thanks for the help

No prob.:)
Keep me posted

Quick Question...Is it possible to completly remove the computer from a 90 camaro?

Quick Question...Is it possible to completly remove the computer from a 90 camaro?

I suppose it is, but you would have to change your car to a carb(no more fuel inj.), and you would loose MPG and probably power to (depending on the carb you put on) and you would never be able to pass emissions inspections.
And you would have to change the fuel pump too(I think)
I dont think it would be worth it. Cheaper to find out what is wrong with your system in both the longrun(and the short...lol) :nono:

I don't mind trying to find the problem but i just get sick of having to kiss the computers ass sometimes to get everything to function properly. Not sure if that's makes sense.

Oh yes!!!
Makes perfect sense, beleave me :grinyes:
Sometimes they seem like more trouble then they are worth, but they are there for a reason...Dont worry, you will find the problem, it may just take a little time :)

Thanks again!!