OK, I've here I am again. Thanks to all who have helped me before, I have done major work on my baby. Please be kind when answering I am not a techi and just got done basically rebuilding the top of my car to the tune of over 6K. Now am baffled and so is my mechanic.

Have replaced the ECM, Heads, plugs, wires, thermostat, distributor, water pump, oil pressure switch, and more I just can't recall right now, oh the starter is fairly new, new coil....

Thought it was water related but now not sure.

A couple times now car turns but wont' start, only for a few turns, then starts no problem, runs great, and starts after several times. does seem to be more when on the cooler side. But then again, on way to work on tuesday it just shut off on me while driving. Pulled over, car started right up and drove fine since. No rhyme or reason.

Runs like a champ otherwise, should after all this money.

Then when I got it back after the work, Heater vents are not working in dash, although heater is working, and found water on my floor on drivers side (after a big rain), not passenger side.

Never had these issues before, have had my car for 8 years.

At first thought water might be getting under hood to ECM, but then if it were that, it wouldn't run again until the car dried out, right? As we just had a hard rain the day before this happened.

Any thoughts on the shutting off/no start issues? That is the biggest one. As i mentioned, runs great, no spitting, backfiring, sputtering etc., just literally shuts off.

Thanks

 

May be a long shot but, have you checked the VATS? Water comment on the floor drivers side prompts the question. This would be for the shutting off/no start issues. Did you have the dash apart at any time? You may have a disconnected actuator behind there preventing the vents from working properly. Hope these ideas help, Good luck.

 

c92 vette

Thanks. I've heard of the VATS on other forums, what is the full verbiage for the abbreviation? Even a long shot is worth it now.

I haven't had the dash out. The heater vents not working is no air blowing when fan on. Not sure if anything under the hood by the wall needs to be disconnected for a head job?

 

VATS is Vehicle Anti Theft System. Lots of info on VATS here:

http://www.vatssucks.com

VATS is only a factor at startup. The ECM remembers that VATS was OK at startup and never looks at it again.

There is a federal law that requires that the A/C system default to heater mode. If you are not getting vacuum to the A/C system controller then it will be stuck in heater mode. There is a vacuum line that goes from the back of the plenum (passenger side, right above the fuel pressure regulator), around the front of the distributor to the vacuum check valve (on the driver's side of the distributor). From there it splits and one vacuum hose goes to the cruise control and vacuum tank. The other side goes into the cockpit to the A/C controller, which controls the various A/C mode doors, etc. One way to check to see if this vacuum connection is partially intact is to see if the cruise control works. If it does then you know that the vacuum is at least getting to the vacuum check valve.

 

Thank you Cliff for the response and link :-)

Now just need to tackle it shutting off by itself...

Anyone.....

Could there be a wire or other electronic component causing this intermittent problem? It truly can go a week without doing it, then one day I'm on the freeway and it turns off. Might happen more than once in week or just once in a month, like I mentioned, no reasoning I have noticed connected to this issue...

Tammy

 

It's hard to diagnose an intermittent problem when it is not occurring. When the car will not start, the first thing I would do is to determine if it is a spark or fuel delivery issue. Spray a small sniff of ether into the intake while cranking, if the car tries to start, your problem is fuel. If nothing happens, ground a spark plug wire while cranking to see if it sparks. Once you know the basic issue, you can pursue specifics.

 

Was the ICM replaced, it will act that way if the grease has dried up.

 

My thoughts exactly sounds like the ICM (ignition control module) might be bad. It is basically a solid state amplifier and can be affected by heat when it starts acting up.

FYI - the ECM drives the ICM (with a small signal), and then the ICM amplifiers it and drives the coil (with a large signal). If the ICM fails, the coil does not get driven hence no spark to the opti cap.

In this situation I would not be looking at the opti. You are not losing any coolant from the water pump are you?

As for the vent problem, check the 3 way check valve under the right side plastic cover on the engine. There are 3 hoses going to a black unit (valve). See if it is cracked, broken or falling apart. That will directly affect you vents in the car.

 

I replaced the ECM (main computer) Brand new this month

Not losing any coolant, new water pump and basically cooling system in general

Thanks for the tips on the vents :-)

So.... It it is the ICM would/could it be so intermittent like this?

Thanks guys, truly, thanks a lot!!

 

Having said what I stated was my best educated opinion. But the right thing to do and if you ever can catch the problem when it is happening is to measure fuel pressure and check for spark. Then you would have all bases covered for a starting point and a higher confidence level.

But you can only do what you can do if the problem is that intermittent. Then you take your best shot.

 

The car not starting acts like a spark issue, however all plugs, wires, heads, coil, distributor are new, newer starter, and these things other than the coil wouldn't cause the car to randomly turn off on me I don't think, unless there is a relative wire somewhere that can cause interfearnace if not connected properly?

If the ICM can also cause the car to die when driving then I am leaning to that.

The biggest issue, as yes it not starting is annoying is it dying on the freeway, like I just shut the ignition while going 80.

The not starting is for a minute, random, not like I have to sit there, pump the gas or anything as when it fires up it acts like "what's your problem, lets go".

I almost thought it was my iginition switch not readig my key chip (even bought a new key), or maybe it's loose in there casuing it to shut the car off if it glitches to not read the chip while driving? I have no idea how that works.

The not starting and shutting must be related. So if you all believe the ICM will do that next :-)

8 years and no real problems with my car until this recenetly.

Ugh....... And thanks a bunch.

 

Shot in the dark... but any time I have an intermittent issue such as this, I start looking for a loose ground wire.
You've had a bunch of work done, and it is quite possible that a ground wire was forgotten and not tightened properly.

Worth a shot.

 

From the description, it sounds like your icm is going funky.
(that is if you have a year/make in the mid-late 80s that's using
the HEI distributor with the ecm under the rotor)
It's supposed to be a reliable part, but it's not uncommon to
get your hands on a defective one. (which I've been plagued with).
It can give you all sorts of grief and going alone by your description
is what that's telling me.
When they're installed, a "heat sink" compound has to be used
to prevent heat damage from the engine.
I think one of the most common mistakes made
is installing one with a dielectric compound instead of a heat sink compound.
A new one usually comes with a small pack of compound for that purpose,
but there are times I wonder of its efficacy since it more resembles vasaline jelly.
(there is a big difference especially when dealing with heat sensitive components).
When it starts getting affected by heat, it starts acting unpredictably.
The next time I replace an icm, I'm going to use a heat sink compound
commonly used in computer equipment.

 

A bad icm will cause your car to quit at any speed and also cause a no start.