Have had car 6 years no problem

Scan for codes and check fue pressure first.

Check cranks sensor and connections then, what were the codes? Fuel pressure should be 41-47 psi at idle. If below that it's a pump. Clean throttle plate on both sides and iac hole as well.

Also have the resistance checked in crank sensor as they can have to much resistance and fail when hot.

Hi guys. Excuse me for butting in; I was just passing through. Don't overlook a plugged pickup sock in the gas tank. They can collapse and block fuel flow, then stretch out again after the engine has been off a while. The main comment I wanted to share is with an intermittent problem like this, any testing, especially things like fuel pressure, has to be done while the problem is occurring, otherwise it's irrelevant.

You asked him to do something that is almost impossible to do, especially with intermittent problems. When the engine is running, there is no defect to be found so no matter where or how hard he checks, the computer is doing what it's supposed to do, ... Running the engine. Engine Computers really don't cause as much trouble as most people think. GM computers from the late '80s were the exception. Mechanics changed so many of them that that's the first thing many of them jump on today.

When you have a no-start condition, it's rarely caused by the computer but when it is, you know it as soon as you plug in a new one because the engine fires up. With intermittent problems that are hard to duplicate when you want them to act up, all we can do is try the most likely causes to eliminate them as suspects, THEN assume it's the computer after there's nothing else left. We have the same trouble with integrated circuits in tvs and vcrs, There is no way to test them. We have to check power supply voltages, grounds, input signals, and be sure the outputs aren't shorted. That takes a long time, but then we can make an educated guess that IC is bad if everything around it is good but it doesn't do what it is supposed to do.

The other problem with intermittent problems is you can never know it's fixed if it doesn't act up after you replaced or did something. If it acts up again, you know it's not fixed. But if it doesn't act up, is it fixed or it just hasn't acted up yet?

Don't be too hard on your mechanic. The only way he could have done what you requested would be to send your old computer to a rebuilder with very expensive test equipment dedicated to your specific computer, or he would have to have a known good used one on hand to plug in and try. As you can see, that still won't tell him definitively if the old one was bad.

What am I wrong about? If you mean testing your computer, I challenge you to find any test procedure or list of steps in any service manual for any brand of car. You requested something that can not be done. All you can do is test other things to eliminate everything but the computer. The people at the dealership only see certain brands and models and they're familiar with seeing the same failures and same causes over and over, so of course they're often going to know the fix sooner. They will also know that when a '90s model GM car has an intermittent problem it is often caused by the computer. I just got done having a conversation with someone who is angry because their mechanic said the problem WAS caused by the computer. The owner spent a pile of money on a rebuilt one and is having the same intermittent problem. What would YOU think of someone who didn't bother to do other tests to rule out other potential causes? No matter what we do, the customers get mad.

Ya but will they complain when a doctor screws up slightly like that, probably not. It's always been that way and will continue because mechanic are thought of as the next thing to dirt.

I just reread the original post. The problem started after he ran it low on gas, (which is a normal condition on any car), so he suspects the Engine Computer. Huh? Where did that logic come from? Then he says the computer was replaced. At least that's more detail than we're getting from many other people lately, but if he had the same problem before and after the computer was replaced, why would he suspect it again? Especially with all the different problems and symptoms they can cause, what's the chances of him getting the only two that will cause exactly the same problem?

There's no denying a third computer solved the problem, and I'm happy for that, but how do we know it's really solved? It's an intermittent problem and maybe it just hasn't acted up yet. We're all frustrated by intermittent problems because we rarely know for sure when they're solved.

I guess the moral of the story is don't run your car low on gas because it will damage the computer.