Mechanics

BUICK LESABRE ENGINE PROBLEM

1994 Buick Lesabre • 54,000 miles

Have had car 6 years no problem. Southern Car. Winter car for so it sits in summer. Gas tank got low this past summer. Then the problem started. Now intermittmently stalls out. The longer you drive it the more it stalls. Then finally can't keep it running for more than a minute or two. Cleaned MAF. Had Computer module replaced. Ignition module was eplaced. Before it stalls it runs fine
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Aajilon
October 30, 2012.




Scan for codes and check fue pressure first.

Hmac300
Oct 30, 2012.
The fuel pressure has been checked and was told it is okay. Given off different codes for computer module which was replaced, MAF which was cleaned. Or no code at all.

Tiny
Aajilon
Oct 30, 2012.
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.

Hmac300
Oct 30, 2012.
I will check on the fuel pressure psi. I do not believe that the cranks sensor has been looked at nor the throttle plate. Thank you.

Tiny
Aajilon
Oct 30, 2012.
Also have the resistance checked in crank sensor as they can have to much resistance and fail when hot.

Hmac300
Oct 30, 2012.
Thank you. That might explain why the car stalls more often the longer I drive it. Will definitely have that checked.

The fuel pressure is in the 40s

Tiny
Aajilon
Oct 30, 2012.
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.

Caradiodoc
Oct 31, 2012.
Thanks for all the suggestions. My Buick is now fixed. Ended up taking it to a Buick Dealership after my local mechanic had the car for over 3 weeks with no diagnosis. Well it turned it turned out to be the computer module. The part which I asked the local mechanic to make sure was good and he did not. Cost me a chunk of change because he did not do one simple thing. Check to see if the part was good.I am going back to them today to request a refund! The Buick dealership had my car in and out in about a 1/2 day!

Tiny
Aajilon
Nov 5, 2012.
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.

Caradiodoc
Nov 6, 2012.
Thanks for your reply but you are dead wrong on this one!
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Tiny
Aajilon
Nov 6, 2012.

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