Oldsmobile/Buick: miss, intake manifold gasket, olds cutlass


Question
I have a 1993 olds cutlass cieara that has a miss at times. I have replaced the fuel filter which was stopped up pretty bad. I did a tune up last fall plugs,wires,filters. This car is used to carry the mail with a lot of idling on the route. The car is a automatic and I cannot here a plug breaking down and I pulled the front three and they were all chalked. I hear no miss with throtle up seems smooth. The idle seems low since its an automatic is the only thing that catched my attention. I don't smell sulfer, no gas smell,
does not miss when put in gear or pulling a hill.
Was driven 300 miles over the weekend and only noticed two slite misses. Really misses when on the route bucks and carries on doesn't die, but really acts up.  

Answer
Hi Gilbert,
There are so many factors that can contribute to your problem. Diagnosing over the internet exactly would be difficult. However, one of the major problems contributing is the condition of your spark plugs, and that helps greatly. Here's what to check. If chalked white, this is a sign that the spark plug is not in the correct heat range. The plug is too hot. Check to make sure you have the proper range plugs for the car and that the gap is set correctly using a quality gapping tool. Second, check the ignition timing, it may be over advanced. Third, lean fuel mixture. You will need the proper equipment to set, so taking to a shop is a must. Fourth, possible small vacuum leak in the intake manifold gasket. Fifth, Sticking valves. Sixth, insufficient engine cooling. These are the areas I'd check. I'd elliminate starting with the plugs and timing, and check the fuel mixture. If that doesn't cure and the car isn't overheating you'll know the the problem is mechanical. Rebuilding the head(s) can be done but is very expensive. If your car has nearly 100,000mi. or over, from a cost standpoint and other headaches arising, I'd replace or rebuild the entire motor. You'll have too spend the money if you plan on keeping the car anyway, and prepare to spend a couple of thousand. My friend use to have a car he used on a paper route. A large amount of delivery work puts a lot of stress on the internal engine parts. Constant idling, stop & go is what killed off his car car. Hope this helps! Ray