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Dave Nova
Dave Nova, Oldsmobile Tech
Category: Oldsmobile
Satisfied Customers: 597
Experience:  ASE Master Certification. GM World Class Certification
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Have a 1989 Olds Cutlass supreme 3.1 L. Motor and having a

Customer Question

Have a 1989 Olds Cutlass supreme 3.1 L. Motor and having a huge surge problem RPM's racing up and down. Dies cant stay running.
Replaced Spark Plug Wires and Plugs, New Fuel Filter, New Air Filter,
What can this be. Engine pops on a little then it goes away.
Submitted: 1 year ago.
Category: Oldsmobile
Customer: replied 1 year ago.
engine Light pop on then it goes off. but its not all the time.
Customer: replied 1 year ago.
it surges ever time you get it running
Customer: replied 1 year ago.
any body working on my Answer?
Expert:  Mike S. replied 1 year ago.

Sorry you have been waiting so long. 2 things that you have mentioned point toward a lean fuel mixture and possibly a vacuum leak. Before suspecting any intake manifold gaskets or anything else like that, you should check all of the vacuum hoses and make sure none fell off, or otherwise leaking. Also, if any work was just done prior to this problem double-check the vacuum hose routing.

Expert:  Mike S. replied 1 year ago.

Lean fuel mixtures will cause the engine to pop or backfire back out the intake because when the cool air hits the unburned gas it explodes when the intake valve is still open. This can be caused by a vacuum leak and too much air entering the intake manifold throwing off the fuel mixture.

Expert:  Mike S. replied 1 year ago.

have you pinpointed the vacuum leak?