hi I have a problem with my 99 chevy blazer.runs terrible check engine light on had it checked maf was one code cleanded it no better also showing misfire number 5 cylinder. need help

 

How many miles on the engine?
Have you replaced the spark plugs? (AC Delco 41-993)
Have you replaced the distributor cap & rotor? (AC Delco)
Have you replaced the spark plug wires with a good quality brand? (not a store brand, Duralast etc)

 

no I was told that if you replase the cap it breaks the dist.no I have replaced the plugs or wires yet I have a set of accel wires and need to get plugs and cap rotor

 

also check engine light still on and also sometimes flashes and goes off and back on

 

The screws that hold the cap on have thread locker on the threads. Do not reuse the screws. Be careful when removing the old ones, and don't overtighten the new screws. As you're tightening the screws, check the cap for looseness. Stop tightening them when the cap is tight against the distributor. If you overtighten them, the plastic "ears" on the distributor can/will break off.

These engines are very fussy when it comes to tune up parts. Use AC Delco only for the plugs, cap & rotor. The Accel wires should be ok.

 

Just want to second the warning on those plastic ears that the distributor cap hold-down screws go into. The good news is that replacement distributors with aluminum housing instead of plastic are only about $50...not the easiest part to change-out...but not to bad. Just need to replace the distributor cap and rotor that come with the new distributor with GM/Delco parts.
Also put dielectric grease on the terminals....delays the corrosion of the contacts.

 

say thanks for the info,

 

what about the checkengine light