misfire???????

Question

i have a 98 c1500 with the vortec 4.3 v6. my check engine light just came on today while i was cruising down the highway. i took it to autozone and used their scanner... it told me it was a random multiple cylender misfire. the truck dosnt have a rough idle and the mid rpms are good the engine dosnt shake or anything so i thought maybe it was just the plugs loaded up... i know it really couldnt be that but it gave me an excuse to beat it. so i got on it in first and took it almost all the way up, when it hit 4 grand it made a loud backfire and blew a ton of black smoke but ran perfectly fine afterwards and the check engine light is still on.. i have not a clue whats goin on i replaced damn near the whole ignition system about 3 months ago... ac delco professional platnum plugs, autolite wires, new cap, new rotor, ignition coil, ignition moduole, crank position sensor, and i put a k&n air filter on it. any help on this situation would be greatly appreciated thank you. keith

Martin Riddle · Accepted Answer

Try putting the old Ignition module back in. I never had any luck with after market ones, its worth a shot. Remove the K&N filter too. Replace one at a time tho to see which one it is.

BTW its possible to get lean miss-fire, if the mixture is too lean. (read: free flowing intake)

Cheers

Eightupman · Answer

I hate replacement platinum tipped plugs.  They foul too easy on the older motors...UNLESS it is factory and the ignition system is tuned to have them.

Charles Bendig · Answer

I dis-like Platinum tipped spark plugs. I dis-like Bosch spark plugs also. I use 4 brands of spark plugs: AC-Delco, Autolite, Accel & Champion.

AC-Delco's for MOST Stock GM Vehicals. Autolite's in Fords. Accel & Champions in Modified Vehicals.

If a car came from the maker with platinum or platinum tipped spark plugs, I replace them with standard core & tipped spark plugs. I do aviod the screw on terminal cap spark plugs. Charles

misfire???????

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