[align=left]My 99 S10 Blazer has recently been running higher RPM's at 70 mph.....but not always.....it seems to happen after I have driven 20-30 miles on the freeway...it dosent act up at slower non freeway speeds......the problem appears most often when the trany down shifts to climb a hill or pass.....the engine will then run at higher RMP..with less power, it seems to be in OD but not firing on all cylinders ....sometimes the check engine light will blink then it will stay on........ the code was cylinder misfire......I did a complete tune up-plugs,wires,fuel filter,rotor button+cap &oil change....this did not solve the problem....where should I look next ????ignition module or coils ,trany, O2 sensors ,I just dont know.......FYI the cat convertor and the fuel pump have both been replaced within last year.

Thanks for help ...my bowtie buddies,
Ezekiel
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A misfire will not cause the engine to run at a higher RPM, that is all controlled by the transmission. Sounds like the transmission is just taking some time to lock the torque converter back up for whatever reason. Have you checked the transmission fluid level and condition? If so, what did you find (level, color, smell, etc)?

Other things that I would do as general maintenance items include cleaning the MAF sensor and EGR valve, and test the TPS sensor. Problems with any of these items can cause erratic shifting and/or general performance problems.

 

When the check engine light blinks you do have a misfire. what cylinder or cylinders where misfiring check them first... pull the spark plugs out inspect them, your running really rich so they will be soaked with fuel, then check the plug wires to see if they are cracked and arcing against anything around them, also check and see if you got a wire crossed somewhere.