93 running awful

bonniville is missing badly. Started with a low rmp high load miss a few months age. Repl plugs, wires, fuel filt, had a 42 code repl cam sensor lost the code but car runs the same. The other day girlfriend (its her car) says cars running bad. Yep not running on all 6. Its a 3.8. Pull plug wires and no spark from th 1,4 coil. replace coil and two plugs, car fires sounds like on six cyl but surging running rough. Go for test ride and feels like two clys are kicking in and out. Back in garage remove crank sensor plug and blow off with air and reconnect. Car runs much better for a couple of miles than back to poo poo. Sounds smooth till put in gear under load. Also coolant leak from area around front of manifold. Want to make it run good before tackling coolant leak. Any ideas? Crank sensor, module,mass air. Help! there is currantly no check engine lite showing amazingly enough.

Did you check coil resistance with ohmmeter.Also maybe the ICM is the problem.

Thanks for replying jdq, do you know the coil resistance values? ICM the module below the coils or the main computor? sorry if I am a little nieve. Have tried to not work on cars for as long as possible and are not to good with the fuel injection computor controled vehicles. Thanx

If you take your multimeter and put it on ohm,check the resistance putting tester to both pins on each coil , all 3 coils should be very close in range.EX mine are 1-4 / 5.76 ohm 2-5 / 5.79 ohm 3-6 5.80 ohm.ICM - ignition control module is what the coils attach to.I am not the pro there are many on here who know more than me and will chime in, this will get you started.Also coil packs are cheap at the wrecking yard if you need one ,I paid 35 bucks in canada.

secondary resistance should be 5k-8k ohms between the two spark plug wire posts. If you remove the coil from the module, resistance between the two female spade connectors should be .8-1.2 ohms.

bonniville is missing badly. Started with a low rmp high load miss a few months age....... Also coolant leak from area around front of manifold. Want to make it run good before tackling coolant leak. Any ideas? Crank sensor, module,mass air. Help! there is currantly no check engine lite showing amazingly enough.

As far as the miss, the latter of your post could also be the problem. It is possible that the upper plenum could be warped, or the upper intake gasket could be cracked or ruptured which is a problem with these motors. The upper plenum is the black plastic piece that sits on top of the motor, and has a water jacket that runs through it to pump heated engine coolant through the throttle body to get it to operating temperature. When the plenum warps, coolant can be sucked into the engine causing it to foul a spark plug or two. You said that it happens under a load, so I would guess that while at idle, the vacuum load is not enough to suck coolant into the lower intake plenum. When under a load, vacuum is greater, causing the upper intake gasket to fail.

I would take the upper plenum off, and put a straight edge of some kind across the bottom to see if it is warped. If it is not warped, I would replace the upper plenum gasket and eliminate the coolant leak first.

I would second the idea of going after the plenum first then see what happens.When you do, check the plenum very carefully at the area between the throttle body and the plenum (throttle body removed) for deteriation they are well known for problems in this area. Good Luck

Update and lessons learned. Well in reality it was a year ago that I had the initial skip. Thats when I replaced the plugs and wires. Before buying an icm I figured I would ohm out the coils (one new and two origanal) and also the wires (even though only a year old) Coils were ok per the info from here.(thanks guys) but two wires had infinate resistance. Returned to parts store and bought much better grade wires.Cheap wires N/G She runs fine now! Pulled off the altanator and found the plastic nipple into the intake broken. Napa had a metal replacement. So happy I even washed her! Moral of the story is you get what you pay for. Don't skimp on parts. Must be a lot of crap out there. Especially ignition parts since you can't see those nutrons and protrons moving around in those components!

Check engine to h frame resistance it should be single digit ohms, otherwise you may have a bad Engine to H frame ground.