Engine Question

Is there a way to check if Iam running on all 8 cylinders? I have a 90 Iroc 350 TPI. My idle is a bit rough and i'm not sure if it is a sensor or if i am missing on a cylinder. I have have a similiar problem in the past where i was running on 6 cylinders and didn't even know it until I took it to the mechanic. Any ideas or suggestions? Thanks

Get it running and remove a plug wire. Does it get worse? If so, put the wire back on and move to the next one. Once you get to a wire that doesn't make the car run worse when removed you have found a dead cylinder.

or a dead spark plug right?

yea, that's usually the cause of the dead cylinder. or an injector not firing of course.

would that mean get a new cylinder or plug???

new cylinder lol. plug, wire, cap, injector, other ignition components. usually whichever fails the testing.

would that mean get a new cylinder or plug???

You can't get a new cylinder*, its part of the block. A cylinder is just the round hole in the block, that contains the piston. Fuel, air, and spark are injected into the top of the cylinder which drives the piston down. So if you have a dead cylinder it means its not getting either Air, Fuel or spark.


*technically you can get a new cylinder but you have to replace the entire block.

ok i admit i am learing. but i was thinking piston when i said cylinder

Get it running and remove a plug wire. Does it get worse? If so, put the wire back on and move to the next one. Once you get to a wire that doesn't make the car run worse when removed you have found a dead cylinder.get it running????????:banghead: , do you realize the shock this guy is going to get.....:nono: ....

get it running????????:banghead: , do you realize the shock this guy is going to get.....:nono: ....

it wont shock you. People have been doing this since the invention of the automobile.

get it running????????:banghead: , do you realize the shock this guy is going to get.....:nono: ....Thats what those little rubber boots are on the ends of the plugs wires, on my 2.8l camaro it had a bad miss, so i did this, ended up being a bad plug wire.

get it running????????:banghead: , do you realize the shock this guy is going to get.....:nono: ....


actually you are right, you can get shocked doing this, you just have to use common sense, when pulling on the boot, dont put your hand on something grounded, like the engine block, chassis, or ground straps. This is why mechanics sometimes buy a spark tool, it is actually a sparkplug shaped light tool, you plug into the plug wire, and then clamp on a ground, you can check for spark that way. but in my own opinion, it takes longer than just popping the boots off one at a time.

but i have been shocked by an HEI setup, and no, it was not fun, but it was my fault, if i had been smarter it wouldnt have happened.

dont worry tho, it wont kill ya... its just gonna hurt a bit. not nuff amps to stop your heart tho

Get it running and remove a plug wire. Does it get worse? If so, put the wire back on and move to the next one. Once you get to a wire that doesn't make the car run worse when removed you have found a dead cylinder.

Something like that jcase, but not exactly.......first, REMOVE a plug, THEN get the motor going, if it turns on then you got spark, if not then a plug, or a wire or the dist. cap is bad, but DONT get it running first because if its running and you remove a wire you'll get shocked and againg if you try and put it back.....WHILE THE ENGINE IS RUNNING:screwy:

Hey, thats right........I forgot about the spark tool that I have sitting on top of my craftsman tool box like every do it yourselfer has......right!!!

i have one

got one too..

although i wonder..if the plug itself is bad, and its getting power from the distributor..will it still light up?

got one too..

although i wonder..if the plug itself is bad, and its getting power from the distributor..will it still light up?

It takes alot for a sparkplug to completely fail. They are a pretty simple peice of hardware. If a plug completely fails, its normally broken in half, which gives you a pretty good indication that its the plug thats bad. Only times i have ever seen a loss of spark, it has been due to a plug wire, rotar, cap, coil, or other ignition component. If you look at a plug it can be worn out, the electrodes will be all eroded. Again, an obvious sign.



and ive got a craftsman toolbox too....... you can get them pretty cheap really. 150-300 bucks for a decent garage box for a range of screwdrivers, wrenches, ratchets, sockets, and some specialty hand tools.