95 9c1 missfire HELP PLEASE

[95 9c1]

hello newbie here hello to all. a friend of mine gave me his 95 caprice 9c1 but it has a miss on two cylinders #1 and#7.replaced all injecters ,plugs, wires [all original gm stuff] and did a compression test 190 psi across the board . today i replaced the optispark dizzy with a new one the car ran well for five minutes now it's missing again. i would be greatful for any help or ideas? Thanks Dan

[rhandwor]

Use your ohm meter and ohm the plug wires to the cylinders. Check the plugs for cracks. Ohm your coil haynes should have a sketch. The plug wires ohm around 1/2 of the scale I have found bad connections on some new brands. But never on origional equipment wires.

[95 9c1]

thank's for the info i'll check them all before i give up on the car. thanks ,Dan

[rhandwor]

If that doesn't work use a noid light and check for power to the injectors.
You can also check compression for these cylinders.

[95 9c1]

thanks i'll let you know how it turns out

[j cAT]

Originally Posted by 95 9c1

hello newbie here hello to all. a friend of mine gave me his 95 caprice 9c1 but it has a miss on two cylinders #1 and#7.replaced all injecters ,plugs, wires [all original gm stuff] and did a compression test 190 psi across the board . today i replaced the optispark dizzy with a new one the car ran well for five minutes now it's missing again. i would be greatful for any help or ideas? Thanks Dan

this is usually bad wires.....so what resistance did you read on your ohm meter....I know this is not easy to do on this engine but checking wire resistance when changing plugs and especially when screwing with opti is a must....


if could also be a cracked plug but if the miss is intermittent this then becomes more of a bad plug wire... did/do you use dielectric grease if not this is another reason why wires will fail.............


new wires still must be measured before installing on this engine......new does not mean good....you put bad wires on this engine you will be not happy....

[95 9c1]

I ohm checked the wires the all read half across the scale,I used dielectric grease on the wires, most people around here think it's a waste of time but it's my car so I do it anyway.
I replaced all the plugs again still same problem.I wiped out the starter today trying to start the car it kicked back and starter parts went allover the ground. but I did manage to check the injectors with a noid there all good[all new too] I am begining to think it might be a bad ecm. guess I'll be putting in another starter and trying another ecm
Thanks for all the help it's appreciated

[95 9c1]

all oem part's [buck's spent]

[rhandwor]

How many miles are on the car? It almost seems to have jumped time to tear out a starter. Pull the distributor cap turn the engine over by hand until top dead center. Then turn it back until the end of the scale. Mark the rotor button and have somebody watch it turn clockwise until the rotor just starts to move. If your over 20 degrees stretch it is time to think about replacing.
You could try a used computer but I don't think its your problem.
Double check the fuel pressure if its on the low side it could lean out a couple cylinders. An engine out of time will kick back.

[95 9c1]

I've checked fuel presure and it's within spec's.
As far miles 197.000, yes I was thinking about the timing chain also.

I'll try the starter and ecm if no change then I'll have to make a decision either pull it apart check the chain or put the car up for grab's
Thanks again

[crash_1333]

have you checked your cap and rotor that could cause a car to miss check that out it will b about25 for everything

[j cAT]

Originally Posted by 95 9c1

I ohm checked the wires the all read half across the scale,I used dielectric grease on the wires, most people around here think it's a waste of time but it's my car so I do it anyway.
I replaced all the plugs again still same problem.I wiped out the starter today trying to start the car it kicked back and starter parts went allover the ground. but I did manage to check the injectors with a noid there all good[all new too] I am begining to think it might be a bad ecm. guess I'll be putting in another starter and trying another ecm
Thanks for all the help it's appreciated

your opti is bad ...only opti,plug,wires will cause missfire if compression is good...computer/ecm cannot cause a missfire...

[95 9c1]

Brand new opti,a friend of mine has the same car and we went through the hassel of switching opti's same issue's with my car, his ran fine with my new opti ??? his car 95 9c1 94,000 miles my car 95 9c1 197,000 miles. I'm about ready to dump it. thanks again

[rhandwor]

Since the car ran good when you first replaced the opti and you seem to have starting problems as you tore up a starter. Try the method I explained in a previous post to check timing chain. It will take less time than changing a distributor. I would estimate less than 1 hr. If it jumped time you probably would have 60 degress slop in the chain. Even a junk yard computer is probably $100.00. If its stretched replace the chain before going over and over the same parts changing.
You could change a chain in less than a days time. You apparently have basic hand tools. Auto Zone and Advanced have loaner harmonic balancer pullers.
http://www.autopart.com/TOOLS/TOOLSMAIN/Tool/T_A810.htm
If the other type use search and 2236 at least one of the pullers will work.

[j cAT]

Originally Posted by 95 9c1

Brand new opti,a friend of mine has the same car and we went through the hassel of switching opti's same issue's with my car, his ran fine with my new opti ??? his car 95 9c1 94,000 miles my car 95 9c1 197,000 miles. I'm about ready to dump it. thanks again

I assumed that you replaced the plugs in the cylinders that were misfiring and also checked compression and wire resistance.....before the opti was switched....

the other possibility is the knock sensor is intermittent causing the timing to retard severely ...


are you sure it's misfiring ....back fire thru exhaust/intake or just die....