Dont fire on 2 cylinders

Tedor

Registered User
Hi!

I have a problem with my 1991 SC, sometimes more often then less the car starts to miss out on 2 cylinders which is the two in the middle of the coil, I think it happens more when the engine is not up to temp but I'm not sure. The car have been standing in the garage for like 5 months, only taking it out to the parking lot sometimes so I haven't been logging any miles. I have located that it is the 2 cylinders in the middle of the coil pack by lifting the ignition cables of one at the time and there simply is no spark in those two when the car dont run as it should.

Also the check engine lights comes on beacuse of this, the spark plugs only got like 2000 - 3000 miles on them and i brought them from super coupe performance. Have never had any running problems before. Only 50k miles total on the car too...

Going to have the car at a car show in 5 days only so fast help would be awesome =)

Thank you!
Fredrik /sweden
 
Few things that can be looked at.

1. Crank sensor can sometimes get for lack of a better term "rust" on the end and that effects how it is ready and will effect how the car runs. Take it off and clean it and the balancer edge where it is read by the sensor.

2. Pull the DIS and take it to a local auto store and see if they will test it for you. American auto parts store do, but not sure about Sweden.

3. This is probably not the issue, but the cam sensor could be bad. Simply unplugg it and crank the car several times before it will start, but once it does see if it runs any different without this plugged in. Probably not the issue, but a simple test to find out.

Just some thoughts on what you can do yourself and that are easy to check.
 
If it's always the center pair of plug wire towers on the coil pack that aren't firing, then it sounds like that coil in the coil pack is on its way out. Replace the coil pack.
 
If it's always the center pair of plug wire towers on the coil pack that aren't firing, then it sounds like that coil in the coil pack is on its way out. Replace the coil pack.

It could also be that the ignition module (DIS) is not triggering the coils. I would suspect the DIS first.
 
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