91 Skylark #1 and #4 cylinders quit firing
bstrom1953
05-28-2007, 03:55 PM
This is a 2.5 L four cylinder, Direct Ignition System (DIS), automatic.
In the middle of a one hour trip home, the engine went from from firing on four to firing on just two. The next morning, it started cold just fine and I drove it 15 minutes, but then it went back to firing on only two.
Cylinders 1 and 4 had stopped firing while cylinders 2 and 3 kept working. I moved spark plugs and wires around to confirm that the wires and plugs were good...just no spark coming from the coil on 1 and 4.
With the DIS ignition, I suspected the coil for cylinders 1 and 4 was bad. I removed both coil packs and checked them with an ohm meter. They both had similar resistance values that matched the Haynes manual.
I took the ignition control module to Auto Zone and their tester said the module was ok. I went ahead a bought a new 1-4 coil. If the control module is good, the coil 1-4 coil had to be bad.
After installing the new coil, the car started on four cylinders! In the time it took to open the garage door and roll the car off the ramp, 1 and 4 quit firing. :(
The problem seems so be heat related, although it doesn't seem to take much heat. The fact that cylinders 2 and 3 continue to work tells me the crankshaft sensor is working. I even wiggled the plug and socket wires at the control module while the engine was running on two cylinders to see if I had a bad connection.
Auto Zone said the control module was good. It looks to me like the module is not sending current to the 1-4 coil (or does so only when very cool). I don't want to buy one...Auto Zone quoted $90. Might have to.
Any ideas? Thanks a bunch. bstrom
In the middle of a one hour trip home, the engine went from from firing on four to firing on just two. The next morning, it started cold just fine and I drove it 15 minutes, but then it went back to firing on only two.
Cylinders 1 and 4 had stopped firing while cylinders 2 and 3 kept working. I moved spark plugs and wires around to confirm that the wires and plugs were good...just no spark coming from the coil on 1 and 4.
With the DIS ignition, I suspected the coil for cylinders 1 and 4 was bad. I removed both coil packs and checked them with an ohm meter. They both had similar resistance values that matched the Haynes manual.
I took the ignition control module to Auto Zone and their tester said the module was ok. I went ahead a bought a new 1-4 coil. If the control module is good, the coil 1-4 coil had to be bad.
After installing the new coil, the car started on four cylinders! In the time it took to open the garage door and roll the car off the ramp, 1 and 4 quit firing. :(
The problem seems so be heat related, although it doesn't seem to take much heat. The fact that cylinders 2 and 3 continue to work tells me the crankshaft sensor is working. I even wiggled the plug and socket wires at the control module while the engine was running on two cylinders to see if I had a bad connection.
Auto Zone said the control module was good. It looks to me like the module is not sending current to the 1-4 coil (or does so only when very cool). I don't want to buy one...Auto Zone quoted $90. Might have to.
Any ideas? Thanks a bunch. bstrom
richtazz
05-31-2007, 03:24 PM
Ignition modules will heat sink on you and fail. Since you replaced the coil and the problem came back on the same 2 cylinders, I would bet the ignition module is your problem. If they only ran the test once, and didn't get it warmed up, that is why it passed their test. Any time you're bench testing a module, you need to have them run the test multiple times to get it warm to the touch.
bstrom1953
06-06-2007, 10:01 AM
Many thanks to richtazz for helping me fix my Skylark. It was the ignition control module. Bought a new one at Auto Zone for $90 and it's runing fine now. Thanks again! :)
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