Weird misfire

[timloomis]

After driving the car for a while,it feels/sounds like 2 cylinders shut down.It does this for a few seconds,then comes back on.The cel comes on too(44,ign coil).Doesnt matter if I'm boosting or I have the cruise set at 65.The ngk's and accel wires have less than 3k on them,a guy just sold me a known working transistor,and I've switched coil packs 3 times.But the coil packs are all used and a few have unknown mileage.Now a cas or ecu wouldnt do this,I think it would just shut off and not spark at all.To me,this sounds like I have 3 bad coil packs,because the plugs arent fouled and the transistor is good.Im confused as to what it could be.Just seems like operating temp is making something not work right.Any ideas?

 

[luv2rallye]

Actually a bad CAS or ECU could do this since the CAS tells the ECU when to fire the power transistors each of which drive 2 plugs. Unfortunately an intermittent problem is the hardest type to find . It could be the CAS, ECU, power transistor, or coil. Since you say it sounds like losing 2 cylinders I would lean towards the power transistor or coil first. Often these fail more solidly under heat so I would recommend heating them with a heat gun (or hair dryer) while engine is running to see the effect. Also measure the coils resistance to make sure it's within spec. Then open up the ECU to check for leaking capacitors. Of course if you can try new items or proven under all condition ones, that would be the best course. Also check for loose wire connections in the ignition circuitry and try jiggling these connectors and wires while engine running to see effect.

 

[timloomis]

I know one of my coils and transistors were good,they came of my old car.I already replaced the caps a few months ago,they werent bad but I changed them anyways.I tried wiggling wires,but it didnt help.I tugged on the plug wires too,but nothing happened.I even tested the coils I took off,and they were good.I just bought some new plug wires,in case my accel's were a bad set and were failing under heat.If this doesnt work,Ill probably change the cas.

 

[timloomis]

I put new wires on it,and it misfired again on the way home today.I hurried and got the ohm meter out while it was still hot.Injectors all test 2.8-3 ohms,coil pack secondary is 15.78k on 1&4 and 15.66k on 2&3.The harness side of the cas checked out ok.I could see it this time.I was at full boost and I noticed it went to about 17-18psi when I have it set at 20.Then it started to die down like I had a boost leak.So I let of the gas to try and boost again,thats when the cel came on.Can a cas mess up like that and throw a code for the coil pack?