HELP!? Misfire/no spark cyl 1+4

[shawnpt]

I just Purchased A 01 PT and the next day when Idleing the engine light came on and the engine seemed to sputter just a but. So I hooked the OBD2 reader up and It said random misfire detected and also cyl 4 misfire. So I went out and bout new platinum bosch plugs, wires and ingnition coil.
Before I purchesd this PT I was researching and I remembered seeing the plugs must be gapped at .40 so I tore it all apart and put those parts in and after I reassembled all of it and started It up the motor ran very crappy like it wasnt getting spark. so I ran the OBD on it and and it said 1 and 4 cyl misfire as well as random misfire. I cleared the code and proceeded to recheck the tightness of the plug wires and still it ran crappy. so since it said 1 and 4 cylinder were misfire I pulled the plugs and rechecked gapping and still the same. so i took a multimeter and checked the new wires to see if they were good and they were. then I checked the new coil pack with the multimeter to verify it was working properly it was as well. So I then started it up and pulled 1 and 4 wires to reveal that there was no spark period. I was very puzzled by this point, so the last things Ive checked was the continuity of the wire that runs from the computer to the coil and it was good. then I have checked is the same wire with engine running to reveal that it is receiving no power whereas the othe side wire that runs to other coil pack does have. I am lost what do I do next I am thinking its the computer and itll be expensive to replace.

[Cartman]

sounds like youve narrowed it down to a bad coil driver in the ecm.

[shawnpt]

should I buy a new ecm or is there a way to fix it?

[shawnpt]

had dealer replace the ecm and still nothing. so I replaced crankshaft pos sensor and camshaft pos sensor and nothing still. any ideas?

[CREWZIN]

Wow. Plugs, wires, coil pack, crankshaft position sensor (where did you get the idea to replace that?) and finally the ECM (Engine Control Module). Talk about throwing parts at a problem.

About the only things left are the camshaft sensor, the PCM (Power Control Module) and something called the ECU (Engine Control Unit).

Is there any history that came with the car. Hope you didn't pick up one of those vehicles in the TV commercials that show a car under water and the ad says: 2001 PT Cruiser, New Upholstery.

Sorry I can't be of more help. Did the dealer have any suggestions after selling and replacing the ECM and it was still having problems?

[shawnpt]

Well I was giving it a tune up so that is why i replaced plugs wires and coil pack. then since it was running only on 2 cylnders I decided to inquire online about it after I double checked the pluges wires and coil to make sure they were working properly. And thru some suggestions I got online I checked the current coming from ecm to the coil that controls the cylinders and I got nothing. and then I check wire continuity and wire checked out good. so I took it to the dealer and told them I think it may be the ecm but asked them to check it out for me and couple hours later they said It was the ecm. so $712.00 later a new ecm and still the same problem. after venting about the cost for not actually being the ecm and paying for it anyway the mechanic told me it is possible to be that same wire that I checked the continuity of. He advised me that the wire could be corroded and just one or 2 strands could still be good which would give a good test out. so I brought the car back home and put a jumper wire from the ecm to the coil and still nothing. so with more advice I have replaced the crankshaft Pos sensor and camshaft pos sensor and today the ASD relay. and still nothing. I am to the point of getting a quarter stick of dynamite and saying 'F' it. any suggestions?

[CREWZIN]

Is a quarter stick enough to do the job?

P.S. I'll swear I didn't say that.

[kviper2020]

we have an 04 PT having the same issues just started tracking the down the source of the problem first off replaced coil pack had a heat crack across top 1/4 an its continuously blowing the ASD / Fuel pump fuse so having fun tracking this thing down I'll keep you posted as to what we come across again thanks for the post

[pdbrains]

The coil is really two coils in one package. This means that the "coil" is always firing two cylinders at the same time. So coil 1 fires cylinders 1 and 4 and coil 2 fires cylinders 2 and 3. One cylinder on the compression stroke and the other is on the exhaust stroke and is wasted. You need to check if the coil that is missing spark is getting its 12 volts on the primary side and being grounded on the PCM side. The ASD relay provides this voltage to the primary side of each coil not the PCM. The PCM grounds the other side of the coil primary side and then "opens" it at the proper time to create the spark. Since it appears that one side is working you can compare whats happening on the primary side of the working coil with the non-working coil. You may be able to see the switching or not switching with a voltmeter when the engine is cranked, but you really need an oscilloscope. This is a very easy test and the dealer should have done this before the PCM was replaced.

So I suggest you take a look at whats happening at pins 1 and 3 of the coil connector. Pin 2 should be steady 12vdc. Pins 1 and 3 should be switching when the engine is cranked or is running. Good luck.

[DJmart]

My car was running poorly on three cylinders, turns out a compression leak between 3-4

The head was warped... replaced under warranty, and the car has never run so smooth.