2001 buick park ave misfire HELP! I have a misfire on cylinder 3 and occasionaly cylinder 1. I have replaced the module and 1 coil pack the plugs and wires. I swapped the fuel injectors. I ran a compression test and have 150 psi across the board. I have replaced the intake gaskets and the upper plenum. I had it to a local shop and they could not find the issue either.

P0304 is engine misfire #4 cylinder Several things can cause a misfire #1 electrical which you have covered #2 Mechanical Test engine compression is should be around 150 cranking and 120 running . internal valve train components can cause bad compression and the valves then self. #3 fuel injector can be the cause suggest swapping with a know good cylinder and see if misfire follows injector.

These engines have 3 coils and are paired 1 and 4 2 and 5 3 and 6 with a spark noid run to see if the paired cylinder has no spark if so remove coil from module and test the power supply to coil and with a logic probe test the trigger side if blinking with no spark your coil is bad. not blinking replace module.

Is the compression good on the clinder that's misfiring ? Are all the injectors firing ? Video's on youtube
How to Diagnose an Engine Misfire Fuel Fire or Compression

cylinders 2-4-6 are on the back side of the engine. 2 is on the passenger side, 4 is in the middle, and 6 is on the drivers side.

Cylinders 1-3-5 are on the front of the engine. 1 is on the passenger side, 3 is in the middle, and 5 is on the drivers side.

The coils should be labeled with there corresponding cylinder number. If it says 2 near the coil tower than the number two spark plug wire goes to that tower and the other end goes to the number 2 cylinder.



I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Yes start with the coil pak. There are three located on the front of the engine on the pass side, you probably know this. They are marked as to which cylinder each wire goes to, disconnect the wire for #5 cylinder, and if the engine misfire does NOT change, it is more than likely that Coil Pak. Replace it, and use dilectric grease on the two contacts when reinstalling it. Now, I have stumbled on this issue many times and if that does not cure the issue (I think it will), the coil module below the coil pack is probably bad...To remove this module, remove the coil paks, the electrical connector in front (has bolt holding it in) and I remember one bolt holding the module to the aluminum bracket.

Again, to be sure you can switch coil paks around to make sure it is a coil pak. When you switch the bad with a good, the misfire will follow the coil pak, if it does not it is the module.]

Hope this helps.

For the 1991 Buick Park Avenue:
Firing Orders & Cylinder layouts are the same. The difference is in the Ignition Coil Connections. I have included all three (3) types of Coil Systems for the Park Ave, Park Ave Ultra, and Park Ave with a Supercharger.

For ALL the 3.8L V6:
Firing Order:
1-6-5-4-3-2
Cylinders:
.......(back).......
|...1....3....5...|
________________
|...2....4....6...|
.......(front)

For the Type I Coil:
.........(back)
3--->o.|//////|
..........|\\\\\\|.o <---6
5--->o.|//////|
..........|\\\\\\|.o <---2
1--->o.|//////|
..........|\\\\\\|.o <---4
.........(front)

For the Rest of the Coils:
(back)
....6
....3
....2
....5
....4
....1
(front)

For this Type II Coil (Solid One UNIT):
(back)
_____
|....o| <---6
|O....|
|....o| <---3
|....o| <---2
|O....|
|....o| <---5
|....o| <---4
|O....|
|....o| <---1
(front)

For this Type Coil (3-Section UNITS):
(back)
______
|....o.| <---6
|O.....|
|....o.| <---3
_____
|....o.| <---2
|O.....|
|....o.| <---5
_____
|....o.| <---4
|O.....|
|....o.| <---1
(front)

Let me know if this helped, or if you have additional information or questions. Feel Free to contact me at FixYa.com!

ive had this problem before and it was a small wire on the ignition key cylinder that had broken but we fixed it by buying a new cylinder and wire

IF SPARK PLUGS AND WIRES IS GOOD.I AM LOOKING AT FAULTY COIL OR BAD IGNITION MODULE.

have you replaced your ignition module?

The problem is the ignition control module such is under the coil packs. It seems to be an internal problem in the design. I have seen it many times and if you don't belive as many will not. So disconnect the modules electrical connector and just let it sit for two to three days. After that clean ir replace your sparkplugs, they will be fails up dew to it running lean and rich. Plug it in. Plug it in and wala its fixed $ but only for a week or two then back to the same thing so in short change the ignition module and save time and money, and don't forget to thank your friendly neighbor hood mexican mechanic.