Misfiring – Hard to figure out!

[dobie]

Re: Misfiring – Hard to figure out!

Here's another thing you can try. Start the car and let it idle.
Make sure you wear insulated gloves because the shock you can get isn't pleasant (unless your into that sort of thing :) I'm not)
Pull a spark plug wire and your idle should get rougher. Put the wire back on and go to the next one. If you pull a wire and nothing happens you found your bad coil pack.

The high tech way to do this is to hook up a scan tool and turn the injectors off one at a time and note which ones have no effect on the idle. Unfortunately the scan tool that does this cost a lot more than I want to spend.

[Break-in]

Re: Misfiring – Hard to figure out!

Ok Thanks for your help and suggestions but I have to say this for the fourth time. :spank:

Misfires only under load; that means that you have to be driving the car in gear, revs fine in N, idles fine. :)

@dobie: They make a scan tool like that? That may be useful but I get really expensive...

[jdkvice]

Re: Misfiring – Hard to figure out!

Is there a reason your avoiding changing the coil packs? We've had this problem before...Misfiring only under LOAD....and that was the PROBLEM. Mine would rev up fin in neutral as well! It was the center coil pack. Just my two cents....again. So try it man, were trying to help.

[dobie]

Re: Misfiring – Hard to figure out!

Ok Thanks for your help and suggestions but I have to say this for the fourth time. :spank:

Misfires only under load; that means that you have to be driving the car in gear, revs fine in N, idles fine. :)

@dobie: They make a scan tool like that? That may be useful but I get really expensive...

Hey, I'm just trying to help you out here. My car idled fine also but with the new coil pack the idle is perfect and yes I could tell the difference.

The scan tool cost around $1200. My local repair shop bought one and fortunately they don't charge me to use it on my car.

[v6mOtOrhEAdftOp]

Re: Misfiring – Hard to figure out!

Ok Thanks for your help and suggestions but I have to say this for the fourth time. :spank:

Misfires only under load; that means that you have to be driving the car in gear, revs fine in N, idles fine. :)

@dobie: They make a scan tool like that? That may be useful but I get really expensive...

I'M TELLING YOU IT'S YOUR IGNITION CONTROL MODULE!!!! Just replace it please

[candela]

Re: Misfiring – Hard to figure out!

Coil packs have 2 coils. Primary and Secondary. You can check them with an ohm meter.

Primary Coil (the end that connects to the ICM(female)) Place the ohm meter in the 200ohm scale. Resistance should be between .2-.6

Secondary Coil (from wire stud to wire stud(male)) Place the ohm meter in the 200K scale. Resistance should be 5-10K ohms.

It could be that one of the coils within the coil pack is defective, therefore the misfire only shows up under load.

I personally have gone through all of this, I have the same problem. My coil packs are fine, ICM tested fine, new plugs/wires..... I have concluded it is my fuel pump. The pressure regulator had been replaced already due to hard starts, which in fact did not resolve my issue.

I'm starting a new thread on this because I have many questions on this same subject and I do not want to hijack your thread even though it is a few weeks old already.

[Break-in]

Re: Misfiring – Hard to figure out!

Coil packs have 2 coils. Primary and Secondary. You can check them with an ohm meter.

Primary Coil (the end that connects to the ICM(female)) Place the ohm meter in the 200ohm scale. Resistance should be between .2-.6

Secondary Coil (from wire stud to wire stud(male)) Place the ohm meter in the 200K scale. Resistance should be 5-10K ohms.

It could be that one of the coils within the coil pack is defective, therefore the misfire only shows up under load.

I personally have gone through all of this, I have the same problem. My coil packs are fine, ICM tested fine, new plugs/wires..... I have concluded it is my fuel pump. The pressure regulator had been replaced already due to hard starts, which in fact did not resolve my issue.

I'm starting a new thread on this because I have many questions on this same subject and I do not want to hijack your thread even though it is a few weeks old already.

Now that is information I really could have used. I ended up buying one coil and replacing each of the old coils one at a time, then test drive.

Today, I finally diagnosed the problem, I used about 4 brass fittings and handful of Teflon tape to test the pressure after the fuel filter (16psi max after cycling through the on/off position about 7 times). While down there, I listened to the pump. It sounded pathetic and quiet with a BZZzzz-Bz-Bz-Bz

We cut the hole and pulled the pump assy, I'm looking for a motor now (cheapest decent brand I could find is Python for 80 bucks online)

EDIT: I also want to add that I hooked up the pump directly to the battery while in car (easily done with the fuel pump connector and needles and jumper cables and other cables...). It made that pathetic sound and the psi was the same as before.

[Break-in]

Re: Misfiring – Hard to figure out!

Just a follow up, I replaced the fuel pump assy and she runs great.

Thanks for the help.