2004 Misfire!

[BODA]

Can anyone help diagnose a misfire I am having with my 2004 Bonneville with the 3.8L?

I just bought the car with 144k on it.
I was told by the owner all maintenance was done regularly and the car is still solid and drives nice and tight.
The previous owner told me he had replaced "One" of the 3 coil packs on the 3.8 motor and I can see it was the
middle one with the numbers 3/4 on it because it looks new and differs from the others.

I have an OBD2 scanner that can clear codes as well but it will read only up to 2002 vehicles.
It was throwing a code when I hooked up my scanner but came up as N/A for the code.
I cleared the code thinking it may reset something and the problem may go away but did not help.
The code or engine light has yet to come back on and the car still misfires.

The problem is I live in a very rural community in Hawaii and to avoid a long trip of 100 miles and the cost to
have it scanned I am hoping the following symptoms may have happened to someone else and you
would be so kind to tell me what it may be or to check.

Assuming the previous owner is correct in how it is running now - the misfire is once again a coil pack problem.
It should be known that there is no smoke from the pipe at any speed or idle, so I am guessing valves are okay.

Symptoms:
Upon start up the car fires great.
Once in gear there is a hesitation until throttle is applied.
Car temp after warm up is 180 to 200 degrees on average.
Hesitation begins in travel and sometimes after leaving a complete stop.
Hesitation is more apparent when the car climbs hills as if it is losing power until throttle is applied
then all hesitation goes away, same with throttling from a dead stop lightly - if throttle is applied all is well.

Is there a way to diagnose the coils the backyard mechanic way?
Or could this be something as simple as a PCV valve replacement?
I would love to get through this with what I have for tools here, and yes I do have an Ohm and voltage meter.

Any help is well appreciated!
I will keep checking back for any answers
Thanks!

BODA

[crash93ssei]

Any idea when the last time it had new plugs and wires? What brand of plugs are currently in it?

Definitely sounds ignition related, either a plug, wire, or coil. I would start by taking a look at the plugs and wires.

[BODA]

Thanks crash93ssei,

I will remove and inspect plugs and wires - you mentioned plug brand - is this crucial for the Bonneville 3.8?
There are several companies to choose from - can you please recommend a brand that is/was good for you?

Thanks again!

BODA

[crash93ssei]

Not necessarily critical on plug brand, but the waste spark ignition system used on these cars doesn't seem to play well with the Bosch plugs, especially the +2 etc styles. Some have good luck with them, but they just seem to have a higher rate of issues with them vs. other brands. Many here prefer NGK TR55 plugs, but there are others that are good as well that may be suggested.

[justin85]

Middle coil pack is suppose to be 2 an 5 on 3.8L.

Looking at coil packs

6. Plug
3 plug

2 plug
5 plug

4 plug
1 plug
( front of car)

Even if your coil says 3/4, try placing 2/5 in position first,

[myfirstbonnie]

Here is how the plug wires should be on regardless of the numbers on the coils. If there is any rust or corrosion, remove it and put some dielectric grease on them.

[BODA]

Thanks to Justin85 and myfirstbonnie, for what could be a valuable lesson here.
I can say this someone has numbered the front plug wires to the block and left to right
1,2,3 as the piston order and I am assuming 4,5,6 is in the back - my biggest question
if the firing order is that much off fro the order you and Justin provided why is this car
still running at all? will have to do some wire swapping it looks like and see what happens.
Again thanks to both of you

BODA

[BODA]

Thanks to Justin85 and myfirstbonnie, for what could be a valuable lesson here.
I can say this someone has numbered the front plug wires to the block and left to right
1,2,3 as the piston order and I am assuming 4,5,6 is in the back - my biggest question
if the firing order is that much off from the order you and Justin provided why is this car
still running at all?
I will have to do some wire swapping it looks like and see what happens.
Again thanks to both of you

BODA

[BODA]

Thanks to Justin85 and myfirstbonnie, for what could be a valuable lesson here.
I can say this someone has numbered the front plug wires to the block and left to right
1,2,3 as the piston order and I am assuming 4,5,6 is in the back - my biggest question
if the firing order is that much off from the order you and Justin provided why is this car
still running at all?
I will have to do some wire swapping it looks like and see what happens.
Again thanks to both of you

BODA

[BODA]

Thanks to Justin85 and myfirstbonnie, for what could be a valuable lesson here.
I can say this someone has numbered the front plug wires to the block and left to right
1,2,3 as the piston order and I am assuming 4,5,6 is in the back - my biggest question
if the firing order is that much off from the order you and Justin provided why is this car
still running at all?
I will have to do some wire swapping it looks like and see what happens.
Again thanks to both of you

BODA

[BODA]

Thanks to Justin85 and myfirstbonnie, for what could be a valuable lesson here.
I can say this someone has numbered the front plug wires to the block and left to right
1,2,3 as the piston order and I am assuming 4,5,6 is in the back - my biggest question
if the firing order is that much off from the order you and Justin provided why is this car
still running at all?
I will have to do some wire swapping it looks like and see what happens.
Again thanks to both of you

BODA

[myfirstbonnie]

If they just numbered the coils 1-6 counting away from the radiator and then numbered the cylinders as you describe, then there is only 2 wires out of place. The wires to the cylinders in the center on each side of the motor (remember the front of the motor is on the passenger side of the car) are swapped.

I suggest following the picture above and make sure they are going to the correct locations. While doing that, make sure none of them are laying against the O2 sensor in the rear exhaust manifold. Keep all the plug wires as far as possible away from that sensor and it's wire.

[justin85]

The picture that myfirstbonnie supplied is best to go with, if problem persists then change out your ICM.

[BODA]

Thanks for the tip and the pic - was a busy day today but tomorrow I am going to use your advice
Will write back with results

Aloha from Hawaii

BODA

[justin85]

How did everything work out for you?

[BODA]

Aloha Justin85,

well the wires are all in the correct position from the previous owner.
I was surprised - I was actually hoping they were out of order so it may fix the problem.
I also made sure no wires were touching or near the O2 sensor - none were but were close
so I repositioned everything just in case.
Unfortunately still runs the same.
I am considering now replacing all 3 of the coils and see if this will remedy the problem.
It sucks because now it has a hard time starting after warmed up and sometimes will even
stall out after the car goes from reverse (Out of a parking stall) into drive - but starts right up
again and drives okay.
I did get pissed off the other day and took it down the hwy about 90mph and the check engine
light came back on again - so now my buddy on the other side of the island can hook his OBII
with the newer car codes in it and tell me what exactly it is.
But I am half saying to myself F**kit! and just buy the new coils which I found on Amazon

here - http://www.amazon.com/three-Pontiac-BON ... B006E5IZ8Y

if you got time take a look at these coils and tell me what you think?
Someone said not to buy cheap ones but my budget may only allow a set of cheap ones for now.
Thanks for writing me back things got a little crazy here from Sun til now.

BODA

[BODA]

Hey Justin,

Can you show me where the ICM is located?
After reading another guy's post it may be just the issue I am having?
I am thinking now maybe I should start there first.

BODA

[Nocrank]

ICM is right bellow the coils its what the coils plug into. I have three stock style SE coils for sale too. They all work perfect. One is fairly new too, but has different numbers then what should be on it. They all work great though.

[gweg_b]

To help you out from my experience:

The ICM (Ignition Control Module) is what your coils sit on. Remove your coils and loosen the small nut in the connector on the front (with all the wires coming into it). My ICM went bad and I went through 2 coils, 3 sets of wires, and 2 sets of spark plugs before I changed it out (every couple of months I kept getting misfires that would go away if I replaced either wires or spark plugs). Once I replaced the ICM, I've had no major misfires in almost 7 months (just 2-4 on cylinder #4 at idle, and that's nothing I feel concerned about).

Here's a pic for reference:


Hope that helps you out some.

[justin85]

Gweg_b has the perfect pic, the bolts are 5.5 mm for coils and plug is 7 mm if you haven't removed them already.