Misfire problems... - Pontiac G6 Forum
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post #1 of 33 (permalink) Old 10-28-2009, 03:49 PM Thread Starter
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Misfire problems...

My girl's car has been running like crap lately, and of course, everytime I drive it, it doesn't do what it does for her. It's odd though, this thread: Transmission Problems / Hard Shifting is somewhat the same we're experiencing, however, her CEL is on now, but I got a PO300 code (random/multiple cylinder misfire.) Now, I know that would most likely be caused by the coils/plugs/wires, but my friend found (not sure where) that I'm not sure is a TSB or not, but said the misfire problem has something to do with the fuel rail being clogged with rust? Has anyone ever heard of that problem? This is what he e-mailed me:

Cylinder Miss On Left Turns And Cylinder 4 Miss On Right Turns - Possible Fuel Contamination - keywords CEL contaminated controls cylinders gas injector intermittent MIL misfire P0300 P0301 rail rust #PIP3333A - (07/12/2007)



Models: 2004-2008 Chevrolet Aveo

2004-2006 Chevrolet Cavalier

2005-2008 Chevrolet Cobalt, Cobalt SS

2006-2008 Chevrolet HHR

2004-2008 Chevrolet Malibu

2007-2008 Pontiac G5

2006-2008 Pontiac G6

2005-2006 Pontiac Pursuit (Canada Only)

2004-2006 Pontiac Sunfire

2003-2008 Pontiac Vibe, Vibe GT

2003-2008 Saturn Ion, Ion Redline

2007-2008 Saturn Aura, Aura Hybrid

2004-2008 Saturn Vue

2007-2008 Saturn Vue Hybrid

with a 4 Cylinder Engine

(RPOs L61, L91, LAT, LE5, LNK, LSJ, LV6, or LXT

Sorry for the long lengthy post, any knowledge will be greatly appreciated. Thank you.

Mine:
'03 Marauder - Vortech eqiupped. 450rwhp/410rwtq
'06 F-150 4x4 - 35's with some bolt ons
Hers:
'06 G6 - 4cyl and stock
Ours:
'95 Mustang GT - 347 build underway
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post #2 of 33 (permalink) Old 10-28-2009, 07:16 PM
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i highly doubt that it's the rust in the fuel rail ... how many miles are on her car?

usually a random misfire indicates a bad coil pack
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post #3 of 33 (permalink) Old 10-28-2009, 08:25 PM Thread Starter
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I know, but the fuel rail thing threw me a curveball, that's why I wanted to ask here. Her car has 55k on it. Out of all the years I've been doing work on vehicles, I haven't had to diagnose a bad coil yet. Correct me if I'm wrong, but these are coil on plugs right? How would I be able to tell what one is exactly bad? Would one be discolored?

Mine:
'03 Marauder - Vortech eqiupped. 450rwhp/410rwtq
'06 F-150 4x4 - 35's with some bolt ons
Hers:
'06 G6 - 4cyl and stock
Ours:
'95 Mustang GT - 347 build underway
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post #4 of 33 (permalink) Old 10-28-2009, 10:18 PM
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I just fixed this horrible issue on my car and the oddest thing ever...it turned out after replacing O2 sensors and all that it was the catalytic converter which was clogged up. The "stone" inside was all cracked! Anyways this was found after having some surgery on the rear of engine and removing plugs, coil, head covers and all. This is easier to check if you go to a muffler shop. So try to check that if you can.
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post #5 of 33 (permalink) Old 10-29-2009, 06:00 AM
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Quote:
Originally Posted by raudermaster View Post
I know, but the fuel rail thing threw me a curveball, that's why I wanted to ask here. Her car has 55k on it. Out of all the years I've been doing work on vehicles, I haven't had to diagnose a bad coil yet. Correct me if I'm wrong, but these are coil on plugs right? How would I be able to tell what one is exactly bad? Would one be discolored?
i've never seen rust in the fuel rail at 55k miles ... that's very unlikely.

Plus if it was misfiring because of the rusty fuel rail you would have a code from the o2 sensors saying "running too lean" i think.

no these have one coil pack and wires going to each plug ... if you're replacing the wires then they come as a set of 6 or 4 depends on the motor.

You can take the coil off and take it to autozone and they'll test it for free.

they'll test the primary and secondary resistance. if it's not the coil then try going with the cheaper solution first - new plugs but i don't know what wold be cheaper new wires or new plugs cuz these take iridium plugs which are $8 a piece.

Take the wires off the plug and see if there any burned marks on them any where.

me personally I'd take it somewhere where they'll be able to tell me exactly what the problem is.
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post #6 of 33 (permalink) Old 10-29-2009, 04:48 PM Thread Starter
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Thanks for the response guys. My friend has a lift so we'll be putting it up on Sunday and checking the cats. We were also going to check all the ignition things as well and go from there.

Mine:
'03 Marauder - Vortech eqiupped. 450rwhp/410rwtq
'06 F-150 4x4 - 35's with some bolt ons
Hers:
'06 G6 - 4cyl and stock
Ours:
'95 Mustang GT - 347 build underway
raudermaster is offline  
post #7 of 33 (permalink) Old 06-26-2015, 09:55 PM
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Hey everyone, new here to the forum. I have some questions regarding my 2007 Pontiac G6 3.5L engine. I have pulled DTC CODE: P0301 which is a misfire in cylinder one. Here is what I have tried to do to correct this matter. I have checked for vacuum leaks, I have done a compression test on cylinders and have got a reading of 140 - 150 psi's in each cylinder, have changed spark plugs, plug wires, ignition coil pack and have swapped the injector around to see if the misfire would follow but it did not. I have the misfire but also have to push the gas paddle at half WOT at times before it takes off like something is holding it back. Could this be the built-in TPS on the throttle body causing this? I also checked the TPS and back probed A&B wires at the plug and it read 0.00 and when moving throttle to WOT it read 5.0 but dropped back to 0.00 and would not stay at a consistent amount of volts before dropping back to 0.00. Please if anyone has ran into this I ask for your help. Also don't know if I tested the TPS the right way so if there is something that I need to do different please let me know

Thanks, Brad

Last edited by Beg38; 06-26-2015 at 09:58 PM.
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post #8 of 33 (permalink) Old 06-27-2015, 01:38 PM
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Quote:
Originally Posted by Beg38 View Post
Hey everyone, new here to the forum. I have some questions regarding my 2007 Pontiac G6 3.5L engine. I have pulled DTC CODE: P0301 which is a misfire in cylinder one. Here is what I have tried to do to correct this matter. I have checked for vacuum leaks, I have done a compression test on cylinders and have got a reading of 140 - 150 psi's in each cylinder, have changed spark plugs, plug wires, ignition coil pack and have swapped the injector around to see if the misfire would follow but it did not. I have the misfire but also have to push the gas paddle at half WOT at times before it takes off like something is holding it back. Could this be the built-in TPS on the throttle body causing this? I also checked the TPS and back probed A&B wires at the plug and it read 0.00 and when moving throttle to WOT it read 5.0 but dropped back to 0.00 and would not stay at a consistent amount of volts before dropping back to 0.00. Please if anyone has ran into this I ask for your help. Also don't know if I tested the TPS the right way so if there is something that I need to do different please let me know

Thanks, Brad

1. misfire in cyl 1:
look for an intermittent in #1 injector circuit

2. "also have to push the gas peddle at half WOT at times before it takes off like something is holding it back":
this occurs how frequently?
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post #9 of 33 (permalink) Old 06-27-2015, 08:44 PM
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Quote:
Originally Posted by greenman View Post
1. misfire in cyl 1:
look for an intermittent in #1 injector circuit

2. "also have to push the gas peddle at half WOT at times before it takes off like something is holding it back":
this occurs how frequently?
1.Whats the best way to check the circuit?

2. This happens quite frequently. Just about every trip. Sometimes it happens 3-4 times a trip and seldomly none at all.
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post #10 of 33 (permalink) Old 06-29-2015, 12:37 PM
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1.using a live data scan tool with graphing. since its an intermittent misfire, testing with a simple noid light or multimeter could easily miss it. looking at the misfire data would likely help a lot in diagnosis.


2.then i wonder if the bank 1 cat is clogging up. a clogging cat can both cause a misfire & be the result of a misfire. i would do an exhaust backpressure test on bank 1 before i did anything else.
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post #11 of 33 (permalink) Old 07-06-2015, 09:13 PM
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Greeman, Thanks for your help. I have now figured out the cylinder one miss fire. Believe it or not it was the coolant crossover gasket located on the front side of the engine that goes from bank 1 to bank 2 and is also the bracket that holds my alternator. Here's a picture, hopefully I can help someone else with a similar problem. This was located on passenger side right at the bottom of the cylinder head on cylinder one.
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post #12 of 33 (permalink) Old 07-07-2015, 01:17 PM
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leaking oem crossover gaskets is a common issue on the 3.5l but i can't really see how that would create a misfire in #1.
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post #13 of 33 (permalink) Old 07-07-2015, 09:24 PM
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Greeman,

Well guess I spoke to soon. My P0301 code is back so scratch all the above. Question. What's the gap on the plugs suppose to be. I have read .060, .052, .050 and .040. Do you know, I called Pontiac and asked what the car plug was stoked with then I found the plug item # in my manual and Pontiac said .040 gap. Does this sound right to you, because my plugs have be gaped to .060 but this is what autozone said the gap was.
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post #14 of 33 (permalink) Old 07-07-2015, 09:27 PM
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Sorry for the bad spelling.
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post #15 of 33 (permalink) Old 07-07-2015, 09:52 PM
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Quote:
Originally Posted by Beg38 View Post
... What's the gap on the plugs suppose to be.
3.5l:
05 & 06: .06"
07 & later: .04"

did u get that bank 1 exhaust backpressure test done?

Last edited by greenman; 07-07-2015 at 09:55 PM.
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