2009 G6, 2.4l, runs but bogs when acceleration - Pontiac G6 Forum
 
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post #1 of 10 (permalink) Old 12-21-2016, 11:04 AM Thread Starter
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2009 G6, 2.4l, runs but bogs when acceleration

Hi! I hope someone can help me figure out this G6's acceleration issue. It bogs down as soon as you give it some pedal. If you just "feather" the pedal, barely push it down, it will go, just wont go fast at all. Slow. And as soon as you go to far with the pedal, it bogs down, just revs up and dont go!

Codes are, in this order, P0300, P0420, P0171.

I've checked all 4 coils, theyre at like 10.08, 10.01, etc. All 4 are good I feel. And the plugs are the GM factory still, the AC delcos that came with the car. No oil in the spark plug tubes and the engine is super clean! No leaks of any fluids over the years(yet), no valve cover gasket "fur" or oil seepage.

Then I checked the throttle body- Butterfly is shiny gold, super clean, all intact, wires tight and no fraying anywhere. When I open the tb and look in there, at the bottom of the intake theres liguid. You can see it fine but it's blackish, dark, so wondering if it's unburned fuel, coolant, etc. Not sure what it is yet.

The fuel pressure showed 58-60 psi. The injectors were all intact and nice and tight. No frayed wires at pigtails or anything noticeable just looking and feeling them. I did'nt use the noid or any checks but I feel theyre good. It starts right up, you can drive it, it's just that if you want to go over 30 or 40, that might take some time to get it there! Def dont try to get on the freeway!

The last few details are these(i'm going to try to write em all real short so this post isnt soooo long, Sorry!)
Compression- all 4 are at 91, 98, 95, 93.
air filter- new
battery- NEW
terminals- 1 new 1 just fine
CATALYTIC Converter- checked temp with my cheap laser tempo thing from HF, got it like 2 years ago, 30 bucks I think, anyway, those temps were 220+/- before the cat and 110+/- after the cat. I held the red light on the edge of the cat on both sides of it. Not on the exhaust pipe before and after.
O2 sensors had a up and down on bank 1, form all way at the top of the graph to the bottom of the graph as it went, and was a steady up and down(not sure the numbers, I prob could've used a diff type of graph setting), the other sensor had a straight line, like no up and down the graph, just straight across the screen. Barely fluctuating at all.

I know this was lot of info at one time but I didn't know if I should try to send it in separate posts or all in one. Sorry if I over loaded ya!
Thanks for any input into this situation. I appreciate it she will appreciate it even more if I could somehow get it to accelerate correctly! I'm going to get the loaner tool for the head gasket check I guess next, or wait to see if you can direct me other directions. THX again!
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post #2 of 10 (permalink) Old 12-22-2016, 01:27 PM Thread Starter
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The cat is prob fine. I unbolted it and it didnt change a thing. So its still a mystery at this point. Will be checking the throttle body and iac, map, tps, etc next. Hopefully I get somewhere with those tests. I know the bogging starts at about 2k+ rpm's. It does good until the pedal gets it up to there.

When you 1st start car, for about 2 seconds you can floor it, no bogging, does like it used to. But right after those 2 or 3 secs, bogging about halfway down with the pedal. Maybe I'll check the 2 actuator solenoids next. The intake and exh.

Thx for help! Will let ya know what these next tests reveals!
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post #3 of 10 (permalink) Old 12-24-2016, 09:04 AM
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Miles? Sorry if I missed it from your post. Make sure your air filter is good. Make sure no leaks are present in the intake. Ensure all the bolts are tight all the way from the filter to the throttle body and that no hoses are disconnected. The PCV could also be dirty. See here.

Clean your MAF sensor. Unscrew it from the intake and use MAF sensor cleaner (CRC) and that may fix your problem. Amazon's a little pricey. Purchase locally.

2008 G6 Dark Gray Metallic SE V6
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post #4 of 10 (permalink) Old 02-28-2017, 01:08 PM
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um, not to revive this thread but shouldn't the exhaust temp after the cat be HIGHER?

https://www.2carpros.com/articles/ho...ytic-converter
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post #5 of 10 (permalink) Old 04-12-2017, 12:09 PM
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I have the same model (2009 g6 2.4) My car has no power going up hill- barely accelerates. My check engine light has even flashed and the traction control came on until I let completely off the gas going uphill. I've changed my camshaft sensors-timing solenoids and even had one of my catalytic converters re-done. We didn't mess with the one on the motor which is my next move. CEL is no longer on- had the codes cleared after I changed all those parts. So far no light. Do you think it would be the other cat-or something else?
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post #6 of 10 (permalink) Old 04-12-2017, 01:03 PM
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Quote:
Originally Posted by Seira Rose Oatman View Post
I have the same model (2009 g6 2.4) My car has no power going up hill- barely accelerates. My check engine light has even flashed and the traction control came on until I let completely off the gas going uphill. I've changed my camshaft sensors-timing solenoids and even had one of my catalytic converters re-done. We didn't mess with the one on the motor which is my next move. CEL is no longer on- had the codes cleared after I changed all those parts. So far no light. Do you think it would be the other cat-or something else?
same situation as you...same year and engine as well as same issues.
I just got the front catalytic converter in the mail yesterday and plan on installing it on Saturday.
I'll report back once it's done with results.

That front catalytic converter is the one that is known to fail, which GM refuses to add our model year to their extended warranty bulletin.
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post #7 of 10 (permalink) Old 04-18-2017, 07:17 AM
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welp, the new one is installed. Took me about 3 hours by myself. (thankfully i have access to a pit to work in to get underneath the car)
Wasn't too difficult. A few of the bolts are a tight reach.

And now...the car runs like a champ. No more misfires or flashing service engine lights. Doesn't bog down and revs clear up to 6500 rpm and shifts nice and smooth now.
Gas mileage is also up. Before at 75mph it was reading 25mpg, now on the exact same stretch of highway it reads 31mpg.

I got the Walker catalytic converter from Rockauto...that and a new upstream O2 sensor were like $320 shipped to my door.

If you can spin a wrench and maybe have an extra set of hands, it's a fairly easy thing to replace.

3 bolts take off the heat shield.
10 nuts on the exhaust manifold (be sure to soak these the night before so you don't snap off a stud in the head)
1 bolt underneath the cat. (best to remove the upstream O2 sensor to reach this one)
1 bolt holding the cat to a bracket on the passenger side.
3 nuts on the exhaust flange....good chance you'll snap at least one of these...best bet is to buy a set of studs/nuts new as the new catalytic converter needs, but does not come with them.
and poof, it's out.
Reverse the process and you're golden.
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post #8 of 10 (permalink) Old 04-25-2017, 03:01 PM
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I think I'm having the same type of issue with my 2008 G6 GT (not sure if It's "bogging"). I'm at a red light. The traction control is off. I give the car enough gas to take off without the wheels slipping then pedal to the floor! About 2 sec into full acceleration, I shift into 2nd gear and there's noticeable power loss and the "check engine" light bings and flashes. My regular garage, and a GM dealer (that also handles recalls) can't find the problem.

If the "check engine" light stays on, It's just a miss-fire code with no other info. Do you guys think it could be a catalytic converter issue??
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post #9 of 10 (permalink) Old 04-26-2017, 06:23 AM
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Sounds similar. Different engine so different cat in this case.

All I ever got was a misfire and it would go away once I let off the throttle and let the engine settle back down.

But I gradually lost rpm range. First I couldn't rev over 5.5k. Then a few weeks later it was down to 5k, then very quickly it dropped to 4k and then 3k. It flat out would not rev above that.
Also when floored the transmission would not shift until I let off the gas...while misfiring.

Any shop should be able to do a back pressure test on a cat to see if it's clogged.
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post #10 of 10 (permalink) Old 04-26-2017, 05:04 PM
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Quote:
Originally Posted by monstermack View Post
Sounds similar. Different engine so different cat in this case.

All I ever got was a misfire and it would go away once I let off the throttle and let the engine settle back down.

But I gradually lost rpm range. First I couldn't rev over 5.5k. Then a few weeks later it was down to 5k, then very quickly it dropped to 4k and then 3k. It flat out would not rev above that.
Also when floored the transmission would not shift until I let off the gas...while misfiring.

Any shop should be able to do a back pressure test on a cat to see if it's clogged.
Wow!!! TY sooo much!!! I found a "back pressure tester" on E-bay and "how to" vids on YouTube!! I'm definitely going to ask those garages I took my car to if they ever heard of a back pressure test!
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