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Hi,
We have a 2009 Traverse AWD LTZ with 138,000 miles. Owned since 2010.
3 new timing chains resulting in new updated long block dealer installed at 85k miles.
All TSBs done, mobile 1 oil changes dealer performed through warranty (for tracking purposes) and me now every 5k miles.
Dealer installed a catalytic converter at about 110k miles. (need to look at paperwork, think bank 2).

Sorry for the long post, but I'm hoping someone will spot something out of it.

Wife drives this car. For the last 8 months, we have gotten a P0420 randomly coming on and off a 1/2 tank or so at a time, sometimes nothing for over a month. I had a simple code reader and was not too concerned, seemed like it could have been bad gas...

In the past 4 months, she had complained that there was a "shudder" sometimes with speed 40+mph rolling on the gas, especially up hill. In the past month it shuddered quite a bit like "going over speed bumps".
So I drove it, but couldn't get it to do it. Until about 2 weeks ago. I researched a ton on here, looking at all transmission issues (3,5,R waveplate TSB that was not done on ours) etc. It did not feel like a misfire like when the timing chains went, so I was thinking we reached the end of life on the trans and I was feeling converter shudder. Weird was in the neighborhood at 20mph uphill it did it sometimes and I know the converter is not trying to lock at that point.

We drove a full load to the airport 2 weeks ago, and on the way I got a message (not a DTC) "trans fluid hot, pull over" or something. At 5:30 in morning, mother in law driving home and picking up the fam in a week, so I got a quart of fluid at a gas station and poured in 1/2 quart and said "take it easy". That message has never come back.

Last week I had a transmission shop drive it with me in the car. Old school tranny guy. It shuddered twice during the drive (mild). Got back and I was embarrassed as the trans fluid was nearly off the stick low. He filled and said, "if this takes care of it you're good, otherwise you need a tq converter".

So, back to researching, I was thinking the entire tranny was trashed. I decided to do a drain / fill since I don't know when the last time it was done at the dealer (will look at receipts) and that he just put in a quart from a bulk can that I'm sure was Dex III, not Dex VI.
Did a 5 quart drain / fill with a tube of the Lubegard instant shudder fix. To note, the drain plug was perfectly clean, not even any gray slime on it. Definitely no bits. I think the waveplate is intact.

For the next week the car felt like the engine was peppier, more "connected" to the drivetrain. No shuddering, etc. Then after a week, it shuddered quite a bit. Ugh.

So I ordered a Foseal wifi code reader so I could log more variables, more to look at the P0420 issue with regards to O2 sensor function, etc.

I've been driving it all week, and it has hardly shuddered at all. I would think if it was a converter issue, it would repeat quite regularly. (My '96 Impala SS had a performance converter that shuddered, and it would always do it at lockup until I pulled it and got another one in, for example)

Could it be misfire causing the shudder at very inconsistent times?

Today I logged and looked at a lot of info on the logger. Its amazing how much info is on there, especially all the diagnostic testing it does.

Did a cat / o2 test. in park hold at 2000 rpm (couldn't hold 2400 as described) and watched the downstream O2 readings. Bank 2 was steady at .1V, Bank one was a bit searchy but around .6V +/- .1V. Bank 1 long term O2 is 0% trim, Bank 2 is -0.78% trim. For secondary O2, bank one is 1%, bank 2 is 12%.
In driving, bank 1 cat temperature is aways about 20C higher than bank 2.

As far as "lazy sensors", all 4 seem to have similar voltage and sensor transition minimum / maximum times and calculated minimum / max times between transitions..

In the self diagnostic list, all is fine except I have an Evap System test: not passed. There is no DTC saved or lit, but the diagnostic test does not pass.

I have to read how to diagnose the evap / purge system issue. There are plenty of counts and some weird (to me) pressure readings that cycle on the purge system.

Just to note, I did research the "coil / plug" issues. I don't know if the dealer installed longblock included coils or plugs or what? I would guess it did but not sure because it was not a detailed list and I know they did not give me a new dipstick because it did not fit correctly. I had to buy the updated dipstick, which was stupid but I didn't catch it until after warranty since I made sure they did all the oil changes during warranty.

I did 3 log sessions going to work today. First time I had 1 misfire on cyl 4. Next I had 2 misfires on Cyl 2, and then I had 7 misfires cyl 6. No dramatic shuddering during these sessions. I know these are all front side coils and plugs, might be able to swap without removing the intake manifold, but don't want to swap them if not necessary. Never had a code for misfires.

My plan:
1) do 1 more drain, fill + lubegard anti shutter to get a little more clean fluid in trans
2) diagnose the Evap issue and fix this.
3) Confirm bad cat and change. I think both cats were definitely damaged with the 3 timing chain failures we had, since it ran like **** all 3 times, and the first time it went several thousand miles because the dealer wouldn't diagnose the timing chain (15k to 18k miles before they confirmed it).

After so many years, we do not really want to drop too much into it. Either I fix it and she drives it another 8 months or so, or we trade it in now. This is dependent on whether it truly is a trans issue or it is actually a misfire issue. I will log more to see what correlates.

I'm very sorry for the long post, but if anyone has more things for me to look at, I will gladly listen.

I can swap a cat / O2s no problem. I can swap the entire evap system. I can change coils and plugs. I will not R&R a trans and on fence to do a $3k installed reman trans with 3 yr warranty vs trade in now.

Thanks for any insight or hints as to where to look/ what other tests to go through.

-PJ
 

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the 2009's are known to have issues with the plugs/coils.


Causing misfires... usually on the highway going uphills. folks thinks its the trans.




The other thing is misfires.


on my 2010, Ill get misfires.
But they usually begin to occur around the 3500-4500 mile mark- since the previous oil change.

And I usually feel it/see it on the tach- and its soon after I leave my house on cold mornings.


I run a bottle of Techron right before every oil change.


So for the misfires to show up at that point-- im not surprissed.
I get the feeling the carbon I get is around the lip of the valves.
After I run a bottle. the misfires go away.
Its also not many. Ill say- 0-20 misfires in 1 or 2 cylinders.


Im at 143,000 and still on my factory coils.
I did change my plugs at 100,000/
 

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Discussion Starter #3
Thank you for this. I don't know that 1-7 misfires in a 20 minute driving range is unusual or not. That is a lot of cylinder events.

When I received new engine from GM (gave me the updated '13 up engine after rebuilding mine at 18k, and 38k) I just don't know what comes on a long block. I would assume spark plugs were included.... BUT:
I had to ask for the new oil cap (I wanted it to say Dexos Only) and I definitely got my old dipstick, so if that's the case I likely got my original coils for sure and would they really put my used spark plugs in? Even so there is 50k miles on the new engine now so all is fair game again.

I agree, seems like misfire. Now that I am logging it as I drive, of course I am not getting the severe stuttering of the converter that it was doing last week when I didn't have a real time monitor/logger. :)

-PJ
 

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@PJGross...This sounds entirely too familiar...I have a 2011 Buick Enclave AWD, and have been experiencing all that you have described over the last year of so...P0420, light misfires tracked on cylinders 1, 3, 5 (bank 1), shudder under light load on inclines...I did not have the timing chain/engine replaced, but I have used the same Shudder Fixx with limited success.

One question for you...What, if any, decrease in gas mileage have you seen??? My wife generally drives 90+% city/hills/short trips, and we are sitting at about 12-13 MPG...I feel like it was better, before, and I want to attribute it to the misfire/catalytic converter/shudder, but maybe the driving environment is just lousy for mileage.

Did you see any drop in mileage as the issues started to materialize?
 

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Discussion Starter #5
When we had timing chain issues, sometimes we had misfire codes, the first and last time they went we did not set a code but gas mileage and driveability became horrible. Yes, 12-13 mpg was in that range.

My current situation is that mileage is 16.5 mpg mixed. About what we've gotten with the new engine for the last 50k miles.

I did another Cat test, but in trying it I think I might be onto something:
Cat test: in park, up to temperature, hold at 2400 rpm and watch up and downstream O2s. Tried it several times, but frustrated that I could not hold 2400 rpm. I thought my foot was sensitive at first, but I have a good constant foot (autocross and roadcourse experience... LOL) so I decided to log fuel trim and throttle position.

@ 30% throttle, I would hit 2400 rpm, but then fuel trim would shoot up (rich) and without my foot moving, throttle % would drop and rpms would drop to 1500 rpm or so, then after a few seconds fuel trim would go negative (lean) and rpms would climb back up to 2400 rpm along with throttle going back to 30% with my foot never moving.

Question is, why? I would guess maybe a vacuum leak of some sort? I logged both bank 1 and bank 2 and they both react in the same fashion. No logged knocks during this sequence.

I would think it should hold 2400 rpm, correct? Maybe I am on to something, I just don't know what else to log to investigate further.

I will order new cat (definitely poor response for bank 1 in the test when I was able to get a stable rpm for a few seconds) at around .6V occilating +/-.2 vs a rock steady bank 2 at >.7V until the high fuel trim event where the downstream 02 drops to .1V.

If no one has ideas, I will fix the known bad cat bank 1, change coils and plugs due to age, and evap purge solenoid for $30 bucks. See what happens and take to local mechanic for further testing if the surging is still present.

-Paul G.
 

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I can't really shed any light on this exact situation. But I will say that the number of misfires required to set the CEL can be higher than you may expect. On my '08 Grand Prix, I've had 2 bad coils (3 coils for 6 cylinders) in the last year. Each time, I've only noticed misfires under harder acceleration or uphills around 2500-3000 rpm. There would be a lot of shuddering and acceleration would flatten until the tranny would eventually shift and the RPM's would lower. Each time, with normal driving, the CEL would not come on. Even with several instances of misfire shuddering every 5 minutes, no CEL. Checking with my scan tool, each round of shuddering would produce more than a hundred misfires. But no CEL. The only way I could set the CEL, would be to floor it when the shuddering started while going slightly uphill on the highway.

Also, it is completely normal to have a handful of misfires in a 15-20 drive. Here's a decent article on misfires: http://www.autotap.com/techlibrary/analyzing_ignition_misfires.asp
 

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Big DS,

A few quick answers: A long block is typically only the block and everything in it (crankshaft, rods, pistons, etc) and the head (valves, overhead cams, etc). The fuel injection, ignition, and other sensors and electronic bits would not be included. Now, if I was replacing a long block, I wouldn't hesitate to change the plugs while I was in there, but they're not technically part of the long block itself.

It's certainly possible for the throttle position sensor to misbehave, and that could cause your symptoms. I'm not familiar with the tool you're using, but if it can graph the TPS voltage for you, that's worth a quick check. With the voltage being graphed and the key on (engine can be off), slowly move the pedal all the way down and then all the way up a few times. Look at the graph - any sharp spikes or drop-outs would indicate a faulty TPS. Try this with the engine cold and with it hot. If the TPS is dropping dramatically, that would certainly cause drivability issues similar to what you'd described.

Good luck!
 

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When we had timing chain issues, sometimes we had misfire codes, the first and last time they went we did not set a code but gas mileage and driveability became horrible. Yes, 12-13 mpg was in that range.

My current situation is that mileage is 16.5 mpg mixed. About what we've gotten with the new engine for the last 50k miles.

I did another Cat test, but in trying it I think I might be onto something:
Cat test: in park, up to temperature, hold at 2400 rpm and watch up and downstream O2s. Tried it several times, but frustrated that I could not hold 2400 rpm. I thought my foot was sensitive at first, but I have a good constant foot (autocross and roadcourse experience... LOL) so I decided to log fuel trim and throttle position.

@ 30% throttle, I would hit 2400 rpm, but then fuel trim would shoot up (rich) and without my foot moving, throttle % would drop and rpms would drop to 1500 rpm or so, then after a few seconds fuel trim would go negative (lean) and rpms would climb back up to 2400 rpm along with throttle going back to 30% with my foot never moving.

Question is, why? I would guess maybe a vacuum leak of some sort? I logged both bank 1 and bank 2 and they both react in the same fashion. No logged knocks during this sequence.

I would think it should hold 2400 rpm, correct? Maybe I am on to something, I just don't know what else to log to investigate further.

I will order new cat (definitely poor response for bank 1 in the test when I was able to get a stable rpm for a few seconds) at around .6V occilating +/-.2 vs a rock steady bank 2 at >.7V until the high fuel trim event where the downstream 02 drops to .1V.

If no one has ideas, I will fix the known bad cat bank 1, change coils and plugs due to age, and evap purge solenoid for $30 bucks. See what happens and take to local mechanic for further testing if the surging is still present.

-Paul G.
Dirty Throttle Position Sensor?
 

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2013 Traverse AWD having a shutter issue seems like in 3rd gear uphill under load....been researching and seems like the oil from PCV valve causing the Throtte Position Sensor to be inconsistent. I have seen some people reference a bad Torque Converter also. Think I will try to clean the whole intake assembly/throttle body of oil and see if this fixes shutter. Hard to tell if it's a misfire or trans issue. Will try to update if cleaning fixes or not.
 

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2013 Traverse AWD having a shutter issue seems like in 3rd gear uphill under load....been researching and seems like the oil from PCV valve causing the Throtte Position Sensor to be inconsistent. I have seen some people reference a bad Torque Converter also. Think I will try to clean the whole intake assembly/throttle body of oil and see if this fixes shutter. Hard to tell if it's a misfire or trans issue. Will try to update if cleaning fixes or not.
Any update?
 

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2013 Traverse AWD having a shutter issue seems like in 3rd gear uphill under load....been researching
and seems like the oil from PCV valve causing the Throtte Position Sensor to be inconsistent.
I have seen some people reference a bad Torque Converter also. Think I will try to clean the whole intake assembly/throttle body of oil and see if this fixes shutter. Hard to tell if it's a misfire or trans issue. Will try to update if cleaning fixes or not.
Let me know if you have oil If your clean air intake or if throttle body is gunked up. The actual throttle body position sensor is outside of the throttle body, so no gunk in it, and it can not be cleaned.

Is what you notice, could it be called a stumble?
I posted this vvt sensor post before... check your solenoid also

My 2 cents,

It is not the timing chain per say, but the two solenoids that adjust the timing chain, that is, the solenoids that advance or retard the timing of the valves opening and closing on this VVT engine, (Variable Valve Timing). ....... Let me explain

The intake and exhaust solenoids use engine oil like a hydraulic fluid, to push a cam, which adjusts the timing of when To open and when to close the intake valves and exhaust valves.

When the solenoids are electrically activated, by the car computer, the solenoids changes the flow of engine oil thru them And the pressure of the engine oil rotates the camshafts thus changing when the intake or exhaust valves open and close.

Since the check valve that opens and closes the oil flow in the solenoid, would not seal properly if the tiniest piece of metal got stuck between the ball and the ball seat, The solenoid comes with a couple of "cigar band" filters to filter the engine oil And prevent any contamination from entering the solenoid
However, these cigar band filters have a very small holes of about 100 microns in size,,,, And these cigar band filters will become plugged with "thick oil chunks", the kind of sludgy oil this engine gets because of its poor PCV design...

What is happening for example, is you start the car, the solenoid opens to retard the timing for idle, but the cold oil is not flowing quickly enough through the plugged up screen cloth on the solenoid, thus the computer throws a crankshaft is not in the right position code..p0017. When oil is warmer, then oil flows thru the plugged up cigar band filters, and valve timing is fine.

Also the car might stumble, at say 30 to 40 mph, as the computer electrically fires up solenoid to advances timing, but the response time is not fast enough because oil is not flowing through the plugged filter screens fast enough as the computer expects it to, and the engine "stumbles", even if it does not throw a code.

The engine oil, and subsequent oil pressure,
is SLOW in flowing thru the plugged screen cloth on solenoid
And engine oil pressure is not able to advance engine timing, fast enough..... hence a stumble.

There is a post on called "Traverse Stumbles on light acceleration No Codes"
where a brilliant "testbob" disassembled
Then cleaned the filter screens on the 2 solenoids....
( one solenoid controls the intake valves, the other solenoids controls the exhaust valves)
He actually has 2 separate posts on the same topic, look for them, read his comment and his solution, he fixed his problem. Here is One post


His 2nd post is a detailed summary of his findings.

I would suggest, removing each of these solenoids and clean the cigar band filters on these solenoids...
This video is of solenoids on 2.4, just so you can see the solenoid filter screen.



In my opinion, use 100 percent synthetic oil, dexos approved, And you change your oil before your oil monitor hits 33 percent or 5000 miles, Then these cigar band filter screens will not get plugged up.
 

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Thanks for all the great info as I also have this problem and suspect it's not the torque convertor or trans.. I tried the link to the cleaning Video but it's not available. Can you repost it?

Sent from my SM-N960U using Tapatalk
 

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Thanks for all the great info as I also have this problem and suspect it's not the torque convertor or trans.. I tried the link to the cleaning Video but it's not available. Can you repost it?

Sent from my SM-N960U using Tapatalk
Video of gM solenoids in. 4 cylinder, a similar pair of solenoids is in the traverse.
the solenoids are named by where they sit in the engine, one advances timing, the other retards timing. You can see the 3 filter screens...in this video.

 
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