2.4L RPM surge while at constant speed. help

[Burgandy25]

I recently bought an 08 Aura XE with the 2.4l 4 speed. It has been a great car but the dealership was crap, thats another story. But anyway, while at a constant speed wether on cruise control or not the engine will surge about 200-400 rpm then settle back down. That cycle will repeat itself every 10-15 seconds. example: while on cruise control at 60mph the engine will be at about 2100 rpm then surge to 2400 rpm for 2 or 3 seconds, then fall back to 2100 rpm. 10 seconds later back to 2400 rpm then back down. It's annoying because you can directly hear the engine speed change and it effects the instant mpg consumption as well. What do you recon is wrong? I don't think it drops into a lower gear it's just the engine speed changes. At any speed. you can be at 30 mph and it will do this. I have found out that the lower the speed the more drastic the engine rpm fluctuation is.
Any and ALL help is appreciated. I have an appointment Tuesday to get it looked at for a faulty TPMS sensor, 3 cylinder oil leak into the spark plug well, speakers that don't work at all, and steering that pulls to the left. This is all from a CPO vehicle. needless to say the dealer did not to the 174 point inspection they advertise (I found a squirrels nest under my engine while I was changing the spark plugs) all this and more in less than a week of owning the car.

Edit: I own an OBDII scanner and it comes up empty for codes.

[greenman]

Originally Posted by Burgandy25

I have an appointment Tuesday to get it looked at for a faulty TPMS sensor, 3 cylinder oil leak into the spark plug well, speakers that don't work at all, and steering that pulls to the left. This is all from a CPO vehicle. needless to say the dealer did not to the 174 point inspection they advertise (I found a squirrels nest under my engine while I was changing the spark plugs) all this and more in less than a week of owning the car.

squirrels love to chew on wires so you have a real wild card there.

on these cars, the oem door speakers commonly fail after 3 years. easily replaced.

the spark plug seals need replacing. it's not difficult.

no warranty at all from the seller?

I'd connect a scan tool & do a thorough check of all the modules.

[Burgandy25]

It was a citified pre-owned, so it has 100,000 miles 3 year warranty so I have about 27,xxx miles until that goes out. This is becoming more and more a crap shoot with this car.
so far:
3rd high mount brake light didn't work when we picked it up
2 speakers out
1 TPMS sensor is out
rear drivers door lock doesn't work
1 of the key fobs doesn't work
spark plug with oil on it
dirty as heck throttle body
fluctuating RPMs at any set cruising speed
wheel wants pull left
@30mph +-10mph if feels like your riding on oval wheels
animals nest under plastic engine cover

tell me what you think about this: It's a Canadian car (which they never briefed us on until I found it out) But the dash is a US spec. And I have seen that when you change the dash the donor cars mileage stay and they new milage isn't transferred over.
There is probably more but I'd have to think more.

[greenman]

Originally Posted by Burgandy25

animals nest under plastic engine cover

that tells me they never even bothered to remove the cover to do any maintenance at all. that's hard to believe that would be sold as GM certified. I'd be very inclined to take this up with GM US customer service directly documenting all the issues you've had thus far.

if it was a rat or squirrel's nest you likely have some chewed wires which can cause all manner of mysterious/hard to find problems.

tell me what you think about this: It's a Canadian car (which they never briefed us on until I found it out) But the dash is a US spec.

the instrument cluster measurement units (metric to US) can easily be changed in the DIC.

And I have seen that when you change the dash the donor cars mileage stay and they new milage isn't transferred over.

not sure what u mean there

[gpartrid]

OP: As you're taking your AURA in today for the check on some of these items, I'd leave the car with your dealer and ask them to complete the 174 point CPO inspection. You're entitled to it. I believe the dealer will need to provide you with a rental vehicle at their cost if they need to keep your vehicle overnight.

Good luck and please keep us posted as to the progress of these repairs.

[Burgandy25]

When we bought the car it was supposed to have the CPO inspection done, the first day we returned it they promised to do the complete CPO inspection again. So when I removed the engine cover after we received it after the supposedly second CPO inspection we found the nest. So that tells me they didn't do it, twice. I will get a loaner at no cost they have told me I also talked to GMs Customer Care and they officially opened a case last night after I provided pictures of the animals nest/oily spark plug.
I will most certainly keep everyone updated.

[golftango]

While these issues are annoying as it was a CPO car, some of them are common issues and can easily be addressed.

Door lock - bad actuator which is an Achilles heel with the G6/Aura/Malibu. Have the dealer replace this and check the other actuators

Inop door speakers - also a common issues and will need to be replaced, better off with aftermarket speakers at this juncture

Key Fob - soldering is a weak point on the board and a common failure. Dealer should replace this

TPMS - probably a dead battery, easily replaced

Have the dealer perform a four wheel alignment and check the tire balancing. Does this have alloy wheels or steel wheels with covers? I've heard the steel wheels can bend easily so that may be the case, especially if this is a Canadian car as there are a ton of potholes up there.

I have nothing on the spark plug with oil on it. I would have the dealer perform a compression test on all cylinders just to be sure. These 2.4s are pretty bulletproof and I haven't heard of any failures.

The fluctuating RPMs sounds like a faulty sensor somewhere.

The good thing is this is CPO and all your issues can be addressed.

[explorerbigjon]

I agree with most of what everyone else says. Being it should have been a CPO car it should have new tires, if not, these tires could be scalloped or cupped, could just be wheel balancing though.

The RPM flucuation would probably be Torque Converter in the transmission locking and unlocking. Mine will do this time to time depending on road conditions, terrain and speed.

[golftango]

Originally Posted by explorerbigjon

I agree with most of what everyone else says. Being it should have been a CPO car it should have new tires, if not, these tires could be scalloped or cupped, could just be wheel balancing though.

The RPM flucuation would probably be Torque Converter in the transmission locking and unlocking. Mine will do this time to time depending on road conditions, terrain and speed.

Ah, another possibility. My V6 VUE was doing the surging and the dealer said the tc was bad. However replacing the transmission fluid cures this. But that is a Honda transmission. Not sure about the GM 6AT.

[greenman]

Originally Posted by golftango

These 2.4s are pretty bulletproof and I haven't heard of any failures.

On the 05-09 2.2 & 2.4l ecotecs, valve seats are failing:

http://www.cartruckinfo.com/engine-m...ough-idle.html

[gpartrid]

OP: Speaking of "CPO", when you purchased your AURA, did you receive two key FOBs and two keys? I just thought of this as people who buy "pre-owned" often don't receive the manuals or both keys / FOBs. It sounds as though you're on top of it, however.

For those reading this who might not know too much about GM's CPO program, here's the link to GM's CPO page which contains the 172 point inspection sheet. http://www.gmcertified.com/used-car-inspection

[Burgandy25]

Originally Posted by gpartrid

OP: Speaking of "CPO", when you purchased your AURA, did you receive two key FOBs and two keys? I just thought of this as people who buy "pre-owned" often don't receive the manuals or both keys / FOBs. It sounds as though you're on top of it, however.

For those reading this who might not know too much about GM's CPO program, here's the link to GM's CPO page which contains the 172 point inspection sheet. http://www.gmcertified.com/used-car-inspection

I received 3 keys and 3 key fobs, They gave us a completely new key fob since the one didn't work at all. They actually gave us a French manual when I went back they laughed and gave me an english one.

Well they got the car done for the most part and it only took one day.
They replaced the TPMS sensor in the right rear tire.
They changed the drivers speaker, and the other blown speaker works now without rattling.
They also rebalanced and rotated the tires, that got rid of the bouncing feeling, also they did a front and rear alignment, the rear was pretty far out of alignment, completely changed the feel of the car.
Then changed the valve cover gasket to fix the oil leak.
They replaced the right rear door actuator.
the noise in the brakes went away so they didn't do anything.
The rodents nest underneath they didn't confirm because I cleaned it out like I'm gonna leave it in there, but they replaced the wire protectors under there that were dry rotted.
The fluctuating RPMs they couldn't reproduce although it always did it when I drove, so i took the main tech for a ride and he saw it finally, and said well it's within operating spec/how it operates so deal with it. He said try a transmission filter and complete flush to see if it would do anything.
They wanted to charge me for the rotation, alignment because its not covered under the CPO warranty, I told them this is stuff that should have been done under the CPO program and I will not pay for it, they were stubborn but agreed to eat the costs. So GM is looking into this and opened a case to investigate this, I told the dealer and they said it's fine and they will have to deal with it and understand my reasoning for being upset.

[gpartrid]

Excellent! You got everything sorted out. You were right to stand your ground regarding the tire rotation and alignment as they're part of the inspection process and needed to be done / fixed prior to the car being put up for sale. Hopefully, you can get the transmission issue get taken care of, as well.

Tire rotations, oil changes and multipoint inspections are included with your first 2 years of CPO ownership. For anyone who might be interested, here's the link to the GM CPO "Maintenance Plan" page:
http://www.gmcertified.com/used-car-maintenance-plan

As I'm not a DIYer, I purchased a General Motors Protection Plan (GMPP) at the time I purchased my AURA so as to make sure I'm covered for the next several years in the event anything major goes wrong (long story but I purchased my AURA new in 2008, traded it in at a major GM dealer in 2011 and bought it back 50 weeks later in 2012 from the same dealer with only 5k miles put on her during that time). That's how much I love my AURA.

The AURA is a terrific vehicle and hopefully your experience will be as satisfying as that of most owners here.

Now, enjoy your AURA and visit the forum often. There's a wealth of information here and a lot of incredibly friendly and knowledgeable people who are willing to share their experiences.

[Burgandy25]

well mostly everything was fixed. They said the surging was normal and within operating specs but I took it to another Chevy dealership and they said that it doesn't sound like it should be doing that so later today I'm bringing it there so they can look at it.

[gpartrid]

You definitely did the right thing by going to another dealer to have the surging checked out. Please keep us posted regarding the outcome of their assessment.

[Burgandy25]

Originally Posted by gpartrid

You definitely did the right thing by going to another dealer to have the surging checked out. Please keep us posted regarding the outcome of their assessment.

So a few things, this is a "known problem" with the RPM "flutter/surging" It is common across all cars with the 4t45e. Gm has been saying for a few years that a "fix" is in the works but none that I have found on any forum with this same tranny. But this is what my quest did find other than its a common problem.
1). reset the adaption process/ re-flash the ECM.
2). replace the TCC (torque converter clutch) solenoid.
3). replace the whole Torque converter. as per this link:
http://content.chiltonsonline.com/TS...bsOLvKhQ%3d%3d
I am trying to get the dealership to do all 3, since it's under warranty and will not cost them anything since GM will re-emburse them anyway. It's better than a process of elimination that could take a very long time. because the adaption process takes about 2k miles and after that magical mile it will come back (as reported on other forums). and some people had the TCC replaced with luck.
I am talking to them tomorrow to try and get an agreement on what to do. thanks a lot. and BTW I'll be posting a "How to:" on transmission fluid/filter change AFTER we get the tranny stuff figured out based on if they have to drop the pan or not. and also a power steering fluid change and brake bleeding, the last two will be ho hum since it's easy. But I will include pics as well.

[Burgandy25]

Well some sad news, they are refusing to fix the tranny they still say it "has no problems" even though I sent them links to others with the same problem that was semi fixed. (different forums) so we are taking them up on their offer to buy the car back. So we will be looking for an Astra or another Aura. We already own an Astra and it's a great car, it really is. We have our eyes on an Aura Greenline, and a few Astras.

[golftango]

If you have your heart set on an Aura, look for '09s. They have the 6 speed transmission and not the 4 speed one.