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Discussion Starter #1
Good day all. Having an issue with my 13 Malibu. 2.5L. Car has been idling rough when in drive at stop lights, ect. But runs fine while moving. And doesn't seem to do it in park as bad. Engine rpm will bounce up and down and engine will shutter and idle poorly. Will do this regardless if the ac is on or not as well. Car has 67k miles on it and has had routine maint upkeep. Just recently changed spark plugs, cleaned the throttle body. New air filter. Lucas gas treatment. (car was idling rough before the plug change and throttle body cleaning) And I only run higher octane gas. No check engine light is on as well.

Any ideas or insight would be greatly appreciated!!
 

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although probably not directly causing your issues, you are wasting your money using higher octane gasoline than is called for in your manual...the higher octane has no more power as octane only raises the resistance to knock...works only in engines designed to run higher octane...try a tankful of 87 octane fuel from a Top Tier supplier and see if that helps at all...

what kind of driving does your car get???...stop and go only?, Highway???...mix???...if mostly stop and go, perhaps a trip with varying higher speeds on the highway might help...

I would have guessed the throttle body needed cleaning but you mention you cleaned that...hopefully someone will chime in here with more ideas as to what's causing your issues...

Good luck,

Bill
 

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Discussion Starter #5
As of today I have also cleaned the MAF sensor. Replaced the plug boots and springs (as I have read elsewhere that they can be an issue). Still having the same issue at an in gear idle at a stop light ect. Car will run fine at speed. Gas mileage isn't too great as well atm. Had a friend ride with me to see if he could notice it and he felt it as well. Car would stutter and drop idle to 500rmp or just above. Misfire perhaps?

With no codes or check engine light being thrown im hesitant to take it to a dealership because im afraid ill get the "we found nothing wrong" answer.
 

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Im experiencing the same issue now (May 2019) on my 2013 with the 2.5 eng., 150,000 miles. I had a check eng. light with a code P06DC that I could not determine the exact cause. it was either the camshaft selenoids or oil pressure control solenoid located by the oil filrter. I replaced both cam solenoids with NAPA parts at $46 each, cheap money to try I thought. That did not resolve the light or code. I replaced the Oil Pressure Solenoid with GM OEM part, the light and code are gone but the engines low idle (500-600rpm) began and then the eng would actually stall at lights after it had been driven for about 30 min. It always restarted but once in drive or reverse it would stall after 3 seconds, consistently but it never dies when in park or neutral.
There are no lights or codes now but engine stalls. Because the camshaft solenoids were not bad, I removed the new NAPA parts and reinstalled the factory originals I removed earlier, so far no stalling but the low idle (600 rpm) and engine shake are still happening.
I have a code reader and it can operate in live mode. I was watching the fuel pressure and other vitals and it doesn't appear to have any fluctuating readings. fuel pump runs 55-60psi at idle and normal driving operation, 72psi if I stomp the throttle. Rail pressure is steady also.
I also cleaned the throttle body which was not very bad and I thought I would clean the idle control unit as in past Gm vehicles but I do not see one on this engine. It has the electronic throttle, no cables and when I was spraying the intake cleaner with the engine running the butterfly would open and close as the computers trying to maintain engine idle.
I'm thinking of disconnecting the battery for a time and reconnect to see if the computer resets itself.
 

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2017 SS Sedan 6.2L
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Try a carbon cleaner like seafoam spray or CRC top engine cleaner spray. Carbon build up causes poor idle and bad fuel economy, and eventually causes engine codes.
 

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I wasnt happy with the cam solenoids from NAPA so I checked the originals on the bench by carefully connecting a +/- power and you can hear them working so I installed. YES, I believe disconnecting the battery overnight did the job.
The engine never ran perfect (as new) but never stalled again for a month. It was then involved in an accident and is now in the junk yard.
 

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Discussion Starter #9
I have just about given up on this issue. The constant rough idle and low idle speed after driving 5 min is still an issue. I have tried top end cleaners, CRC, and an AC Delco version too. Replaced the vacuum tube off the brake booster thinking it could have a small leak. Cleaned the throttle body, MAF sensor. Changed plugs and boots. Tried leaving the battery disconnected over night to do a ecm reset. I have pretty much come to the conclusion this car is a pile of junk. And the Chevy dealerships are about as useless as anyone ive ever had to deal with. They wont even look at it since its "not throwing a check engine code" Ive honestly no clue what it could be now. I used to enjoy jumping in my vehicle and just taking random drives somewhere, but I hate driving this pile of crap the 2 mile drive to work. Transmission shifts so hard its not funny. But I wont go into that. This turdbox is about to get traded in on something other than a Chevy product. Worst car I have ever owned, and I will never buy another chevy again.
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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"Hi, I need help. I tried X, Y, and Z. Since nothing I do helps, it must be a pile of junk."

Your 2-mile commutes aren't helping, but at least your random drives could have been its biggest lifesaver so long as they were long enough to get things up to operating temps and also burn out any build-up inside the cylinders.

Honestly, having posted only 3 times here, and only 2 of those being to ask for our help, you haven't brought much to the table on what's happening, what you've done, and any changes after what you've done.

You've shared pretty much nothing, and answered no questions by those whose help you requested. What are we to do? You get folks here interested in helping you and you disappear until you decide to complain more. Our members here are pretty much having a conversation with someone who isn't invested.

Then you cop an attitude and throw a tantrum. I'll spend my time helping folks who participate in the process, and I think others have already taken the same course judging by the contents of this thread.
 

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Discussion Starter #11 (Edited by Moderator)
I apologize for not posting after every time I have tried a, b, c, d, e, f, g, ect. But I have fought with this issue for over 2 years now. I have driven this car on very long road trips over the last 2 years, and it does the exact same thing. every time. I have tried recommendations from other people, with no avail. Ive been told by dealerships that since there is no engine code thrown there is nothing they can do. So yes, i feel the car is a pile of junk. Pardon me for being frustrated and having a **** attitude about it.

CMF edit: removed profanity
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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@beeanner

Take a look at the above from last year when you started this. You asked for help, then got replies not long after. Then a month later you commented again, but it was 2 weeks after someone was again trying to help you.

Now a year later you want help and what do you think folks are expecting? They'll ask questions and/or offer helpful ideas, only to be left out in the cold for weeks or months.

If you really want help, you need to participate in the discussion, especially since you're the one who started it.

These are frank and straightforward remarks because we see so many who are "one-and-done", and even more-so recently now that the site owners have made it a lot easier to find stuff with Google's SEOs. Heck, there was a fella here a few weeks ago who was asking what a code on his car meant. I Googled the code and the very first result was his post, and it was only 43 minutes old! He never even tried and never answered when he was offered help. With him it was just take, take, take with no sense of decency to even say "thank you" for what he got.

So, let's start this all over and move on to see if we can get you some help.

You're working on a 2013 2.5L L4 with a rough idle.

The air filter was replaced last year, MAF sensor cleaned (2x), TB cleaned, new plugs and boots, brake booster vacuum line replaced, and an ECM reset by removing the battery cables overnight.

What is the state of the intake tubing and any vacuum lines to the engine (including the PCV)?

What brand and octane of fuel do you use? (Have you ever heard of Top Tier fuels?)

What is the fuel pressure when the key is turned on, when the engine is running, and what is the fuel flow rate?

Do you feel like spending about $25 to have a diagnostic tool? If so, get the "Torque Pro" app (about $5 when I bought it) and a reasonably reliable bluetooth OBD dongle. With those you can not only read P codes, but you can also watch a whole lot of sensors while the engine is running. You can see what the fuel is doing, what the O2 sensors are doing, and many others. They can be needles, digital, bars, or graphs, or all of those.

I have it on my Android phone, so that means I can see it on my 10" Android tablet as well, making it a lot easier to see details better and/or put more info on the screen. I have also used it to reset error codes and made the CEL turn off.
 

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Discussion Starter #13
@beeanner

Take a look at the above from last year when you started this. You asked for help, then got replies not long after. Then a month later you commented again, but it was 2 weeks after someone was again trying to help you.

Now a year later you want help and what do you think folks are expecting? They'll ask questions and/or offer helpful ideas, only to be left out in the cold for weeks or months.

If you really want help, you need to participate in the discussion, especially since you're the one who started it.

These are frank and straightforward remarks because we see so many who are "one-and-done", and even more-so recently now that the site owners have made it a lot easier to find stuff with Google's SEOs. Heck, there was a fella here a few weeks ago who was asking what a code on his car meant. I Googled the code and the very first result was his post, and it was only 43 minutes old! He never even tried and never answered when he was offered help. With him it was just take, take, take with no sense of decency to even say "thank you" for what he got.

So, let's start this all over and move on to see if we can get you some help.

You're working on a 2013 2.5L L4 with a rough idle.

The air filter was replaced last year, MAF sensor cleaned (2x), TB cleaned, new plugs and boots, brake booster vacuum line replaced, and an ECM reset by removing the battery cables overnight.

What is the state of the intake tubing and any vacuum lines to the engine (including the PCV)?

What brand and octane of fuel do you use? (Have you ever heard of Top Tier fuels?)

What is the fuel pressure when the key is turned on, when the engine is running, and what is the fuel flow rate?

Do you feel like spending about $25 to have a diagnostic tool? If so, get the "Torque Pro" app (about $5 when I bought it) and a reasonably reliable bluetooth OBD dongle. With those you can not only read P codes, but you can also watch a whole lot of sensors while the engine is running. You can see what the fuel is doing, what the O2 sensors are doing, and many others. They can be needles, digital, bars, or graphs, or all of those.

I have it on my Android phone, so that means I can see it on my 10" Android tablet as well, making it a lot easier to see details better and/or put more info on the screen. I have also used it to reset error codes and made the CEL turn off.
First I apologize for my piss poor attitude. It was uncalled for. Long week, and weekend. And, I apologize for not trying to be a little more helpful in answering questions that have been asked. It has def been a frustrating issue. And a pissy attitude isn't going to help one bit.

I will do my best to answer in the best detail I can.

What is the state of the intake tubing and any vacuum lines to the engine (including the PCV)? From what it looks like everything is in good shape. no cracks, bends or breaks. I did replace the main line that t's off the brake booster line and goes to the pcv vales on the back side and top of the engine. Replaced that about 6 months ago. Did not replace the PCV valves yet. I also replaced the purge solenoid as I had seen where that was a possible cause.

What brand and octane of fuel do you use? (Have you ever heard of Top Tier fuels?) I generally use a mid octane fuel from OnCue. its always above 89. usually 90 to 91. I have not heard of Top Tier fuels, you will have to pardon me on that one. I have tried various other fuels from stations around the city at times. Never really noticed any difference. I usually will also add in a bottle of lucas fuel cleaner every 2 months to a tank of fuel.

What is the fuel pressure when the key is turned on, when the engine is running, and what is the fuel flow rate? This I am unsure of. Seeing your question below I will purchase the Torque pro app and get a odb dongle and get this info.

Do you feel like spending about $25 to have a diagnostic tool? If so, get the "Torque Pro" app (about $5 when I bought it) and a reasonably reliable bluetooth OBD dongle. With those you can not only read P codes, but you can also watch a whole lot of sensors while the engine is running. You can see what the fuel is doing, what the O2 sensors are doing, and many others. They can be needles, digital, bars, or graphs, or all of those.

I have ran a CRC valve cleaner through it twice, it usually would help for a day or so, and then back to the rough idle. I also use a synthetic Valvoline oil every time the oil needs changing.

I just replaced the camshaft position actuator solenoids this evening. They were cheap, and probably didn't hurt to replace them anyhow as I had also read a few people replacing them and it helped solve an idle issue. I did notice that one had a little plastic cover on the bottom, and one did not. I removed the little cover on the end and installed it on the new one just in case. Seemed a little loose and tad worried it could come off. Is the little cover meant to be on there or removed?

I usually drive about 30 miles during my m-f commute and an average of 300 or so on the weekends. The rough idle only occurs at a stop. Car runs perfectly fine at speed with no issues, other than the transmission shifting a bit hard. Car isnt hard to start. it always fires right off with no over cranking. Other than the rough idle and the tach bouncing between 500 and higher it honestly runs great. I am more irritated with the Chevy dealerships here than anything.

I do appreciate the help. And again, i apologize for my horrible attitude and lack of effort to post results of what i have done.
 

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2011 Malibu LTZ 3.6L V6 Red Jewel Tintcoat
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You're a bigger person than many. Good job!

And thanks for the extra info.

Top Tier fuels are those that have at least 2x as much detergents than is mandated to be in normal fuels. That said, some, such as Shell, tout as much as 5x in their premium grade. This helps to keep clean anything that the fuel touches.

If your engine is DI (direct injection) as opposed to SPI (sequential port injection), then you could have build-up on the back of the intake valves since the fuel never touches them there. If so, you'd need to use a "top engine" cleaner, such as SeaFoam. Used as directed, it fogs the entire intake plenum and works on the intake valves to soften and break down any build-up. It could take more than one application to do the entire job. If you can borrow a borescope, you can look into the intake plenum and snake it down to look at the backs of the valves to see if or how much crud needs attention.

After replacing the camshaft actuators, it is generally recommended to change the oil.

Please keep us posted with your efforts and the results. Hopefully, others will come along and offer some input, too. I'm no tech or mechanic, so a lot of what I'm sharing is taken from what I've read on CMF and I hope it's right. You're always more than welcome to check what is suggested to see if you're comfortable doing it.

BTW, on that Torque Pro app, once you have any of the Real Time displays showing, click the gear icon and you can toggle HUD mode. That way, you can put it on the dash and see it reflected in the windshield. So long as the lighting is right it's ok, but it's not as good as a real HUD. It works better at night. You also have to have a way to keep the phone/tablet from sliding around, but isn't that what gum is for? ;)
 

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you are probably wasting your money buying any fuel other than 87 octane regular unleaded...higher octane does not produce more power and may be causing a small part of the issue using gasoline that burns at a different rate than your motor requires...(I'm not saying that's your motor issue however)

...you may want to check the intake/throttle body as well as the Mass Air Sensor (MAF) cleaning...use the proper cleaners...

sounds like you are doing a lot towards diagnosing your issue...good luck

Bill
 

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Discussion Starter #16
Oil is getting changed today, its at that regularly time for it.

I will look into the top tier gas from places here and give that a go. And will find out what octane the car actually calls for and give it a shot as well.

When I cleaned the MAF sensor and throttle body I made sure to use only specified cleaners for each of them.

I just keep hoping one day it will pop a check engine light when it starts its rough idle and erratic tach movement. But until then I will just keep trying things!

Thank you for the responses. Hopefully im on the right track to finally getting this resolved. I do have to say, its at least given me something to tinker with :)
 

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Just replied to another thread with some info that hopefully may be of use here. After cleaning my throttle body, I only did that procedure where you let the car idle 3 minutes, off 1 minute, then idle again 3 minutes to relearn the idle. I was watching the Idle Airflow Compensation value start from 40% and settle about 32%. Drove it around a day and felt only a slight difference. The next day, I used a scan tool to reset that value to zero (just like alldatadiy says to), then did the relearn procedure. The Idle Airflow Compensation value went from 0 and settled at 10%. The difference was like night and day! The car quickly got quieter and idled smoother. I've been driving the car about a month now without the hesitation or lack of power I had been experiencing prior.
 

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Chevy Malibu 2015 LS here...facing the same issue. Gave up and trying to sell it now it doesn't seem like its going anywhere tho being an American specs in Dubai. How screwed am I?
 

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Have not been on in a while but this is great info, Thanks for sharing!!
 
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