Caterpillar34

Hey everybody, I have a 2013 Chevy Malibu with the 2.5l engine Auto transmission. My issue is when I'm driving and come to a stop light or sign usually completely stopped brake applied in drive the car will sometimes just idle roughly then stall. Drives completely fine when not stopping. It only does it sometimes, but when it starts doing it doesn't stop when you continually drive it. If I throw it in neutral before I stop it wont stall. Problem is NO CODES! It's my girlfriends car and we have had it 5 months, when we got it, it had a pile of codes, P2097 Generic Current Post Catalyst Fuel trim system to rich, P228D Not Found in Database, and Evap codes P0446 and P0442. I took a day soaked the o2 sensors in gas and cleaned throttle body and air sensors, erased codes and they never came back to this day, but still my stall issue continues, I also replaced the throttle body for the heck of it, still stalling continues. Advice?! Thanks!

oilcanhenry

They sure dont make it easy to work on the Malibu 2.5l throttle body, but the 2.5L is a great motor. How many miles are on the odometer? I would start with cleaning or replacing the MAF sensor, as that can cuase problems without throwing a code. Its also possible that you might have an intake leak at idle, that goes away when you are driving, but I doubt thats the problem honestly.

You can clean it with MAF cleaner but also soaking it in rubbing alcohol overnight which works, as does WD-40 contact cleaner, which is half the price of MAF cleaner and you can use it for other things. Just make sure that its totally dry before you reinstall it, which with the WD-40 contact cleaner is just as fast drying as the MAF cleaner is.

Have you used any intake valve cleaner yet? With GDI, its important to use quality gasoline to keep the fuel injectors clean, but no gasoline can clean intake valves on a GDI engine. I use the CRC brand, but Seafoam is supposed to work just as well.

Caterpillar34

Thanks for the response, there is roughly 202,000 miles on the car. I have only used cataclean and some injector cleaners, but not lately I'll go buy some intake valve type cleaners today. I'll also go ahead and soak that maf sensor tonight in alcohol. I will just order a new one on rock auto as non of my local auto stores carry the MAF sensor on hand. I also could spray starting fluid around the intake to try and find the leak correct? when engine is cold? I also just read a couple minutes ago to check the transmission oil and that the torque converter may not be working correctly with low oil and could cause the stalling issue at idle seems strange but worth looking into. It's also rumored even timing chains could be the cause or a bad ECM but I obviously want to try the little stuff first.

oilcanhenry

Well if your 2.5 liter GDI made it this far without any valve cleaning, thats good news! Yeah I used the CRC Intake Valve and Turbo cleaner on my Malibu 2.5L, but I used some Seafoam Intake valve cleaner on my old 1998 K-1500 too for the hell of it, even though it's not a GDI motor. You should have seen that thing smoke and I use good gasoline in it too. Either one will work well,, IMO.

Yeah, I wouldnt use starting fluid on a warm or hot motor, and I'd be sure to have a fire extingusher handy with eye wear and mechanics gloves on. Used to see guys put some gasoline in a squirt bottle on a hot engine on the intake manifold, but luckily they didnt start a fire, but that was years ago when carburetors were still around and those alone could leak and start an engine fire easy enough with all the leaks they developed over time.

Not fond of not having a transmission oil dipstick, but its not really that hard to pull the side plug out and check it out The 6T40 will drop about 4.25 to 4.5 quarts of Dexron VI fluid if you change it out. The filter is up inside the tranny so no way to change it like we used to do on the older automatics. Hopefully your timing chain is OK. I put a Cloyes chain in my K-1500 but that was easy to do, compared to installing a new timing chain in a tranverse mounted motor like the 2.5 Liter has, with twin camshafts too.

Thankfully we dont have to work on a turbocharger either, which I love about the 2.5 liter LCV motor..NO EGR valve either to cuase issues, which is great news!!

Caterpillar34

Alittle update, cleaning the maf sensor did not work, still stalls. I ordered a new one on rock auto and a new PCV valve because it was cheap enough wont be here til Friday tho of course but I doubt that either are the issue at this point. Tonight I drained the transmission oil, completely black came out looking like it had been in a diesel engine. drove it after the change of new oil and it ran good for awhile when stopping thought maybe it resolved the issue but no it stalls again and it's topped off I drove it and rechecked level several times so I know it's full. I also learned tonight the transmission oil has NEVER been changed 203,000 miles. I'm really leaning towards something in the transmission causing the issue. For example when i'm sitting in my driveway and i'm in park 900 to 1000 rpm low idle and shift into drive and brake fully engaged not allowing car to move it stumbles to about 700-600 rpm then stalls after will say 3 seconds. If i do the exact same thing go from park to drive again but in stead after about a second of it stumbling and me being on the brake, if I take my foot off the brake pedal and let it go forward on it's own it snaps out of it and it idles fine again only happens when I get on the brake and completely stop. I really hope the torque converter isn't bad on this thing. Any other ideas? All my ideas are risky and cost a lot of $$$$, once again no codes to go by so I'm chasing a ghost. Btw are there any service manuals for this car on this forum somewhere? Any help is appreciated!. I also have been running the cleaners thru the cars fuel system lucas oil brand, it's suppose to be the complete engine treatment including intake valves, yet hasn't seemed to make any difference.

oilcanhenry

Sorry to hear the MAF cleaning didn't work but at 200k its likely time for a new one. 203K with no tranny fluid change isn't good. This idea that the car-makers have of never having to change the transmission fluid is why the previous owner likely never changed the fluid. Dexron VI is not cheap, but neither is a rebuilt transmission.

Valvoline makes a very good full synthetic Dex VI fluid which is what I used, but you can buy the GM Dexron VI fluid which I am told is full-synthetic too, cheaper. Summit racing has it at 7.99 a quart plus 9.99 USD shipping, so you'll save about $20 bucks over Valvoline Dex 6 fluid. Of course, you are only getting 4.5 quarts at a change, but that's better then nothing. At least GM gives you a good drain plug which doesn't make a hell of a mess like the old filter pan change did unless you had an extended drain pan which I've had for a long time now.

Yeah, I bought my Bu' used at 40k and the fluid was black as all hell, even then. I plan on 25K fluid changes since I can't drop the filter in the 6T40 tranny. That might be overkill, but the tranny shifts very well and the gas mileage and power with the 2.5 liter motor is quite terrific. When you say the transmission seems to work well if you let up on the brake, are you on auto start/stop mode then?

I don't have any experience with Lucas additives, but I hear some really good things about them, never bad. The real issue with a direct injection gasoline motor like the 2.5 liter (and the 1.5 and 2.0 liter) is that the gasoline never hits the intake valves, so using a good additive like Lucas might well be good for keeping the fuel injectors clean, but the intake valves get hit with oil fumes from the PVC system and never get washed down with gasoline, thus the need to use the intake valve cleaners in a GDI mill.

I don't think there are any DIY manuals of the newer vehicles, but Autozone seems to have some pretty good online tech on their site. Some even with diagrams, but I've not seen a diagram there on the Gen 8 Malibu there. A shop manual will cost about $300 bucks. I wish I knew why Chevy dropped the 2.5 liter from the Malibu engine lineup in 2016, as its only available in the Caddy, the Colorado pickup and the Impala now. I don't want a turbocharged motor, as I drive those all the time in class 8 vehicles and when they go out, its a real money pit. As far as idle, my Malibu runs around 6-700 RPM in idle, never higher then that, unless it's at a cold startup.

Caterpillar34

I'm not familiar with the start/stop mode on this car? I've really been thinking on this issue this week and I've been stalling the car listening and just thinking what all my possible problems could be, but it begins with when the engine is cold and you start it you get a chatter from the engine when first starting it and a slight chatter when running it as well, but the thing is when the car stalls and you immediately start it back up the chatter can be heard again but quite loader, so yesterday I went for it and pulled the valve cover off, and I find the timing chain is as loose as goose. I can't say for sure if the chain is stretched or if it has a failed tensioner or guide because you can't see to much with the front cover on. I ordered my parts off a really decent website I found gmpartsonline.net out of Texas, really good parts breakdowns for my vehicle, I only have to get a few select seals from my local Chevy dealer, hopefully my parts come before the upcoming weekend I want to get to work on it asap. Below I will upload the photos of my chain slop the pictures dont justify just how bad it actually is. I'm also getting new cam phasers/actuator sprockets for the intake and exhaust cams. Upper chain guide removed for clarity.

oilcanhenry

Engine looks pretty clean to me. Can't comment on the chain being too loose from photos, but look to loose. GM parts should work out well.

Janice Dunbar

Curious if you have found the issue because I have exact same problem with my 2013 Malibu an don't know what it could be thanks in advance for any help

Caterpillar34

Hey Janice I can't say for certain why, but right now the car hasn't stalled in a couple months, I believe its because I repaired the downstream o2 sensor when reading data I saw it wasn't working like it should so I changed it and repaired my a/c and car hasn't stalled since. I will say that the car seems to idle rough at a stop and when in drive but doesn't stall so I'm going to repair the upstream 02 sensor to rule that out as well. I'll keep y'all updated I've just been busy lately, i'm going to make more time for the forum!