2008 Chev Malibu 2.4 stumbling/stalling

[Trav]

No, you can run the engine with the MAF unplugged, if it runs better than with it plugged in you possibly have a bad MAF. On some cars with the MAF mounted in the throttle body many are killed with throttle body/carb cleaner when people clean the throttle body.
Remove this type before cleaning.

 

[The Critic]

I had a 2008 Malibu 2.4 that ran terribly and the fuel trims were pegged out at +25%. A review of the live data showed the IAT readings to be completely erroneous; the IAT and the MAF are one unit on those cars. Replacing the MAF corrected my erroneous IAT reading and fuel trims.

 

[Trav]

The Baro sensor is incorporated into some also, I had a Ford that thought it was at 10K feet sitting at Boston harbor with the sea only feet away.

OP a new Hitachi sensor is only $28 from Rock and is the actual OE part. HITACHI MAF0034, not a lot of wood even if you keep one for future testing.

https://www.rockauto.com/en/moreinfo.php?pk=3020331&cc=1441621&jsn=455

 

[irv]

Originally Posted by Trav
No, you can run the engine with the MAF unplugged, if it runs better than with it plugged in you possibly have a bad MAF. On some cars with the MAF mounted in the throttle body many are killed with throttle body/carb cleaner when people clean the throttle body.
Remove this type before cleaning.


I am hopefully going to try it when the car acts up but since I think this is a moisture problem somewhere I am not anticipating this will show me anything.

Originally Posted by The Critic
I had a 2008 Malibu 2.4 that ran terribly and the fuel trims were pegged out at +25%. A review of the live data showed the IAT readings to be completely erroneous; the IAT and the MAF are one unit on those cars. Replacing the MAF corrected my erroneous IAT reading and fuel trims.


That is something that hasn't been checked so I guess that could be a possibility?

Originally Posted by Trav
The Baro sensor is incorporated into some also, I had a Ford that thought it was at 10K feet sitting at Boston harbor with the sea only feet away.

OP a new Hitachi sensor is only $28 from Rock and is the actual OE part. HITACHI MAF0034, not a lot of wood even if you keep one for future testing.

https://www.rockauto.com/en/moreinfo.php?pk=3020331&cc=1441621&jsn=455



I priced one on Sunday at Parts Source when I originally thought I had found my problem and was shocked when the guy told me it was $167 dollars!

He did say, however, if I returned the old one/core within 48 hrs, I would get the $67 dollars back.
I never priced out an actual OE one but I bet it is cheaper and likely of better quality?

Thanks again for the info guys.

 

[clinebarger]

On GM vehicles with a 5-pin MAF........You un-pin the Yellow wire (MAF Signal Circuit) out of the MAF connector, Then plug the MAF connector back in.
The IAT sensor is incorporated into the MAF & needs to function as there is no good back-up strategy for erroneous IAT input.

Let P0101/P0102 set.....The engine will now run in Speed Density Mode, DO NOT clear the codes!!!

It's pretty straight forward......Unplug the connector, Pry off the Purple retainer, Remove the 2-tab lock on the back of the connector, Then lift-up the small plastic tab that retains the terminal in the connector....Then pull the wire/terminal out.

However.....Generally, There will be telltale signs of faulty/intermittent MAF readings, Like High/Low fuel trims!!

 

[The_Eric]

GM 2.4s are notorious for failed vvt actuators also. When they go bad they do the same you're describing. First, check the oil level - if it's low they won't work right, if level is fine then most likely the actuator(s) are bad. They're cheap at the dealer - shop cost is like $35

 

[irv]

Originally Posted by clinebarger
On GM vehicles with a 5-pin MAF........You un-pin the Yellow wire (MAF Signal Circuit) out of the MAF connector, Then plug the MAF connector back in.
The IAT sensor is incorporated into the MAF & needs to function as there is no good back-up strategy for erroneous IAT input.

Let P0101/P0102 set.....The engine will now run in Speed Density Mode, DO NOT clear the codes!!!

It's pretty straight forward......Unplug the connector, Pry off the Purple retainer, Remove the 2-tab lock on the back of the connector, Then lift-up the small plastic tab that retains the terminal in the connector....Then pull the wire/terminal out.

However.....Generally, There will be telltale signs of faulty/intermittent MAF readings, Like High/Low fuel trims!!

Originally Posted by The_Eric
GM 2.4s are notorious for failed vvt actuators also. When they go bad they do the same you're describing. First, check the oil level - if it's low they won't work right, if level is fine then most likely the actuator(s) are bad. They're cheap at the dealer - shop cost is like $35


Sorry for the late reply guys.

Touch wood but so far, after a few rains and car washes, the car has not acted up???

I have done nothing to it other than what I have mentioned previously. My son took my truck a few times to work a couple weeks ago when it rained or was raining out and when I took his car for some 10-15 minute drives or longer, I could not get it to stumble or stall.

I am not writing anything off just yet but maybe, just maybe, it was an anomoloy or something that somehow cleared itself up? Here's to wishful thinking anyways!!

I appreciate all the help/info that was provided.