Dirty MAF? 08 Malibu 2.4 Ecotec. stall/stumble?

[irv]

My son told me yesterday that his car stalled on him while he was in transit taking his girlfriend to work. He pulled/coasted over and it took 3 times/turns before the car would start again. Once started, he made it to her work and home without any further incidents.

He just came home himself from work for supper and he said the car is stumbling again but it hasn't died on him yet. He is obviously concerned as he is working until midnight tonight but of course I told him I will get him if it does die or doesn't start.

We purchased this car back in Aug. It has 145,000 kms and other than oil/filter changes, I don't know much of anything about this engine.

MAS is what I want to conclude but I open to other ideas as well. I don't think plugs/wires/coils would act like this but I want to hear others opinions.

If it is the MAS, I assume get some MAS cleaner and spray/clean everything good?

ChrisFix has a pretty good vid but I don't have the computer/laptop to test things like he does in it. A volt meter is about the extent of my electrical type tools I own.

 

[Leo99]

I'd clean the MAF and look at the spark plugs and probably change them if it's about time for them to be changed.

Could be some sensor going bad. Do you have an obd11 reader?

 

[clinebarger]

The easiest way to check the MAF sensor on a GM vehicle with a MAP sensor; Without a scan tool or a scope........Is to Unpin the Yellow wire out of the MAF connector & force the ECM to operate in Speed Density mode, VERY easy to do on GT-150 connectors!
*Remove the weather pack lock from the rear of the connector.
*Remove the terminal pin lock from the front of the connector (Usually Purple in color) with an awl or pocket screwdriver by lightly prying at the narrow ends of the lock.
*Looking at the mating end of the connector.....You will see a small black tab that secures the terminal pins, Using an awl lightly pull the black tab away from the terminal pin while simultaneously pulling on the yellow wire at the back of the terminal.
*Isolate the Yellow wire from shorting against anything.
*Replace the 2 locks on the connector & plug the MAF back in.

The reason it's not wise to just simply unplug the MAF altogether is because the IAT sensor is built into the MAF! The ECM will now set P0101 (MAF Sensor Performance) & operate in Speed Density mode.
*Do not clear P0101 with the yellow wire unpinned!!

IF the engine now runs like it should.....You have a MAF sensor issue.

If this car rolled into my bay, I would do the following.....
*Scan for DTC's & record. Clear the DTC's (Reviewing the freeze frames before clearing the DTC's is a good idea)
*Set-up the scanner to only display engine performance related PID's.......TPS-vdc, MAP-vdc, MAF-Hz, STFT, LTFT, Engine Load-%, Engine temp, IAT temp.
*Install a fuel pressure gauge as GM & fuel pump failures/issues go hand & hand!
*Thoroughly test drive the vehicle while watching the fuel pressure.
*Hit "record" soon as it acts up, This will data-log the custom data parameters/PID's that I selected.

 

[Leo99]

What kind of reader would you recommend for what you described, Cline?

Could it be something as simple as a bad tank of gas or dirty fuel filter? Does this car even have a fuel filter?

 

[clinebarger]

Originally Posted by Leo99
What kind of reader would you recommend for what you described, Cline?

Could it be something as simple as a bad tank of gas or dirty fuel filter? Does this car even have a fuel filter?


Snap-on Solus Ultra is what I use at work, I personally own a GM Tech 2 that will data log but does NOT allow a custom data list or PID graphing.

HP-Tuners Scanner....Which I also personally own works just as well if not better than the Snap-on offerings on GM/Domestic vehicles. The sample rate is lightning fast no matter how many PID's you have selected & the graphing resolution is really good. Requires a Laptop PC.

There could be really good scan tools that do the same things at a lower cost?

His problem could be many different things, I haven't gotten bad gas/fuel or even seen bad gas in so many years that I don't even test for it. The fuel filter is not serviceable & mounted in the tank. Just about all gasoline GM products have been this way since 2004.

 

[irv]

Originally Posted by Leo99
I'd clean the MAF and look at the spark plugs and probably change them if it's about time for them to be changed.

Could be some sensor going bad. Do you have an obd11 reader?


I am going to purchase some cleaner today and see what that does? Plugs are likely due but I don't think they would cause this problem, but I could be wrong?

Originally Posted by clinebarger
The easiest way to check the MAF sensor on a GM vehicle with a MAP sensor; Without a scan tool or a scope........Is to Unpin the Yellow wire out of the MAF connector & force the ECM to operate in Speed Density mode, VERY easy to do on GT-150 connectors!
*Remove the weather pack lock from the rear of the connector.
*Remove the terminal pin lock from the front of the connector (Usually Purple in color) with an awl or pocket screwdriver by lightly prying at the narrow ends of the lock.
*Looking at the mating end of the connector.....You will see a small black tab that secures the terminal pins, Using an awl lightly pull the black tab away from the terminal pin while simultaneously pulling on the yellow wire at the back of the terminal.
*Isolate the Yellow wire from shorting against anything.
*Replace the 2 locks on the connector & plug the MAF back in.

The reason it's not wise to just simply unplug the MAF altogether is because the IAT sensor is built into the MAF! The ECM will now set P0101 (MAF Sensor Performance) & operate in Speed Density mode.
*Do not clear P0101 with the yellow wire unpinned!!

IF the engine now runs like it should.....You have a MAF sensor issue.

If this car rolled into my bay, I would do the following.....
*Scan for DTC's & record. Clear the DTC's (Reviewing the freeze frames before clearing the DTC's is a good idea)
*Set-up the scanner to only display engine performance related PID's.......TPS-vdc, MAP-vdc, MAF-Hz, STFT, LTFT, Engine Load-%, Engine temp, IAT temp.
*Install a fuel pressure gauge as GM & fuel pump failures/issues go hand & hand!
*Thoroughly test drive the vehicle while watching the fuel pressure.
*Hit "record" soon as it acts up, This will data-log the custom data parameters/PID's that I selected.


Cline, that is all great information, but I have nothing more than a volt meter and although your suggestion is likely spot on, I don't think I will be getting into pulling wires like you suggest.

I'll see what my son says here this morning or afternoon then take it for a test drive myself to see if I can mimic what he says it is doing.
He said he did just fill his car with gas but like you, that is a rarity and the place he got it is a busy gas station and a top tier one at that.

If I can't do it myself, I will take it to my bud who is a mechanic who has all the necessary tools/readers/scanners. He is just swamped currently so I know it may be a few days before I can get it in.

Thanks for suggestion, gents.

 

[dogememe]

Originally Posted by clinebarger
I haven't gotten bad gas/fuel or even seen bad gas in so many years that I don't even test for it.



I was not a believer of "bad gas" until a few months back when I filled up my Crown Vic at some ghetto station somewhere between here and Humbolt where I had to get my Escape out of impound (don't lend cars to "friends") and it ran noticeably worse by the time I pulled out of the station. When I got home I dumped in a few containers of O'Reilly brand generic gas treatment and octane booster and it made a noticeable difference, so I'm pretty sure bad gas was actually the problem.

 

[MasterSolenoid]

I wouldn't do anything until you connect a Code Reader to it.
Get some prices and consider buying one.
This could be an easy fix for you to do at home and you'll always have it.
Twice a year I connect my Reader and look for 'pending' codes.

My vehicle was stumbling once and my Code Reader told me it was the Throttle Position Sensor.
Another time it was the Spark Plugs and Wires.

Good luck.

 

[irv]

Originally Posted by MasterSolenoid
I wouldn't do anything until you connect a Code Reader to it.
Get some prices and consider buying one.
This could be an easy fix for you to do at home and you'll always have it.
Twice a year I connect my Reader and look for 'pending' codes.

My vehicle was stumbling once and my Code Reader told me it was the Throttle Position Sensor.
Another time it was the Spark Plugs and Wires.

Good luck.


Yes, a code reader is something I likely should have purchased years ago but I thought they were rather pricey! I just did a quick google search and seen they weren't actually that bad.

I assume some are better than others so what do you, and others, suggest?

I seen this one just now but there is also another for about $50 dollars less.
https://www.amazon.ca/Autel-Scanner...&hvtargid=pla-523483233581&psc=1

https://www.amazon.ca/Actron-CP9125...&hvtargid=pla-571542206341&psc=1

Thanks

 

[MasterSolenoid]

I have no recommendations on specific models.
I bought mine at AAP for around $70.
It fit my requirements Inexpensive and simple to use.
Maybe others here can give better advise.

Edit: Mine is Actron Model: CP9550

 

[irv]

Originally Posted by MasterSolenoid
I have no recommendations on specific models.
I bought mine at AAP for around $70.
It fit my requirements Inexpensive and simple to use.
Maybe others here can give better advise.

Edit: Mine is Actron Model: CP9550


I just purchased this one. It is currently on sale for 50% off at the place, (Part Source) where I purchased my CRC MAF cleaner.

Maybe my luck is changing?

https://innova.com/en-US/Product/Detail/3020a
https://www.youtube.com/watch?v=bjMXdUkVrOw

 

[SatinSilver]

Hi irv,

I'd also clean the throttle body with some CRC cleaner while you're at it. And probably dump in a container of Chevron Techron fuel system cleaner. Since you don't know much about the history of the car a little preventative maintenance may help with the issue.

I remember my dad taking in my mom's 96 Saturn with low miles to the dealer. It had a cel and the dealer did a tune-up on it, new spark plugs, etc...As he was paying the $350 bill the guy said if that didn't help go to the store and buy the cheapest fuel cleaner you can buy. A short time later the cel came back so he bought some cheap fuel cleaner. After using it the cel never came back on.

 

[irv]

Originally Posted by SatinSilver
Hi irv,

I'd also clean the throttle body with some CRC cleaner while you're at it. And probably dump in a container of Chevron Techron fuel system cleaner. Since you don't know much about the history of the car a little preventative maintenance may help with the issue.

I remember my dad taking in my mom's 96 Saturn with low miles to the dealer. It had a cel and the dealer did a tune-up on it, new spark plugs, etc...As he was paying the $350 bill the guy said if that didn't help go to the store and buy the cheapest fuel cleaner you can buy. A short time later the cel came back so he bought some cheap fuel cleaner. After using it the cel never came back on.


I seen the throttle body cleaner there and almost purchased some but since the day was ticking on, I decided against it.
I just finished boxing everything up after cleaning the MAF and the bottom of the air box. I couldn't believe, when I opened it up and removed the filter, there was a bit of water sitting in it? I am perplexed how water got in there and I know it was dry when I put a new filter in back in August.
I suppose it's a possibility that I didn't put the lid/cover on correctly when I replaced the filter back in August, but I am usually pretty anal about stuff like that.

My son said he did drive through a big puddle not long ago, but even still, I don't think water should be getting up in there, should it?

Anyways, I received no codes with my new scanner but I did clean the MAF nonetheless. The car seems peppy and it didn't act up on me at all when I took it for a good drive.
I have some plugs that I'd like to do but I'm heading out to a Gen's game shortly so that is going to have to wait until another day.

Fingers crossed here that what I did cured it, but of course, only time will tell?

P.S. I did dump a full can of Seafoam in it to help if he did in fact get some sh*tty gas and to do some cleaning as well.

Thanks SS.

 

[Leo99]

Good luck. Hope you fixed it.