Cleaned the Mass Air Flow (MAF) Sensor . . .

[tpenfield]

My car has been acting fairly sluggish over the past year or so . . .

- hesitation like an old dog
- rough idle
- reduced gas mileage
- the CEL would come on if I stomped on the gas too much
- etc.

So, I finally did some research and discovered that a dirty MAF sensor (MAS) can cause all of these symptoms. I found a MAF cleaning spray at the auto parts store then came home and took the air intake apart to find the MAF assembly.

I removed the MAF assembly and cleaned it with the spray, then put everything back together. . . took the car for a test drive, and . . . WOW . . . . . . what a difference. The symptoms seem to be gone. I'll have to see how the mileage does over the next few weeks or so. :thumb:

Since I have EFI engines in the boat and they have 800 hours on them, I am wondering if that sort of thing needs to be done on the boat engines . . . :noidea:

 

[bruceb58]

I had same issue with my Lexus at 150K miles. I was going to clean it but decided just to spend the $70 for a new one. Drove like new after I replaced it.

If you happen to use a K&N filter, that can cuase these to get dirty faster. One of the many reasons why I would never use one.

 

[ezbtr]

yup every other year or so Seafoam on Yukon, boy throttle response comes right back, etc, and it had a K&N on it when I bought it, it's a 99 350 Vortec and 121K on it

 

[tpenfield]

I had same issue with my Lexus at 150K miles. I was going to clean it but decided just to spend the $70 for a new one. Drove like new after I replaced it.

If you happen to use a K&N filter, that can cause these to get dirty faster. One of the many reasons why I would never use one.

Yea, my car has 125K miles on it. I remember changing the spark plugs at 100K, thinking that it would improve the performance (didn't do much) and I replaced the air filters this past spring thinking that new air filters would do the trick (didn't either). So, I'm pleasantly surprised on how much of a difference the MAF cleaning made.

I don't drive my car much, since I do the commuter train to work, so maybe it has been sluggish for a few years.

I'll have to check out my boat engines, to see if they could benefit from similar sensor cleaning, etc.

 

[Fun Times]

Most GM based marine engines do not utilize the MAF sensor as they are a speed density system. The MAF sensor is pretty important to keep clean as it will slowly start to have a big effect on the performance of your vehicle should it utilize one. Cleaning a really dirty MAF sensor usually gives you the WOW response like tpenfield experienced.

On either system it's also best to keep the throttle body and IAC valve passageway clean as they do start to get a carbon buildup that will affect both idle and higher end performance.

It's also worth noting that if you have the speed density system then adding a better flowing air filter/flame arrestor typically has no better affect on performance like it would on a MAF sensor system. So save your money on buying into the cold air intake advertisements.

Here's a good read about the differences between the two systems if interested,
http://www.carcraft.com/techarticles/electronic_fuel_injection/

 

[bruceb58]

It's also worth noting that if you have the speed density system then adding a better flowing air filter/flame arrestor typically has no better affect on performance like it would on a MAF sensor system. So save your money on buying into the cold air intake advertisements.

Yeah, it doesn't with a MAF either. Cold Air intakes are the biggest waste of money as are K&N filters. Seafoam is the last thing you want to be putting in engines with O2 sensors.

 

[ezbtr]

Yeah, it doesn't with a MAF either. Cold Air intakes are the biggest waste of money as are K&N filters. Seafoam is the last thing you want to be putting in engines with O2 sensors.

Pretty sure Seafoam is safe for all sensors???

 

[bruceb58]

Pretty sure Seafoam is safe for all sensors???

It's 40% - 60% oil. Not good for O2 sensors. Seafoam claims it won't hurt them but Seafoam came out long before O2 sensors were put on cars. If a car that has bad rings and burns oil can cause O2 failures, makes sense that Seafoam will do the same thing.

 

[bigdee]

If you happen to use a K&N filter, that can cuase these to get dirty faster. One of the many reasons why I would never use one.

Agree. K&N filter may be OK on a marine engine BUT I would never run one on a motor vehicle!

 

[tpenfield]

Most GM based marine engines do not utilize the MAF sensor as they are a speed density system. The MAF sensor is pretty important to keep clean as it will slowly start to have a big effect on the performance of your vehicle should it utilize one. Cleaning a really dirty MAF sensor usually gives you the WOW response like tpenfield experienced.

On either system it's also best to keep the throttle body and IAC valve passageway clean as they do start to get a carbon buildup that will affect both idle and higher end performance.

It's also worth noting that if you have the speed density system then adding a better flowing air filter/flame arrestor typically has no better affect on performance like it would on a MAF sensor system. So save your money on buying into the cold air intake advertisements.

Here's a good read about the differences between the two systems if interested,
http://www.carcraft.com/techarticles...uel_injection/

Good info as I am learning a few things about the EFI/MPI engine control systems. I'll have to check out what sensors I have on the Merc 7.4LX MPI's and what cleaning may be appropriate. No real performance problems with the boat, but maybe something to consider given the 800 hours on the engines.

Meanwhile, I drove (my car) to CT yesterday and there was a fair amount of stop & go traffic . . . even so, I got 30 mpg, which seems really good considering the conditions. Best I've gotten is 35 mpg on a 6 hour trip to PA.

 

[tpenfield]

Just reading up on things and looking at the parts diagrams of my Mercruiser engines, they are speed density type control system, (so MAP instead of MAF) . . . SD systems also typically have an O2 sensor in the exhaust track (from what I read). My engines do not seem to have an O2 sensor, nor could I find anything in the parts diagrams that indicate there should be an O2 sensor.

I am wondering if many marine engines EFI go without the O2 sensor for its control system? :noidea:

 

[Fun Times]

Just reading up on things and looking at the parts diagrams of my Mercruiser engines, they are speed density type control system, (so MAP instead of MAF) . . . SD systems also typically have an O2 sensor in the exhaust track (from what I read). My engines do not seem to have an O2 sensor, nor could I find anything in the parts diagrams that indicate there should be an O2 sensor.

I am wondering if many marine engines EFI go without the O2 sensor for its control system? :noidea:

No O2's on your stock 7.4 MPI to worry about. Merc just recently (2010ish) started using O2's on the new catalyst exhaust systems. Some of the high performance engine builders/tuners may use O2's on non catalyst exhaust systems though.

 

[NYBo]

Seafoam (or any other fuel additive, for that matter) won't do anything for a dirty MAF because air/fuel mix never touches the MAF.

 

[tpenfield]

Seafoam (or any other fuel additive, for that matter) won't do anything for a dirty MAF because air/fuel mix never touches the MAF.

Yup, certainly makes sense since you want to measure the flow of air separately from the fuel. . . . so it would logically exist after the air filters and before the injectors.

Anyway, I drove back from CT to MA and combined that with a bit of city driving and some stop & go . . . got 31.5 mpg overall, so cleaning the MAF definitely helped with the fuel efficiency. . . . probably about 10-15% verses what I was seeing previous to the MAF Cleaning.

 

[robert graham]

My 1996 Buick 350 LT-1 has something that looks like a mass air flow unit on the intake.....at 186,000 miles, should I remove and clean this item....car seems to run fine, but maybe I need to do this?....what you guys think?....

 

[bruceb58]

My 1996 Buick 350 LT-1 has something that looks like a mass air flow unit on the intake.....at 186,000 miles, should I remove and clean this item....car seems to run fine, but maybe I need to do this?....what you guys think?....

You have a MAP.

 

[robert graham]

Should I remove it for cleaning just for routine maintenance?.....

 

[bruceb58]

Post a picture of what you are referring to.

 

[bigdee]

You have a MAP.

MAP sensors normally do not require cleaning b/c they are not in the airflow path. MAP measures negative air pressure rather than air flow. MAP IMO is a more fail safe method of fuel management.

 

[Idlespeedonly]

Should I remove it for cleaning just for routine maintenance?.....

Your maf sensor is right next to the air filter housing.
If your fuel mileage isnt suffering and there are no driveability issues I would leave it alone.