MAF Sensor

[jakeyf08]

I have had a maf sensor issue...my check engine light came on and it was running like garbage the code came up for maf sensor so I replaced it and reset my truck. now my check engine light is still on with a maf sensor or maf sensor ??? circuit???? it still isnt running like it should. any solutions to this problem?

[MT-2500]

Originally Posted by jakeyf08

I have had a maf sensor issue...my check engine light came on and it was running like garbage the code came up for maf sensor so I replaced it and reset my truck. now my check engine light is still on with a maf sensor or maf sensor ??? circuit???? it still isnt running like it should. any solutions to this problem?

What year make and model and engine and transmission and mileage?
What was the code np?
Has codes been cleared and recheck for what code no comes back?

[jakeyf08]

it is a 96 blazer with a 4.3l v6 vortec. It has 200k on it. auto. I can't remember the code off the top of my head I will have it scanned again and post it. and I did have it reset once a few months ago. I will have it reset again and try that...

[jakeyf08]

I took off the negative for a few nights becuase I wasnt driving my truck. When I hooked it back up i drove it nearly 40 miles with out any problem ran great and then my ses light came back on and its not running 100% again. I recently had a bad cat and it was replaced. them my tail pipe fell off and it was running rich. i fixed that and reset the codes and it is back on once again with the maf sensor code....idk what is going on. ( the maf sensor was replaced only 2 months ago )

[MT-2500]

We need the code no?

[MT-2500]

There is 3 or more different codes for MAF sensor.
And they take you in different directions of repair.
Your best bet is to get the repair manual repair flow chart for the code you have and go threw it step by step.
A GOOD FACTORY MANUAL OR A ALL DATA ON LNE SUB HAS THE CODES AND REPAIR FLOW CHART FOR THEM.
http://www.alldata.com/products/diy/index.html
Good Luck

[jakeyf08]

Finally I have the codes! The MAF Sensor codes did not come up. The only two codes that I have now are:

P0174 System too lean bank 2
P0171 System too lean bank 1

I have an intake, high flow cat, and high flow muffler. The tail pipe came off the universal muffler and I did not have a chance to fix it for a few weeks so I can understand why it was running lean. Now that the tail pipe is back on could I need new 02 sensors????

ANY HELP WOULD BE GREATLY APPRECIATED!

[discnik]

With both banks reading lean it sounds like a vacumm leak from an area common to both banks. Have you checked PCV valve, vacuum lines, Intake manifold, plentum gasket ? I had a 96 F250 with this problem turned out to be the MAF sensor, but you have already replaced yours. Also had an 01 Explorer Sport with same codes turned out to be the rubber elbow on the PCV tube, squeezed elbow taking tube off and noticed cracks along the mold seam. Does yours have the poppet valve type fuel injection ? There has been a problem with the injectors on this system.

[MT-2500]

O2 sensor codes do not say replace 02 sensors.
Is it a cold air intake or cone filter setup?

Also confirm good fuel pressure.
Low fuel pressure will make it run lean.


The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[jakeyf08]

It is a cold air intake with the cone filter. (aftermarket K&N made for blazers). I am waiting to go home to check the fuel pressure. I am at school and I need to find some time to go home and check everything out.