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Question re: cleaning the MAF Sensor

M

mjagusch

New CEG'er
Joined
Dec 28, 2006
Messages
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I have a couple of questions about the MAF sensor I was hoping someone could help me with.

For background I've recently started having a hard start & rough idle (along with a P0175 and some other symptoms described in TSB #982310.

Since the symptoms seemed consistent with those caused by a contaminated MAF sensor (per the TSB), I thought I'd try the cleaning procedure documented on this site.

First, I did not have the tamper proof T-20 that I needed to remove the MAF, so I removed the air filter box instead and attempted to clean it "in place" - hopefully this was a bad thing to do.

Looking at the sensor I could see "gunk" on the wires. I uses electrical contact cleaner to clean the sensor. The wires looked clean when I was done.

So I let the cleaner dry off and reassembled the filter box. Unfortunately I did not notice any improvement in performance.

Do I need to also reset the computer to clear any bad MAF readings before I notice an imporvement?

Or did I just do an improper job cleaning the MAF by not removing it completely? I went to Autozone today to get the right set of torx so I should be able to disassemble properly tonight if need be. One thing that I noticed about my sensor though that differs from pistures posted on this site it that I have only one torx screw - the other side of the sensor looks like it's riveted (it's got a rounder head anyway). Is there any trick to getting this apart?

Or I guess the third possibility is that I either need a new sensor or I'm barking up the wrong tree entirely and my problems are caused by something else.

Any advice is appreciated - thanks in advance!
 
Great article - thanks!

Cleaning the MAF didn't seem to help and I've replaced all the easy stuff (plugs, fuel filter, etc.) so I'll be trying to test my sensor tonight. Anything else I should be checking that I may have overlooked?

Thanks again.
 
Not sure what year you have, but test the Intake Air Temperature sensor and Engine Coolant Temperature sensor too.
 
mjagusch said:
For background I've recently started having a hard start & rough idle (along with a P0175 and some other symptoms described in TSB #982310.

Since the symptoms seemed consistent with those caused by a contaminated MAF sensor (per the TSB)
Click to expand...

In my experience a dirty MAF reduces measured airflow and leads to a lean condition.

When faced with a rich condition - consider high fuel pressure, leaking injectors, or a bad ECT as Tony suggests.

If the problem started or is worse with cold outdoor temperatures, check the function of your secondaries.
 
I started with the MAF mainly because googled my symptoms (including P0175) and came across TSB #982310 which deals with the MAF.

I did try the MAF test procedure in the Autozone article linked a couple of posts up and I did not get the correct voltages. Still not sure if this is because I screwed the tests up or because the MAF is bad :rolleyes:

If anyone's got experience doing these tests, here's what I did.

First, I do not have a shop manual or any way to determine exactly which leads are GND, VPWR, SIG, and SIG RTN.

Left to right I have white/blue, brown/blue, black/brown, and green wires going to the MAF sensor.

I deduced that the green lead is ground. (With the connector off the impedence between green lead and ground was zero.)

Similarly I believe the white/blue lead is VPWR because it was the only lead that registered voltage (~12.5) when the key was on (but engine off).

With the engine on, the voltage on the other two leads was 14+ volts. The Autozone article says the correct voltages are at least 4.5 V for SIG (but does not list an upper limit), and between 0.34 and 1.96 for SIG RTN.

Am I doing something wrong with the tests or do these results indicate a bad MAF? I'm mainly wondering if there's any way I messed up which lead was GND?

As always, any thoughts or advice is appreciated!
 
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