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PostPosted: Mon Aug 10, 2009 9:22 am 
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Joined: Sat Aug 08, 2009 9:03 pm
Posts: 174
Location: Winnemucca, NV
I did this the other day and posted on the other boards I participate in. Since I'm new here, I'll now post it here.

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Working at Kragen Auto, I recently learned about CRC brand Mass Air Flow Sensor Cleaner. The concept sounds logical - your Mass Air Flow Sensor (MAF) tells your computer how to set your fuel injection system to run at optimum. A dirty sensor can cause false readings that result in poor performance or increased fuel consumption.

Recently my friend Graham C., often seen on my website, went on a 11 day long off road excursion with a group of other off roaders in the red rock country of the northern Grand Canyon rim. Getting home, he found that his 2000 Toyota Tacoma TRD 4WD pickup started acting up in high idling, poor acceleration, high gas consumption. He pulled apart his intake tract and found heavy accumulation of red dirt and dust all the way to the engine. All this got by his air filter.

A couple weeks later I learned about the CRC cleaner and suggested it to Graham. As yet he's purchased it, but yet to apply. Today I decided to apply it to my Tacoma, now that it's getting on the high side of 130,000 miles, I figured it should become a part of my routine maintenance.

The task was rather daunting, mainly because of the potential of inflicting damage on high cost parts (remanufactured MAF sensors I've sold run nearly $200). I thought I'd pass this information along in case some of you might think this beneficial to your maintenance plan.

Some photos and notes:


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The MAF sensor in place before I cleaned the unit. It's a tight squeeze on my truck due to the proximity of what I believe is to be the cruise control equipment (which is just visible on the lower left corner). It is held in place by two Phillips head screws.


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To get in there, I used an offset Phillips to start the screws out, because at the time I couldn't find my stubby Phillips in my admitedly messy tool drawers. But the screws have a fairly tight thread and require quite a bit of turning, so it was a pain because there's not enough room to make a good arc on the offset driver. I finally found my stubby Phillips, and even then the upper screw was a bit difficult to get to and you couldn't get the driver straight on; but I could get it on enough to finish removing the screw.


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Here's the MAF sensor inside. It was fairly dirty and there was visible residue built up on the probe on the outside. There are three sensor wires I could see - the one on the left side of the proboscis (the sensor of which is shaped sort of like a tonsil) and two thin wires inside it.


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Since the instructions on the can says to remove the connections so that you can spray the contacts, I removed the connector. It wasn't easy. There's nothing to really grasp. Plus you have to pull out on a hard plastic tab to release it simultaneously. I used my small straight screw driver to stick in there so the tab was releasing, but I had to get a larger screw driver to work the connection off. It's a very tight fit and the dirt and crud build-up wasn't helping. Plus I was being very careful so as not to break anything or touch the exposed MAF sensor wires. It took me nearly 15 minutes to work the plug off.


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Close-up detail of the housing with the MAF sensor out and the connector. Surprisingly (but not surprisingly due to the tightness of the fit), the connections on both sides were very clean.


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The instructions say to spray liberarlly the MAF sensor and connections. So I did. I cleaned it up inside and out.


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Here you can see the two wires inside the proboscis looking straight down on it. When I got back outside, I was doing some further spray cleaning and noticed down below the two wires was a small segment of a foxtail burr. It took quite a bit of flushing with spray cleaner to get it out. You can barely see it behind the wires.


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Everything buttoned back up again. I found it not easy to get the MAF sensor back in. It was a cinch to get it out, but the O-ring bound up getting it back in. You can't get anything around the entire unit because of the mouldings in the intake tract, you can't turn the sensor so as to work the O-ring in because there is a slot inside the opening and a corresponding ridge on the proboscis so that it can only go in one way.

It took me about five minutes or so to get the unit on somewhat straight and tight and the two screw tabs equidistant from the opening and the screw seats. I then put in the screws and tightened. There's no way to tell if the O-ring is bunched or pulled from its seat now that it's all in there. Unless I were to pull out that short section of intake pipe, which doesn't look to be all that easy either.

The whole job took me 45 minutes to do. Admittedly, I was taking photos and making notes on my voice recorder. It was rather draining on me, because of knowing the potential to break something. And if I broke the connector, who knows what that would entail to repair or replace, especially since there is no Toyota dealership within 130 miles of here.

CRC recommends cleaning the MAF sensor with each cleaning and replacement of the air filter. With practice, I should be able to do this much quicker, especially now that the connector should come off much easier since it's clean.

I haven't yet driven the truck but did start it. I figured if I damaged the sensor the truck wouldn't start or the CHECK ENGINE LIGHT would come on. But it started and the light remained out. CRC claims 10%-40% more power at the rear wheels, I'll get back here in the future to let you know if I can feel a difference or see a difference in fuel consumption.

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D.A. Wright
~When You Live in Nevada, "just down the road" is anywhere in the line of sight within the curvature of the earth.


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PostPosted: Fri Aug 14, 2009 4:09 pm 
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Joined: Sun Nov 23, 2008 3:07 pm
Posts: 148
Location: Henderson
terrific tutorial

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Kelly aka Mr. D

04 Rubicon;66 F100


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PostPosted: Sat Aug 15, 2009 1:26 pm 
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Joined: Sat Aug 08, 2009 9:03 pm
Posts: 174
Location: Winnemucca, NV
Though specific for Toyota 3.4 V6 engines in the 2001-2004 series of trucks, most any fuel injected vehicle will have a MAF sensor in the air intake tract and applicable.

A few points since doing the sensor:

* I haven't really had a chance to do some acceleration or fuel economy tests. Just back and forth to work on posted 45mph county roads and 25mph Winnemucca city streets. Need to get onto I-80 and put the pedal to the medal. And compare fuel mileage over a couple of tanks. Fuel mileage isn't a strong suit for TRD Tacomas with manual transmissions, since their overall gear ratio is close to 4:11 and at 70mph the tach is a needle width under 3,000 RPM. Plus the aerodynamics of a brick. I generally get mid 17s on the road at posted speed limits, 13-15 off road.

* I put this same thread on other forums. Some feedback:

> Lube the O-ring with dielectric grease. Conditions the ring, plus makes it easier to reinstall.

> Many vehicle computers won't remap parameters for 50-80 ignition cycles. So the vehicle will still run as though you hadn't cleaned the MAF sensor for a while. If you want instant results for comparison, pull the battery terminals, let the capacitors drain (about five minutes) then reconnect. The computer will then automatically remap itself and you will be able to determine results immediately.

> The can suggests cleaning the sensor with each filter cleaning and/or change. Most practicers of MAF cleaning suggest annually.

_________________
D.A. Wright
~When You Live in Nevada, "just down the road" is anywhere in the line of sight within the curvature of the earth.


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