Solder/repair MAF '92 Q

[kdkrone]

Here are two photos of the boards on the inside of my intermittently malfunctioning MAF. I don't know much about electrical connections, but is it likely that the bubbly mess along the right side of the photo communicates with the broad connecting band that runs in the plastic matrix and might be causing a short? I don't see any metal/solder connecting the two parts. If so, how does one clean this up??? I have dental tools and a magnifying glass for starters.

I have a functioning MAF at the moment, but it would be nice to repair this one to have as a spare.

ThanksKen K

[qship96]

Take it to an old timer local TV/stereo repairman, who can test all solder traces and touch up as needed. A lost art in todays parts swapping mentality.
Modified by qship96 at 12:42 AM 2/23/2009

[Infinitiguy19]

ALL the joints are toast, and your missing a solder joint too.

[kdkrone]

ALL the joints are toast, and your missing a solder joint too.

Well, Paul Wall, you raise interesting points. 1, does the little brown ooze around the edges of each solder joint mean there is a problem with the solder connection--is that what you mean? 2, it doesn't look like there was ever a solder connection of the third post from the right. Are you assuming that there should have been one, or have you taken apart one of these puppies and know that this should have a solder joint, or is it just that the post is bare that concerns you? I clearly have no idea!! (although until a month ago, there had only been a two widely spaced [once a year] episodes that I see now, in retrospect, were a problem with the MAF)

I guess the big question is whether this is a salvageable part or if I should trash it and not consider even trying to salvage it?

ThanksKen K

[Q451990]

The 3rd from the right pin obviously was never used... no lead on the board for it.

The brown ooze in and of itself isn't a bad thing... just the resins from the solder. The bubbly stuff on the end looks like that area has overheated. I would try cleaning it up with a fine wire brush. Can't hurt retacking each solder joint with a soldering iron... just don't heat things up too much in case the components are heat sensitive.

Heath

[Infinitiguy19]

Sorry I assumed there was supposed to be a joint there but it just fell off.

But this is one of my MAF's I have taken apart and it looks like there was some solder there before:

Here is a better picture of the MAF:

[kdkrone]

Thanks very much for posting the images of your MAF. The bottom one is oriented the same as my photo and also does not have solder on the third bottom post from the right.

I will look for someone my age (60's) who has a small TV repair shop and ask him to touch up the connections.

Thanks again

Ken K

[captainluigi]

This is a very easy DIY. Mag glass, 10x, fine elec. solder , solder sucker, an alligator clip will work for a heat sink. A $10 to $15 solder iron w/ small tip + 1 to 2 hrs. start to finish. Go to Radio Shack, they will help you.

[Q45tech]

Important to understand what you are doing because if you somehow send the +12 volts to ecu instead of +5 volts maximum you can destroy ECU instantly.

[kdkrone]

So is there anyone on the forum who knows what they are doing who would like to earn a few bucks rehabbing my MAF???

[Infinitiguy19]

Important to understand what you are doing because if you somehow send the +12 volts to ecu instead of +5 volts maximum you can destroy ECU instantly.

If You just re solder the connections whats the possibility of this happening?

[kdkrone]

If one is re-soldering joints, does one heat up and remove the original solder, replacing it with fresh solder, or does one just heat the, or does one just heat the solder to let it re-melt? Also, if the trick is to remove the solder and replace it, how does one remove the solder in such a way as to not leave a thin film of solder?

Thanks Ken K

[Q451990]

I think reheating the solder is sufficient in most cases, assuming the leads on the board are good. That said, I'm not an expert. Removing solder can be done with a product called "chem wick" which is basically a flat strip of braided copper that will absorb solder when it's heated.

Heath

[96'er]

Ken:

Reheat the solder that is already there and let it fill any gaps around the wire and board.

I re-soldered my MAF and when I took it apart I noticed that one of the connectors that is soldered to the pins, the pins that the plug harness connects to, had a broken solder point. I re-soldered that connection and have not had any problems with stumbling, rough idle, etc.

Before you re-solder the board I would make sure the contacts to the pins are good and not the issue. Stress is created at this point on the MAF and you plug and unplug the harness.

[kdkrone]

96'er,

You bring up a good point about the contacts for the connector. Those inside the connector seem fine, as they work just fine with my spare MAF. But where those three stiff wires connect to the wires from the board inside may be a problem. I will have to re-solder them anyway, as I did not know what I was doing, unscrewed and removed the small piece which is the connector, and pulled it out, thereby disconnecting all three of the wires to the main board in the MAF...!! Oh, well. At least my spare works well....!!! The original MAF will give me some soldering experience..

How do I re-seal the unit? Just some black caulking material?

[maxnix]

RTV should work well if applied carefully.

[kdkrone]

I need a definition for RTV, please....

[qship96]

Room Temperature Vulcanazation, look for a tube of silicone caulk or gasket maker- any autoparts store will carry it for $5 or so.

[kdkrone]

Like Permatex. Got it. Thanks.

[Q451990]

I will have to re-solder them anyway, as I did not know what I was doing, unscrewed and removed the small piece which is the connector, and pulled it out, thereby disconnecting all three of the wires to the main board in the MAF

Glad to know I'm not the only one to do this!

Room Temperature Vulcanazation

Wow... I learned something today! I have used the term for years without ever knowing the words behind the letters.

Heath

[Q45tech]

The reason I don't sell the units I repair is because they you can never be sure after spending an hour rehabbing one that it will not act up again within 12/12k so you have a warranty claim.To cover the potential you need to double the price say to $200 to include some on car testing [cold heat cycling]. And then you still have 18 year old components.

[kdkrone]

Understood. Well, at this point I have accumulated and tested (only with a few cycles of running cold-hot) a few times each 4 MAFs that I was able to find for a total cost of about $150. From my last experience, I know that as the units fail, they will fail either when heated (about 4-5 miles seemed to be the case with two units) or at start-up (including strange idle patterns while warming up). I am glad that I had purchased a cable and Consult program, as the CEL did not always come on to signal the MAF circuit error. Anyway, as it now takes me about 4 minutes to change out the MAF, I have one in my trunk with a screwdriver taped to it. The alternative to all of this would be to purchase a new part for ~$500 (discounted price) from infinitipartsusa.com...

Meanwhile I will play with the unit that failed and see if re-soldering it solves the problem. I have a mechanic now who likes electrical issues and has offered to test the failed unit to see if it is a diode failure or just a solder joint issue...

Thanks, all

[Mint Q45A]

Here is a link to a site with some information on how to solder. It seems to be very important to clean all the surfaces, removing the old solder before re-soldering. Hope it helps....

http://www.aaroncake.net/electronics/solder.htm

[kdkrone]

still haven't played with the broken unit yet, as I have purchased 3 backups(...!) (belt and suspenders approach!) The article is very clear and helpful. Thanks

[goody90q45]

This is a very easy DIY. Mag glass, 10x, fine elec. solder, solder sucker, an alligator clip will work for a heat sink.

I understand the magnifying glass, thin solder and solder sucker parts but don't understand the alligator clip as a heat sink.

This thread and this post prompted me to go to Radio Shack and talk to the resident soldering expert. The solder sucker was my missing tool for working on circuit boards. I used it last weekend to R&R the stop/tail lamp sensor in the 90Q and it's working again. I'm stunned at my random success.

Here is a link to a site with some information on how to solder.

http://www.aaroncake.net/electronics/solder.htm

Excellent article. Thanks for posting it.

[mrbill4108]

Is there a trick to opening the MAF sensor body?Mine does not seem to want to open up. OH I'm working on a 1996 Nissan PU with a 2.4 motor.

Thanks,

Bill

[Q451990]

Totally different design. Mine is integrated into the throttle body I think?

Heath

[1990Q45'r]

Remove the brown crud (flux) with a little carb or flux cleaner . It can cause a short!

[Q451990]

My Q has had a minor issue for years... it started out feeling like a "bump" at idle. I would literally look in the rear view mirror at a stop light to see if someone had rolled in to my back bumper. This happened maybe once a month. Then in the late spring/early summer I noticed it happening more frequently. I could even see the tachometer drop for a second if I glanced down quickly enough, and I noticed it buck once or twice at WOT. So in June I put my resoldered MAF from my old Q in and it ran great all summer.

I recently opened up the MAF that came on my current Q and found it to be in pretty good conditon from a visual inspection. The only thing I saw was a possible cold solder joint around the transistor (green three pronged part in the upper left corner of Paul's picture below. So I added some solder, wicked it all up with some chemwick and then resoldered the connections. The car ran great tonight with this MAF. I'm not ready to declare it "cured" yet - but I wanted to mention where I found the cold solder joint or evidence of overheating.

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