Bruce89TA

Hey Guys,
Well, now that I need a MAF sensor, does anyone have one I can borrow? I'm going out of town for a month and I'd like to bring my car into the tranny shop to have them look at the tranny but I need a MAF sensor to borrow for a month or buy. If anyone has one or knows of a way to fix a MAF sensor. I don't particularly want to pay Autozone $160 they want for a new MAF. THanks.

-Bruce

Vader

Repairing the MAF depends upon what's wrong with it in the first place. I tried it once. The hot wire had failed on mine, and I tried to replace it just to see what was involved. The first thing I had trouble with was trying to find platinum wire that was the correct gauge (AWG41 (0.0028" / 0.071mm) Platinum or Pt/Ni wire, annealed, plain, .54189 ohms/cm).

The availability isn't as common as one might believe. I checked:

MWS Wire Industries
31200 Cedar Valley Drive
Westlake Village, CA., 91362
Phone: 818-991-8553
Fax: 818-706-0911
E-mail us at mws@mwswire.com Bruce


WireTronic Inc.
Toll Free 1-888-WIRETRO (947-3876)
Sales Office Hours: - 7:30 am - 4:00 pm Pacific Time, Monday - Friday
Email: sales@wiretron.com

Johnson Matthey,
1401 King Road,
West Chester,
Pennsylvania, 19380

I finally found a place in the Chicago 'burbs that had what I needed. It was $21 for 6" of wire, and they gave me a break on it (I saw the list price in their catalogs).

After carefully removing the sealed cover on the electronics package, disconnecting the electronics from the sensing element, and removing the sensing tube, I was ready to remove the broken hot wire. They are crimped in place, so it isn't just a matter of "plug-and-play". solder is not an option since the element generally operates at 160°C or higher, and even hotter during the burn-off cycle. Fortunately, I have tools and experience necessary for component replacement on surface-mount electronics, so small parts and assemblies are not completely foreign to me. Still, this was a chore. I was able to measure the correct length of wire, insert a replacement, and crimp the wire in place on only my second attempt. I only had enough wire to make three tries, so the "pucker-factor" was fully engaged.

After replacing the wire, the resistance test showed what I expected. I reassembled everything and sealed the electronics package again. Installing the unit on the car was the easy part. Upon startup I had NO error codes, however, the engine ran like crap. This was after the battery had been disconnected for a day or more. I checked the MAF output voltage, and it was way on the low end of the scale. Once the engine was warmed, I increased RPM and monitored the MAF output. Not only did it NOT increase enough, but it was low enough at that RPM and throttle position to set the DTC '34' again.

After further research (many thanks to Brian Garrow, Wells Automotive) I understood what my problem was. The alloy of the wire was not a typical PtNI alloy, but a special alloy made as a proprietary material for Bosch. The resistance curve was completely different than I had anticipated. The MAF worked, but not right at all. Output was linear, but certainly low. I ended up with the higher-flowing Wells/Conrad SU-145 MAF with the thick film sensor instead of the hot wire element. I'll never replace that MAF again, and it was less expensive than a remanufactured MAF from other companies. You should check it out.

Bruce89TA

Thanks for the info Vader,

I woudln't have a problem trying to replace surface mount electronics either. I have a Hakko Soldering station and can get myself on a surface mount heat gun to remove anything that's been soldered to a PCB. I know it's not the filament. I jumpered the burn off relay and it glowed so at least that tells me the filament hasn't been broken.. I'm assuming it's something else but I dont' have enough information on the circuitry to do an accurate diagnosis.. I guess I'll keep looking for a used MAF.

Thanks again,

-Bruce

Vader

Bruce,

Exactly what symptoms are you experiencing? What drove you to determine the MAf was a problem?

Bruce89TA

I ran through the MAF diagnosis instructions and from that I determined that my MAF was bad. My engine won't run while the MAF is plugged in. It will start quickly and die quickly. With the MAF unplugged, the idle is high but it will remain running.

I checked all connections from the ECM to both the relays as well as the MAF to ECM and I have a known good ECM and swapped that. Both relays are good, I checked them for continuity while energized and not. Connections from the relays to the maf connector are good and the 5V reference signal is steady at the MAF connector. I'm pretty sure I've ruled out anything else except possibly the MAF connector itself. It's possible that might have gone bad but I did jumper the burn off relay and the filament lit up so I assumed all connections were good.

Is there anything else I need to check?

-Bruce

Bruce89TA

Vader, if you still have that MAF, do you want mine to pirate the Platinum wire? I probably wont' be able to send it to you until I get back but you can have it if you like.

-Bruce