Stealth 993

This is all I have found for the 993
http://www.durametric.com/

This is what I have for the Audi
http://www.ross-tech.com/

autobonrun

Here's another option on P-Car.com.

http://p-car.com/obd-2/

It's around $122. I'm told it will work on my 96 993 and my M5 which would be great. I just spoke with the company and was told MAF flow in lbs/hr is available to view. This is the value I want to see rather than the actual MAF voltage output. It would be nice to plug in a laptop, go for a drive, and record all the measurements. A main point will be determining what values the sensors should be producing at wide open throttle so I have comparison points.

If I can line up a laptop, I plan to give it a try. Right now I just have a company laptop with no administrative priviledges to add software.

I recognize that if I'm going to continue working on these cars in the future, having OBD software will be a requirement, unless I just want to do trial and error; so I might as well get the setup now rather than waiting for a problem to crop up.

Stealth 993

Cool, I am going to check that out!

This is a log that I graphed with my Vag-com


I use a older Dell laptop, that is super small, is only a p800, it's like $150 used! Runs XP fine, the only downside is it doesn't have a internal CD, but it's like 3lbs & fits in my lap when I drive.

1pcarnut

[QUOTE=Stealth 993;4995629]This is all I have found for the 993
http://www.durametric.com/

Don't have have a laptop so the Durametric isn't under consideration. The two handhelds I've seen that have "live scan" are the Actron 9145 and Equus 3130. I wonder if these more sophisticated type of hand-helds can check the function of the MAF and specific sensors?

Receiver

My 96TT with 54k on it is stuttering under load. We hooked up to the OBD 11 and the reading indicated the MAF Sensor. The techie took out the Sensor and cleaned it. No change. He recommends replacing it. You've said that it isn't a regular maintenance item. have you seen many that have failed? Any other things that might cause this stuttering? Thanks for your help. Everyone on this Board appreciates your constant input.

JasonAndreas

The MAF used in the M5 is based on newer hot-film technology (the writeup on the M5 BBS has the terminology wrong) like the type 996 and unlike the type 993 that uses an older and more robust hot-wire based sensor. Two different technologies that shouldn't be compared. At most you should clean the 993 MAF sensor and only replace if the sensor readings starting biasing in one direction or get all wacky.

Steve Weiner-Rennsport Systems

As Jason wrote, the 993 hot-wire MAF's are pretty trouble free and I've not seen many outright failures unless they became contaminated by something like an over-oiled K&N.

Receiver

Thanks Steve.

autobonrun

Jason, therein lies my question. How do you know when the readings are biasing in the Porsche? I've yet to get an answer to that question. On the M5, the ideal flow has been determined to be around 140 L/H. I can find no such figure for the 993.

Even on the M5, there are few if any outright failures of the MAF despite the difference in technologies you mention. The entire purpose of my question was around MAFs that had not failed outright.

The issue is how to tell if the 993 MAF reading is inaccurate. What I understand is that the deviations from factory accuracies will occur over time regardless of the robustness of the sensor. I understand that the same deviations occur with the O2 sensors over time so they do have a recommended replacement interval.

I'll do a little more digging into the issue later this year to see what I find out.

trevi1

Do you have a DIY to clean the MAF? I used the search engine and nobody have one.. I clean my ISV yesterday but it was not to bad. And now I want to clean the MAF... Anybody can help me...

Jenner

This is a guide for the BMW E39 M5 but it applies just the same to any MAF. Since you cleaned the ISV you know where the MAF is. Just remove it and follow this guide. This guide is a bit overkill though.
http://www.louv.tv/cars/m5/MAF/

In simple terms, remove the MAF cylinder(you don't have to take out the MAF sensor from the cylinder unless you want to inspect it) and give it a few lengthy shots of CRC MAF sensor cleaner from autozone/pepboys etc. I've used this on both MAFs in my M5 and the single MAF in my 993 Turbo. I have NOT used simple green on it.

Stealth 993

FWIW, I would STAY AWAY from Simple Green! It doesn't totally wash off, & will leave a film. It's good for dirt, not good for sensors.

maurice97C2S

Jason,

Is that correct re the 993 sensor ??

I have checked in Porsche 911 Story .. Paul Frere says on p 96 (7th Ed), when discussing M64 05/06 engines (first 993 motors), that the hot wire system of the M64 /01 (964 engine) is replaced with the 'latest' Bosch hot film system .. likewise Tobias Achele's 911 Engine History & Development p 74 ..

Definitively, Workshop Manual Vol VIII p 24-13 "Hot-film mass air flow sensor" ..

cheers, Maurice

TheOtherEric

Thanks for that reference. Whoever wrote that is a serious hack, though! Simple Green on your MAF? Vaseline on your rubber gaskets? That author has no clue. Useful pics, though.

JasonAndreas

The books are wrong... The M64.01/02/03 used a vane type air flow meter (AFM), the 993 engines used the Hot-wire MAF and the 986/996 used the HFM5 Hot-Film MAF. If you look at the sensor in your 993 you'll find a wire whereas the 996, etc. uses a thin-film like the one in the 1st image below. The 2nd image is a photo of the sensing element inside the 964 AFM.



996 MAF HotFilm Sensor


964 AFM Sensor