I've never seen this addressed before, but I am swapping out my Bosch MAF for a new MicroTech unit. The car sputters and dies within 15 seconds of start up, do I need to reset the ECM for my car to regocnize the new MAF?

Thanks,
Eric

 

Nevermind, I tried that and it din't work. Any ideas why my car won't accept this MAF?

 

After clearing the ECM, restarting, and having the engine die with the new ECM, are there any stored error codes? Did you check the MAF power and burnoff relays BEFORE replacing the MAF? The sensor itself may not have been faulty, just a relay or connection.

 

Vader, I think you misunderstod my issue, although I thank you for the reply. I did not replace the ECM, just the MAF. I thought if I "erased" the ECM, it would learn the new MAF, but it din't. Everything works fine w/ the old MAF, but the new one doesn't seem to wanna co-operate. There is no idiot light on, but I have not used my Auto Xray on it to check for codes. The old sensor isn't bad and any relay associated with it are fine, it was more for "performance" as I have read the MicroTech/"Wells" unit flows more (for future upgrades).

 

It's possible you were given an incorrect or defective unit. There is another recent MAF post where someone got an analog MAF for an FM system.

Just a dumb question, but the MAF is installed with the arrow pointed downstream, correct?

 

LOL, and I wouldn't put it past me to face it the wrong way but it is facing the right way. I guess defective may be the answer but I had hoped my bad luck had run its course. If you think that may be the only solution, I can take it back tomorrow (before the Cowboys game!!!!!!) and swap it out for another one. Is there anything else I can do? What is an FM system?

 

i had the exact same problem with the microtech unit. bought one when i lived in louisville, you know, where microtech is located. installed it and tried everything to get it to work and it wouldn't. i had to go buy a reman one.

 

I know, but I just had to ask, just in case. Not that I would ever do anything like that

FM = Frequency Modulated. The MAF design used on '86-'89 TPI systems generates an analog voltage signal between 0-5 VDC. The signal varies linearly with the mass of air flowing through the unit. The MAF design used on 1985 TPI and V-6 MPFI systems (both Buick and Chevrolet) generates a constant 5V P-P square wave output at approximately 50% duty cycle. That signal varies linearaly in frequency with the mass of air flowing through the sensor. The two types are NOT interchangeable, despite some claims to the contrary. The analog MAF TPI ECM has no internal provision for D/A conversion of the signal. In fact, just the opposite is true, since the analog signal that is supposed to be sent to the ECM is A/D converted for integration into the calculations. The V-6 MAF ECMs conversely have no provision for A/D conversion, and are simply counting the input frequecies after buffering and signal isolation.

I have read some claims that there are MAFs that are "universal" and will work on either system, and that kind of poor understanding of the systems and their components is frightening. That is tantamount to stating that a single cow can produce both milk AND lemonade. (HINT: If someone attempts to prove this to you, don't drink the "lemonade.")

If the original MAF works just fine in the system, there is likely nothing else wrong with relays, wiring, connections, or ducting, so there is little else you can do but return the sensor and try a different replacement.

If you have a voltmeter and/or an oscilloscope or frequency counter, you could test the output signal of the replacement unint to be sure it is either an analog or FM type. Connect the voltmeter to the 'C' termial with the sensor connected and engine running. Output votage at a normal warm idle (about 850-900 RPM) should be in the range of 750-900mV. If you are reading about 2.5VDC, the meter is averaging the 5V P-P square wave signal and trying to display its RMS value. You can verify this by connecting an oscilloscope on a scroll raster and watching the waveform. If you see something other than a relatively linear trace, you've got the wrong MAF (FM type).

Either test would give you the relative confidence to return to your parts supplier and inform them that the part in the box is not what you need, and why, so that they can go back to their supplier and inform them of their screw-up.

 

I took the Microtech unit back and swapped in another one just like it to see if it was defective. The "new" one produced the same results (dies at idle). So after the "Wells" unit turned out to be a Bosch unit and sent back, now the MicroTech unit doesn't want to play nice with the other kids, I'm back to the original Bosch unit.....I'm just about finished trying to get "hi-flow" from a MAF. Just incase anyone wants to suggest it, I'm not gutting my MAF.

Thanks to everyone who has helped me with this issue over the last month and a half. One day I hope to be able offer beneficial advice in return.

Go Cowboys!
Eric