Pro M maf conversion took a dump.

[Martin in Bellevue]

Disclosure is provided here, for those interested in the maf conversion. Pro Flow is now out of business.
Last weekend, after making a slight adjustment to the 2nd pot, for off throttle response, the motor developed a bad tip-in response. The adjustment was minute, with the pots in "fine setting" mode. Normally, pot adjustments can be fairly broad while maintaining good running characteristics. A few days ago, the dme decided that the signal afm signal was crap & lit the check engine light. It now ran poorly.
I checked the maf wiring for continuity & shorts. I replaced the maf with a rebuilt maf for a 98 mustang cobra. It was better, but still not right. I swapped in a good, never-opened dme for no change. After Jeffro's track day, maybe we'll compare & isolate the exact problem. Oh yeah, the signal box still talks to the peecee & can accept new curve settings. Its output on the car is limited to about 0.2v, the problem.
Borrowing Jeffro's afm was a revelation. The throttle lags a little against the maf setup, but otherwise, the stock afm can be good. Driving around town for a day now, with the Jim C chip, the 284 regrind cam, the headers, 15lb flywheel & some other questionable mods, left the impression of a very tractable, torquey motor. Even with the 21lb injectors, the mile-o-meter shows a little love.
I may look at the latest split second maf signal conversion box. It allows secondary inputs for mapping purposes & looks to be well supported by the company. Daniel Ma had this on his '88 m5 & commented on its ease of tune. Walt's early pro m maf conversion died a couple months ago & he recently went with the latest split second maf setup. I may get another afm with wire connector. I gave my afm to a local e28 guy in need.
Up to that time on a ferry back to hippieland, the maf ran great. I mean to say, it pulled hard & made a glorious cavitating sound past mid-throttle.

[Robin-535im]

Sorry to hear that. Power output bad - could be a transistor somewhere. Might be worth having a local electronics shop take a look... heck, ship it out to me and if I can fix it, I'll install it on my car and tell you it just couldn't be fixed

Or, it might be time to upgrade to an ///M5. Or maybe that Dinan E39 touring.

[Jeff N.]

Confess sinner. Tell us about the wires you crossed up!

Robin: Holmes here shorted out his unit. Could that kill a transistor?

[Robin-535im]

Confess sinner. Tell us about the wires you crossed up!

Robin: Holmes here shorted out his unit. Could that kill a transistor?

Oh, I see now. All bets are off if a powered wire hit a signal wire somewhere... that could have cooked the microprocessor depending on whether or not the i/o is isolated properly, which it may not be for a custom-built MAF.

I was thinking a power transistor somewhere or a capacitor got too hot from being inside that engine bay. Beyond my simple EE classes to fix it then

BTW - looks like I won't be able to make it out for the wedding / install (or should I say, install / wedding... got to get my priorities straight!) With the new business and all, $$ are in short supply for the next few months. Heck, I'm downloading the *trial* version of Intel Fortran instead of spending the $400 bux to buy it outright! (doing this now on the other PC).

[Jeff N.]

Bummer.

Fortran? huh...people still use that stuff?

Oh, I see now. All bets are off if a powered wire hit a signal wire somewhere... that could have cooked the microprocessor depending on whether or not the i/o is isolated properly, which it may not be for a custom-built MAF.

I was thinking a power transistor somewhere or a capacitor got too hot from being inside that engine bay. Beyond my simple EE classes to fix it then

BTW - looks like I won't be able to make it out for the wedding / install (or should I say, install / wedding... got to get my priorities straight!) With the new business and all, $$ are in short supply for the next few months. Heck, I'm downloading the *trial* version of Intel Fortran instead of spending the $400 bux to buy it outright! (doing this now on the other PC).