I am trying to take some readings on MAF wiring to chase down a code 34 problem.

There are five wires on the Plug. The drk green is the signal wire to the ECM. In park I am getting a less then 1 volt reading about .65 to .95. Is this a good range? Any one know what the correct voltage on the signal lead should be. I know it should vary. But what is a range of voltage matching rpm.


Also, how do I check if there is a short to ground.

Car is an 88 IROC 305 TPI Auto.

 

IIRC, Vader posted somehting sometime back, regarding MAF voltages, do a search fopr "MAF Voltage" user namer "Vader".

To test a short to ground...meter on OHMS, one lead to a good ground and the other to the suspected area...direct short would be "0" (zero) ohms. Depending on what you're testing, resistances (in ohms) will vary...i/e if you test through a bulb, you may see just 1-2 ohms...which is okay for a device, but not a wire....assuming the wire should not be grounded.

 

What you will read at the MAF connector 'C' at idle depends on the engine speed and displacement. Your 305 with a stock or mild cam and corresponding valve timing should read about what you indicate at a normal hot idle RPM of 800-ish.

 

See...talk about him...and he appears from the Dark like a Stealth Bomber.....

 

But with a lot less noise and smaller heat signature. I'm generally under the radar, anyway.

 

Do you know where ca I get the Wells su-145?

I think that I have big air restriction with the stock MAF on my 383, what I really like to have is an adapter from the LS-x type of sensor to the TPI electrical signal, if I knew the characteristic of each one I may be able to do something.

 

Did someone say MAF??? .

Heres an excel sheet from a dusty corner of my hard drive. I think this has the MAF frequency vs flowrate for a variety of freq. based MAFs. Dont have excel on this machine so I dont know if this is the right file. I think it is. Rename to .XLS when you DL it.

 

https://www.thirdgen.org/techbb2/sho...hreadid=277691

Heres a link to what I did, as well as some schematics that may help. You also will need some input protection, like a transient voltage suppressor, voltage regulator and some filtering. All in all, though, its an easy, low cost way to do it. The only special concern is the capacitor and resistor that determines what the output will be. This needs to be a specialty low tolerance cap as youll get massive ammounts of fluctuations and errors with a standard made in china ceramic cap and cheapie resistor.

 

It probably wont be as hard for you as you already have a MAF ecm. I had to write all my own code to use it.

 

Thanks for the info, i'm sure I'm going to have a ton of questions.

 

If you saw the link in the other thread you posted on DIY-Prom board, that would be the unit to have. The simple IC frequency converter works well, but with the PIC based unit, you can adjust the output curve to help improve resolution where you need it.

 

I checked the site, the unit is not in the market yet, it sounds very interesting, I wounder what the price would be.