kingtal0n

iTrader: (1)

Actually in my context I am using turbocharged engines which will run richer. I did not specify? - thanks for reading, the solution exists if there is any boost pressure the maf will increase in voltage when there are leaks, so richer in that situation. Since I mentioned boost leak test, I was thinking air leaking out under pressure, follow me now?

I didn't know that you guys had that kind of maf. Are you sure? The maf sensors on Nissan/Toyota and others I am familiar with use a 0-5v DC current

joecar

Ah, ok, I see, TC'd.

joecar

Yes, GM MAF is reported using frequency...

frequency goes as the 4th power of air mass flow.

joecar

If you're interested, you can download/install the EFILive V7 software (run it i demo mode) and view some of the stock calibration files from www.tunefiledepot.com (the EFILive repository)

(...HPT has a similar infrastructure but I don't know the details...).

Won-Ton

Awesome I will have to check it out.

joecar

I was also pointing kingtal0n to the software so he can see what the MAF table looks like.

gtfoxy

Correct on the rich running if the MAF is in front of the turbo.

There was once a MAF adapter, not sure if it's still around, that converted the factory GM frequency output that you could trim the signal to tune the factory PCM. I used this primarily on DSM's.

kingtal0n

iTrader: (1)

This device
http://www.ebay.com/itm/APEXI-NEO-AF...9SJ975&vxp=mtr


Adjusted maf voltage (perhaps it does freq? I didnt think so though) and in the 80s and 90s people used them ALL the time for making larger injectors work with factory ECU. The problem is that they only adjust maf voltage, so the computer's timing goes along for the ride. With larger injectors you are dialing maf signal DOWN so it looks like LESS airflow, and with less airflow comes more timing, so many of the engine suffer detonation and knock related failures (often a connecting rod bearing or ring land)

They are great for low power applications though. For example, the factory KA24DE engine in the nissan 240sx only produced 150rwhp but it can handle 250rwhp easily for 250,000 miles. SO people slap a T-25 on them with all original parts, except injectors and the turbo of course, and drop in that extra 100 horses for $700~, since the power is so small and the injectors are so close you can dial the timing back a few degrees at the distributor and be ok for 150k miles (plus 100k already on the engine when you got it)

gtfoxy

Not quite like that. More basic.

Yeah they have their limitations but I wouldn't say it was lower power cars using them. It was guys needing the added airflow & reading capability the GM MAF's offered over the factory ones. I knew a couple 10 second DSM's using it. I had one on a Galant GSX running a 57-Trim TO4E. I was turning about 22-24psi on it. Went 11.3-11.4's.

The factory DSM MAF reads in hertz also. It worked best in conjunction with a burned E-prom with the right injector size & MAF tables. Then you are just dialing in A/F mixture at that point.

LilJayV10

iTrader: (39)

After you get both 02's working you need to fail the MAF and tune the VE first. Below approx. 4500rpm or so the PCM uses the VE and MAF to determine fueling. IMO stop and go driving it uses the VE more than the MAF due to the constant change in manifold vacuum.

Once the VE is dialed in make it so you are running solely on the MAF and tune it.

That's just my .02 and the way I learned how to do it. I know there is more than one way to do it, that way just makes sense to me.

bcsobulldog13

I recently bought a 2002 b4c. Car was in garage conditon.
But I hadn't be driven in a couple years. The power steering pulley bearing wore
down and I didn't know until it failed and threw the belt,
by this time the oully had been riding crooked on the shaft
and wore a hole in the reservoir. Which forced me to buy a new set up
and alternator cause the other one got soaked with fluid and failed.
Now since I took the intake off to replace all this I've been getting
a maf code and intake temp code after cleaning both and
having the code cleared 3 times. I can unplug the maf and notice
zero change in the way the car runs. When I'm sitting parked
the car has a wobble feeling, and when I put it in drive with my foot
on the brake it get a little worse. When I let off the brake it gets a little better
but still noticble. It didn't do any of this before it started throwing
codes. Can anyone help me with this?

joecar

You need to diagnose the codes you got you did not mention the actual codes) using the GM service manual diagnostic charts...

also, you may need a more thorough visual inspection.

Won-Ton

When you unplug the MAF, is the car up to operating temperature? And if your code(s) are (correct me guys if I am wrong) a 0101, 0102, etc it will force the car into open loop thus not looking at your maf/o2.

joecar

MAF DTC does not force OL... it forces VE/SD but CL operation is retained.

LilJayV10

iTrader: (39)

Fail the MAF in the tune and you can set the 0101 and 0102 DTC to MIL on the first time so the CEL will come on. Some people do that so they can see the PCM has actually failed the MAF.