MAFT and relearnng
03-13-2002, 08:36 AM
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MAFT and relearnng Ok, I understand that a MAFT is a good way to do some minor tuning. However, I just heard that the MAFT is fine for the dyno, but the computer will "learn" around it, and that will bring it back to the way it was. This is from a fairly reputable souce... opinions and ideas?
03-13-2002, 02:56 PM
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Re: MAFT and relearnng Team ZR1, I got one thing to say to you:
RIGHT ON!
In fact, since I went from 0 base to +20% on the MAFT, I did a PCM reset. The PCM learning process then took about 20 minutes, maybe.
RIGHT ON!
In fact, since I went from 0 base to +20% on the MAFT, I did a PCM reset. The PCM learning process then took about 20 minutes, maybe.
03-14-2002, 12:39 AM
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Re: MAFT and relearnng The PCM only knows what the MAF sensor puts out. The signal from the MAF is frequency (Hz). The PCM has a look-up table whereby the frequency is associated with a specific amount of air flow.
What the MAFT does is that it modified the frequency signal before it gets to the PCM. The PCM has know way of knowing that the signal has been modified. Therefore, the PCM can not learn around the MAFT.
At least that is my take on the situation. My MAFT diffinately help my lean cruise/rich WOT situation. With the MAFT, I was able to reduce +15% to +20% LTERM FUEL TRIM down to 0% to -5%, while at WOT, my O2 sensor readings went from 960mV to 980mV down to about 900mV. The car was faster with the proper settings on the MAFT and the changes were permanent.
I hope this helps,
Doc
What the MAFT does is that it modified the frequency signal before it gets to the PCM. The PCM has know way of knowing that the signal has been modified. Therefore, the PCM can not learn around the MAFT.
At least that is my take on the situation. My MAFT diffinately help my lean cruise/rich WOT situation. With the MAFT, I was able to reduce +15% to +20% LTERM FUEL TRIM down to 0% to -5%, while at WOT, my O2 sensor readings went from 960mV to 980mV down to about 900mV. The car was faster with the proper settings on the MAFT and the changes were permanent.
I hope this helps,
Doc
03-14-2002, 12:53 AM
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Re: MAFT and relearnng I agree the rumor that the PCM goes back to where it was before the MAFT was installed is not correct.
I have had a MAFT in for over a year and it never went back to the way too lean conditon I had.
The problem is that people do not wait long enough for the LONG TERM fuel trims to be properly averaged out.
So they adjust with the MAFT, do a scan and then make changes again without waiting for LTFT to average out and then a week later do a scan and are not seeing what they saw when the change was first made and assume PCM is learning around the MAFT.
All the MAFT is doing is adding or subtracting to the freq MAF is putting out and PCM has no way to know anything is out of the norm.
The best process is to start with WOT switch on MAFT at zero, adjust base switch, get at least 1 hour of drive time between changes to allow LTFT to average out, then do a PCM scan. Once LTFT is around zero and is pretty stable staying there, then fine tune with WOT switch.
I have had a MAFT in for over a year and it never went back to the way too lean conditon I had.
The problem is that people do not wait long enough for the LONG TERM fuel trims to be properly averaged out.
So they adjust with the MAFT, do a scan and then make changes again without waiting for LTFT to average out and then a week later do a scan and are not seeing what they saw when the change was first made and assume PCM is learning around the MAFT.
All the MAFT is doing is adding or subtracting to the freq MAF is putting out and PCM has no way to know anything is out of the norm.
The best process is to start with WOT switch on MAFT at zero, adjust base switch, get at least 1 hour of drive time between changes to allow LTFT to average out, then do a PCM scan. Once LTFT is around zero and is pretty stable staying there, then fine tune with WOT switch.