After reading up on VAF's , I learned that some 1994 and 1993 FZJ80 owners have upgraded to the 1995 FZJ MAF. Has anyone here tried this yet? If so, was it worth it?
VAF to MAF Conversion (1 Viewer)
- Thread starter hidesertfj40
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not familiar but id like to see who responds 
haven't heard of that. i doubt that it is possible.
- Thread starter
- #4
Hey guys,
I'm waiting for a response too. I read the Maf resolved the rough idling and increased fuel efficiency...
I'm waiting for a response too. I read the Maf resolved the rough idling and increased fuel efficiency...
94SRUNNER
GOLD Star
Possible but you would be better off buying a 96 or 97' 80.
semlin
curmudgeon
not aware that anyone ever did it. 98% of the tech needed to do it will be found here.
https://forum.ih8mud.com/80-series-tech/151783-93-94-truck-vaf-maf-conversion-project.html
the conversion is pretty simple in theory but the problem is cost. you need a maf sensor, a landtank maf mount or oem, a new bellows, a voltage signal converter, a wideband o2 sensor, and a dash readout. all that is available off the shelf but for all that expense you will only get very slightly improved performance. the main reason to do it would be to add a supercharger or turbo.
https://forum.ih8mud.com/80-series-tech/151783-93-94-truck-vaf-maf-conversion-project.html
the conversion is pretty simple in theory but the problem is cost. you need a maf sensor, a landtank maf mount or oem, a new bellows, a voltage signal converter, a wideband o2 sensor, and a dash readout. all that is available off the shelf but for all that expense you will only get very slightly improved performance. the main reason to do it would be to add a supercharger or turbo.
TrickyT
Hate that mud...
Agree with semlin. Technically feasible but would require money and time to get it right. The ECU is unchanged, so the challenge is to make the output of the MAF and associated signal converter look similar to that of the VAF over the full rpm range. Would not be difficult if both VAF and MAF behaved in a linear fashion or at least had the same air flow versus output voltage response curve, but I haven't seen any data that this is the case. So some engineering effort would be required, and this would necessitate instruments and a test jig.
- Thread starter
- #8
Semlin and Tom,
That's what I was looking for. Good information.
It looks like I won't be attempting this unless someone posts information otherwise..
Thank you for your input.
That's what I was looking for. Good information.
It looks like I won't be attempting this unless someone posts information otherwise..
Thank you for your input.
You can resolve rough idle by fixing whatever is causing your rough idle.
In my case it appears to have been a bad seal at the TB end of the plenum. I need new hose clamps.
OBD2 trucks are more efficient but i doubt that the MAF is the only reason.
iirc someone once tried to figure out everything required to convert an OBD1 truck to OBD2. I believe they determined that there are so many sensors to add or change and so much rewiring that it isn't worth it.
semlin
curmudgeon
i agree about money, but if you read the old thread link, you will see that it looks like not much tweaking will be needed. from mudder testing and the toyota literature the curves for vaf and maf output have a similar slope so it appears likely all you need to do is set the voltage range.
also, if you look at the acceptable benchtest voltage range of the vaf, a 1 volt swing is permissible. this suggests the 93-94 ecu must be very adaptable which makes sense if you consider how crude a vaf is and the kind of environment those trucks were intended to operate in.
if i was going to do this, i would get an o2 wideband sensor and a/f display to keep an eye on things, but i would start with just plugging everything in and seeing whether the ecu could adapt to it.
semlin
curmudgeon
lack of a crankcase position sensor in the early trucks is the main stumbling block. much easier to convert a vaf truck to maf.
semlin
curmudgeon
i agree with this. the maf is not even controlling fuel flow at idle: the fuel pressure regulator is doing it.
OK, that makes sense, but i have to ask: To what end?
I can lean out my '94 without removing the VAF. I'd still need the wideband though, to be safe.
semlin
curmudgeon
as i said earlier in the thread, the only logical reason to do it given the cost would be if you were adding boost. the hope would be the more acurate maf signal would allow the ecu to manage fuel flow better and avoid the lean problems that are often encountered running a 93-94 under boost.
this depends on the vaf ecu being able to take advtantage of better information from a maf. the experience of tuners using other toyota vaf ecus is that they can. worst case, if it did not work, you could do some tuning by tweaking the voltage signal convertor output to fool the ecu into sending more fuel.
if you are not going to boost, then what you would get out of this conversion is slightly better throttle response and fuel economy.
Ah. Makes some sense then.
Sorry i didn't go read the other thread.
Sorry i didn't go read the other thread.
- Thread starter
- #16
Well, with all said, it looks like a tough project.
- Thread starter
- #17
All,
I wanted to let you know that after I replaced the VAF with another one with 130K miles, my rough idling has disappeared!!!
I wanted to let you know that after I replaced the VAF with another one with 130K miles, my rough idling has disappeared!!!
