TPS and MAF adjustment

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lionrover88

Guest
Here are the pics for the adjustments of the TPS and MAF. This should be easy to do.:D
These adjustments should be made with a warm engine, ignition on, motor off.
 

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Diggaz

Guest
I could be mistaken, but those pics just look like the values. How do you do the actual adjustment?
 

92rrrandall

Well-known member
Jul 30, 2004
316
0
69
Cary NC
If the TPS has two mounting holes then it is non-adjustable. The earlier TPSs used on the 13CU system had mounting slots on it and the mechanic has to adjust the base setting.

When you install a TPS on a 14CU or 14CUX or GEMS or Bosch system, the computer adapts to the new one after a few minutes of driving. No adjustment is required by the mechanic.

Regarding the air flow meters used on the 13CU, 14CU and 14CUX: These Hitachi made AFMs are labeled as 3AM or 5AM and are completely interchangeable so long as they came off a Land Rover. They are adjustable for idle mixture only. The idle mixture adjustment feature has no bearing on air mass measurement.

The engine actually does not have to be warm to make the idle mixture adjustment. However warming the engine is part of the procedure for checking the output of the mass sensor. I would not worry about the mass sensor too much because these AFMs rarely fail. You can also clean the hotwire with a quick blast of electronics cleaner.

It is easy to adjust the idle mixture: Turn the ignition to ON, but do not start the engine. Leave the connector on the AFM and pull back the rubber boot so you can see the wires(just like the picture on the far right in the first post of this thread). Set your volt meter to DC volts and put the probes on the two outside wires(just like the picture on the far right in the first post of this thread). These AFMs on NAS engines were set at the factory to ~2.0 volts. Most non-NAS engines had this AFM set at ~1.0 volts.

If you want your engine to idle better and burn much less gasoline while idling do this: Remove the tamper proof cap. There is a potentiometer under the cap which turns like a screw. It is not a actually a screw so you will have to experiment with different small screwdrivers to get it to turn. The potentiometer can be adjusted anywhere from 0 to 3.5 volts. It is very easy to set it at precisely whatever voltage you want. More volts mean richer idle mixture. You can also use an exhaust pipe sniffer to fine tune the CO content if you are so inclined.

Randall
 

landrovered

Well-known member
Nov 28, 2006
4,289
0
rover4x4,

You are simply adjusting the gain (for lack of a better term) of the MAF, there is nothing else to do with it. It has a wire that heats up and the amount of current needed to heat it determines the mass of the flow, that is why it is called a hotwire MAF.
 

rover4x4

Well-known member
Apr 21, 2004
5,228
45
41
North Carolina, Raleigh
landrovered said:
rover4x4,

You are simply adjusting the gain (for lack of a better term) of the MAF, there is nothing else to do with it. It has a wire that heats up and the amount of current needed to heat it determines the mass of the flow, that is why it is called a hotwire MAF.


This is the explanation I have been needing for months. It sort of spells it out in the RAVE but I wasnt clear that the allen screw under the plug really did. Why did Land Rover program the trucks to run rich, to keep the cooler? Does a hotter plug with the pretuned rich mixture make more "power"?
 

landrovered

Well-known member
Nov 28, 2006
4,289
0
As far as I understand it, they did it so the cats would get hot enough to complete the combustion and pass emissions, also reduce pre-ignition.
 

kk88rrc

Well-known member
green said:
"Remove the tamper proof cap." by this you mean the brown plastic square piece that is glued down to the top of the MAF that has the LUCAS name on it?
Nope... it's the little round thing on the upper right corner circled in red.
 

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landrovered

Well-known member
Nov 28, 2006
4,289
0
Mine was aluminum, if you use a drill bit and turn it by hand you can open it up without damaging the pot under the cap. After the adjustment, I plugged mine with a plastic plug that came on a set of brake calipers that I had, it fits just right.
 
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lionrover88

Guest
I'm Sorry People, i have issues with my PC, Please forgive me if i was not very clear with the pics.
The MAF is adjusted with a #5 allen wrench the red circled location in Kevins pic is the only location that has a screw hidden under a aluminum cap/plug there is no other adjustable screw on the MAF.

The throttle position sensor is adjusted by loosening up the two screws and turning it untill the desired value is reached, after that hold it in place and retighten the screws.

This information is for the 3.5ltr Gems motor, that is in my 1988 RRC. I played around with these adjustments after reading a thread on discoweb that talked about these adjustments for a 14cux ECU. The 3.5ltr uses a 13cu ECU but i experienced bettter performance as i did the adjustments. Even though DO NOT EXPECT THESE ADJUSTMENTS TO BE A WAY TO MAKE YOUR ROVER A RACE CAR IT IS NOT!!!!!! ALL IT DOES IS, IT MAKES THE ROVER MORE EFFICIENT!!! It is advisable that you write the original values down BEFORE making any adjustments, so you can go back to the original settings in case you experience problems.