MAF setting 3.9EFI

[knuts2au]

A young ex Landrover Mechanic i was talking with the other day said about checking the MAF sensor. On the outside terminals it should measure 174ohms resistance, if not adjust it, as mine measures 272ohms i am wondering what effect it has on things. I thought the adjustment on the back of the MAF was only idle mixture, or does it do more :?:

[DEFENDERZOOK]

<span style="color:blue">can you post a pic of the maf.....?</span>

[knuts2au]

it's a standard hotwire, 14cux i think they are, the sticker peeled of long time ago, it has a hole with a blanking plug which give access to the multi-turn trimpot inside. Can't grab a photo at the moment, too bloody hot outside (44), and windy (40Km/h gusts) and not sure where my camera cable is.

[disconut]

Off the disc,

The MAF sensor is located in the intake system between the air filter housing and the turbocharger. The ECM uses the information generated by the MAF sensor to control exhaust gas recirculation (EGR).
The MAF sensor works on the hot film principal. The MAF sensor has 2 sensing elements contained within a film.
One element is controlled at ambient temperature e.g. 25 °C (77 °F) while the other is heated to 200 °C (360 °F) above this temperature e.g. 225 °C (437 °F). As air passes through the MAF sensor the hot film will be cooled.
The current required to keep the constant 200 °C (360 °F) difference provides a precise although non-linear signal
of the air drawn into the engine. The MAF sensor sends a voltage of between 0 and 5 volts to the ECM, proportional to the mass of the incoming air. This calculation allows the ECM to set the EGR ratio for varying operating conditions.
Inputs / Outputs
The MAF sensor receives battery voltage (C0149-3) via the ECM on a brown/orange wire. Signal output on a slate/light green wire from the MAF sensor (C0149-2) to the ECM (C0158-11) is a variable voltage proportional to the air drawn into the engine. The MAF sensor is provided an earth (C0149-1) via the ECM (C0158-20) on a pink/black wire.
The MAF sensor can fail or supply an incorrect signal if one or more of the following occurs:
• Sensor open circuit.
• Short circuit to vehicle supply.
• Short circuit to vehicle earth.
• Contaminated sensor element.
• Damaged sensor element.
• Damaged wiring harness.
• MAF sensor supplies incorrect signal (due to air leak or air inlet restriction).
In the event of a MAF sensor signal failure any of the following symptoms my be observed:
• During driving, engine speed may dip before recovering.
• Difficult starting.
• Engine stalls after starting.
• Delayed throttle response.
• EGR inoperative.
• Reduced engine performance.
• MAF signal out of parameters.
In the event of a MAF sensor failure, the ECM will use a fixed default value from its memory.

Trev.

[knuts2au]

Turbo?, one should be so lucky, it's a 3.9l V8i, no cat, no EGO sensor. Still can't find that camera lead, was on the table before Christmas....

[disconut]

Pulled it off the TD5 disc, but the principal of operation for the MAF should be the same?

Trev.

[Rovernaut]

Originally posted by knuts2au
A young ex Landrover Mechanic i was talking with the other day said about checking the MAF sensor. On the outside terminals it should measure 174ohms resistance, if not adjust it, as mine measures 272ohms i am wondering what effect it has on things. I thought the adjustment on the back of the MAF was only idle mixture, or does it do more :?:

I'm very interested on your post!.
Which out side terminals are you talking about.
The 1st terminal on the left and the last one on the right on the connector of the MAF.
Mine measured 171 on the above.
But what about the ohm measurements on the other terminals?

[discowhite]

this is DW's 14cux 5am MAF.
my outside terminals measure 56 Ohm. its a 3.5L so the value might be
differant.
dose your terminals look like this??


phil.

[knuts2au]

Yep, thats the same looking air flow meter, i notice the left outside terminal actually doesn't have a wire connect to it in the mating plug on the loom, so must only be there for measuring purposes? I'll adjust before i go for a run into town this afternoon and see if it does make any difference.

[knuts2au]

Well i adjusted it back to 174ohms, and took it into down, it seems to idle smoother, but it does that some days, then again it could be my imagination. Going to call in and see an old friend i had forgotten about who is a LandRover specialist and RR owner ( the young mechanics father) and see if i can find out the rest of the story.
I got a picture of the MAF and connectors but can't work out how to attach it to the post?[/img]