Discovery 1 MAF 14 CUX

hi_arshard said:

Hey Allan,

Thank you very for the information shared it was very helpful really appreciated.

I have done the test and following are the results.

Mean time I have ordered the cable for the USB FDTI cable for the Rover gauge, will be working on that soon.

Reading from MAF,

Red/Black - ground
Blue/Green - air flow signal

Reading ignition on - 0.22 to 0.24
Idle cold 1.65 to 1.67
Idle hot - 1.58 to 1.62

Idle CO mixture adjustment
Red/Black
Blue/Red
Idle 1.87

As you mentioned the CO adjustment on the MAF, this adjustment is sealed and unable to access the adjustment screw. Is there a way to open this or some comes sealed ?

Also I have black smoke issue, if I press the throttle full I see thick black smoke.

Appreciate your input…

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AllanWorms said:

As long as the 0.64 drops pretty quick, it might be OK. Settling to .24 may depend on the quality of your meter and leads - that IS fairly close to 0.30 to 0.34 though.

The Coolant temp sensor for the ECU is the one with the square "timer" plug on it, kind of behind the distributor near the thermostat.. Not the round single pin (gauge), nor the big one with two spade teminals (cooling fan). If you unplug the "timer" plug and measure the resistance of the sensor, then heat up the engine and measure the resistance, it should change with the temp (I can't recall the expected readings, but Uncle Google should know). The resitance should decrease as the engine heats up. something like 2K ohms "cold" to a few hundred ohms "hot".

Again, Rovergauge would tell you exactly what the ECU sees there, too (I really like Rovergauge )

It runs it very rich on initial cold start, so maybe check that as they are a some-what common failure item. If its dead, or the wiring in faulty, it tries to run it like a cold engine the whole time.

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hi_arshard said:

Hi, few more readings from MAF which I missed in the last post,

Idle CO mixture adjustment
Red/Black
Blue/Red
Idle or with ignition on the reading is same 1.87

Also reading from air flow signal, as switch on the ignition its shoots to 0.64 and settles back to 0.24, does this means that the MAF is bad ?

Yes by factory it’s without catalytic.

I have to fix the black smoke issue as MOT test is scheduled for next week.

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AllanWorms said:

That's why I like auto-ranging, like on my Fluke meter

So, very liekly your meter is like most: when set on 20K, the 1.58 mean 1K58 or 1580 Ohms - thats plausible for a temp of around 30-something C? The 0.22 would be right up there, with your Viscous fan locked, very close to 100C - seems fairly plausible too. That actually seems like it might be OK! The other issue though - is the ECU seeing that - a broken wire can affect that (Rovergauge wins here, again )

The other sesnor is Fuel TEMP, too, not pressure - just FYI. It's readings are usually less of an issue, but do influence mixture somewhat.

Have you checked the fuel pressure regulator? Do you have the Evap cannister? Could it be jammed open and sucking fumes from the tank 100% of the time? (Honestly - I think you're richer than that would do anyway!).

It might be worth checking the fuel pressure with a mechanical gauge to see it going up and down, to spec. Idle, with high vacuum tries to suck fuel from the injectors, so pressure it lower at idle, or should be. Do you have a gauge you can use for that? I've rigged up a water pressure gauge before... but obviously you have to be a bit careful with high pressure fuel!!!

This is the point where Roverguage will become more helpful - in case a reading is out of whats expected at the ECU end. A mechanical fuelling issue is still a possibility though!

Also - I just realised: You said your plug was on the MAF the wrong way??? There could be ECU damage, I guess - I don't know if it would do that, but possible). Again, Rovergauge would help (sorry!).

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sierrafery said:

Yes, your readings are way too low, it should be like in the table corroborated by a laser thermometer pointed to the engine head, buy a new sensor and measure that one to compare maybe your multimeter is making tricks... how many digits you see on the screen when you set it to 20k with probes in the air?

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hi_arshard said:

Thank you for the input, the issue connector was connected other way around. Following are the readings which connected and on idle speed,

Wire color
Red/black
0.06

Blue/Green
1.64

Orange/Brown
13.7

Blue/Red
1.94

Kindly advise if this readings are correct for idle speed.

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hi_arshard said:

Hay Allan,
Thanks for the detail Input.
I realized how much you love the rover gauge…! . My USB cable is arriving on 14th for the rover gauge. Still looking for a 390 or 400 ohms resistor.

pls tell me more on how do a test fuel pressure regulator? I don’t have a gauge. Specially fuel pressure gauge I am unable to fine. Any alternative gauge I can use for this ? I can purchase one.

Yes, I have a evap canister… is the canister related to this ? How can I check on that?

Regarding the MAF connected wrong side, 2 of my MAF was reading defective readings. The 3rd one was working fine. I believe this is coz of the wrong connection.

Hope ECU is not effected, will get to know once the Rover gauge is up.

Many thank

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discool said:

That MAF sensor wiring colour code above is for the 1994MY 3.9.
The 1995MY (300series) introduced in June 94 in the UK, has different wiring colour codes.

So I’m hoping the info you’re referring to is correct but I expect its similar, but it’s worth checking your on the correct page

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hi_arshard said:

Mine is 1995 V8 3.9. Should be same yaa?

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discool said:

The fuel regulator is a basic mechanical valve operated by vacuum from the plenum chamber, basically if the fuel pressure exceeds the spec. the valve operates and petrol is returned back to the tank.
Simples and effective.Is the vacuum pipe is ok and connected with out any leaks

There is no diagnostic available for the evap canister, the LR recommendation is replace it every 96,000 miles, so check the pipes / electrical connection, or if you not concerned about emissions remove it altogether, I believe some have already done that.

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hi_arshard said:

Hello guys,
I had an explosion while driving at around 110kmph on highway. When I checked it was the silencer center muffler. Any idea why did this happens all of a sudden . Attached pictures of the explode unit. I am noticing there is a slight vibration when accelerating or picking up speed. Specially as the gear changes, when press the gas peddle the vehicle vibrates while picking speed, once it he speed is picked up, don’t feel the vibration much. Is this vibration anything to do with the explosion?

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AllanWorms said:

Oof. I bet that was exciting

I think you're having a misfire, or leaking injector - either way, it appears you've had some fual vapour accumulate int he exhaust, and it's been ignited.

In the old days, we use to do this for fun... Turn off the ignition, pump the gas and turn it back on, hoping for the kind of BANG you got.

A missfire on the V8 can be a bit rricky to hear, as they have so many cylinders. That vibration you mentione though - it's quite possibly a missfire. You might need to check the ignition spark plus leads for the correct order, and that all the spark plugs are OK, and firing

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hi_arshard said:

Hi, I have checked the firing order, looks good. Anything I have to check in the distributor ? Rota ? Is there are timing to set on the rota arm. I have a doubt this might be something to with the dizzy… pls advise how can I Check and confirm the dizzy and dizzy arm working in the correct order ?

Thanks
Arshard

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Stanleysteamer said:

Don't forget that with modern petrol you can't set the timing to the figures in the original handbook!
When green petrol first came out my missus blew the centre box on her Citroen BX completely apart with the most spectacular backfire! We had to retard it a long way to make it run properly!
But do make sure that all timing gear is in good nick, no stretch, no wear in any part of it.
To check firing order, if you do not have a reliable firing order, whcih sounds barmy.
Find out the compression stroke for each cylinder, by removing all the spark pluga and using a compression tester, or one of those whistle things, or, if you can get to it, by putting a thumb over the spartk plug hole!
Once you've done that then you can write down the firing order and make sure that the spark plug leads are in the same order.
Once that is done you need to make sure that the rotor arm gets to each plug contact when the cylinder in question is at top dead centre more or less, but on the compression stroke.
If it was way out it wouldn't run at all.
and It is unlikely to happen all of a sudden unless the distributor locking device has slipped, or the distributor cap came loose.

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