3AM Airflow Meter

Hello All;

I've a 1990 Disco V8i. Today I've changed the Spark Plugs and have noticed they are extremely 'sootie'. On 'idle' the RPM's are hovering around the 1500 - 2000 mark. Is it possible the 3AM Airflow Meter could be at fault here?

The Engine hasn't been started for over a year now. I've fitted New Plugs, Bosch Ignition Coil, Distributor Cap, Rotor Arm and Leads. How importnat is the Airflow Meter??

We are getting the Disco setup for next year to tow a caravan (1300 kgs). Can anyone advise me of it's likely towing abilty for such a caravan?

Any advice would be welcome.

Wobbly_Ron said:

Hello All;

I've a 1990 Disco V8i. Today I've changed the Spark Plugs and have noticed they are extremely 'sootie'. On 'idle' the RPM's are hovering around the 1500 - 2000 mark. Is it possible the 3AM Airflow Meter could be at fault here?

The Engine hasn't been started for over a year now. I've fitted New Plugs, Bosch Ignition Coil, Distributor Cap, Rotor Arm and Leads. How importnat is the Airflow Meter??

We are getting the Disco setup for next year to tow a caravan (1300 kgs). Can anyone advise me of it's likely towing abilty for such a caravan?

Any advice would be welcome.

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If the engine has not been run for such a long time then I would consider taking it for a long drive before changing anything and certainly before hanging a caravan on the back.

It is possible the soot comes from the starting up and leaving to idle for a while, switching off and restarting ect which you might be doing whilst fettling (is that spelt right?) it ready to go back on the road.

But you should try running it for a few miles at speed and see if they clean up. The idle speed is a little fast but the injection system should be metering correctly, I would be looking for a sticking idle control valve ect/air leak ect.

Also, fuel systems are designed to go a little on the 'rich' side at that particular rev range as this supplies a little extra power for pulling away, as oppossed to 'leaning out' which is a problem with petrol engines.

So if your engine is 'idling' at 1500 rpm then it will be in the 'rich' range and soot up the plugs.

Although I have worked on many injection systems I do not have first hand on the Land Rover one so I may be barking up the wrong exhaust pipe. Someone else will no doubt offer other suggestions so keep checking back.

Hope this helps before you go spending money for (possibly) nothing,

regards

Dave

Wobbly_Ron said:

Hello All;

I've a 1990 Disco V8i. Today I've changed the Spark Plugs and have noticed they are extremely 'sootie'. On 'idle' the RPM's are hovering around the 1500 - 2000 mark. Is it possible the 3AM Airflow Meter could be at fault here?

The Engine hasn't been started for over a year now. I've fitted New Plugs, Bosch Ignition Coil, Distributor Cap, Rotor Arm and Leads. How importnat is the Airflow Meter??

We are getting the Disco setup for next year to tow a caravan (1300 kgs). Can anyone advise me of it's likely towing abilty for such a caravan?

Any advice would be welcome.

Click to expand...

The Disco is designed and rated as being able to tow 3500kgs, so your 1300 caravan will be towed easily.

Re the state of the plugs and the tickover speed, I would do as others have said and take the car for a good half-hour run to get it thoroughly warmed through, before adjusting or replacing anything.

Usually, the tickover speed is higher on a cold engine, deliberately.

Cheers
Dave

Hello

Many thanks for your replies. The information is very useful. Have you got any idea what the air flow meter does, and how important is it

Thanks

Graham

The engine is idling to fast, suggest first change the temp sender about £12, this sends a signal to the computer to inform it of engine temp.this then controls mixture strength. Secondly, throttle position needs to be checked with engine off, potentiometer on plenum chamber needs to be checked for correct position. These checks need to be carried out before trying to set up engine. All settings and how to carry out are in workshop manual. Also I have complete system for 3.5 flap type. and also 4.2 type, and loads of injection parts. Hope this helps ranger41.

Wobbly_Ron said:

Hello

Many thanks for your replies. The information is very useful. Have you got any idea what the air flow meter does, and how important is it

Thanks

Graham

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The air flow meter, oddly enough, measures the air flowing into the engine and sends this information to the ECU which controls the correct operation of the motor and the measurement of the fuel/air ratio.

So it is pretty vital.

Cheers

Dave

Wobbly_Ron said:

Hello

Many thanks for your replies. The information is very useful. Have you got any idea what the air flow meter does, and how important is it

Thanks

Graham

Click to expand...

Exactly what it is called, it measures the airflow into the engine, this will give the ecu information on how much fuel to supply consistant with the amount of air, the fuel amount is also 'trimmed' by engine temp, throttle position, air temperature, mainfold vacuum ect ect.

I noted ranger41 said purchase a temp sender which for that money is good advice, I am not sure if the temp sender which operates the temp gauge is the same for the ecu so check that out so as not to get confused which one is which.

regards

Dave

Dave 2000 said:

Exactly what it is called, it measures the airflow into the engine, this will give the ecu information on how much fuel to supply consistant with the amount of air, the fuel amount is also 'trimmed' by engine temp, throttle position, air temperature, mainfold vacuum ect ect.

I noted ranger41 said purchase a temp sender which for that money is good advice, I am not sure if the temp sender which operates the temp gauge is the same for the ecu so check that out so as not to get confused which one is which.

regards

Dave

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Temp guage sender and coolant thermistor are different. Also, if idle high, do check your alternator and battery.

You can check your airflow meter, I posted some info on this recently, can't remember which thread though so do a search I'm sure you'll find it. Check that you have good connections where the AFM plugs in, mine has a dodgey connector in the plug but I managed to wedge it up and had no problems since.

The other thing is that if there was a problem with the AFM, your engine would run very unevenly and chances are the engine management warning light would come on, your ECU would default to limp home mode and would run very rich (like 6-8MPG). Happened on my classic, that problem was a duff ECU.

If you can get hold of another 14CUX ECU, you could try plugging it in to see if it makes any difference.

Hello

Thanks very much for the advice

We have taken the lovely Disco for a 60 mile run, after about 10 miles, idle revs seemed to drop to about 1000, but then revs seemed to increase up and down like someone was bleeping the throttle for a while

Suddenly, after about 30 miles, everything seemed to drop into place, and idle speed settled at around 500 - 600 RPM

Engine seems to be running lovely and smooth, but we still have concerns why the plugs have become so sooty

Is there any way you can do a simple test to check 3AM air flow meter

Many thanks for your help people. It's very much appreciated

Thanks very much

Graham

Wobbly_Ron said:

Hello

Thanks very much for the advice

We have taken the lovely Disco for a 60 mile run, after about 10 miles, idle revs seemed to drop to about 1000, but then revs seemed to increase up and down like someone was bleeping the throttle for a while

Suddenly, after about 30 miles, everything seemed to drop into place, and idle speed settled at around 500 - 600 RPM

Engine seems to be running lovely and smooth, but we still have concerns why the plugs have become so sooty

Is there any way you can do a simple test to check 3AM air flow meter

Many thanks for your help people. It's very much appreciated

Thanks very much

Graham

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Try this, find a nice steady stretch of motorway with a service station about twenty miles away, hold a steady speed perhpas 60? and then pull into the service station and switch of the engine immediately, now pull a couple of plugs and check the colour. If you can get all the plugs out and keeping them in order see if there is a variation in colour.

As you have now found out a good run can bring all sorts of rewards (visions of forum members huddling together giving high fives)

Let us know,

regards

Dave

Wobbly_Ron said:

Engine seems to be running lovely and smooth, but we still have concerns why the plugs have become so sooty

Is there any way you can do a simple test to check 3AM air flow meter

Many thanks for your help people. It's very much appreciated

Thanks very much

Graham

Click to expand...

There isn't much to test. You can check for ground, supply voltage, CO trim and air flow signal all with a digital volt meter. All fairly easy should only take a few minutes.