Thread: MAF FAULT POSSIBLE

also the maff and tps have been adjusted and dont make nay difference
seems a bit intermitant had it running sweet for about ten seconds then went bad again tps adjustment is .34v and is smo0th up to 4.8 v when i first adjusted the maff it was reading 0 volts so this may be an indication that its on its way out adjusted to 1.3v made no difference or so little it was nothing noticeable to running but ever so slight to injector pulse width. also has a different sealant on the back cover of the maff near the trim pot showing it may have been repaired before. running and injector pulse width doesnt change when you change maff trim pot voltage or even diconect it looks like a diesel at idle and runs sweet at wot cheers

Ok I have replaced the maff and made no difference still running very rich and miss firing badly this has been of the road for months now and on the verge of driving it of a cliff

do you have lpg? if so do you run it 99% on lpg.
if so then maybe your injectors are stuffed. Happened to me by lack of petrol driving, the bottom of my injectors perished, and driving on petrol made my plugs black from over fueling as the injector were leaking

na no lpg straight fuel and the injectors are new there just pulsing at 4.5ms at idle instead of 2.4ms and cant figure out why fuel reg and pressure has been tested and is good it has used 70 litres of fuel in 90 kms

70 litres per 90 K , you sure the return line is going back to the tank and not on the Ground !!! .You Wouldnt think the injectors were capable of delivering that much fully dutied out , You havent mentioned the Fuel pressures , yours sounds like its at 100PSI instead of 35 PSI , as if the return line is Blocked , regulator stuffed !
If all thats good , then you probably got the cam in a mile out , whats the static compressions say ? Whats the Lift at TDC on number 1 Inlet ?

Originally Posted by nigelbuilding1984

Ok I have replaced the maff and made no difference still running very rich and miss firing badly this has been of the road for months now and on the verge of driving it of a cliff

You don't say what year model, but if it has an IAC valve on the back of the plenum then it is likely that that is your problem, if so take it off, clean the stepper motor and the seat in the plenum with Carb cleaner, let us know if that works, Regards Frank.

I would be treating the wide injector pulse width with caution. There may be something else loading up the engine and the PCM is trying to recover the engine.
For example (not engine specific) a faulty cannister purge valve will cause this, an incorrect voltage from a MAF (100mV is enough) is another one. Leaky EGR.

I guess you have checked the pressure regulator for leaks.
Whats manifold vacuum at idle? What does the needle do?
Whats the output from the O2 sensor's?
Does the problem occur hot and/or cold?
Are you able to get any live data from the PCM?
Are you able to confirm the PCM is getting the signal voltage from the coolant temp?
Whats MAF voltage now?
And from your fuel consumption I'm assuming the problem exists off idle as well?

Also I'm assumming this is a Land rover. But info helps.

Can you measure the coolant temp? do you have a stat in the housing.

What do you plugs look like?

If its a 13 / 14 CUX ECU, it will run rich up until 83c, then trim itself out, as its operated at the correct engine temp, have you checked the fuel temp sensor?

I would do an oil change as well, you will be washing all the bores out with that amount of fuel used in under 100km's, it must be running out of the exhaust pipe like water.

Coolant sensor should read between 300 - 400 ohms around 80c

Fuel temp sensor should read the same i.e. 1100 - 1300 ohms 40c / 500 - 700 ohms 60c

If either of those are not correct, it will cause the ECU to run rich.

If you can test the injectors, more then two drips a minute, then overhaul them.