MAF sensor issue?

[PeterH]

Hi everyone, was driving my 2001 HSE 4.6 up the Westgate the other night and noticed the engine hesitating under load, felt a bit like not enough fuel being delivered.
It was fine from a standing start, but the idle was slightly rough.
From my past experience with classic Rangies, I gave the throttle body a good clean out and also cleaned the contacts on the maf sensor plug.
Hey presto, running much better, idle perfect, no more hesitating under load.
Tonight the same problem returned, I'm guessing it must be something to do with the maf sensor.
Does anyone have any tips as to how to tackle this problem?
Can they be cleaned, or is it time for a new one?
Cheers, Pete.

[Hoges]

Spraying the sensor with Carburettor cleaner or non-residue disc brake cleaner often gets rid of any stuff which may have collected on the MAF

It may also be an electrical issue with the spark breaking down under load...have you checked the plugs/ignition leads and coil block? I'd also be checking all earth points....

[Derham18B4]

I would also check the fuel pressure at the fuel rail. If possible connect it to the fuel rail and take it for a drive and see if there is sufficient pressure.

[PeterH]

Thanks for the replies.
I usually suspect the sensor with these type of problems before looking deeper.
I've never had to play around with the maf sensor before though.
Is it safe to spray the sensor with carby cleaner?

[33chinacars]

You can buy proper MAF sensor cleaner. Got some for my P38 when I owned it . Most good auto shops should have it

Gary

[BusinessConnected]

CRC Branded "MAF Sensor Cleaner".

[Hoges]

A left field worst case scenario... carbon fouling of valve stems



http://www.robisonservice.com/servicedep/pdfs/carbon_fouling1.pdf

http://www.robisonservice.com/servicedep/pdfs/carbon_fouling2.pdf



It's worth a read...even if to positively rule it out as a cause...

[PeterH]

Thanks fellas, I'll try the maf sensor cleaner, sounds like a much easier start than pulling the heads off! I'm away for a couple of weeks, will do that when I get back and let you know the results. I hope that's all it is.
Cheers, Pete.

[PaulP38a]

I just use Isopropyl Alcohol from JayCar to clean mine... think it was someone here that recommended it a few years ago.
Is it any better or worse than MAF Cleaner?

[PeterH]

Bit of an update for you, I tried the crc maf sensor cleaner, now running much smoother.
It's probably one of those things that gradually gets worse over time, so you don't really notice it until it gets bad enough.
What a difference, the idle is perfect, runs beautifully.
Still noticing some hesitation accelerating uphill though.
Will have to check the ignition leads next I guess.
Cheers, Pete.

[wayneg]

I clean my MAF every 6 months or so. Get rid of the silly security screws holding the insert in and put some normal ones in place. Can be out, cleaned and back in in 5 minutes. If driving on very dusty roads I would do it monthly, it amazes me how I continue to get a very very fine dusting inside the air intake, nothing I do seem to stop a tiny ingression of fine dust

[poleonpom]

I have just replaced my MAF sensor and what a joy to have the performance back.

In the notes that came with the MAF, they suggested that the system would need to reset itself to the new MAF sensor and recommended disconnecting the battery, applying the brake for a minute (to discharge the electrical system entirely) and then wait 15 minutes.

I did this and the new MAF is working a treat, if yours is still hesitating then perhaps you may want to give this a go (but make sure you have your radio code)

Jonathan

[PeterH]

Hi Poleonpom, just out of interest, what symptoms did you have to indicate the maf sensor?

[poleonpom]

Hi Peter,

The car was more lumpy at idle, would hesitate on acceleration with a huge flat spot from tickover to about 1,5 rpm. It felt like the acceleration was either off or on - ie no gentle acceleration.

Prior to the MAF, I'd also replaced my Cam and Crank sensors as well as my fuel pump - they all decided to give up at the same time!:o

[Disco Dave]

Where did you source the new MAF sensor, if you don't mind me asking.

[poleonpom]

Where did you source the new MAF sensor, if you don't mind me asking.

I bought it direct from driven2automotive.com, it cost 51.65 gbp inc shipping, which I thought was quite good compared to oem and some of the other prices I had seen asked

[stopover]

Bit of an update for you, I tried the crc maf sensor cleaner, now running much smoother.
It's probably one of those things that gradually gets worse over time, so you don't really notice it until it gets bad enough.
What a difference, the idle is perfect, runs beautifully.
Still noticing some hesitation accelerating uphill though.
Will have to check the ignition leads next I guess.
Cheers, Pete.

New spark plugs and leads might help?