Cleaning Engine Sensors.

[Andy_B]

Hey guys,

Hey guys, I was wondering what you guys, use to clean your engine sensors (Like the MAF and other), and how you do it too. I'm use to old diesel engines, so the 3.9 V8 in my 97 disco seems a little more complicated.

Thanks

Andy

[BigJon]

I don't use anything as a general rule. Why would you need to clean your sensors?

[PhilipA]

Its well publicised in the USA that dirty MAF sensors can take a car out of emission compliance. They can be fouled from fibres from air cleaners or oil if a K&N is fitted. The 3.9 Hitachi MAF is unusual as it does not have a "burn off Phase" on shutdown so is more susceptable than most to becoming fouled.
www.gatewaycleanair.com/mechanic/air4_4/dirtymaf.htm
I use Jaycar electronic contact spray, and spray a lot into the small hole , with the unit off the car. I then wave it around for a while to dry out. After cleaning you will see the 2 wires are nice and clean.

I recently had a high fuel consumption problem and cleaned the connector contacts on the MAF and the temp sender with contact cleaner and then a clean rag for the MAF. Fixed the problem.

Regards Philip A

[Rayngie]

I'm joining in on this one as I'm looking to do the same, once you have the clip and the plug / wires off the MAF, how do you get the rest of the unit off?

[PhilipA]

The MAF is held only by 2 clips. All you do is undo them, and the hose clamp on the other end. This is for an early 3.9 but I am pretty sure that the plastic filters are the same. Be careful you do not lose the O ring and be careful not to dislodge it when assembling.
Funny , I was just down at British and Swedish this arvo to put my car in for a new rear main seal. Ouch.
Told the mechanic that mine had been running rich , and I had cleaned the connector and now OK.
He replied that it was a well known problem (That I had not heard of before)
Apparently you have to clean the early ones regularly as the steel pins get dirty. He said Rover changed the pins to Gold plated later 97? because the resistance changes from dirty connections caused the mixture to go rich.
So thats why they cost so much. they ARE gold plated!! LOL
Regards Philip A

[vrdw]

Glad I'm following the thread as I have a rich mixture problem on my '98 Disco so will check and clean the contacts.
One thing that I did today was disconect the MAF plug with the engine running. I reconnected it but it ran as if it was on four cylinders, really rough. One guy suggested disconnecting the negative terminal on the battery to reset the ECU? (engine switched off) Does that make sense? Anyway after about an hour without the disconnect advice (didn't do it) the engine started running fine again? any thoughts?

Viv, Doha Qatar

[PhilipA]

Anyway after about an hour without the disconnect advice (didn't do it) the engine started running fine again? any thoughts?


As I think Justin said in another thread, the 14CUX ECU resets after turn off and off long enough for the capacitors to discharge.
This was a response to my question as I had removed the MAF plug and found that the mixture went rich (limp home) and did not restore with the MAF reconnected . I then disconnected the battery but this was unnecessary.
I was checking with an old Colortune that I have, and the mixture change was quite visible.
Regards Philip A

[rjhjstr]

I've generally used either a soft brush (camera lens cleaning type) with metho or aerosol carburetor cleaner (Supercheap). Both methods work successfully with a variety of engines including high performance types.

Russell

[Graeme]

Its well publicised in the USA that dirty MAF sensors can take a car out of emission compliance. They can be fouled from fibres from air cleaners or oil if a K&N is fitted. The 3.9 Hitachi MAF is unusual as it does not have a "burn off Phase" on shutdown so is more susceptable than most to becoming fouled.
www.gatewaycleanair.com/mechanic/air4_4/dirtymaf.htm (http://www.gatewaycleanair.com/mechanic/air4_4/dirtymaf.htm)
I use Jaycar electronic contact spray, and spray a lot into the small hole , with the unit off the car. I then wave it around for a while to dry out. After cleaning you will see the 2 wires are nice and clean.

I recently had a high fuel consumption problem and cleaned the connector contacts on the MAF and the temp sender with contact cleaner and then a clean rag for the MAF. Fixed the problem.

Regards Philip A

I finally got around to getting a can of Jaycar contact cleaner for my TD5 after reading this post. The 1st short drive after cleaning the MAF and its contacts revealed a greatly improved throttle response at lower revs. It will take a few more drives to get the full picture but it feels very promising.

Thanks for the advice.
Graeme