Bloody MAFs!!!

[Timbo_1975]

What is it with the Bosch MAF's on these trucks? A bit of cold weather and it goes haywire!

Got a customer with a LWB T2 and i've put a genuine new one on about 12months ago and less than 12k miles. During the bout of -12 and again last few days around freezing the truck has been off colour. Hooked up the PC and the bloody maf reading is all over the shop sometimes stuck low, sometimes normal, and sometimes stuck high.

I'm working on a conversion box to use a regular 3bar MAP sensor and throw the maf in the bin permanantly. Watch this space.

 

[badger]

self cleaning kills them in cold weather, common on VAG cars.
hitachi are best, no self burn/clean

 

[solarman216]

Hooked up the PC and the bloody maf reading is all over the shop sometimes stuck low, sometimes normal, and sometimes stuck high.

I'm working on a conversion box to use a regular 3bar MAP sensor and throw the maf in the bin permanantly. Watch this space.

What sort of interface do you have, is it expensive, and the program? I would be interested in this if not going to break the bank, one point thou will it work on the petrol version, Rick

 

[rayf3262]

What sort of interface do you have, is it expensive, and the program? I would be interested in this if not going to break the bank, one point thou will it work on the petrol version, Rick

Steve...
Send Solarman the consult stuff I sent you and a link to the I/F you got for 18 quid.
R

 

[makeitfit]

Is there some sort of "Plug" I could buy to connect me early type ecu to a laptop?

 

[rayf3262]

http://cgi.ebay.co.uk/Nissan-Consul...iagnostic_Tools_Equipment&hash=item45f76451dc

Is there some sort of "Plug" I could buy to connect me early type ecu to a laptop?

 

[Timbo_1975]

Fisrtly it wont work on a petrol motor where the MAP sensor needs to be able to read vacuum- a maf never reads vacuum!

It's an adjustable 'translator', and still at the first prototype stage as yet.

The problem is a maf is self compensating for changes in altitude and a map isnt- so i need to build in an air temp sensor and compensation for it.

 

[solarman216]

Fisrtly it wont work on a petrol motor where the MAP sensor needs to be able to read vacuum- a maf never reads vacuum!

It's an adjustable 'translator', and still at the first prototype stage as yet.

The problem is a maf is self compensating for changes in altitude and a map isnt- so i need to build in an air temp sensor and compensation for it.

Sorry mate think you misunderstood, I am interested in hooking up a lap top to my motor to read the outputs from the management unit, thats all, Rick

 

[rayf3262]

Sorry mate think you misunderstood, I am interested in hooking up a lap top to my motor to read the outputs from the management unit, thats all, Rick

This will work for you:
Originally Posted by rayf3262
It's free and works pretty well, spent some time testing for diesels....
http://www.ecutalk.com/

 

[Timbo_1975]

Sorry- you'll need the nissan consult software then, although both the Galletto and kwp2000 will show live data in real time. Mind the cloned knock-offs on the 'bay though.

 

[solarman216]

This will work for you:
Originally Posted by rayf3262
It's free and works pretty well, spent some time testing for diesels....
http://www.ecutalk.com/

Thanks Ray, lots to look at here, will check it out, cheers, Rick

 

[badger]

hi ray,
yes that is the one i ordered, should be here soon, i will feed back how it works.
software you sent link for looks good, like the live logging idea, as you say will bring in maf data, so can gauge volume at given loads.

the bosch units do self clean, they heat up to 1000" on some you can disable this, but to be honest they are not that dear oem, even found the hitachi ones brand new for £75.

 

[lacroupade]

hi ray,
yes that is the one i ordered, should be here soon, i will feed back how it works.
software you sent link for looks good, like the live logging idea, as you say will bring in maf data, so can gauge volume at given loads.

the bosch units do self clean, they heat up to 1000" on some you can disable this, but to be honest they are not that dear oem, even found the hitachi ones brand new for £75.

say what??? thats about a sixth of their normal price.......! please tell where at once LOL

 

[lacroupade]

So what causes this self-clean process to kick off then? :nenau

 

[lacroupade]

Think I answered my own question....

http://www.aa1car.com/library/maf_sensors.htm

BUT, if correct, whats it got to do with the weather, looks as if this cleaning takes pace EVERY time the engine is turned off.

 

[rayf3262]

So what causes this self-clean process to kick off then? :nenau

Bosch hot wire units have a self-cleaning cycle where the platinum wire is heated to 1000 degrees C. for one second after the engine is shut down. The momentary surge in current is controlled by the onboard computer through a relay to burn off contaminants that might otherwise foul the wire and interfere with the sensor's ability to read incoming air mass accurately.

 

[rayf3262]

Think I answered my own question....

http://www.aa1car.com/library/maf_sensors.htm

BUT, if correct, whats it got to do with the weather, looks as if this cleaning takes pace EVERY time the engine is turned off.

I wonder how well the Bosch MAF's handle water/condensation... might be a bit more to it than just plain cold, after all the chill factor in that venturi has got to be severe even at modest ambient temps.

 

[lacroupade]

I wonder how well the Bosch MAF's handle water/condensation... might be a bit more to it than just plain cold, after all the chill factor in that venturi has got to be severe even at modest ambient temps.

well I guess its one of those times when having a K&N under the bonnet helps, what with all that allegedly red hot air it sucks in and all....:augie

All I can tell you is that in freezing cold weather, its like having around ten more horses under the bonnet because of the denser air:thumb2 Which I suppose means that if your truck isn't running noticeably better in sub-zero temperatures, then your MAF might not be funtioning 100%.

 

[badger]

not sure it is every time on the bosch, but think about how much longer it will take to get to 1000" if the weather is -8.
i know it is only a few degs below normal, but it must take longer and use more current? must do, even if only small, also i think they are thichfilm units, which become more brittle with time and temp, so could play a part.
i have found an audi site where they are converting cars from bosch to hitachi, re-mapping ecu to cope, as they are the best
all seem problems to me, first came across them on vw golfs, had same problems on all, including failing always in the winter.

is yours hitachi?
the primera p11 used same as terrano, both hitachi and bosch, and are much cheaper.
found a place in spain (the home of the terrano) which is selling brand new primera hitachi maf's for £75, 12 month warranty, not bad.
they do bosch as well, again well worth checking with mr nissan, who may well be milking 4x4 owners like everyone else?

 

[badger]

thinking about what you said ray, if it was -5 driving, add windchill could be at 70mph what -30?? or less.
maybe needs air inlet point to manifold, just like the old days?
i have opened up a hitachi one, well potted in semi fluid grease, no sign of water ingress, small area of localised overheating, which appears to be an earth point to the plate below, maybe worth runing a wire from the screw/plate to the ground, is it ecu of vehicle ground?