[Diy_efi] What Injector Is This?

Mike erazmus at iinet.net.au
Fri Apr 4 05:33:11 GMT 2003


At 09:19 PM 4/3/03 -0800, you wrote:
>200C is 424 degrees farenheit.  That is really damn hot.  Consider
>also that it's above ambient.  If it's 100 degrees ambient, that element
>is 524 degrees.  That is about like a soldering iron.

Yeah sure, and lots of things do stick to hot surfaces, bits of dead
bugs that pass the filter, silica, resin, plastic particulates,
rubber etc... My soldering iron which is at around 230deg C has
to be cleaned quite often - even when I'm not using it...

>The bosch MAFs don't get nearly that hot, that's why they have a burn
>off pulse.

Your logic here is a bit flakey, a colder surface is less likely
to stick to organic material that it comes in contact with than one
that is hot enough to polymerise organics.
It also makes a lot of sense for Bosch to have a burn-off cycle,
cant you see the result is far better repeatability and negligible
reliance upon manual intervention...

>The Ford MAFs are dumb, they have no external "burnoff" signal.  The
>circuitry inside is just the driver and calibration.

Fine, and there are bound to be much cheaper than the Bosch units
and who knows, there may be a patent issure re burn off cycle that
precludes Ford's use so Ford rely on their service intervals to
manually clean them.

>I have not looked inside the MAF at poweroff.  The MAF is directly
>powered via 5v from the ECU, it doesn't have an external power.  When
>the ECU powers down the MAF loses all power.

OK, I'll bear in mind if I come across a Ford MAF that it needs
to be cleaned manually, what period do they suggest between
cleans and is there a recommended solvent ?

rdgs

mike




>--Perry
>
>On Fri, Apr 04, 2003 at 11:40:04AM +0800, Mike wrote:
>> At 12:14 PM 4/3/03 -0800, you wrote:
>> >My Probst book has a blurb about the MAF, I'll fine the schematic
>> >of it elsewhere.
>> 
>> Great, I'm interested in alternatives,
>> 
>> >The cold wire which is not exposed to the air stream is not heated,
>> >it simply is a thermister.  The Hot wire is heated to 200C above
>> >ambient, so you can see, it's always very hot.
>> 
>> Yes true, I have the old Bosch yellow book from 1982 same mostly,
>> 
>> I'm curious if you have ever looked down the throat of the AFM
>> when powering off etc ?
>> 
>> rdgs
>> 
>> mike
>> 
>> 
>> 
>> 
>> >--Perry
>> >
>> >On Thu, Apr 03, 2003 at 07:36:22PM +0800, Mike wrote:
>> >> Its very similar, the bosch element in mine is not
>> >> that small - looks like the wire length is some 60mm
>> >> arranged in a loop.
>> >> 
>> >> I dont think its a design issue (read flaw) wich means
>> >> the Bosch 'needs' a large clean current as might be
>> >> implied. Bosch seem to go to some trouble with
>> >> issues like cal and an automatic clean as such is
>> >> bound to be more reliable than relying on people to
>> >> do it - which I still find perplexing.
>> >> 
>> >> Have you ever looked into the throat of one of these
>> >> ford MAFs and watched if it does or doesnt apply a
>> >> current pulse - maybe it does but its not enough to
>> >> make the wire glow.
>> >> 
>> >> Yes, I would like to see a schema of the ford MAF,
>> >> the 'clean' may well be supplied by the ecu and not
>> >> be inherent in the MAF as it is for bosch, as far
>> >> as I can determine from all I've read on these
>> >> issues - some sort of 'clean' burn is very helpful...
>> >> 
>> >> rgds
>> >> 
>> >> mike
>> >
>> >-- 
>> >Perry Harrington			Data Acquisition & Instrumentation, Inc	
>> >perry at dainst dot com					 http://www.dainst.com/
>> >
>> >Those who would give up essential liberty to purchase a little temporary
>> safety
>> >deserve neither liberty or safety. Nor, are they likely to end up with
>> either.
>> >                             -- Benjamin Franklin
>> >
>> >_______________________________________________
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>> >
>> 
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>
>-- 
>Perry Harrington			Data Acquisition & Instrumentation, Inc	
>perry at dainst dot com					 http://www.dainst.com/
>
>Those who would give up essential liberty to purchase a little temporary
safety
>deserve neither liberty or safety. Nor, are they likely to end up with
either.
>                             -- Benjamin Franklin
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://www.diy-efi.org/mailman/listinfo/diy_efi
>
>

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