L-Jet AFM Question - where to find "042 manufacturing date"?
10-20-2006, 12:42 AM
#1
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L-Jet AFM Question - where to find "042 manufacturing date"?
In the WSM there are two sets of test numbers for the AFM.
It says: "Beginnin gwith manufacturing date 042 (stamped in housing of air flow sensor)"
Where is this?
I have two used AFM here with a rebuilt on the way from 928INTL. Now I fully understand the numbers in the WSM for the AFM need to be taken with a grain of salt - just curious how I determine if any of these are the "042" model.
I plan on letting these three meters sit for a overnight to reach the same temperature then compare readings. Per the WSM the readings could be way off between working meters if you have an 042 and a non 042 meter.
EDIT - numbers to add:
Original AFM from my 81:
Part Number: 280 203 015
Inside the mouth of the meter (outlet side):
1285
101 106
Stamped on the under side of the meter:
030
1285501
033
Used AFM - I suspect rebuilt since the epoxy around the plastic cap is not original:
Part Number: 280 203 009
Inside the mouth of the meter (outlet side):
1285
101098
Stamped on the under side of the meter:
030
1285501
033
Will be interesting to compare these numbers to unit #3 on the way from 928 International. Will be here tomorrow. In case anyone cares, I'll pst the results after I run through the WSM tests with these units. So far these two fall within the "042" section of the AFM testing page.
It says: "Beginnin gwith manufacturing date 042 (stamped in housing of air flow sensor)"
Where is this?
I have two used AFM here with a rebuilt on the way from 928INTL. Now I fully understand the numbers in the WSM for the AFM need to be taken with a grain of salt - just curious how I determine if any of these are the "042" model.
I plan on letting these three meters sit for a overnight to reach the same temperature then compare readings. Per the WSM the readings could be way off between working meters if you have an 042 and a non 042 meter.
EDIT - numbers to add:
Original AFM from my 81:
Part Number: 280 203 015
Inside the mouth of the meter (outlet side):
1285
101 106
Stamped on the under side of the meter:
030
1285501
033
Used AFM - I suspect rebuilt since the epoxy around the plastic cap is not original:
Part Number: 280 203 009
Inside the mouth of the meter (outlet side):
1285
101098
Stamped on the under side of the meter:
030
1285501
033
Will be interesting to compare these numbers to unit #3 on the way from 928 International. Will be here tomorrow. In case anyone cares, I'll pst the results after I run through the WSM tests with these units. So far these two fall within the "042" section of the AFM testing page.
Last edited by hacker-pschorr; 10-20-2006 at 01:37 AM.
10-20-2006, 11:38 AM
#2
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On ^ note, did some more searching. The 944 crew spends a lot more time messing with their AFM then the 928 guys.
Found this:
http://www.clarks-garage.com/shop-manual/elect-22.htm
Does anyone know what needs to be changed (like voltage used) to test a 928 meter? I would hate to blow my meter. Now that I think about it, I could hook up a meter to the harness plug, turn on the key, see the voltage applied to the meter - correct?
What I did notice last night is opening the barn door while measuring resistance causes the value to jump all over the place. Staring at say 200ohms, then up to 1,200, back down to 400 back up to 1,000 etc... this alone tells me my contact strip is dirty / with deep groves. That is unless the 928 AFM is unlike every other AFM that the resistance should be a constant rise / fall as the door opens / closes.
The other unit I "found" yesterday acts the same way.
Found this:
http://www.clarks-garage.com/shop-manual/elect-22.htm
Does anyone know what needs to be changed (like voltage used) to test a 928 meter? I would hate to blow my meter. Now that I think about it, I could hook up a meter to the harness plug, turn on the key, see the voltage applied to the meter - correct?
What I did notice last night is opening the barn door while measuring resistance causes the value to jump all over the place. Staring at say 200ohms, then up to 1,200, back down to 400 back up to 1,000 etc... this alone tells me my contact strip is dirty / with deep groves. That is unless the 928 AFM is unlike every other AFM that the resistance should be a constant rise / fall as the door opens / closes.
The other unit I "found" yesterday acts the same way.
10-20-2006, 12:24 PM
#3
Burning Brakes
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Hacker,
Well there's actually a hot, ground,signal return, ref return, temp.
If you have the manuals, there's a whole section in there about the AFM.
Anyway, if you try ohming it out just using a pole to pole method and a medium level meter (non-lab grade) you'll see all sortsa jumpy numbers - even on a brandnew AFM. If you really want to see what it does, my recommendation is interceptor box and datalog. 0-10v on the datalogger for L-Jet.
Even though the carbon strip is basically just a rheostat - it's a bit more complicated than that. You'll never move it smoothly enough by hand to see linear readings. It's also not really going to read linearly in straight resistance mode. It needs juice across it and then tap out the V from the wiper - then you'll see the linearity you're looking for.
The AFM top pops off and you can look at the carbon trace and the metal wipe and get a better visual idea. If you look at the electrical diagram you might get some idea of what I'm talking about.
I'd write more but I gotta run.
Greg
Well there's actually a hot, ground,signal return, ref return, temp.
If you have the manuals, there's a whole section in there about the AFM.
Anyway, if you try ohming it out just using a pole to pole method and a medium level meter (non-lab grade) you'll see all sortsa jumpy numbers - even on a brandnew AFM. If you really want to see what it does, my recommendation is interceptor box and datalog. 0-10v on the datalogger for L-Jet.
Even though the carbon strip is basically just a rheostat - it's a bit more complicated than that. You'll never move it smoothly enough by hand to see linear readings. It's also not really going to read linearly in straight resistance mode. It needs juice across it and then tap out the V from the wiper - then you'll see the linearity you're looking for.
The AFM top pops off and you can look at the carbon trace and the metal wipe and get a better visual idea. If you look at the electrical diagram you might get some idea of what I'm talking about.
I'd write more but I gotta run.
Greg
10-20-2006, 12:50 PM
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Originally Posted by 2V4V
It's also not really going to read linearly in straight resistance mode. It needs juice across it and then tap out the V from the wiper - then you'll see the linearity you're looking for.
The factory tolerances are so braod, an AFM within range may not work all that well when you are trying to fine tune a higher output setup. For the factory 220hp a broad range works fine for regular driving - I'm tyring to fine tun my car and make sure I fully understand what is going on with my setup.
The 951 guys have quite a few write ups for fine tuning AFM. These procedures should transfer over to the 928 unit - except I need the voltage ranges to test them.
