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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

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  #136  
Old 01-25-2013, 03:39 PM
n4ynu1010 n4ynu1010 is offline
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Bad ECM

Quote:
Originally Posted by DPDISXR4Ti View Post
Having pulled apart at least ten PCMs to examine more closely the capacitors, I've got some additional data that I believe supports my previously proposed theories of why the F150 PCMs of this era are more prone to failure.

For starters though, all of the circuit boards use Nichicon capacitors rated at 105' C. From there, things get different in two ways. First, and perhaps most significantly, the F150 caps are physically smaller than all the others. The ones used in the F150 PCM are 6.5mm in outside diameter while all the others use caps that are 8.3mm in O.D.

Second, the specs for the F150 caps are unique, as follows:
Qty 1 10uF 63V
Qty 2 47uF 16V

Compare that to what is used on the others I examined ('88 - '94 Mustang & Ranger):
Qty 1 3.3uF 63V
Qty 1 47uF 10V

Or, for those that also use three capacitors ('87 - '89 Merkur XR4Ti):
Qty 1 3.3uF 63V
Qty 2 47uF 10V

Lastly, I had one EEC5 PCM that used the following (1997 Explorer):
Qty 1 47uF 63v
Qty 1 47uF 10v

My best guess is that the smaller physical size may be the biggest thing that's causing the earlier death of the caps in the F150 PCM. Smaller size would likely mean greater heat build-up.

I don't understand the ratings well enough to have much of a valid opinion there, although it's interesting that Guy's approach was to increase the voltage value of the replacement caps for the lower voltage part (from 16 to 25). It would seem however that the factory went in the other direction, from 16V down to 10V. Of course, I'm assuming that this is the comparable 5V circuit doing comparable work.

Note, I hate questioning Guy's recommendations, as clearly he know more than me on this topic and his replacement solution has worked. I thought it might be worthwhile to bring this data forward regardless if only because it does finally point to some reasoning for why this problem is so much more prevalent with the F150 PCMs.
I made my decisions based on the ECM I had , the spec changes I decided to make were the only that I could make as I could not increase Temp Rating as that is the best I could find , that which matched , I could not increase the design rating as it applies to rough service which is part of the Temp rating , Again I could not change base Capacitance either as that would change the operation and design specs of the circuit .
But I was able to raise the rated Voltage as a extra measure regarding possible spikes that could have caused early failure , it is none the less the only preventative measure I could take , I also as in previous pots went to great measure to validate that the Capacitance Values would be effective in the circuit even at far lower voltages , many caps when you raise the Voltage you actually raise the applicable working voltage for that Cap to operate at it rated Capacitance value , so you have to be careful regarding that , in the case of the other Caps you listed being a lower voltage rating , that is simple , it means they have lower circuit operating voltage and can then afford to lower the rated voltage .
What I have posted in these posts is not and should not be taken as applicable to all ECM's , in every case , the ratings should be adhered to , but if you can improve the rating without compromising design function , then it is a good thing in my opinion as whatever you can improve regarding temp rating if possible and or rated voltage will just extend the life period .
So I hope all understand that you need to get the original specs on the components and then do extensive homework if you choose to raise rated voltage , design Capacitance values would never be able to be changed ot you WILL change the designed function of the circuit , but if you can raise temp rating and or voltage keeping the specified values then it is going to do nothing but add life to that you have already had fail .
And in regards to this , the proof is in the pudding , the ECM is communicating and functioning perfectly as evident by bench testing I had done to make sure there were no other issues

Guy
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  #137  
Old 01-29-2013, 11:52 AM
DPDISXR4Ti DPDISXR4Ti is offline
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Quote:
Originally Posted by n4ynu1010 View Post
What I have posted in these posts is not and should not be taken as applicable to all ECM's
Understood. My rationale for providing the info on the caps used in other Ford PCMs was to demonstrate that the full-size truck computers of this era are somewhat unique in their circuit design, and perhaps that is why they are failing at a much more rapid pace. It would be interesting to know what the truck EEC-V PCMs look like inside.

Back to the selection of the proper replacement caps, do you happen to have the part#'s for the ones you used Guy? Even if I limit my search to Panasonic, I'm finding multiple choices of caps with the same exact specs. The ones I've tentatively selected are from the NHG series as follows...

10UF 63V 105c NHG Series PANASONIC ECA-1JHG100

47UF 25V 105c NHG Series Panasonic ECA-1EHG470

Here's a link to the spec sheet...
http://www.mouser.com/ds/2/315/ABA0000CE26-7739.pdf

An interesting note on this series of caps, which may mean something, or nothing at all.... Panasonic doesn't even offer the 47uF in 10V or 16V; the lowest voltage offered is 25. Perhaps they were problematic in the lower voltage spec parts and thus no longer offered???
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  #138  
Old 01-29-2013, 06:01 PM
n4ynu1010 n4ynu1010 is offline
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Quote:
Originally Posted by DPDISXR4Ti View Post
Understood. My rationale for providing the info on the caps used in other Ford PCMs was to demonstrate that the full-size truck computers of this era are somewhat unique in their circuit design, and perhaps that is why they are failing at a much more rapid pace. It would be interesting to know what the truck EEC-V PCMs look like inside.

Back to the selection of the proper replacement caps, do you happen to have the part#'s for the ones you used Guy? Even if I limit my search to Panasonic, I'm finding multiple choices of caps with the same exact specs. The ones I've tentatively selected are from the NHG series as follows...

10UF 63V 105c NHG Series PANASONIC ECA-1JHG100

47UF 25V 105c NHG Series Panasonic ECA-1EHG470

Here's a link to the spec sheet...
http://www.mouser.com/ds/2/315/ABA0000CE26-7739.pdf

An interesting note on this series of caps, which may mean something, or nothing at all.... Panasonic doesn't even offer the 47uF in 10V or 16V; the lowest voltage offered is 25. Perhaps they were problematic in the lower voltage spec parts and thus no longer offered???


I purchased these from Digi-Key @ DigiKey Electronics - Electronic Components Distributor
47UF 25V $.33 ea Part # P14411-ND
10UF 63V $.30 ea Part # P13467-ND

From my research as well as speaking directly to Panasonic Techs , these caps will operate at specified values well below 6.3V , so not sure about the specs you have there , but those are a different type as well , so that may be the difference .

Guy
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  #139  
Old 01-29-2013, 10:51 PM
DPDISXR4Ti DPDISXR4Ti is offline
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Quote:
Originally Posted by n4ynu1010 View Post
47UF 25V $.33 ea Part # P14411-ND
10UF 63V $.30 ea Part # P13467-ND
Thanks Guy, I hadn't found those but indeed they look like a better choice - newer design, specifically formulated for longer life.
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Old 01-29-2013, 10:51 PM
 
 
 
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