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SD pcm in OBS

67K views 99 replies 34 participants last post by  m j 
#1 ·
so this afternoon i decided to tackle this project, actually went pretty smooth i moved pins around and added a couple i will post all the pins and their new locations later. the only problem i have is that my TACH read about half of the actual rpm i was wondering if someone who had already done this had this problem and what they did to fix it.. any input would be great.
 
#3 ·
No 160/100 i have the tuning to run the single shots
 
#5 ·
because you have better tuning capabilities
 
#6 ·
faster processors that allow more data to be calculated, a smoother overall fuel curve, voltage based map sensor input instead of frequency
 
#7 ·
Did you change the map sensor?
 
#10 ·
Joey, you wouldn't happen to have a list of the pins that need to be moved and their new locations do you?
 
#14 ·
No, I did not write them down. I will next time, as I plan on converting the 95 as well. My 97 is a Cali truck, so they are an odd ball already compared to the federal trucks.

We used a shop manual for the 97 and the laptop for the SD to convert, side by side. Then every wire for the trans was retraced back to the PCM to be extra cautious.

The 97 has a 4R100.
 
#11 ·
What are you guys doing for tuning on the E4OD? Or did you swap in a 4R100? Stand alone trans controller?

Been thinking about this mod for a long time.
 
#13 ·
Yes i did change the map sensor and my truck is a manual so it does save alot time here is a list of the pins that i changed
Cam Sensor Dark green wire change from Pin 49 to pin 21
Idle Val switch Red/org wire change from Pin 5 to pin 10
Brake Warning Pur/wht wire change from Pin 4 to pin 5
Wait to Start Blk/pnk wire change from Pin 80 to pin 70
IDM enable Wht/Blk wire change from Pin 70 to pin 80
MAP sensor LtGrn/Blk wire change from Pin 34 to pin 79
Tach Wht/pnk wire change from Pin 50 to pin 19

Pins 8, 9, 34 are all glow plug monitor circuits they all go to the glow plug side of the glow plug relay i tied them all together at the pcm and ran one wire to the glow plug relay with a fusable link that they came with on the SD i ran it from the pcm to pin 41 in the 42 pin connector near the valve cover

Pin 62 is for the Air Charge Temp sensor you have to add this sensor i ran it from the pin 34 at the pcm to pin 14 in the 42 pin connector the SD use a red/yel wire so thats what i used you have to "T" the other wire for the sensor in to the signal return wire it is a gry/red wire it is pin 19 in the 42 pin connector

pin 40 at the pcm is for the cruise control you will need to remove this pin and "T" it into the gry/red wire that goes into pin 91

you will have to get a map sensor and the plug off a SD you will need to wire plug on as follows
Gry/Red to Gry/Red
LtGrn/Blk to LtGrn/Blk
Brn/Wht to Brn/Wht

you will also need to remove pin 76, 64, 84 i just un pined them and put some heat shrink on the pins and taped them up in the harness

my truck is 97 so i didnt have to mess with the TPS wiring but if your truck is a 96 or older you will need to cut the gry/red wire at the pedle and run a wire to pin 24 of the pcm

Pin 40 is control power for the fuel pump

i dont run a fuel bowl so i didnt mess with fuel heater wiring or the water in fuel sensor and i didnt mess with the air heater wiring
 
#15 ·
just thought i would give you guys an update on this i got my tach working properly today i used a Dakota Digital SGI-5 universal signal interface unit. It says its for speedometer but it works for the tach in this situation, the tech a Dakota digital told me this gives you a lot broader spectrum to tune it in better. You will have to take your cluster out and cut one wire it is a white with pink wire it is pin #9 in connector A. You will want to splice a couple feet on to both end of this wire after you cut it, this will make it easier when you a calibrating the unit. The wire coming from the PCM will need to go to the signal in on the SGI-5 and the OUT1 will now go to the cluster (tach) then you will have to run a key on power and a ground to the SGI-5 also i set ended up setting the dip switches 1 and 2 to "off" and 3 and 4 to "on" i set the coarse adj to 13 and the fine adj to 16. I used my scanner to watch the RPM to set this up, and you can purchase this unit for about 80 bucks.
 
#19 ·
just thought i would give you guys an update on this i got my tach working properly today i used a Dakota Digital SGI-5 universal signal interface unit. It says its for speedometer but it works for the tach in this situation, the tech a Dakota digital told me this gives you a lot broader spectrum to tune it in better.
I'm curious as to why the tech did not recommend their SGI-8 unit which is specifically made for tachometers? Is there a reason to use the SGI-5 or was the issue not brought up? Asking as I had planned to use their tach unit when I do this conversion.
 
#17 ·
can you or someone else tell me how to do that?
 
#20 ·
the obs computer send out 12 pulses per revolution to the tach the superduty computer (99-01) sends out 4 pulses per revlolution, the tech didnt think the SGI-8 would multiply the signal enough to make it work properly
 
#27 ·
Got it thanks for the response! How did you decide on which manual SD pcm to go with? I see there are several to choose from.
 
#21 ·
So after all of this, HOW DOES IT RUN in comparison? DO you notice any difference at this point? What all is done to your truck already?
 
#22 ·
Idle quality is way better, lot more responsive right out of the hole with less smoke, the mid range power curve seems a lot smoother i haven't had it on the dyno yet to see what my top end horsepower did but seat of the pants i can tell a difference but i need to get some numbers and compare my truck is a 97 f-250 i put a dana 60 in it did away with the ttb 4 inch lift with 35's i put 3.73 gears in, swapped out the 5 speed for a 6 speed, south bend dual disk clutch, as far as the engine it has full force 160/100, 17 degree HPOP, 910 valve springs, smith brother push rods, arp head studs 140v idm, air dog II with a regulated return, banks i/c, the stock turbo was swapped out for a Gillette diesel TP38 upgrade CHRA and a 1.0 exhaust housing that i added a 44mm external waste gate, and a S475 as my atmospheric turbo, last time i had it on the dyno it made 472/860
 
#24 ·
Idle quality is way better, lot more responsive right out of the hole with less smoke, the mid range power curve seems a lot smoother i haven't had it on the dyno yet to see what my top end horsepower did but seat of the pants i can tell a difference
So, the just swapping to a SD PCM, did that? If that's the case, this mod could get real popular quick. What was your goal for swapping, Are there other known benefits?

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#23 ·
and it was tuned by No Limits Tuning
 
#25 ·
thats what I was thinking Jeremiah, so some rookie newb questions, I have Gearhead tunes for my OBS PCM, will the same chip go in the SD PCM, or will I need different hardware? I am not after huge power, but do want the best running 7.3 OBS I can have..
 
#26 ·
Your hardware can still be reused, it will just have to be updated to the newer PCM family code

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#29 ·
#30 ·
So is this a worth while mod, what are all pro/benefits of doing this?
The "worth while" part would be your own opinion. If you're anal about how your truck runs and want it to be the very best it can than yes I certainly think this is worth the effort.

Benefits are a faster more powerful processor. More tables are available for tuning and I believe they're of a finer resolution so smaller adjustments can be made.

I've been wanting to do this for years and personally think there is enough advantage with the SD pcm that I'll invest in a PCS for my trans and use a manual pcm for the engine.
 
#31 ·
Hmmmm, sounds like its worth while to me. Does it idle any different? Does the power come in faster? What are some specific differences as far as the engine running.

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