UDC and ECM replacement help.

Nootch

Nootch

nosprkreqrd
Joined
Jan 13, 2013
Messages
1,360
Background---

Been chasing a P0107 and various other MAP sensor codes on my 05 CR. when the code is one i am spiking my rail pressure to 29k and i don't like that. Finally got a warm day and snuck my head under the hood. Previously replaces sensor to no help and i have 4.999V at both power terminals to the sensor and 12.3V (12.4 at batt) back to gnd on the return lines. Ohm checked all 4 back to the ecm and got a consistent 0.2 Ohm reading on all 4 lines.

Troubleshooting tree takes me to ecm replacement option. To which i am not completely surprised. I have a remote battery that is hard line grounded to frame, and i forgot to disconnect the common + wire last i welded on the exhaust.

PROBLEM---

Now that i am at replacing ecm for testing the code, i have found a replacement that is supposedly good. How do i go about replacing it with my UDC programing? Do I just return it to stock, pull the ecm, and program UDC back on? or is there some type of issue with the Dongle and my laptop i have to work out as well.


Side note, i have returned to stock and ran the engine for 2 weeks and the code was still present.

Thanks in advance.
 
figure i will take some time out tomorrow during business hours. Was hoping for sunday evening knowledge from the forum.
 
I believe the ECM will need to be programmed with your vin number.
 
Called up Smarty today and got some answers. So this will be for the record of others searching.

for $50 and my VIN currently, they will build a "rescue" tune that will overwrite the brandused ECM and flash my vin into it, from there it will act as the old one and I can tune and play as normal.

Got to thinking this afternoon. CAT engines LOVE to use the pressure sensor in the air filter, or in the engine block to set the nominal pressure value for the elevation. This measurement it taken at key on before start usually, or during crank if you are johny on the spot with the key. So i looked at my IAT that would normally reside in my air box but has been living outside of it for a while and found corrosion on the sensor. Ordered a new one and will see if that helps out. Will take the time to drill and mount it into the elbow I have as an intake now to keep it out of the elements and work as intended. If it doesn't work, no big deal, still have that ECM available from a 04.5, which I am 98% sure is completely compatible with mine.
 
I had forgot to plug in my iat sensor on the puller after a freshen up. It caused all sorts of problems with fueling. Truck had no power and no fuel. cant recall what rp was. It never once threw an iat code. Only map sensor. Changing that never fixed it. My iat is not in the intake pipe. I found the iat and plugged it in. All fueling problems solved. Truck is an 03 and was runing original ecm/harness at the time.
 
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