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P1271-1278 after install of UVCH and unplug of ecm

350 Views 5 Replies 2 Participants Last post by  PSTROKEN
Hello I have a late 99 Ford super duty 7.3. Truck was missing on cylinder #1 "bad at 1000-1350 rpms. Truck also had low IPR voltage. Brand new HPOP,MOTORCRAFT IPR/pigtail and standard brand icp/pigtail.,,,,
I removed both uvch to inspect them and I unplugged the ecm to try to test and find culprit of the P1280 low icp code. I also ohm tested the IDM at harness all 3.ohms.Buzz test of all 8 new injectors was also good.
Went to start truck and cylinders 1-8 throw 1271-1278 code and truck won't start. Both uvch are tight and look fine, tested from black connector above drive valve cover too injectors and all pins ohm perfect. IDM plug ohm tested again all good.
This truck would fire right up prior to me working on it and I was just trying to fix a miss and low icp. Now all high too low side open.
Any ideas what else I can test ? I really don't know what to do from this point, I do not think it's my IDM but any advice be helpful thanks.
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What did it turn out to be?
Sorry, I don't know much about the 7.3
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