Ford Powerstroke Diesel Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
Please help
I'm really frustrated at people telling me to throw parts at this truck!
Stock engine
430,000 mi
Has been hard to start when cold forever. (Separate issue)
Was running fine stopped at store. Came out 5 min later......Crank No Start. (Runs on either) .....I know here's my hands get the ruler.
Changed the camshaft sensor(Again).
No start.
Unplugged IPR.
No start.
Walked to Uhaul rented a truck.
Went to Harbor Freight bought a tow bar. Towed the 13,000 lb truck home slowly. (90 miles) 12 on dirt road.
Pulled the IPR, cleaned but didnt really need it. Air hose checked it...turns on and off with 12v.
Took out the IDM, checked power, checked ohms to injectors. Found a rub through on the harness from the IDM to the engine plug. The shield was rubbed through and 2 wires had insulation rubbed through. Taped insulated wires and soldered shield back together. Taped harness.
Bought scanner and downloaded ForScan.
Buzz test won't buzz injectors but...when the buzz test is ran the RPMs go up to 3000 then zero then flash to 1200 or so, 8 times.
Code P1668 comes up, reads no communication between IDM and PCM.
I don't want to just throw in another IDM and hope whatever fried this one (if it is fried) doesn't fry the new one.
How can I test this IDM.?????
And what about Keenan Laws YouTube videos repairing an IDM. Has anyone done this? Replaced kikthe resistors, capacitors and transistors to repair an IDM for pennies?
Thanks in advance.
Any help will be appreciated.
 

·
Registered
Joined
·
2,053 Posts
Swamps can test the IDM if you have the time to send it to them.
 

·
Premium Member
Joined
·
3,507 Posts
"Buzz test won't buzz injectors but...when the buzz test is ran the RPMs go up to 3000 then zero then flash to 1200 or so, 8 times "
This one is of interest -- need to figure why the rpm would do anything at all with a buzz test
possibly an open ground and the reason you are having troubles

"Changed the camshaft sensor(Again) "
If you are getting RPM, then the cam sensor is good
 
  • Like
Reactions: 7.3_TurboDiesel

·
Registered
Joined
·
1,775 Posts
"Buzz test won't buzz injectors but...when the buzz test is ran the RPMs go up to 3000 then zero then flash to 1200 or so, 8 times "
This one is of interest -- need to figure why the rpm would do anything at all with a buzz test
possibly an open ground and the reason you are having troubles

"Changed the camshaft sensor(Again) "
If you are getting RPM, then the cam sensor is good
When I buzz test my trucks the rpm needle sweeps as each injector is activated as well as when all 8 are activated.
 

·
Premium Member
Joined
·
3,507 Posts
When I buzz test my trucks the rpm needle sweeps as each injector is activated as well as when all 8 are activated.
Thanks for confirming the operation
my 6.0 does not sweep the rpm needle
was not sure how the older models worked
 

·
Registered
Joined
·
246 Posts
Seems to me if the buzz test is not firing the injectors there's a reason. I haven't broke out a schematic but the PCM fires the signal to the IDM to fire the injectors. So either the signal is not coming from the PCM or the IDM is not amplifying it to fire the injectors. It looks like you have narrowed it down to those two pieces of hardware. The wires that rubbed through may lead you to the answer. Were they on the PCM side or the IDM side? I'm willing to bet they are on the IDM side and its been shorted. You can test it if you have a scope and some basic electronics experience just be careful because the IDM puts out 140VDC to fire the injectors.
 
1 - 7 of 7 Posts
Top