Alright, so I got the swap of the 7.3 into my Bronco and it went well for a few days. Everything seemed great.

Yesterday, while driving, I very abruptly lost power like several of the injectors stopped firing. The truck was idling rough (because I assume several injectors weren't firing), and when I went to take off at a stoplight, I stalled out because I didn't give it enough throttle (due to lack of power and misjudgment.) It started right back up but was still running rough.

About 20 seconds of driving, it went back to normal the rest of the night.

The next morning, I went to start my truck and it barely started. It again was running very rough as if some of the injectors weren't firing. I tried wiggling the UVCH plugs and nothing happened. I had to get home so I drove it about 3 miles when it all of a sudden came back to normal.

The rest of the drive home (about 15 miles) it was fine. I tried starting hours later and the truck wouldn't start at all. I couldn't see any white smoke either when cranking. I just tried starting again but still got nothing. It just keeps cranking.

Here is some things I looked into:

- Fuel bowl is full to the top with diesel
- HPOP reservoir is full and the oil gauge goes up when cranking
- Tach bounces when cranking (until I ran the batteries too low, then it stopped bouncing when the cranking was getting weak)
- I unplugged the sensor on the driver side head near the front of the motor and tried cranking but got nothing.
- Tried checking codes with the superchips tuner thing I inherited but it only came up with p1661 and p0603 (which I've had all along so far)



What else should I check from here? Does this seem like a bad IDM, or is the CPS or cam sensor (thing's I've read but don't know where they are) something I should look into?

Thanks for any help!

 

I would unplug the uvch and look at the po sand see if any look burnt

 

I just took a peek and they all seem good, at least from the outside. The driver side UVCH was replaced, as well as the pigtail. The passenger side wasn't replaced but the pigtail and connector look good.

 

Did you put a new ford crank shaft sensor in? If so check the plug and wiring.

 

I did not put a new one in. I just left the old one in place. Is the crank shaft sensor and cam position sensor the same thing? I've normally only heard about the cam position sensor, but saw a thread where people where referring to the crank sensor as well.

I pulled the plug on the CPS near the harmonic balancer and the pins look fine. There was a little oil around there but I believe that was when my HPOP gear cover was leaking down the front.

If my tachometer registers some movement while cranking, could the CPS still be bad? From the little amount I understand from these engines, I'm thinking this no start/very rough running (that cuts in or out suddenly) can be caused by 4 things:

- Cam Position Sensor (CPS) I think may be good if the tach registers movement
- Injector Pressure Regulator (IPR) I don't know how to test. I do have the tin nut on it as well
- Injector Control Pressure sensor (ICP) I unplugged it but still didn't start and had no white smoke
- Injector Driver Module (IDM) I don't know how to test this either...

Could I be missing something?

 

The part is pretty cheap and if it doesn't fix your problem, you'll have a known spare for the glove box. My truck was doing some completely random things that was fixed with a new CPS.

CPS at riffraff: $25
Motorcraft Cam Position Sensor CPS 94-03

CPS at dealership as of last week: $27

 

There is no crank position sensor on these trucks. It is a cam position sensor. What some call crank sensor is actually the cam sensor. The CPS can be bad even though the tach moves. I read threw your build thread in the Bronco section, and you referenced discolored pins in the valve cover gasket. If the pins /harnesses go bad, the IDM can shut one bank down to protect itself. If you replaced just the one gasket, the other one could be bad. If you used a Doorman brand gasket, they seem to be a crap shoot. Some have reported them bad out of the box, while others have had them run for thousands of miles.

 

Sounds to me like UVCH or at least the pins. If you get it started feel each exhaust port, you'll know right away which cylinders aren't firing without pulling the valve covers.

 

Hmm okay. I did use a doorman brand gasket for the driver side because I was short on money at the time. The passenger side plugs and connectors look good from the outside. The glow plug pins might be a little discolored on the passenger side, but the injector pins look great. Would it still be worth changing that out? Also, is there a way to test the harness with a multimeter to see if it's within specifications?

I believe I'll try and pick up a new CPS today at Ford if they really are only around 30 bucks just to test. If it doesn't work, then I'll have a spare at least. For the UVCH gaskets, would I be best trying to order them online? As of now, I might not have the funds to buy a set of Ford gaskets so I'll have to wait on that. I think when I looked them up, it was about 300 for the kit for both sides.

I'll try to do some more poking around, but I have a statistics project due tonight at midnight worth 30% of my grade! I'm due to graduate in two weeks but not if this project doesn't get done!

 

I understand the short funds. I have had that problem all my life. LOL The CPS is a good start, and if it doesn't fix it, you will have a spare. It's hard to say with the doorman gaskets. What has been reported, some are bad out of the box, but they didn't run right from the get go. You can ohm the injectors and GPs threw the gasket, but I don't recall what the values should be. You might want to check the repaired harness plug. You said in the build thread that you soldered them, but sometimes things happen. I was in a hurry one time replacing a harness plug and used butt connectors, which was a mistake. It ran good for a couple of years, then developed a miss on hard pulls, which progressed to a miss all the time. I removed the butt connectors, and soldered the wires, and all was good. I always thought the center pin was a common ground, but after doing some digging around on these forums I found that it is actually a high voltage wire to the injectors.

 

Do you have a friend that has a powerstroke truck? If so remove the IDM from your Bronco and install it in their truck and take it for a drive. If it starts and runs OK, the IDM is good. T IDMs are pretty reliable. Water getting into them is usually the problem when they fail.

 

Yeah I could try that! A buddy I know works at a shop in town and he drives a powerstroke truck. I didn't think about putting my IDM in his, that would make a lot more sense than me asking him to try his and bring it all the way back. I'll see if I can get a hold of him to try that out sometime this weekend to rule that out (or find it's the culprit) of the equation.

 

I haven't had a chance to test another IDM from my friends truck so I'll see if I can do that soon. I actually don't know him too well but we were good acquaintances in high school. I don't currently have his number so it will take some time to set up testing my IDM on his truck.

I bought a new CPS from Ford to try and test that at least. When putting it in, it ended up my batteries were dead. I replaced one battery with a new one because I had a warranty on it and replaced the other battery with one that was charged. The cranking sounded great and the tach was bouncing, but it still didn't try to start and no white smoke was noticed from the exhaust pipe.


I wish I knew how to get an IDM to test but I'll have to wait. Are there any other tests I can do without advanced diagnostics tools? Any other parts I recommend trying to replace?

 

Your fuel bowl heater still hooked up? If so check the fuse for the idm. If it is blown un hook the fuel bowl heater and replace the fuse

 

Thanks for the reply! However, I did unplugged that when I resealed the fuel bowl. It's unplugged from the inside, but the fuses to the PCM and IDM are good. I believe it's fuse #22 that blows when the fuel bowl heater grounds out and that was is good as well...


I don't know much, but I'm leaning towards it being the IDM because the weird issues it had the day before the no start. It did feel like several injectors cut out, but they came back later on. The truck definitely idled very rough when there was a power loss.

The other thing I'm thinking maybe is something to do with the IPR, but I wouldn't think the IPR would cause the symptoms of some injectors cutting out, then going back to normal.