hey i have huge issuses with my 7.3 f250, it seems like it hasn't been reliable since i bought it. i have mt degree in auto and diesel tech so i figured i could fix it my self but im down to asking other people. so here are the problems,

truck wont start without starting fluid even on a 70 degree day (yes i know you are not supposed to use starting fluid with glow plugs but im frustrated)
what ive done for this problem: replaced glow plugs, glow plug relay, valve cover gaskets, valve cover gasket harnesses, fuel pressure regulator, ICP, and cam position sensor. still no go but the other day i ohmed out my glow plugs and only 3 of them were good (just my luck) so i am hoping that is the problem.

second issue is when it does start, since i put the cam position sensor in it acts like the sensor is bad, is it possible i got a bad one of those too??

third issue transmission wont shift into overdrive, its a brand new transmission from transplus down in florida maybe 5000 miles on it, it acts like it wants to shift into OD but never does, i cant get over 50 mph. trans mission fluid is full and smells normal.

Forth issue the only one popping a code or light of any sort is when i got it fired up to take it to my shop in town it died when i put it in gear. code p0720

any help would be greatly appreciated thanks

MODS: S&B intake, 5" turbo back exhaust, TS 6 pos chip, upgraded turbine and compressor wheels, 8" lift 40" tires, 456 gears

 

A tech troubleshoots they don't just throw parts at something. I'm not a diesel guy but these guys are going to need more to go off. Have you checked fuel pressure or anything?

 

Moved to the 7.3 forum

 

i wasnt throwing parts at it, i replaced the sensors that were out of range on my scan tool. and rplaced the glow plugs relay and harnesses, the basics. dont accuses me of something im just trying to get some help

 

What brand glow plugs did you put in? Also, more than once, I've noticed I did not put on the glow plug connectors all the way on and they have vibrated nearly off - any chance the plugs you ohmed out have the connector backed off? I only got a year out of a replacement OEM glow plug relay, and decided to replace it with the Stancor mod - much better.

What scan tool are you using?

The OEM cam sensor Clay at Riffraff sells has good feedback. It has a dark body. The light grey one that was often installed by Ford during the recall is not so good. What color is the body of your sensor and where did you get it?

Pretty young trans - can you ask the transplus folks about this - warrantee? Might be related to the P0720 code though. P0720 indicates an insufficient output from the OSS sensor. Reading about some folks experience with this code, it may be the OSS sensor, but could also be the VSS sensor on the rear pumpkin, or alternator interference, or... With a sensor out or intermittent, might have locked the TC and cause the engine to die. Did your O/D light on the shift lever blink?

 

A good start would be to monitor RPM, Voltage, ICP, IPR duty cycle and injector pulse width while cranking and post those a graph (or raw .csv data) of those values if you can.

At 70F ambient, the glow plugs should be pretty much irrelevant to starting. When you're cranking the engine, are you getting any smoke from the exhaust?

And really, if you're going to use ether, disconnect the output wire from the glow plug relay before your frustration costs you a connecting rod or two.

 

Unplug the chip and be sure the connection there isn't an issue. You do need to know the fuel psi. Be sure your oil is full, low oil pressure will effect the hpop. I agree at 70* glow plugs shouldn't matter, at least not much. As was mentioned, what brand? Motorcraft are recommended.
And, most scan tools don't give us good info.
What do mean "cps acts bad"?

Most folks here are happy to help, but better info is needed.

And it's not only the glow plugs, but 22:1 compression doesn't like ether!

 

Welcome Brandonroos44!

I hope I'm not being impolite, and I really want to help... but I must share something: If a customer came to you and said "since I put the cam position sensor in it acts like the sensor is bad", your very first questions would be "What was the truck doing to make you replace the CPS, and what is it doing now that makes you think this one is bad?"

I don't doubt that you know how to fix stuff, but the 7.3L is a wily bugger - it can make you think something major is wrong, and it's usually the simplest thing that gets you.

Starting with the glow plugs and the truck acting like it has a bad CPS, If I were in this situation - after unplugging the performance chip, I would find the root cause of the bad conductivity of the glow plugs and I'd ohm out those injectors way back at the 42-pin connector. Click this link for more info: [LINK]

 

If you have to use ether to get it to fire when it is 70 out, you might have a compression issue. As others have stated, taking the chip out will help you trouble shoot more accurately. If the chip isn't the problem.

 

I had a similar problem it ended up being the hpop. It kept getting worse and worse until it left me stranded 1000 miles from home. I'm not saying that's your issue, just something to check

 

hey guys sorry ive been away on work for a while and havent had internet connection or a chance to work on the pickup, when i got back yesterday i came back with motocraft glow plugs and put them in and it fired right up so at least ive eliminated that problem it had auto lights i didnt think brand would really make a difference.
transmission is still funky though im almost thinking about taking it to the dealership for that because my scanner wont read the trans and i have about 0 free time with my new job.

 

You're getting some great information.

Here is where you'll get the help you need.

NEVER use Starting Fluid on these engines. You may get away with it a couple times. But, a Ring or connecting rod will set you back about $3,000 - $5,000 in Parts and Labor.

The guys have spot-on comments.

P0720: Is the output shaft speed (OSS) sensor is mounted externally on the top of the transmission extension housing. The PCM uses the OSS sensor signal to help determine electronic pressure control (EPC) pressure, shift scheduling and torque converter clutch (TCC) operation.

Check the connection and call the company who re-manned the unit. I'm sure they will help. They may even send a sensor which is fairly easy to change or provide some troubleshooting processes for you.

 

Don't overlook the connector to the transmission. Mine was loose after the shop installed a bigger transmission... and the neutral/park switch wasn't making contact. The truck wouldn't crank.