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Old 10-31-2011, 02:13 PM
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Noob with 7.3 Issues

HELP!

Towing a very heavy trencher (14klbs or so) out of Phoenix, AZ on I-10. Slow going coming up the hills and EGT's in in the 1,000* range down in 3rd gear. My truck is a 94, 5 speed, long-bed crew with a 4.10 gear. It has runn very well for the 4 months I've owned it and I've put about 5k miles on her. It indicates 198k miles though with the speedo acting goofy, bouncing around between 10 and 85 MPH at a steady 75 on the GPS, it doesn't count the miles properly. Could be up to probably 240k - 250k on it.

Nearing the top of a fairly long hill, the truck suddenly lost power like somebody flipped a switch and killed half the cylinders when under power but it would idle normally. Barely nursed it into a brake check station. It took about a 1/2 hour for the EGT gauge to come down under 300 deg at an idle. Another hour sitting and cooling then we were off again. Ran like a champ.

Decided that possibly the Tow Tune from the Edge Tuner should be set back to stock in an effort to control the EGT issue so we planned to stop at the very next rest area. As soon as we hit the off-ramp for the rest area, the shuddering and severe loss of power reappeared. This time I looked at the Boost gauge and saw zero boost though I had my foot in it pretty hard.

By the time the tow truck got to us, my truck has barely enough power to get it on the trailer to bring it home.

Some of the issues I've been told it may be are:

O-rings on the injectors leaking pressure away on the HP oil system when the oil is thin and hot requiring new o-rings/injectors
Bad CPS though it does not seem to have the classic symptoms of that issue
Overall bad HP oil system pressure, likely to due to o-rings and worn HPOP.

I've also been told the injector replacement is a huge pain in the butt, the injectors are terribly expensive ($300 each or so?) also requiring replacement of the glow plug/injector harnesses plus associated gaskets etc, totaling around $2,400 in parts alone.

The guy that gave me most of this info also said I'd be better off swapping to a newer version of the 7.3 as many mods have been made at the factory to resolve many issues the early models had. If the swap actually IS a good idea, anything like computer, wiring, other issues I should know about before I rip into this thing?

Or should I just go get a pack of matches to go with the 5 gallons of gasoline I've had my eye on?

How much did it suck that I had to buy another truck to pull my Ford home, and that other truck was a Chevy?
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Old 10-31-2011, 11:06 PM
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Start off simple. Scan for codes and do a buzz test on the injectors. Also check your fuel filter and the ICP pressure.
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Old 10-31-2011, 11:54 PM
Can you hear the derail??

 

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Welcome to the org, sounds like you may have blown one of the boots out on you turbo outlet y if your getting zero boost, I have run mine on up to 15-1600 for a second or 2 on the tow tune on an edge programmer, what mods do you have other than the edge programmer, an intake and downpipe would help a bit too. Good luck, and welcome to the org.

Pull and clean off or replace your vss sensor. It plugs in the front of your rear axle, that should correct or atleast help a lot with your bouncy speedo and uncertain odometer reading

Last edited by 351fifty; 10-31-2011 at 11:57 PM.
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Old 11-01-2011, 08:15 AM
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Thanks for the replies guys!

The codes it was throwing was for the CPS, the Exhaust Back Pressure Valve and a low system voltage code. All were reset. The only recurring codes were the CPS and the EBPV codes.

Buzz Test the injectors? I've seen that mentioned a couple of times on the site. How does that work? ICP pressure?

All of the boots and tubing are connected. She started building boost again as soon as I let it cool off and started down the road again. It's got a 3" straight pipe with no muffler exiting in the stock location and a K & N filter. I'll give that VSS sensor a shot. I looked at the wiring to the trans and there is one plug connected however there is an additional connector that is in that same loom to the trans but has a cover over the end and isn't plugged into anything.

I've worked on engines for over 30 years but this is my first real diesel so I'm kinda lost here. Had one or two of those ultra-raggedy Olds 350 diesels but those don't really count.

Quote:
Originally Posted by JSchuricht View Post
Start off simple. Scan for codes and do a buzz test on the injectors. Also check your fuel filter and the ICP pressure.
Quote:
Originally Posted by 351fifty View Post
Welcome to the org, sounds like you may have blown one of the boots out on you turbo outlet y if your getting zero boost, I have run mine on up to 15-1600 for a second or 2 on the tow tune on an edge programmer, what mods do you have other than the edge programmer, an intake and downpipe would help a bit too. Good luck, and welcome to the org.

Pull and clean off or replace your vss sensor. It plugs in the front of your rear axle, that should correct or atleast help a lot with your bouncy speedo and uncertain odometer reading
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Old 11-01-2011, 08:22 AM
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I'm thinking idm is going out. Hard to say without any codes. Agreed the vss needs cleaned or replaced
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Old 11-01-2011, 08:27 AM
Can you hear the derail??

 

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The cps is your cam position sensor, its 2 10mm bolts and a plug wire that hook it up, just go from the bottom of the engine (crawl up under the front) and remove it and replace, very simple to do, its like $20-30 at advance, most here recommend carrying a spare anyway, and as for the exhaust back pressure valve, sounds like it may be sticking and you could delete it, but I've never done that and dont know how, you would have to search it, and you should ditch the k&n in favor of a DIY intake, you will notice a great improvement over it, i spent $20 at pep boys and used the fram ca8037 filter, same as a napa 6637 and remove the stock air box. Also get a 45* elbow and you will enjoy the throttle response and turbo whistle, maybe even some fuel mileage increase too over the k&n drop in.
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Old 11-01-2011, 08:47 AM
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And an IDM would be?

Quote:
Originally Posted by Gruss View Post
I'm thinking idm is going out. Hard to say without any codes. Agreed the vss needs cleaned or replaced
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Old 11-01-2011, 05:37 PM
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Injector Drive Module, It's the computer that fires the Injectors. It's mounted on the drivers side fender by the hood hinge. When mine went out it would drop a bank of cylinders at a time and smoke REALLY bad.
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Old 11-01-2011, 11:12 PM
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Looks like you are off to a good start. The Exhaust Back Pressure Valve is used to block the exhaust to aid in warm ups. If it's sticking it will cause a loss in power and boost. The Cam Position Sensor will also cause many issues if it's going out. The buzz test will fire each injector with the motor off so you can listen and hear if all 8 are fireing.
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Old 11-02-2011, 09:55 AM
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How does one go about doing the buzz test?

Quote:
Originally Posted by JSchuricht View Post
Looks like you are off to a good start. The Exhaust Back Pressure Valve is used to block the exhaust to aid in warm ups. If it's sticking it will cause a loss in power and boost. The Cam Position Sensor will also cause many issues if it's going out. The buzz test will fire each injector with the motor off so you can listen and hear if all 8 are fireing.
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