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1999 7.3 lacks power

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have a 99 f550 7.3 liter came in was building 1 to 2 psi mgp replaced turbo no help replaced map sensor now i have 5 to 6 psi of boost still needs more .map baro and ebp all within .5 of each other koeo any idea's i'm stuck ebp at wot in park will go to 39 psi,is that enough to cause not enough boost thanks for any help in advance,kevin

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did you check the basic's? engine oil condition, fuel pressure and also vacuum the pump pulls on the suction side of the fuel pump? exhaust leaks? you said replacing the turbo got a few more psi of boost, what condition was the previous turbo in? possible base engine damage like a dusted motor? crankcase pressure test? need more info i would think to give you a more exact thing to look for

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did you check the basic's? engine oil condition, fuel pressure and also vacuum the pump pulls on the suction side of the fuel pump? exhaust leaks? you said replacing the turbo got a few more psi of boost, what condition was the previous turbo in? possible base engine damage like a dusted motor? crankcase pressure test? need more info i would think to give you a more exact thing to look for

I have gotten in the habit of checking & correcting the oil level, then with a hot engine pull the oil cap off and stand up on the throttle while looking thru the gap between the hood and cowl. If it looks like a steam engine out he oil filler then it's dusted. You then pull the intake hose to the turbo and snap a pic of the turbo to show the customer...

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As FTCA states... (especailly with a truck this old) a crankcase pressure test is going to be valuable... just to keep some logic to what you are doing, look in the PC/ED in section 4 - "Diagnostic Subroutines" and scroll down to "Performance Diagnostics".... this section covers about most of anything you will need to check.

 

Not wanting to be confrontational, I find it necessary to remind my techs constantly to check the resources we have..... manuals, OASIS, hotline. It appears that these are becoming forgotten in some cases. (There are many TSBs floating around that cover some of the most mundane topics, yet offer some good tips on the subject at hand).

 

Some things I see get missed on the preliminary checks too often - high side exhaust leaks (manifolds - especially the left side one... up tube leaks.... oil level and condition.... come to think of it, most of the basics get missed too often).

 

If the truck has a catalytic converter, I have found that I can't rely on EBP readings - It only takes a few minutes to split the exhaust and look inside the cat to see if anything bad is happening.

 

If a truck is seriously down on power, we would expect some sort of trouble code in the system but, if there aren't any to be had, we can look at section 3 for some guidance - "Lack/Loss of Power" is symptom chart 10. The introduction list the OASIS codes we should use when consulting online resources... Some of the stuff in the pin point testing is way off the wall when it comes to those things we should check - but I'll be the first one to admit that brain farts are a way of life.

 

When all else fails, there is scan tool diagnostics.... it's not difficult to make a recording of an event or a condition and to post it to FDDTS and have some pretty good help deciphering the information....

 

Take a look at your options and decide what you need to do to make your customer happy... Someone like me will likely bust your chops but all of us are more than willing to help.

 

Sidebar... turbo replacement is always a sore point with me.... We're about $2500 CA for a turbo. If I'm changing one of these, I am going to be able to show a cutomer why I am changing it - dusted fins (ooops, what was that crankcase pressure?), oil leaks, impeller touching the housing, overheated turbine..... There is going to be an identifiable "why"....

 

Yes, I'm a dink at work, too...

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the turbo was replaced because it came apart in center and rubbed housing but not severe damage to turbine ,oil is new,it has some light smoke from oil cap but not huffing and passes crankcase test won't move the guage i think the exhaust is restricted will drop pipe monday thanks for the info i'm still learning the procedures

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  • 4 months later...

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