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Glenn, Technician/Trainer
Category: Ford
Satisfied Customers: 606
Experience:  28 years experience, Interprovincially Licenced Motor Vehicle Mechanic and Instructor
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1997 f350: the orings on the injector cause it to miss

Customer Question

1997 f350 7.3turbo...misses bad when cold, alot better when do i find the problem injector(s) andcan i just replace just the problem ones? can the orings on the injector cause it to miss?
Submitted: 7 years ago.
Category: Ford
Expert:  Glenn replied 7 years ago.

Hello and welcome to Just Answer.


Does it start ok when warm ? Be advised that when the o rings leak that this will usually cause extended cranking when warm. As the oil thins down, the oil can bypass the orings more easily. The injector driver module (high voltage driver module for the injectors) has been known to cause problems with cold operation . You might be barking up the wrong tree here. There are also common wiring problems that can affect the operation of the injectors and the glow plugs. .


How many miles on your truck? If there are a lot of miles on it, servicing only one or two injectors is not a realistic approach.


Have you seen any loss of engine coolant?


There are several ways of pinpointing injector problems. The powertrain control module (PCM) has a BUZZ TEST that will actuate the injector solenoids to allow the technician to test the injectors with the engine stopped. This gives an audible indication of injector activation.


The key on, engine off and the engine running self tests will check the engine management system for components that are no longer operating within determined limits. Once the engine is FULLY warmed up, the CYLINDER BALANCE test can be triggered through the Ford scantool to pinpoint non-contributing cylinders.


It takes a lot of training and experience to be able to build up a reasonable level of proficiency in the diagnosis and repair of this engine . I'd suggest that you may want to try to find a good Powerstroke technician.



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Customer: replied 7 years ago.
starts good when warm.the warmer the better it runs. 275000 miles, no leaking of coolant. once fully warmed up runs good but still feel a light miss. stopping for fuel cools it enough that you can feel the miss is a little harder. is a scan tool needed to run these tests? i worked on the 6.9 a lot but not on the 7.3 di
Expert:  Glenn replied 7 years ago.

Hello and thank you for the ACCEPT.


Yes, an enhanced Ford scantool is required for these tests. If you are going to do a lot of this work, you can get a kit for a pc that will provide these features. Let me know if you want more details on this.


I've used an infrared temperature gun on the exhaust manifold or simply touched the manifold on some diesels to isolate the non-contributing cylinders, but the exhaust backpressure regulator and turbo charger make that a little less effective on this model. The cylinder that is misfiring will have a noticeably colder "leg" on the manifold.


Let me know if you have further questions on this. Thanks for using Just Answer.