my 99 7.3 f450 starts and idles rough after sitting all night at any temperature outside i had checked all the usual stuff hpop levels new oil new filter new fuel filter ect.using AUTO ENGINUITY SCANTOOL no codes icp good ebp good icp duty cycle good all tests look good.when engine gets to operating temp. engine smooths out, still a little bit of a stutter though. anyway heres the question i buzz tested it 6 or 7 times cold and injectors seem to get a little louder each time #8 is pretty loud but it was just installed new from ford.#5-6-7 are very quiet.at also seems to start and idle better after multiple buzz tests before cold start.would the buzz test liven up the poppets for a better start could this be my problem?injectors bad?170,000 miles stock its maintained pretty well.
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Yes, the repeated buzz tests will "free up" the poppets, which is why the truck starts better after repeated buzz tests. What you're describing is usually seen on trucks with higher mileage where the oil change interval has been somewhat ignored.

I've got 269,000 on my stock injectors, but I change my oil religiously. Proper, clean oil is vital to these engines.

Go to this link FDDTS - Tech Publications , scroll down to the bottom and read the last page on the Technician High Pressure Pump Guide for the 7.3 Power Stroke Engine. Their description matches yours.

If you're not looking to change the injectors right now, you might try switching to a synthetic oil to see if it's better cold flow characteristics help things. I'd also recommend you try doing the upper end oil change (HPOP reservoir and possibly even draining the oil rails) to get as much of the current oil out of the system when you change over.

 

thanks again for your help with this post and my others. i think you were the one who suggested the buzz test in my other post.

 

Yea Chris is the man always has great advice and knowledge

 

Glad to help. Now you understand why I suggested the buzz test. Hopefully this will serve as a reminder to others about the importance of changing your fluids.

 

this truck was bought from a fleet lease i got with 160,000 miles on it so i really don't know how it was treated right now i'm trying to get it in the best shape i can, it's my work truck and can't afford any more down time.thanks for the help getting me on track.

 

I remember you mentioning you had gotten it used. I was referring more to the others who may read this, and are currently not paying close enough attention to their maintenance intervals.

You've got a pretty good understanding of things, so just pay attention to any other hints your truck may give you. If you try the synthetic oil, let me know what kind of difference (if any) it makes.

 

no disrespect intended thanks

 

Here's something you may want to read up on and consider.
https://www.ford-trucks.com/forums/6...-additive.html
https://www.ford-trucks.com/forums/7...ve-update.html

I'm not much on oil additives, and can in no way endorse this product, but you might start a new thread here in the 7.3 section to get feedback from anyone who has tried it.

It's at least cheaper than new injectors, and I'm curious to read what others have to say since that seems to have fallen off the radar, so to speak. If you do try it, please share your results with the rest of us.

 

thanks again i will.