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Old 12-15-2019, 08:24 AM   #1
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T444e (7.3) Injector Buzz Test

I am having starting issues. I have a 2004 international bus with the the t444e and 124k miles.

This summer it ran rough. Now I need to fix it but it doesn't start.

I have checked the glow plugs and they get voltage and ohms are about 0.6.

I replaced the cps. No change.

The icp sensor looks dry.

I was wanting to check the injectors next. Is there an affordable scan tool that works on these that does a buzz test. Looks like there are plenty for the standard obdii but I'm not seeing many options for the HD 9 pin.
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Old 12-15-2019, 09:31 AM   #2
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Look for Nexiq, they are the brand name most folks go with. On Ebay there are a lot of chinese clones for a big discount, people seem to have success with them and they include a bunch of "trial" software.

if your glow plug are working properly but still no start I'd be looking at a fuel supply issue. Filters bad or full of water, or possibly lost prime.

Review this thread also: http://www.skoolie.net/forums/f37/96...art-19524.html
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Old 12-15-2019, 10:56 AM   #3
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the hardware is a Nexiq USB link 2.. there are chinese fakes for half the cost of the genuine one..



Navistar gives away the version of software free that lets you do a Buzz test.. it is called ServiceMaxx J1708. and can be downloaded diurectly from navistar...


if your issue is a starting issue then you will want to perform the Buzz test Cold... when these injectors first start to fasil, they are notorious for going InOP when the engine is cold and then work fine after it is warmed up... the test will require a good charge on the batteries or the software will fail it..



to do it charge the batteries with a trickle charger over-night and then do the test without having run the engine that day...



-Christopher
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Old 12-15-2019, 03:33 PM   #4
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Also the buzz test only tests the electrical part of the injector.
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Old 12-19-2019, 06:50 PM   #5
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I found the USB reader. It's on the way.

To check fuel supply do I need to get one of the adapters to check at the fuel bowl?
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Old 12-19-2019, 08:08 PM   #6
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That’s where I tested. I have a test gauge that fits into the s reader at the bowl ore screen. 444e has mechanical lift pump so your pressure will bounce up and down but generally should hit 40-45 if you have the old spring and can go as high as 72. (Engine running),with the new spring.
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Old 12-22-2019, 07:47 PM   #7
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I ran a buz test today. I got 5 light buzes. Nothing else. Rebuild them all?
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Old 12-22-2019, 08:33 PM   #8
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Should have got 8. Either the injectors are actually bad or the under valve cover harnesses or actual valve cover gaskets/connections have an issue.
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Old 12-22-2019, 09:14 PM   #9
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The under-valve-cover wiring harnesses are commonly replaced as part of an injector replacement. At 15 years of age (I'm assuming they have never been replaced) the wiring harnesses may be degraded pretty well by now; 125K miles is a bit premature for new injectors as far as wear goes (I can't speak for the electricals, though).
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Old 12-22-2019, 09:39 PM   #10
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When I had my injector O rings replaced by Ford they also replaced the under valve cover harness as part of the job.
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Old 12-22-2019, 11:10 PM   #11
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I checked the ohms of each injector and they all were about the same. I can't remember the amount though but they did conduct.

Also the software says I have 214k miles. Looks like the odometer is off.
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Old 12-23-2019, 12:14 AM   #12
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Quote:
Originally Posted by Imfrankyj View Post
I checked the ohms of each injector and they all were about the same. I can't remember the amount though but they did conduct.

Also the software says I have 214k miles. Looks like the odometer is off.

Close to the same mileage I have. Dash replacement is *VERY* common on these as the soldered circuit board connections fail with age (Can be fixed fairly easily without needing to replace the dash).


If the injectors have never been replaced, they may be getting close to due and can often be a source of difficult starting and poor fuel economy, but they're not cheap, either, at about $200 each. This is *NOT* the first thing I'd replace while diagnosing a no-start issue.


Mine sat for a few months while I was otherwise busy and didn't want to start right up when it was time. I suspect it may have lost prime in the fuel system and I had to try it a few times before it started up. I did get it going and it's run fine since. I try to avoid letting it sit more than a month or so between being started/driven.
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Old 12-23-2019, 02:43 AM   #13
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The navistar buzz test sounds different than the ford test. Navistar buzzes all 8 at the beginning of the test, then it does a single tick of each solenoid in cylinder number order. Odd is right side starting right front as 1, left front is 2 and left side is even.

When counting ticks if you notice all your ticks are on one side of the engine then wiring (and checking for IDM codes) is a good place to start.
The presence of resistance but lack of tick could be sticking solenoids inside the injector..

Pulling the injectors on a standard conventional bus is not a bad job at all. Much easier than a ford truck or flat nose.

If your city has a known reputable diesel shop you can have your injectors tested, typically for not a crazy fee.

You can also replace them. Be careful of cheap reman injectors. There are good ones and bad ones.
Biggest mistake people make removing and Then installing injectors is not properly emptying the cylinders of oil and fuel. It’s tedious and a pain to rotate the engine by hand 2 revs but necessary .

Ford stopped selling 7.3 in 2003 ( in the USA) so very little info on the web mentions 2004, your injectors should be AD code except for number 8 which is an AE.

There are a ton of performance injectors out there, don’t buy them unless you know what you are doing with adjusting your computer and monitoring EGT., your transmission limits etc. Stick with stock.

As for why yours are possibly bad at 214k?
Poor oil and fuel maintenance causes them to get sticky. Sometimes open sometimes closed, stunk open injectors result in smoke and often rising oil levels and eventually ruins the engine. Stuck closed injectors result in hard start, rough idle, lack of power, bucking..
How many hours did the computer say you have? A lot of school busses rack up hours quickly from lots of idling or in town use
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Old 12-24-2019, 06:00 PM   #14
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It said 7k hours.

When I get it to start it is really weak.

I will do another Buz test. I don't remember a louder first buz like there was more than one. But if so then that would sound like maybe only half with the count of 5. When I got it running a few weeks ago (lots of cranking) I checked the exhaust manifold temp right at the head after a few minutes and one was still cold while the others were warm.

Would it be worth pulling the injectors and having them tested and rebuilt?
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Old 12-26-2019, 09:03 PM   #15
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Not to sound any dumber than I actually am, but what's a buzz test on a fuel injector?
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Old 12-26-2019, 09:20 PM   #16
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These iniectors use engine oil pressure and electric solenoids to actuate and inject the fuel.

The engine oil pressure creates the force necessary to inject fuel into the compressed cylinder.

The electric solenoid opens up the valve in the injector so it starts injecting fuel.
The solenoid is timed perfectly by the computer so the fuel injects at the correct point. The solenoid stays open for a certain length (calculated by the computer)

When you suspect that iniectors aren’t working properly one of the tests that the diagnostic software on a laptop has is to activate the electric. Solenoid on the injector even when the engine is off..

It makes a distinct Click!!! Sound when it activates..

The buzz test first hits all 8 injectors at the same time so it makes a loud Buzz under the hood..

Then it clicks each injector one by one just about 1 second apart. So you count the single clicks and note any that sound quiet or where instead of a click after 1 second you hear nothing.. you notes the soft and silent ones as bad injectors (or bad wires)..
after it’s done all 8 it hits them all at once again to let you know the order is repeating and to start counting clicks at 1 again..

Christopher
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Old 12-26-2019, 09:55 PM   #17
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Thanks! - Dan
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