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Discussion Starter #1
Truck has a rough idle that goes away about 1,000 rpm. No blow by. No fuel in oil. Mannie. Starts fine, drives fine. Only had the truck (93k miles) for a couple weeks, so no idea as to its maintenance history.

With my bi-di scan tool, I shut off each injector after I ran the truck for 40 min.

Injector 1: engine got rougher when it was shut down.
Injector 2: engine got smoother.
Injector 3: rougher
In 4: very little/no change
In 5: very little/no change
In 6: rougher.

I'm just a shade-tree mechanic-- does this test indicate that injector #2 is bad? Another question: I assume on the scan tool that cyl #2 correspond with cyl #2 on the engine. Is that counting from the front or the back? thx.
 

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Discussion Starter #2
PS: from what I've read, it could be the clutch/dmf, but would rather rule out injectors first.
 

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I've not had to deal with injectors (yet). But you might consider swapping #2 and #3 and see if the behavior follows the injectors.
 

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Discussion Starter #4
That's an idea. Thanks. I wonder though, with all the trouble that it is, maybe buy a single new injector, install it in #2, and see what happens. If the problem is fixed, great... if not, then I have a spare working injector.

Some mechanics on youtube recommend that if you replace one, just replace them all.
 

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if you stopped cylinder 4 and 5 injectors and nothing changed would concern me .
153624 is firing order, number 1 cylinder is front of engine bay
What does rail pressure show??
 

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avg when ?
Demanded RP should be with in 500 hundred psi of actual RP .
When you shut off any of cylinders does idle and RP change the same amount ?
both should behave the same with any of 6 cylinders not taking fuel, ECM adjust fueling.
FWIW, If injector check ball is leaking or solenoid not functioning properly, electrical kill test is not really shutting off injector that is why test with rail cap is specified.
 

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Electronically shutting down injector should only be used for Touchtone purposes ONLY, Never and I MEAN NEVER use to condemn Injectors.

That being said you can use it to determine that 1 may be bad, But it takes someone that runs that type of test regularly and knows the tone difference.

Generally Rough or loping Idle is related to FCA. Rail cap As RGHava suggested is best. The LV/FCA would need replacing to KNOWN as good, Owners drop $$$$ on Injectors and its the LV/FCA problem. In the end You may have assorted problems FCA 30% ,LV 30, and Injectors the rest 30%, 10% for just guessing. Just thinking one part is 100% of the problem Not the cases with HPCR engines.
 

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Discussion Starter #9
Thanks guys. In my little corner of Eastern WA, there isn't anybody that really knows Cummins engines, so I have to do all this myself.

FCA-- they aren't a huge investment, unless anybody objects, I'll throw a new one on, and get the fuel line cap as well.

7000 avg psi was at idle. I'm not sure if I can measure rail pressure and do the shutoff test at the same time, with alphaobd. I'm not opposed to dropping a grand on a nice scan tool, but they all have their pros and cons.

thx
 

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Alfaobd II will allow viewing of Rail pressure, DO NOT BUY FCA that are impostors, If Bosch Name is NOT on the FCA, the packing with Bosch name is has been misused ,its most likely China Junk, testing the Injectors with OEM LV will not provide correct Data.

We will be coming out with YOU TUBE video soon on the Injectors and Parts even In Bosch BOXES that are impostors. Its the source more than the Labeling, If the source sells more then BOSCH Genuine WATCH out, Some of the grocery sellers are putting impostors in BOSCH BOXES and plastic wrap, its everywhere and up to this point it seems BOSCH is powerless to stop it.
 

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Discussion Starter #11
Thanks so much TCD. Fu%&ing China. Tired of their parts; tired of their pandemics.

I've read Geno's is good place to buy parts-- I'll start there.
 

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Thanks so much TCD. Fu%&ing China. Tired of their parts; tired of their pandemics.

I've read Geno's is good place to buy parts-- I'll start there.
I like Genos and do buy from them, but recently got a new FCA and got it from Rock Auto as it was cheaper with cheaper shipping. You can also always google a 5% discount code for them. Just don't buy bosch products on amazon or ebay. ever. They are almost never genuine.

BOSCH 0928400666
 

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Discussion Starter #14
Counterfeit parts have been a problem for as long as I can remember-- airline, medical, you name it.

We need to treat that country as if does not exist.

Looking forward to your video.
 

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Jkline, Citizens need to just Stop buying into the Bug spray that clouds this problem. Some of My associates ask Me not to move forward in the past, I have waited Long enough. If YOU TUBE takes it down I will setup My own Hosting if Necessary. Kinda short handed Right Now but its coming.
 

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O, I forgot to add, Also the solenoid nut is laser etched with the Bosch reman number. Why would there be a reman number on a so called new Bosch injector? The nut also says Crin2, a 6.7L injector is a Crin3. Idiots!
 

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Putting in only 1 new injector is like a teenage boy sniffing panties. Highly frustrating and often creates an even worse problem/imbalance.

Going CHEAP in replacement parts purchasing is like picking only cheap women.
Comes back to bite you in doctor and real diesel mechanic big bills.

I've got some internet ebay corona proof N95 masks to sell you cheap, $1 each but delivery is 6 weeks out.

Lots of "rebuilt" in the USA junke injectors ran on a cheap quicky test that does not meet full specs
Cummins HPCR injectors, being sold out there as "New Bosch" when they're lower spec & quality tractor injectors made by Bosch for specific low pressure apps at a lower price requested by tractor manuf.
Or some BS "rebuilts are as good as new" Bosch with Chinese offbrand internals
Even the rebuilt in Bosch factory injectors have a higher warranty failure rate than new off the assembly line.

Buy ONLY from reputable dealers that have a long and good reputation, few complaints and are Bosch cert. dealers. They are basically the only ones that have access to the real stuff.
Even the cutrate cheapest internet dealers and their buyers get ripped off with imported Far East junke

Cheap leaking nozzles will fry one of these Cummins pistons in minutes towing heavy.
 

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Discussion Starter #18
@steel-- for future reference, where should one purchase new injectors? thx.

I'm hating how fragile/over engineered these engines have become. Have a '93 with 400,000 miles that has never needed a damned thing done to it. Not even a valve lash adjustment. Have a '99 with 235k, with zero issues except for the fuel pumps 100k miles ago. Never had a VL adjustment. Regretting this '07 purchase-- I feel like this truck is a ticking time bomb with the injectors and a possible DMF underneath.
 

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BBI injectors reman or new is where it's at.
 

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nosympathy, Although BB are a quality product its still overseas, and they are subject to all the problems that May develop that off shore Products inherit.
 
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