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Damaged caused by high exhaust backpressure


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Jumppy
New User

Aug 11, 2014, 8:24 PM

Post #1 of 5 (1711 views)
Damaged caused by high exhaust backpressure Sign In

My Euro II coach is equipped with DPF exhaust system. In recent inspection, high exhaust backpressure was found and smoke level was high (> 50HSU).

The workshop said the backpressure caused engine problems and "solved" the problem by replacing all fuel injectors.

I am interested in whether the backpressure has an effect on the operation of the injectors? How does it damage the injectors?

Thanks!


Hammer Time
Ultimate Carjunky / Moderator
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Aug 12, 2014, 2:19 AM

Post #2 of 5 (1696 views)
Re: Damaged caused by high exhaust backpressure Sign In

I don't see the connection there.



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Discretesignals
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Aug 12, 2014, 4:32 AM

Post #3 of 5 (1693 views)
Re: Damaged caused by high exhaust backpressure Sign In

What was the shop's answer to your question?





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Tom Greenleaf
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Aug 12, 2014, 4:47 AM

Post #4 of 5 (1687 views)
Re: Damaged caused by high exhaust backpressure Sign In

I don't see the connection either. Injectors in anything close to current are told what to do, when and how much based on several bits of info. Back pressure can and does count in the plain flow of intake air, manifold vacuum that are measures of what is being asked an engine to do and the load on it and can fool the fuel delivery but in this case injectors should have plain worked on the incorrect input and not been the cause up front. Not sure how they would be damaged or replacement would solve a back pressure problem?


T



nickwarner
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Aug 13, 2014, 9:24 PM

Post #5 of 5 (1663 views)
Re: Damaged caused by high exhaust backpressure Sign In

High backpressure wouldn't cause injectors to fail. But if your DPF was clogged it could be from a bad injector. When the DPF starts to need a cleanout, the PCM goes into regen mode. Most will simply fire the back two injectors on the exhaust stroke, putting raw fuel down the pipe where is basically starts a fire in the DPF to burn out the soot residue. Problem is that its hell on the turbos as the stuff starts to burn inside the turbo and raises the temps in it. Also wastes fuel. But if your injectors were bad enough to not allow regen you would've been noticing issues while driving before that.

I don't have any familiarity with the model you are talking about, but to toss a set of injectors at something for a clogged DPF sounds like a scam. Most manufacturers have a recommended service schedule for the DPF as the regen won't get everything out. A special machine is used at specified intervals to get it completely clean.

Also realize that if you have been running anything other than ultra-low sulfur diesel as fuel you will plug this DPF up in a hurry. Saw a farmer do that with a Mack truck once, didn't make it through half a tank and he was on a wrecker. Was running on agricultural diesel fuel with a higher sulfer content.






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