Isx 400 hesitating
04-08-2019, (Subject: Isx 400 hesitating ) 
Post: #1
Isx 400 hesitating
When I down shift and the the rpms reach a hair under 1200 the turbo starts to whistle and I get a hesitation from the engine. I’ve changed the dpf doc egr, turbo. I just had a truck inspection at Kenworth because I was going to get a extended warranty. All the numbers were good. But the weird turbo whistle was there even before I changed turbos.
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04-08-2019, (Subject: Isx 400 hesitating ) 
Post: #2
RE: Isx 400 hesitating
What year, make, model engine, truck?

some history?

does it sound kind of like a screech? - (like someone letting the air out of a metal balloon)?

or does it sound like a high-speed smooth sounding whine?

BTW: Mistake #1,.. taking it to the stealershit is worst place a person can go these days.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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 Thanks given by: hhow55 , Waterloo
04-09-2019, (Subject: Isx 400 hesitating ) 
Post: #3
RE: Isx 400 hesitating
What do you mean when you downshift and your RPMs get to 1200? When you downshift your RPMs should go up. Hopefully somewhere around 1700 or higher. You're not operating your engine under 1200 RPMs all the time are you?
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 Thanks given by: Rawze , Signature620
04-17-2019, (Subject: Isx 400 hesitating ) 
Post: #4
RE: Isx 400 hesitating
(04-09-2019 )Chamberpains Wrote:  What do you mean when you downshift and your RPMs get to 1200? When you downshift your RPMs should go up. Hopefully somewhere around 1700 or higher. You're not operating your engine under 1200 RPMs all the time are you?

When you shift at about 1700 it drops to 1200. That’s when you get the hesitation which turbo hissing at you
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04-17-2019, (Subject: Isx 400 hesitating ) 
Post: #5
RE: Isx 400 hesitating
(04-08-2019 )Rawze Wrote:  What year, make, model engine, truck?

some history?

does it sound kind of like a screech? - (like someone letting the air out of a metal balloon)?

or does it sound like a high-speed smooth sounding whine?

BTW: Mistake #1,.. taking it to the stealershit is worst place a person can go these days.

2009 kw T660 isx400st
I’ve changed egr doc dpf turbo and the part that goes beneath the turbo changed the computer the sound is the turbo I guess like the high speed smooth sound. So when I shift from like 6th to 7th which goes from approximately 1700 to 1200 rpms it hesitates while that whistling is happening and it slowly goes away than accelerates like normal. Also this doesn’t happen all the time now that the dpf was replaced. Kenworth dealership said all systems working correctly after dpf was changed. I was trying to get a extended warranty so they have to do a major inspection on the truck. Thanks again for the help
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04-17-2019, (Subject: Isx 400 hesitating ) 
Post: #6
RE: Isx 400 hesitating
something does not sound quite right?. 1700 all the way down to 1200 when shifting gears?. sounds kinda tall.

(maybe its the 3 beers i have in me atm?)


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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04-18-2019, (Subject: Isx 400 hesitating ) 
Post: #7
RE: Isx 400 hesitating
Mine is about a 500rpm drop between gears by the time I get it back in the next hole.

Have you checked for CAC leaks? There is a small rubber hose that connects the air compressor to the intake. This little 4" hose cracks and leaks on the back side where you wouldn't see it.
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04-18-2019, (Subject: Isx 400 hesitating ) 
Post: #8
RE: Isx 400 hesitating
(04-17-2019 )Rawze Wrote:  something does not sound quite right?. 1700 all the way down to 1200 when shifting gears?. sounds kinda tall.

(maybe its the 3 beers i have in me atm?)

Sorry guys. I meant shifting from 6 to 7th. Also if I let the speed come down barely by letting up on the throttle as soon as it reaches 1200 rpms you can hear the whistle of the turbo
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04-18-2019, (Subject: Isx 400 hesitating ) 
Post: #9
RE: Isx 400 hesitating
problem #1. your taking it to the stealershits and they are clueless morons who do nothing but blind guess to sell expensive parts.



Could be a lot of things. Have you pressurized the engine and checked it for intake, egr, and exhaust leaks?


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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