Boosting while stationary
06-03-2018, (Subject: Boosting while stationary ) 
Post: #1
Boosting while stationary
So ive got a friends truck (KW T908 w/ cm871 NOT deleted) in our yard that he's sold and is getting picked up Tuesday.. I had the job of making sure it started/was all good to go (its been sitting here a couple of months now). Eventually got it going and noticed that while parked, I can get it to boost to 55-70kpa for a few seconds before it drops back to nothing (thats after revving it to about 1600rpm and holding it there).
I disconnected the egr temp sensor and did the same thing and it only went to about 10-15kpa.
Ill be going in later to do some more work and was just gonna clean out the back pressure sensor/tube and imap sensor before taking it down the road for a drive to see if it does anything. VGT looks fine and can hear it doing its sweep when turning the truck on and off and it atleast sounds like its getting proper travel. No codes logged in roadrelay.

Anything else I should look for?
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06-03-2018, (Subject: Boosting while stationary ) 
Post: #2
RE: Boosting while stationary
Hmmm, a T908 w/an 871...

It's defective, no good, scrap metal. Take it to the Port of your choosing and send it overseas to Canada and I'll recycle it for ya...pleeeaaase


User's Signature: Why? Why do I always ask "why?" Because I can't learn or help teach others with "'cause I said so..."
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06-03-2018, (Subject: Boosting while stationary ) 
Post: #3
RE: Boosting while stationary
(06-03-2018 )Hammerhead Wrote:  Hmmm, a T908 w/an 871...

It's defective, no good, scrap metal. Take it to the Port of your choosing and send it overseas to Canada and I'll recycle it for ya...pleeeaaase

I wish we could have it! Too long and too heavy for down here. Big spec truck 50" bunk, 165ton rating, 6 rod rear end, greasless driveline, auto greaser, roadrelay, ice pack, plenty of fuel capacity.. all for $140,000 AUD
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06-04-2018, (Subject: Boosting while stationary ) 
Post: #4
RE: Boosting while stationary
A bad exhaust gas pressure sensor can cause one to overboost too. I have seen a few where the sensor was reading so bad that it caused a cracked head or dropped a valve in the past without ever throwing a code. Just something to keep in mind while troubleshooting it.


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: zyNoT
06-04-2018, (Subject: Boosting while stationary ) 
Post: #5
RE: Boosting while stationary
(06-03-2018 )Tanker Wrote:  I wish we could have it! Too long and too heavy for down here. Big spec truck 50" bunk, 165ton rating, 6 rod rear end, greasless driveline, auto greaser, roadrelay, ice pack, plenty of fuel capacity.. all for $140,000 AUD

Jeesh, your guys' trucks are pricey! AU$140k = CA$137k.
I paid CA$153k for my '09 T800 heavy haul truck new in Sept '08!
I'm not even close to 165ton though, I run in the 70-90ton range loaded.
But I love the look of the 908, wish they'd build that for us special application guys over here.


User's Signature: Why? Why do I always ask "why?" Because I can't learn or help teach others with "'cause I said so..."
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06-05-2018, (Subject: Boosting while stationary ) 
Post: #6
RE: Boosting while stationary
This truck would've been probably somewhere between $420-480k brand new. Certainly getting jipped for price over here on the Kenworths.. but they're Aussie built and probably the only truck in the heavy duty market thats actually built with quality. The rest (from my perspective as the mechanic) just look thrown together. Kenworths hold their value very very well too especially when presented well.
As for the range on KW you guys get over there, I dont blame you for loving the look of the ones we get here.. however I envy the bunk sizes alot of you have there and the fact that you can still get C500's new.


As for the original issue, I did those things I said in the original post and they didnt fix the problem. While trying to undo that pesky lock on the back pressure sensor plug, it broke.. mainly due to being old and brittle so I just cable tied it down thinking it would be all good. The guy that bought it picked it up in the morning and then brought it back in the arvo saying it had a check engine light coming up and some performance issues.. checked codes and sure enough, high voltage fault in the exhaust back pressure sensor circuit.. I went straight to it (had a spare lock tab in my toolbox) and had it fixed in less that 5 minutes so now he thinks im some young gun mechanic because I also didnt tell him the whole thing was my fault hahaha
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 Thanks given by: Rawze




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