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Unread 02-11-2014, 08:20 AM   #1
Red_liner740
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Join Date: Sep 2013
Location: Tottenham, On
Posts: 130
CRD: Slight hesitation on higway, CPS or EGR

So yesterday on my way home driving 60mph on the highway i started to feel an intermittent hesitation. Very, very slight. A passenger wouldnt even notice it.

It feels exactly when a gust of wind hits your truck and it slows down a bit.

This morning, driving to work, same thing. except that it did it basically the entire 15 min highway ride. A hesitation every few seconds.

Doesnt do it at ALL in city traffic, accelerating, WOT redline pulls, every other time it runs fine. Doesnst stall. It only does it steady cruising on the highway

Only other time i've experienced anything similar is when moving cars around in the driveway, once or twice it had a slight stumble when giving it a bit of gas. I attributed it to a cold engine as its been averaging -15C for last month+.

No CEL's or any other warnings.

So doing research, its attributed to different things.
One is bad fuel, but i put 600 km on this tank of gas with no issues and i get my gas from this same station all the time.
Fuel filter was replaced 15,000 km ago when i got the truck in November.

So i'm trying to narrow it down.

Crank Position sensor may be it. but it should show the symptoms in other driving conditions as well.

EGR. This is where i'm confused as i have an Eco Tune from GDE and it should have disabled the EGR no??

Any insight would be greatly appreciated.

Oh, and i'm sure this is just a coincidence, but i fully snapped my valve stem on my front right wheel and had to put my spare wheel on. Now i have the flashing TPMS light.

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Unread 02-11-2014, 10:09 PM   #2
Red_liner740
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RESOLVED:

Now this may sound as weird as ****, but it does sorta make sense.

Turns out it was the spare tire...

I took the truck to a tire shop, replaced the valve stem on the messed up tire and put it back on the truck, drove out and the hesitation is gone... I drove it 60 km since then without a single hickup in the same driving conditions as before.

My hypothesis is that the rolling diameter of the spare was different than the other tires and that was throwing traction control into a fit. The light on the dash wasnt flashing but it def felt as if though the power was being cut the way TC would cut power.

My OBD reader showed steady throttle input during the hesitations and the fuel pressure would drop by several hundred PSI.

First hint was when joining the highway this morning and taking a long curve with no snow, ice or moisture had my TC light flash once. Weird.

Anywho, thought i'd report back.
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Unread 02-12-2014, 07:11 AM   #3
Red_liner740
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Just to add: No issues this mornings drive...

RE: EGR. I spoke with Keith from GDE and he confirmed that EGR is fully disabled with his tunes. The exhaust valve stays closed and the intake valve remains fully open.

Chalk up another point to GDE Tune. If you have an acting up EGR, the Tune will get rid of it.
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Unread 02-12-2014, 09:44 AM   #4
suzieque
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2008 WK 
 
Join Date: Mar 2009
Location: Canada
Posts: 1,809
all wheels have to be the same diameter. even mixing different brands of tires that are supposedly the same dimensions can trigger problems with the transmission because the PCM is sensing different wheel speeds.
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Unread 02-12-2014, 02:12 PM   #5
jediknight
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2008 WK 
 
Join Date: Oct 2011
Location: Montreal, Qc
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I felt something like that a while ago and it ended up being the crank sensor becoming faulty. Changed it once it has finaly thrown a code and It seems to run fine since then.
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Unread 02-15-2014, 09:15 AM   #6
Sizzlenut
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It would be fantastic if you could put your spare back on to make it happen again. Then hold the traction control button down for 15 seconds or whatever to fully turn it off to see if it clears it. That would definitely be confirmation.
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Unread 02-15-2014, 01:39 PM   #7
chrali
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My tyres are all over the place wear wise and one is even 10 mm narrow than it should be. On occasion I get exactly the same sensation and turn off the tcs to continue without the annoying sensation, especially on pot holed bumpy roads. I use the single press not the 15 second one. Mostly down to the un-rotated spare being full tread and now on due to puncture and the rest being nearly done.
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