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Do you smell that?
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Discussion Starter · #1 ·
Um hello, well i am a new member to this forum. Im still getting the hold of things here but not with my truck. The story is i got my truck 6 months ago, fell in love with her but ever since she had problems. She still hasent cost me any out of pocket money because im still in warranty just time dealing with all of this. One day i was driving home in the dark i was coming up to a red light so i put my truck in neutral and the lights dimmed, as a natural reaction i look at my RPM gauge and notice that the needle dropped to 500 revs almost to the point where i feel i have to give it gas because i feel its going to stall. I took it to GM dealer ship to get diagnosis and i found out there was a recall for bad cylinder heads. Of course it was a bad cylinder head, cylinder number 3 pressure was 50% it got fixed, got my truck and was pleased. Next it does the same thing, rough idle 500 revs sometimes it jumps almost as its going to stall but it doesnt let it happen. It only happens when im moving and i put my truck in neutral just for the weight of the truck to push me to the stop ahead. When im staying still in neutral it idles fine around 800 or 700 revs. Also when the truck warms up it runs perfectly fine this problem only occurs when my truck is still trying to warm up or do semi hard turns. I want some ideas of what it might be i think its a vaccum leak. but the guys at the dealership are stubborn that they only work on a certain part of the engine, no full diagnosis. This should of been on the beggining but i own a 06 GMC Canyon manuel 2.8 inline 4, Help Me so i can go to the dealership to give these guys a hard time and get my truck fixed and get her runnign flawlesly.
 

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1,407 Posts
hey man welcome
ummmmmmmmm
this is weird
maybe bad piston ring?
sign up on SoCal and NorCal sites and see if the other guys there can help you out
 

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3,034 Posts
Hey I just fixed mine this morning. I have been having the same problem for 2 years . Tried everything cleaned the throtlebody replaced coils. The problem always screamed vac leak. I found a picture of the intake with the outer box removed. There is a vac hose buried inside the outer intake box that connects to the driverside of the valve cover. It will leak at the nipple on the intake. The dealer only sel this hose as part of the intake manifold. I used my dremmel tool to cut an access into the outer box then used zip ties to clamp the hose to the nipple and to the hard line. Instantly my idle is smoth and it has s much power. I am not where I can get to my pics right now. Send me a pm and I will send pics.
 

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US Army 19yrs and ......
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45,275 Posts
Wow that waas hard on the eyes; paragraphs please!

Did the dealer reflash your PCM with the updates; yes your PCM needs updates just ike your home computer.
 

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Do you smell that?
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807 Posts
Discussion Starter · #6 ·
Hmm well i dont think so. I just looked at my receipt and i see no updated pcm information anywhere .
Ill just march my way back to the dealership and give these guys a hard time and leave it overnight so they can test drive my truck cold so they can feel how harsh it idles.
 

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Premium Member
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8,695 Posts
Hey I just fixed mine this morning. I have been having the same problem for 2 years . Tried everything cleaned the throtlebody replaced coils. The problem always screamed vac leak. I found a picture of the intake with the outer box removed. There is a vac hose buried inside the outer intake box that connects to the driverside of the valve cover. It will leak at the nipple on the intake. The dealer only sel this hose as part of the intake manifold. I used my dremmel tool to cut an access into the outer box then used zip ties to clamp the hose to the nipple and to the hard line. Instantly my idle is smoth and it has s much power. I am not where I can get to my pics right now. Send me a pm and I will send pics.
Bingo was his name-o! I knew that hissing was coming from inside the cover. Looks like I have some work to do.

As for you Canyon, I'd inspect the same.
 

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Stat with the simple stuff first: clean the throttlebody. These engines are famous for low/rough idle issues due to a dirty throttlebody.
 

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my truck has been falling on its ass when cold for the 3 years that ive owned it. its got a new head, vac lines, updates, new pistons, and all the "go fast" parts. mine to is a manual, just a 3.5. ive got a feeling some of these motors just do that :shrug:
 
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