Clean the throttlebody and MAF.

 

You posted this 1 minute after you posted the EXACT same thing in the TB Cleaning thread...wow...

 

well i don't know exactly what to do to fix it- but if it makes you feel any better- mine does EXACTLY the same thing. originally i thought it might be the compressor kicking on and creating a little more drag on the motor etc etc... but it seems to do it no matter if i have the ac kickin or not. does yours also have a habit of dipping below 500 rpm when you come to a stop?

 

Clean the throttlebody and MAF.

 

yes it does. It now only really seems to happen when I stop at a light.

It will idle around 600 to 650 RPM.

Weird thing is.... is that it really gets bad when I get off the highway.. it will dip down to about 480 rpm.... stay there for about 10 -15 seconds... then go back to 650 rpm.... then bounce back and forth for awhile.... but then a mile or so down the road it will go back to (somewhat) normal and idle at a stop light around 650 RPM.

 

Well I briefly looked at the throttle body without taking it off.. ( Mainly because I do not know how to take off the plastic housing around the top of the engine) and it didn't look dirty... Could the dirt be on the other side of the throttle body???

And how easy is it to do.... I have family member that worked in the auto industry back in the 80's... that help me out quite a bit... but my knowledge is limited to what I learn on the internet...

I really appreciate the help... Any instructions or pics would greatly help me.

 

Open your eyes and you will see how to take off the plastic... its so obvious(not to try to be an ass), and yes the dirt will be behind the throttle plate. 4 bolts take it off... VERY simple. I have a link to help you below.


http://www.coloradofans.com/forums/viewtopic.php?t=54407&highlight=throttle+body

If you dont feel confident then do everything except the seafoam because you can hydrolock your engine. Good luck with your issue.

Welcome to CFans!!! :welcome

 

Well I briefly looked at the throttle body without taking it off.. ( Mainly because I do not know how to take off the plastic housing around the top of the engine) and it didn't look dirty... Could the dirt be on the other side of the throttle body???

And how easy is it to do.... I have family member that worked in the auto industry back in the 80's... that help me out quite a bit... but my knowledge is limited to what I learn on the internet...

I really appreciate the help... Any instructions or pics would greatly help me.

The dirt builds up on the inside of the TB.

 

well i don't know exactly what to do to fix it- but if it makes you feel any better- mine does EXACTLY the same thing. originally i thought it might be the compressor kicking on and creating a little more drag on the motor etc etc... but it seems to do it no matter if i have the ac kickin or not. does yours also have a habit of dipping below 500 rpm when you come to a stop?

Thats exacly what i thought when i read his problem. When i used to own an explorer (live and learn) i had the same problem and it was the AC clutch kicking on. Only happens when you stop b/c the rpms are low. I think the problem was with the idle control. Had to replace the pcm.

 

Is there anything with the design of the Colorado, that causes the throttlebody to have so much build up in such a short period of time???

I had a 01' S-10, and I never had issues like this.

Reading up on the forum this seems to be a common issue with the colorado.

 

It could only some from the breather hose (oil vapor) is my guess. I bet an oil catch would solve this problem

 

I just wanted to thank all of you for your help.

I took the throttle body off on Saturday, and I can not believe with only 42,000 miles on it, it had so much build up. It was mostly where the butterfly met the edge of the throttle body. I bought some throttle body cleaner for like $4.00, and it only took me 45 minutes to do.

The truck now runs like it use to when I first bought it. The power is back, it doesn't hesitate, and no rough idling.


Has anyone figured out what can be done to prevent this, or any preventative treatment??

Again Thanks for all your help.

 

it's the throttle body. I cleaned mine and it purs like a kitten now. the steering wheel doesn't shake anymore. All u need is throttle body cleaner (Less than $5) a tooth brush, and a rag. Read the How To section for taking it apart. but u won't need to spray it down hose, and u don't need to unplug the cables from the throttle body, u can just turn it on it's side and place a thick rag under it to collect the cleaner run off.

 

New guy here. I have been having this very issue on and off gradually for some time and it wasnt until the last week when the CEL came on that i decided to finally take action. I found this forum through my research and i gotta say its pretty cool. Im not a very auto-savvy guy by any means (way more of a computer nerd) so i was a bit hesitant to tackle something that sounded like minor surgery to my newbie-mechanic ears. Ill jump into my computer enclosure face first but the hood of my primary transportation is a different story. I just wanted to thank those that reply on this forum and CpnBnanaMn for his detailed "How to:" on the TB cleanup. Only 43K miles but $5 and an hours time and shes running like day 1 again. Next up....spark plug replacement. Thanks for the help guys!

 

Thanks to all of you on this thread, My 06 (4 cyl) started the rough idle on start up (every cold start) a couple days ago. Found this site via a Google search and cleaned the throttle body as you guys recommended. The problem seems to have been cured. It was amazingly filthy with only 16,500 miles on it. Thanks a bunch. Jay

 

I have this pronlem with my truck too. I work for GM and it sounds like the problem is with the intake valve seating... i think thats what they said. There is special warranty coverage for it has been made for 7 years/100,000 miles on '04-'06 Canyons and Colorados. If I remember right the valve seating wears because the head isn't hardend. It usually causes a rough idle and the check engine light will eventually come on. The special warranty coverage for this will only cover it if it pulls the right misfire code. So if you have a rough idle and a check engine light and it falls within the warranty coverage then i would go to a Chevy/GMC dealership and have them check it out. I hope this helps.

 

I have this pronlem with my truck too. I work for GM and it sounds like the problem is with the intake valve seating... i think thats what they said. There is special warranty coverage for it has been made for 7 years/100,000 miles on '04-'06 Canyons and Colorados. If I remember right the valve seating wears because the head isn't hardend. It usually causes a rough idle and the check engine light will eventually come on. The special warranty coverage for this will only cover it if it pulls the right misfire code. So if you have a rough idle and a check engine light and it falls within the warranty coverage then i would go to a Chevy/GMC dealership and have them check it out. I hope this helps.

i was just about to say that... i found it today... 07123 - SPECIAL COVERAGE ADJUSTMENT- engine intake valve seat SERVICE CAMPAIGN BULLETIN, issued aug 07, 2007.

involved are ALL 2004-05 Chevrolet Colorado and GMC Canyon midsize pick up trucks, equipped with eitehr a 2.8L (RPO LK5) 4 cylinder or 3.5L (RPO L52) 5 cylinder engine and built within the following VIN breakpoints:
04 colorados- 48100001 to 48224869, 05 canyons- 48100024 to 48224884, 05 colorados 58100001 to 58292845, and 05 canyons AGAIN 58100051 to 58292847...

special coverage covers the condition described for a period of 7 years or 100,000 miles, whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. the repairs will be made at no charge to the customer.






hope that helps

 

I received a letter from GM in august of '08 stating that an unusual wear of the intake valve seat causes rough idle and the check engine light to come on but put it aside. I was having the same problem as "t_demars". I took my truck to Advance Auto Parts, Napa Auto parts, and a friend to check the computer and all three stated that there were missfires on cylinder 2 and of course everybody suggested different things, including replacing the "mass airflow sensor"; I changed the spark plugs as someone suggested. Two weeks ago I took it to Chevy and they said that the valve seat needed to be replaced but the check engine light was b/c the "mass airflow sensor" was bad and needed a new one which would cost over $200. I told them to only do what was covered in the warranty. I got my truck back today (it took them a while to get the parts) and now it's running fine; on their Work Order says "#2 intake valve leaking valve seat". I would've wasted over $200. Hope this helps everyone.

 

I just bought an 05 colorado with the straight 5, and the last 8 #'s in the VIN are 58166241. I called the dealer and asked them if the Recall on the intake valve seat problem was addressed on my truck and they said "no" and my vin # doesn't fall in the range and told me I was good??? Unless I'm reading it wrong it appears that it falls in the range.

what do you guys think, should i call another dealer?

I have 90K miles and it idles like a v8, but doesn't have CEL on. Ordered some Denso plugs to see if it helps make it run better.

 

Your truck does fall within the VIN range: http://www.naskie18.com/colorado/TSBs/L ... 20Seat.pdf
Get your truck scanned for codes first and let us know what they are (if any).

 

I tried Autozone this morning and they said they can't retreive fault history, they can only get active faults with there scanner. I'll just have to wait and see if i get a misfire, i have 10K miles to get one.

I wonder if there is an updated VIN break list out?

 

Do you have any active codes?

 

my truck aggrevates the hell outta me it has that rough idol as explained above but it's not the TB cause i already cleaned it. it's not the head either. it's pulling like a low idle code. i have no clue what it is and my dad is starting to think it may be a bad computer.

 

no active codes right now

 

Im having the same exact issue with my truck. The CEL keeps turning on randomly and when I scan it at Autozone it comes up as a misfire, but somehow it magically turns off before i make it to the dealer. It runs really rough, and my gas milieage is horrible. Im actually sitting in the dealer waiting room, since I kept the light on long enough to make it here. Long story short, i told the service tech i read something about valve seats and he says im not eligible, and that my warranty is long expired. I have on 05 98kmiles on it and vin is 5828**** so i told him to check it out regardless. Their supposed to charge me 98bucks to look at it. Any ideas on what to do when I come back to pick up the truck.