2005 Trailblazer LT idle issues [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: 2005 Trailblazer LT idle issues


ajayen
01-16-2009, 11:11 AM
2005 Trailblazer LT 4.2L with 34000 miles(yes only 34k)

The problem Im having is when Im parked or stopped Im having rough idling issues. I have not had the vehicle die on me yet, but I try to prevent by gassing it a bit. When Im driving theres no issue at all, the check engine light is on and solid. But when I come to a stop it idles very rough and seems to want to die, just hasnt yet.

Ive dealt with this on other vehicles but thought Id get some other opinions from here. The 2 things I believe it could be is the O2 sensor, or Clogged dirty Injectors. Im trying to prevent taking it to a dealership because frankly the one we have here is shady and I cant trust them.

Any advice would be great.

On a side note. Also having an issue with my fuel gauge. When I completely fill up, it bugs out. Sometimes showing Im completely empty then half then 3/4. And it does it till Im down to 3/4 of a tank and its fine after that.

Bill2003
01-16-2009, 11:57 AM
My first stop would be at Advance Auto or O Reilly to get the codes read. You can do that for free, then you will have a much better starting point.

Bill

Super 88
01-16-2009, 11:59 AM
2005 Trailblazer LT 4.2L with 34000 miles(yes only 34k)

The problem Im having is when Im parked or stopped Im having rough idling issues. I have not had the vehicle die on me yet, but I try to prevent by gassing it a bit. When Im driving theres no issue at all, the check engine light is on and solid. But when I come to a stop it idles very rough and seems to want to die, just hasnt yet.

Ive dealt with this on other vehicles but thought Id get some other opinions from here. The 2 things I believe it could be is the O2 sensor, or Clogged dirty Injectors. Im trying to prevent taking it to a dealership because frankly the one we have here is shady and I cant trust them.

Any advice would be great.

On a side note. Also having an issue with my fuel gauge. When I completely fill up, it bugs out. Sometimes showing Im completely empty then half then 3/4. And it does it till Im down to 3/4 of a tank and its fine after that.
You need to get the codes read so we can see why the check engine light is on.
Often on these vehicles, rough idle is caused by a dirty throttle body.

Your second problem with the fuel gauge is most likely a bad sending unit. It is part of the fuel pump assembly. I believe the sending unit itself can be replaced - but if it were me I would just replace the whole unit.

rbarrios
01-16-2009, 03:21 PM
when it idles rough- are you using AC?
if you are.. turn of AC and if it idles fine- its a dirty throttle body...

do get the codes read...

try running a bottle of Chevron tecrhon fuel system cleaner.
you may have sulfir buildup...
few members have gotten the eratic reading and the techron helped.
if it doesnt.. then a new sending unit would be needed.

Jens
03-07-2009, 05:03 PM
I had the same problem and it turned out to be bad ignition coils. I must have had one bad one early on; the first several years I had my Envoy, I noticed it idled rough whenever I was stopped at a light with my foot on the brake. I was initially told that "all Envoys do this" and my dealer suggested adding fuel injector cleaner to the gas tank (which did nothing). I started taking the Envoy to another dealer after I moved and they diagnosed it right away. Once I had that fixed it ran like a brand new car. Then I had the same problem occur again within several months, only magnified ten times over, with decreased engine power, and finally the SES light came on. I had more bad ignition coils. Those were replaced last summer and no problems since, engine runs fine.

Good Luck

gpderk
08-21-2010, 12:30 AM
I have a similar problem with my TB 4X4 LS 4.2L. Engine Idles rough/misses when the vehicle is stopped and the A/C is running, but stops missing when the A/C is turned off. The engine miss continues when accelerating even with the A/C off. I was on the "FixYa" website after trying tips from this site...(clean throttle body / replace battery / reset computer by holding the battery cables together for 10 seconds) that did not correct the problem...I drove the vehicle for over an hour after completing the above mentioned solutions and the problem still persists. The technician on the "FixYa" website stated that the problem was with either the IAC Valve or Throttle Position Sensor (TPS); both are integrated with the throttle body (TB) hence you have to replace the entire throttle body to replace these two parts. I am still trying to confirm that the IAC and TPS are built into the the TB. I did check the cost of the TB...Advance Auto sells it new for right around $250...15% discount if you are military! I saw a used one on the web for $179, but I would not consider buying this part used! I'll post again once I find the solution to my specific problem. Also, I had the engine scanned at Advance Auto for free and there were no error codes. My check engine light is not on.

Blazernut
08-21-2010, 01:09 AM
I have a similar problem with my TB 4X4 LS 4.2L. Engine Idles rough/misses when the vehicle is stopped and the A/C is running, but stops missing when the A/C is turned off. The engine miss continues when accelerating even with the A/C off. I was on the "FixYa" website after trying tips from this site...(clean throttle body / replace battery / reset computer by holding the battery cables together for 10 seconds) that did not correct the problem...I drove the vehicle for over an hour after completing the above mentioned solutions and the problem still persists. The technician on the "FixYa" website stated that the problem was with either the IAC Valve or Throttle Position Sensor (TPS); both are integrated with the throttle body (TB) hence you have to replace the entire throttle body to replace these two parts. I am still trying to confirm that the IAC and TPS are built into the the TB. I did check the cost of the TB...Advance Auto sells it new for right around $250...15% discount if you are military! I saw a used one on the web for $179, but I would not consider buying this part used! I'll post again once I find the solution to my specific problem. Also, I had the engine scanned at Advance Auto for free and there were no error codes. My check engine light is not on.

Rock auto has them for less than $200 shipped with the 5% discount using this code until September - 36450171161269

http://www.rockauto.com/catalog/x,carcode,1431163,parttype,6472

gpderk
08-21-2010, 11:15 AM
Thanks for the lead on the cheaper throttle body...good info!

gpderk
08-29-2010, 08:58 PM
Update on the fix for the rough idle / engine misfiring with my 2005 TB. I replaced the throttle body and the problem continued. Replaced spark plugs using Bosch Platinum IIs and the problem continued. On the advice of a GM service technician who works at a local part store, I removed the newly installed Bosch plugs and replaced them with "genuine GM parts"...AC Delco plugs, and the problem was solved. I don't know why my ignition system didn't like the Bosch plugs, but the GM technician said he had similar experiences with this in the shop where owners replaced original parts with aftermarket parts and they did not work right with the GM electronic system. Sooooo....bottom line in dealing with the rough idle issue in these models, the most common causes that I have found in my internet research and personal experience is this: Dirty throttle body, fouled/worn out spark plugs, or a bad coil, and when it comes to your spark plugs use the AC Delco brand! I hope this is helpful for other DIY people out there.