Hey All-
Thanks for reading my post. I've read through several rough idle posts on the forum here, but nothing that quite touches on what I'm experiencing.
I've got a 2003 Trailblazer EXT, 4.2 I6 - it just developed a rough idle. No service engine light, no codes, no nothing.
Vehicle only idles rough when sitting. Does not matter if it is in Park, Drive, Neutral. Idles rough regardless.
When accelerating the vehicle operates smoothly. Driving around town and/or highway it runs as smooth as it can be.
I have read and saw all sorts of things people have suggested: Clean Throttle Body, bad ignition coils, Camshaft sensor, etc...before attacking any of that, I'd rather look at a couple of other things regarding vehicle to get thoughts from you if whether any of it could be related.
Recently I fixed heater control valve found on firewall to get heat to rear of vehicle. I have ensured vacuum line is attached to valve properly. Vehicle has rear heat - so valve is operational.
In conjunction with the rough idle - I have noticed that the vehicle is absolutely in need of a water pump. There is excessive play in the water pump pulley with obvious noise that the fan is coming into contact with the shroud.
The vehicle itself is not running hot. The temp needle doesn't quite reach 210, so I have to believe the pump itself and thermostat are still functional despite the bad pulley.
I know stranger things have happened, but just the sheer fact that the rough idle and noise coming from/caused by water pump have seemingly happened simultaneously has led me to believe these two items are possibly intertwined.
Has anyone ever seen a water pump causing a rough idle at low RPM's - or have any justification that a pump could create this condition?
The fact that there are no codes (been driving it daily with rough idle for a week) and it does not accelerate rough or have any loss of power when accelerating leads me to believe its not ignition related.
I came across a guy who was experiencing similar issues in his 06 TB (rough at low RPM smooth through acceleration & at speed), same motor - he replaced what he identified as a MAF sensor on his 06 and he also replaced his MAP sensor and he said this fixed his problem.
I don't have any tools to read live data unfortunately. I do know a guy in our area who owns a shop, but he's busy so I thought I'd turn here first for any suggestions before scheduling something with him.
Thanks for taking time to read my post. I look forward to any feedback you may have.
Thanks for reading my post. I've read through several rough idle posts on the forum here, but nothing that quite touches on what I'm experiencing.
I've got a 2003 Trailblazer EXT, 4.2 I6 - it just developed a rough idle. No service engine light, no codes, no nothing.
Vehicle only idles rough when sitting. Does not matter if it is in Park, Drive, Neutral. Idles rough regardless.
When accelerating the vehicle operates smoothly. Driving around town and/or highway it runs as smooth as it can be.
I have read and saw all sorts of things people have suggested: Clean Throttle Body, bad ignition coils, Camshaft sensor, etc...before attacking any of that, I'd rather look at a couple of other things regarding vehicle to get thoughts from you if whether any of it could be related.
Recently I fixed heater control valve found on firewall to get heat to rear of vehicle. I have ensured vacuum line is attached to valve properly. Vehicle has rear heat - so valve is operational.
In conjunction with the rough idle - I have noticed that the vehicle is absolutely in need of a water pump. There is excessive play in the water pump pulley with obvious noise that the fan is coming into contact with the shroud.
The vehicle itself is not running hot. The temp needle doesn't quite reach 210, so I have to believe the pump itself and thermostat are still functional despite the bad pulley.
I know stranger things have happened, but just the sheer fact that the rough idle and noise coming from/caused by water pump have seemingly happened simultaneously has led me to believe these two items are possibly intertwined.
Has anyone ever seen a water pump causing a rough idle at low RPM's - or have any justification that a pump could create this condition?
The fact that there are no codes (been driving it daily with rough idle for a week) and it does not accelerate rough or have any loss of power when accelerating leads me to believe its not ignition related.
I came across a guy who was experiencing similar issues in his 06 TB (rough at low RPM smooth through acceleration & at speed), same motor - he replaced what he identified as a MAF sensor on his 06 and he also replaced his MAP sensor and he said this fixed his problem.
I don't have any tools to read live data unfortunately. I do know a guy in our area who owns a shop, but he's busy so I thought I'd turn here first for any suggestions before scheduling something with him.
Thanks for taking time to read my post. I look forward to any feedback you may have.