Fuel economy has diminished.
01-02-2011, 11:50 AM
#21
Platinum Member
Join Date: 05-09-2006
Location: "Upland" Mesa, Arizona
Posts: 6,805
Frankly from what I am told, when fuel pumps are removed from the tank, NOTHING is discovered on the filters. So either the filter sock is not filtering enough and "crud" is bypassing (highly unlikely without an injector problem), or the owners were purchasing fuel from dealers and companies that do a good job.
The fuel filters that were previously installed externally, were to capture rust and other crud formed because of the metal tanks. We no longer have those tanks.
The filter sock is a secondary catch all. The primary filtering responsibility is with the retail fuel distribution network.
The fuel filters that were previously installed externally, were to capture rust and other crud formed because of the metal tanks. We no longer have those tanks.
The filter sock is a secondary catch all. The primary filtering responsibility is with the retail fuel distribution network.
07-29-2011, 02:12 PM
#22
Join Date: 03-19-2009
Location: Canada
Posts: 6
economy
Realize the thread is old and topic has drifted but thought I would chime in anyway with my observations.
I drive an 06 LT with the 2.4 and automatic. Here in the frigid north with our 10-15% ethanol garbage fuel, mine varies tremendously with driving style and other factors (AC, wind etc).
I used to drive a 2007 Cobalt with the 2.2 (just got totalled, miss it!). The Cobalt was very stable mileage wise, typically getting 30 mpg on my mostly country backroad commute, and at absolute worst dropping to 25mpg while in the dead of winter being driven like I stole it.
The HHR on the other hand, will get as poor as 21mpg in the middle of winter while my wife drives it using the gas and brake as on-off switches (she chewed through the original factory ceramic pads in 25,000 miles, I got 60,000 out of mine on the Cobalt). Under optimal, laboratory like conditions in a straight cruise on the highway I can squeak 29.5mpg out of it at best.
-Dirty air filter on both cars will drop mileage 1-1.5mpg and make the engine noticeably bogged down. I can tell when its dirty without looking at it.
-At oil change time the engine starts to get louder and doesn't rev quite as smoothly. Minimal mileage drop, maybe 0.5-0.9 at most.
-Upping tire pressure from 30psi to 40psi improves mileage by up to 1mpg. This of course depends on tire quality, wear, and ride comfort preference.
-I think the 100,000 mile iridium spark plugs are a lie. On the cobalt I could feel power loss by 30,000 miles and decided to pull the plugs on it and the HHR at that time (HHR only had 15,000 or so miles at that time). On both they were already pretty well stuck into the block to the point I was afraid of stripping them taking them out, fortunately had no mishaps. All 8 plugs between them were fouled and the gaps were all over the place. After cleaning and regapping the ones in the HHR and replacing the ones in the Cobalt, the HHR idled and revved noticeably smoother and the Cobalt did also, with a noticeable improvement in power. I reinstalled the plugs with a little antiseize on the threads and dielectric grease on the coil boots so they would not seize in later on.
Overall, yes these engines are computer controlled and can run for ages without intervention, but are tuned to squeeze out every bit of economy possible and noticeably benefit from basic regular maintenance above and beyond what GM says.
I drive an 06 LT with the 2.4 and automatic. Here in the frigid north with our 10-15% ethanol garbage fuel, mine varies tremendously with driving style and other factors (AC, wind etc).
I used to drive a 2007 Cobalt with the 2.2 (just got totalled, miss it!). The Cobalt was very stable mileage wise, typically getting 30 mpg on my mostly country backroad commute, and at absolute worst dropping to 25mpg while in the dead of winter being driven like I stole it.
The HHR on the other hand, will get as poor as 21mpg in the middle of winter while my wife drives it using the gas and brake as on-off switches (she chewed through the original factory ceramic pads in 25,000 miles, I got 60,000 out of mine on the Cobalt). Under optimal, laboratory like conditions in a straight cruise on the highway I can squeak 29.5mpg out of it at best.
-Dirty air filter on both cars will drop mileage 1-1.5mpg and make the engine noticeably bogged down. I can tell when its dirty without looking at it.
-At oil change time the engine starts to get louder and doesn't rev quite as smoothly. Minimal mileage drop, maybe 0.5-0.9 at most.
-Upping tire pressure from 30psi to 40psi improves mileage by up to 1mpg. This of course depends on tire quality, wear, and ride comfort preference.
-I think the 100,000 mile iridium spark plugs are a lie. On the cobalt I could feel power loss by 30,000 miles and decided to pull the plugs on it and the HHR at that time (HHR only had 15,000 or so miles at that time). On both they were already pretty well stuck into the block to the point I was afraid of stripping them taking them out, fortunately had no mishaps. All 8 plugs between them were fouled and the gaps were all over the place. After cleaning and regapping the ones in the HHR and replacing the ones in the Cobalt, the HHR idled and revved noticeably smoother and the Cobalt did also, with a noticeable improvement in power. I reinstalled the plugs with a little antiseize on the threads and dielectric grease on the coil boots so they would not seize in later on.
Overall, yes these engines are computer controlled and can run for ages without intervention, but are tuned to squeeze out every bit of economy possible and noticeably benefit from basic regular maintenance above and beyond what GM says.
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