Poor Gas Mileage/Power. Cleaner/High Octane makes it worse
 

Hi,

I have a 2006 LT2 with a 2.4. Bought it with 40K and have 65K on it now. Gas mileage has never been what everyone else seems to rave about. I am averaging 23 on my daily commute which is 18 miles one way with an even mix of highway and city. If I try really hard I can get it up into the 24s but when I turn the AC on it drops. I tried runnnig premium and ran a bunch of cleaner through it but that just made it hard to start. It would turn over until the starter stopped and then start the 2nd try. One mechanic told me that the fuel pressure was bleeding down and that the fuel pump assembly needed changed to the tune of $700. I started running regular in it again and the hard starting went away. Now it's just a poor mileage issue. I have verifed the mileage manually and get close to the same numbers. Any thoughts / ideas. Anybody heard of starting issues?

Thanx!!!!

Could you define "a bunch of cleaner", fuel system cleaners are not something you should "overdose" on. Your mechanic may be onto something if the fuel pump has been damaged by too much of a good thing, excessive cleaner use can absolutely play havoc with system components.

24 mpg overall isn't that bad for a 2.4, it really depends on the nature of your commute, whether its stop and go or all highway miles. Premium is the recommended fuel for the 2.4 and I've never experimented with regular, at the very least it causes the engine's computer to retard the timing in order to avoid detonation.

You may want to get a second opinion from another tech, the possibility of the fuel system bleeding off pressure when it shouldn't means you need to address that issue to either confirm a failure or not.

You MIGHT want to do a search for "fuel pressure". Here's one to give you SOME ideas.


https://www.chevyhhr.net/forums/show...=fuel+pressure

JMO you might try and reset your ECM couldn't hurt and it may even help a bit.

And also check with your dealer or tech on any updates that may be applicable for your model year.