Terrible fuel economy with light to moderate driving
Terrible fuel economy with light to moderate driving Hey guys, recently purchased a 2002 Z28 Camaro with 21k miles. It was bone stock when I purchased it at Carmax and I have since added an SLP lid/new filter. Below is a picture of my gas gauge and trip meter. Trip meter was reset before I left the gas station on the last fill up. This has been consistent the past few fill-ups.
My driving is light to moderate at the most. I typically shift at about 2k rpms. Any thoughts? I'm not expecting Honda Civic fuel economy, but 10-12 MPG on conservative driving is a good bit worse than I expected.. and definitely worse than other friends with f-bodies. Is this consistent with what the rest of you are seeing?? Any feedback is greatly appreciated.
My driving is light to moderate at the most. I typically shift at about 2k rpms. Any thoughts? I'm not expecting Honda Civic fuel economy, but 10-12 MPG on conservative driving is a good bit worse than I expected.. and definitely worse than other friends with f-bodies. Is this consistent with what the rest of you are seeing?? Any feedback is greatly appreciated.
Last edited by Onyx_Black_Z28; Jan 28, 2012 at 12:35 AM. Reason: Picture link was WAY too big
Lemons12 - you are correct, M6. Forgot to mention that. No codes - the engine runs/pulls great, just like any other stock f-body I've been in.
plugs
plug wires
o2s
fuel filter
injectors
mass air flow
Just a few things that I would look into... Hooking it up and scanning it wouldn't be a bad idea. I have seen cars have codes and no "SES" light coming on.
plug wires
o2s
fuel filter
injectors
mass air flow
Just a few things that I would look into... Hooking it up and scanning it wouldn't be a bad idea. I have seen cars have codes and no "SES" light coming on.
Plugs and plug wires are definitely on my list of tune up items, along with the fuel filter. Do you know of any signs that demonstrate the O2's, injectors or MAF have issues if no codes are present upon scanning? Or am I just stuck with the same diagnostic procedure found in a dealer handbook?
Last edited by Onyx_Black_Z28; Jan 28, 2012 at 01:11 AM. Reason: Grammar
Plugs and plug wires are definitely on my list of tune up items, along with the fuel filter. Do you know of any signs that demonstrate the O2's, injectors or MAF have issues if no codes are present upon scanning? Or am I just stuck with the same diagnostic procedure found in a dealer handbook?
Scan it first, then go from there.
Again, both of these should show their self fairly easily if there is a problem. Diagnosing a bad maf (if the normal signs are present, which you say the car is running fine) is as simple as unplugging it and seeing if it clears up. You would have to replace yours... Used they run 20-40$ on here... And lt1 MAFs are interchangeable. Finding a buddy that would is in a situation to let you borrow one for 3-4 days would be perfect.
o2s? Replace them.. Not much else you can do. You can buy them off here used for usually 30-50$. I *might* have a set I will sell cheap if you end up getting here. I will have to double check the shop though.
You could take the injectors off and inspect them.. You can get stock injectors for roughly 20-45$ on here used.
I would scan it then look into plugs/wires/fuel filter first... They are cheap and easy. Then go from there.
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Lemons12, that is fantastic information. Because the car is 10 years old and doesn't look like anything other than oil/filter changes have been done, I'll probably end up replacing all of the above items you mentioned (with the possible exception of the injectors). I will post back results as soon as I've had a chance to scan/replace a few of these items. Thanks so much for your time.
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Verdad Gallardo Glad I could help, definitely report back with updates... Your update could point in a direction to solving an issue, even if it doesn't fix it. Or you could replace everything, give updates, and it still not be fixed. 
Not funny, but its what happens with cars! LOL
Not funny, but its what happens with cars! LOL
On The Tree
Joined: Jan 2012
Posts: 158
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From: Elswhere
I really can't think of anything that would have such a profound effect on fuel economy. Far too much fuel is being injected. If the maf and o2's are working correctly, It's most likely the fuel system. Scanning it will probably reveal the problem.
It could be something as simple as having a hole in a line or something, who knows. Just have to see what you can find out once you dig in.
I had an Mr2 turbo several years ago that drove great but would get zero extra power under full boost.. it was the strangest thing. I replaced half the parts on that car and saw ZERO difference. Here's hoping my new Camaro is different!! 
TECH Enthusiast
Joined: Mar 2009
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From: West Chester, PA
I'm also thinking what was stated above, check the plugs and wires. The stock wires can be somewhat difficult to tell if they are secured on the plug. I also ran Champion plugs for a few months, absolute worst mistake I have ever made in my entire life. Another thing is you can clean out your throttle body too, could possibly help.
And does your car pull as hard as I should, any power loss?
And does your car pull as hard as I should, any power loss?
Last edited by RikkiTorment; Jan 28, 2012 at 03:13 AM.
Tuneup? On a car with 21k miles that is equipped with wires, plugs, etc. that will go a min. of 100k miles. That would be throwing money out window. Definitely pull the plugs and see what color they are. While you have them out run a compression check. Just like they said above, it would not be a bad idea to look over your tune to see if has been messed with. Scan computer for codes to see what gremlins you have. Doubt the injectors are stuck open otherwise you would smell gas while engine was running and would eventually hydro lock.
Tuneup? On a car with 21k miles that is equipped with wires, plugs, etc. that will go a min. of 100k miles. That would be throwing money out window. Definitely pull the plugs and see what color they are. While you have them out run a compression check. Just like they said above, it would not be a bad idea to look over your tune to see if has been messed with. Scan computer for codes to see what gremlins you have. Doubt the injectors are stuck open otherwise you would smell gas while engine was running and would eventually hydro lock.
I'm also thinking what was stated above, check the plugs and wires. The stock wires can be somewhat difficult to tell if they are secured on the plug. I also ran Champion plugs for a few months, absolute worst mistake I have ever made in my entire life. Another thing is you can clean out your throttle body too, could possibly help.
And does your car pull as hard as I should, any power loss?
And does your car pull as hard as I should, any power loss?
I'll check that out - thank you!
Tuneup? On a car with 21k miles that is equipped with wires, plugs, etc. that will go a min. of 100k miles. That would be throwing money out window. Definitely pull the plugs and see what color they are. While you have them out run a compression check. Just like they said above, it would not be a bad idea to look over your tune to see if has been messed with. Scan computer for codes to see what gremlins you have. Doubt the injectors are stuck open otherwise you would smell gas while engine was running and would eventually hydro lock.
Remauto1187 and _JB_ thanks for your feedback. I do have to agree with _JB_ that those items do probably need to be replaced - Even though I only have 21k miles, I am about 8 years past the point it's recommended to replace those in the maintenance schedule.
I don't have HPTuners or any kind of scanning equipment yet, so checking out the A/F ratio and codes will have to wait until I have access to those something to that can provide that information. I'll be surprised if there is something so major wrong with the car that a compression test would yield poor results. I definitely don't smell gas and the car runs great - if it ran rough or anything, I would have simply returned the car within the 5 day return policy rather than try and hunt down issues. I don't do a ton of driving, so it took me a week to burn a full tank of gas.. go figure. Thanks again everyone - you have all given me a number of leads to follow up on. I will report back once I've had an opportunity to try some of these things!