Tuners.....whats the unusual causes you find that causes BAD gas mileage....?
11-04-2014, 08:53 PM
#1
Tuners.....whats the unusual causes you find that causes BAD gas mileage....? My engine runs great.....smooth...powerful.....no misfires.....no codes.....no smell or leaks of gas anywhere......
If I drive like a grandma I am getting 8-9 mpg CITY (about 120 miles on the odometer per full tank)........maybe 15-17 mpg HWY. NO RACING....NO WOT runs......
Brand new spark plug wires and spark plugs....TR5 gapped .050
Engine has about 4,000 miles on it. Burns no oil at all between changes. Doesn't smoke at all. Starts up every time first bump of the key.
02 sensors are new and switching normally.
MAF is clean.
My last engine, the 427ci stroker got about 230 miles to a tank of gas CITY and upwards of 25 mpg HWY cruising. So theres something very wrong here.....
What can I look for next....?
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If I drive like a grandma I am getting 8-9 mpg CITY (about 120 miles on the odometer per full tank)........maybe 15-17 mpg HWY. NO RACING....NO WOT runs......
Brand new spark plug wires and spark plugs....TR5 gapped .050
Engine has about 4,000 miles on it. Burns no oil at all between changes. Doesn't smoke at all. Starts up every time first bump of the key.
02 sensors are new and switching normally.
MAF is clean.
My last engine, the 427ci stroker got about 230 miles to a tank of gas CITY and upwards of 25 mpg HWY cruising. So theres something very wrong here.....
What can I look for next....?
.
11-05-2014, 08:26 AM
#5
m wondering if fuel injectors can leak or not be atomizing properly
What kind of compression and timing do you have in this engine compared to the other one? What specs where on the old engine (heads, cam etc.)? What's the weight, gearing and stall in this setup compared to the old one?
11-07-2014, 07:35 PM
#6
Leaking you'd know based on O2 and WB reading (if you have one).
What kind of compression and timing do you have in this engine compared to the other one? What specs where on the old engine (heads, cam etc.)? What's the weight, gearing and stall in this setup compared to the old one?
What kind of compression and timing do you have in this engine compared to the other one? What specs where on the old engine (heads, cam etc.)? What's the weight, gearing and stall in this setup compared to the old one?
390ci.....239/235 .600/.600 114 lsa, 10.8:1 cr
Everything else is the same. heads, intake, TB.....I transferred to the 390ci. Rear end, gears, tranny, stall converter.....all the same.
Same injectors from
Basically I just did an engine swap. 390ci is built for boost so we went with a little lower compression. The tuner just did a conservative tune until I boost it later.
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Last edited by LS6427; 11-07-2014 at 07:43 PM.
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11-17-2014, 10:05 AM
#9
Everyone seems to be looking in the right direction. Fuel trims and spark is where I would look first. Also, is your torque converter locking up correctly?
I tuned my 420rwhp LS1 on my C5 and was able to get 32mpg (fillup verified) out of that built motor on long highway trips. I had the timing cranked way up at part throttle/light load, the trims were in the -1-3% range, of course I had an M6. Are you running SD or MAF/SD tune? I know SD will almost always get worse MPG than a solid MAF tune. Interested to see what you find.
I tuned my 420rwhp LS1 on my C5 and was able to get 32mpg (fillup verified) out of that built motor on long highway trips. I had the timing cranked way up at part throttle/light load, the trims were in the -1-3% range, of course I had an M6. Are you running SD or MAF/SD tune? I know SD will almost always get worse MPG than a solid MAF tune. Interested to see what you find.
11-18-2014, 08:31 AM
#11
TECH Resident
Tyres pumped up to a good PSI? any signs of brakes rubbing? Something simple to check, other than that I would check the fuel trims, check air filter if you haven't changed it in a while, a clogged air filter can alter fuel trims.
11-27-2014, 11:31 AM
#12
Everyone seems to be looking in the right direction. Fuel trims and spark is where I would look first. Also, is your torque converter locking up correctly?
I tuned my 420rwhp LS1 on my C5 and was able to get 32mpg (fillup verified) out of that built motor on long highway trips. I had the timing cranked way up at part throttle/light load, the trims were in the -1-3% range, of course I had an M6. Are you running SD or MAF/SD tune? I know SD will almost always get worse MPG than a solid MAF tune. Interested to see what you find.
I tuned my 420rwhp LS1 on my C5 and was able to get 32mpg (fillup verified) out of that built motor on long highway trips. I had the timing cranked way up at part throttle/light load, the trims were in the -1-3% range, of course I had an M6. Are you running SD or MAF/SD tune? I know SD will almost always get worse MPG than a solid MAF tune. Interested to see what you find.
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11-27-2014, 11:34 AM
#13
Can you guys tell me what fuel trims are supposed to be....?
Any other numbers that are important....?
So when I go to the tuner to have this all checked to see where its at.....I can make sure its all good.....or verify its messed up and needs to be done over again....
Thanks...
.
Any other numbers that are important....?
So when I go to the tuner to have this all checked to see where its at.....I can make sure its all good.....or verify its messed up and needs to be done over again....
Thanks...
.
11-27-2014, 11:39 AM
#15
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If its stock vehicles, I have found the biggest thing for me is to get the timing dialed in right for mpgs.
If its a modded vehicle, power enrichment settings have always been a place to look. Depending on driver, I've seen some people who tip into enrichment on just average driving just from their driving styles and how I have the enrichment delays setup.
If its a modded vehicle, power enrichment settings have always been a place to look. Depending on driver, I've seen some people who tip into enrichment on just average driving just from their driving styles and how I have the enrichment delays setup.
11-27-2014, 12:18 PM
#16
If its stock vehicles, I have found the biggest thing for me is to get the timing dialed in right for mpgs.
If its a modded vehicle, power enrichment settings have always been a place to look. Depending on driver, I've seen some people who tip into enrichment on just average driving just from their driving styles and how I have the enrichment delays setup.
If its a modded vehicle, power enrichment settings have always been a place to look. Depending on driver, I've seen some people who tip into enrichment on just average driving just from their driving styles and how I have the enrichment delays setup.
Unless it has nothing to do with the tune and something has gone bad....but theres no codes, just terrible gas mileage and fried passengers side 02 sensors after a few months.
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12-01-2014, 07:27 PM
#17
THIS!!!!! Sounds like your MAF tables are raped. Tuner is probably making up for it on PE, and going into PE too easy. Mine was like that from a "well known tuner". My swap was getting 12mpgs on the highway. I got some help, and get some guidance, and got it fixed. Now it's getting ~23 on the highway, and ~17 in town, like it should.
There should be a competency test before people are allowed to charge for a tune IMO.
12-01-2014, 08:54 PM
#18
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This is going to sound silly but I see you have Tr5 plugs. When I put TR5s in my car my MPG went to ****... And I was still stock motor at the time no cam yet. Im not sure if it's possible for it to have something to do with the plugs, or if it's just a coincidence with another problem. Get about 12mpg city, and 19ish highway from a factory rated 19/28. Prior to the MPG drop the car got around 17-18 city and 23-24 highway. So not great to begin with even from when I first got the car. I wonder how my MAF tables and power enrichment are in my tune...
12-02-2014, 01:04 PM
#19
This is going to sound silly but I see you have Tr5 plugs. When I put TR5s in my car my MPG went to ****... And I was still stock motor at the time no cam yet. Im not sure if it's possible for it to have something to do with the plugs, or if it's just a coincidence with another problem. Get about 12mpg city, and 19ish highway from a factory rated 19/28. Prior to the MPG drop the car got around 17-18 city and 23-24 highway. So not great to begin with even from when I first got the car. I wonder how my MAF tables and power enrichment are in my tune...
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