Yeah cables are routed normally and static ignition timing (Spout connector out) is set to 14* BTDC
Fox Xtremely high fuel consumption
- Thread starter PonyGTrider
- Start date
Holy 
e you don't have a/c dang, I get better mileage with my a/c on full blast.
e you don't have a/c dang, I get better mileage with my a/c on full blast.
No AC here…Holy
Hehehe no it is a headlight ballastThis wouldn't happen to be a MAF adjuster, would it?
Yeah the old style still working beautifully with my diamond cut ultra clear headlights. Can’t afford the newest LED units
Yeah I'm still rocking my h.i.d.s from twelve years ago,ever other light is led including the gauges.
Well hell, that's the issue, damn bright headlights, don't even need to be on to effect fuel mileage 
Don't believe me? Put the old headlights back in and prove me wrong!!
Yeah, ok,ok I'll stop
Try a different BAP sensor, can't hurt, just remember if there is no change put the old one back on, that said, we may be on to something, need to back up and look at posted specs.....
lets start with the cats, if you're running just the upper stock cats that would be suspect, the 307 and top end you have should be spunky, not so sure I'd run 19lb squirters, I think you're gonna 'run otta gas' on the top end and may be a contributing factor, did you get all the way through the computer check including the engine running test?
Don't believe me? Put the old headlights back in and prove me wrong!!
Yeah, ok,ok I'll stop
Try a different BAP sensor, can't hurt, just remember if there is no change put the old one back on, that said, we may be on to something, need to back up and look at posted specs.....
lets start with the cats, if you're running just the upper stock cats that would be suspect, the 307 and top end you have should be spunky, not so sure I'd run 19lb squirters, I think you're gonna 'run otta gas' on the top end and may be a contributing factor, did you get all the way through the computer check including the engine running test?
You’re correct we ran off the main subject and thanks for your interaction.Well hell, that's the issue, damn bright headlights, don't even need to be on to effect fuel mileage
Don't believe me? Put the old headlights back in and prove me wrong!!
Yeah, ok,ok I'll stop
Try a different BAP sensor, can't hurt, just remember if there is no change put the old one back on, that said, we may be on to something, need to back up and look at posted specs.....
I went to autozone and a good guy told me when I asked for a BAP sensor price, he said “You know what? Just buy the sensor and if it doesn’t solve your problem bring it back to me and I will take it back and simply will give you a credit to pick up whatever you want to match the price of the sensor” Not a bad idea Ha!!!
So I might do that and see what happens.
With regard to the removal of the secondary cats I wouldn’t thing it would affect my fuel economy. The reason I removed then was because I deleted all the anti-smog system and they could clog it because of zero fresh air flow from the smog pump.
But in that same tenor, what about all of those using off road exhaust pipes? Do they have the same pathetic fuel economy?
Thanks for your ideas
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I'm gonna probably say something really stupid now.
Could your fuel tank be leaking? Slow enough that it evaporates before a puddle is seen?
Could your fuel tank be leaking? Slow enough that it evaporates before a puddle is seen?
There are not stupid questions or suggestions.
I haven’t seen any fuel dripping from the tank, but according to they fuel tank capacity and the miles driven my car 9.5 miles per gallon I should be losing roughly 45 to 50 % of the fue tank capacity….
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DadLife0724
Active Member
I have headers, no cats, x pipe, and flowmaster 40s. I don't get the greatest mileage. I haven't done any math on it, but it sux. @General karthief raised some good points.
With that kind of mileage it isn't *just* a tune issue, though you should check for the presence of a J3 port chip in your computer and remove it *with key off* if one is there.
You have some kind if a load issue. You said your brakes aren't dragging and you'd know it if they were, but there are other types of load problems:
- clogged exhaust
- wrong plugs or another issue causing failure to burn fuel in at least one of the cylinders
- clogged/ restricted intake ports
- valve or seal damage (compression & leak down tests would help here
It could be several factors, combined. I recommend resetting your timing to baseline and verifying with a second timing light. Also, ensure with the resistor plugged in that the computer is properly controlling timing, and able to make it move off of baseline. It should be close to 40* at cruise in some cells.
AFR would be nice to check, and I recommend tuning to everyone, but unless you're running so fat it'd smoke & make your eyes water, this can't be the issue rending 10mpg. You should be running at least 16, and in my case, I'm also seeing 18-22/tank in mixed driving conditions.
You have some kind if a load issue. You said your brakes aren't dragging and you'd know it if they were, but there are other types of load problems:
- clogged exhaust
- wrong plugs or another issue causing failure to burn fuel in at least one of the cylinders
- clogged/ restricted intake ports
- valve or seal damage (compression & leak down tests would help here
It could be several factors, combined. I recommend resetting your timing to baseline and verifying with a second timing light. Also, ensure with the resistor plugged in that the computer is properly controlling timing, and able to make it move off of baseline. It should be close to 40* at cruise in some cells.
AFR would be nice to check, and I recommend tuning to everyone, but unless you're running so fat it'd smoke & make your eyes water, this can't be the issue rending 10mpg. You should be running at least 16, and in my case, I'm also seeing 18-22/tank in mixed driving conditions.
All good points and will try to answer one by one:
No chips in the computer, I have two computers and both run fine
No clogged exhaust
I run FR5 or Autolite 3924 calibrated from 0.054” down to 0.040” in an attempt to fix the poor fuel economy issue and finding that the engine runs the strongest at 0.040”
No apparent extra fuel in the cylinders and all the plugs support that with very little fainted dark coloration.
Zero restrictions in the intake ports.
No known burned valves but I haven’t performed a leak down test and here are the compression test results:
1.- 120
2.- 130
3.- 130
4.- 125
5.- 110
6.- 142
7.- 141
8.- 140
In the past I backed down the timing to the stock 10 deg BTDC but haven’t verify the total advance
To be honest I don’t feel watery eyes or smell too much fumes out of the pipes, what I smell is probable because the secondary cats were removed.
9.5 mpg is so pathetic tha I’m tempted to disassemble all the the way down to the deck and do a valves job and reassemble everything from scratch.
Thank you for all the suggestion.
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