After adding my exhaust, I noticed the gas mileage go down (figured it was me), then noticed after driving more conservatively, still sucking the fuel down, and got black soot out of the exhaust, thought it was the stuff burning off, but its been almost a month, and still sucking down gas. Today after work, gave her some gas, and got black smoke, that definitly tipped it. Any idea why she could be running rich? The Header's O2 was replaced few months back, used an AC Delco, is it possible for it to be damaged somehow in installing it into the header? I wanna think my power sucked/poor gas mileage happened after installing my header. Ive got the DCSport 4-2-1 for the LD9, and a Magnaflow catback and cat, with a thrust glasspack. The O2 in the cat is the original, no codes. Ive got an AEM short ram intake, had it months before the exhaust. Tried resetting the pcm, didnt seem to help. Also, not sure if its related, but when i start off (5spd), and fully off the clutch, it'll almost bog, then like automaticly pickup power, steady pedal, its like a lag. Any help would be appreciated.
is your filter clean....i had a cheap cone filter on my s-tube and then i put the stock airbox back on.....i went form about 220 a tank to 270.....just a thought i had the same problem running rich and bad gas mileage....
Thanx Charles
Yeah, its the AEM one, less than id say 7k miles on it. Im looking into upgrading to the new dry synthetic filter soon though.
Are you sure the black smoke is fuel and not carbon burning off. I have gained gas mileage with all my mods and my car runs 14's all motor.
FU Tuning
Im thinking so, she got 18mpg today when i filled up from the check gauges light (13.9g @253 miles). I usually get between 20-22 on average. My last tank was 17mpg, but that was probably due to my driving habits, like said before, very conservative in driving this tank, and still bad gas mileage. Dealer wants $80 for the front O2, which is an expensive choice.
Ender_Wiggin wrote:Im thinking so, she got 18mpg today when i filled up from the check gauges light (13.9g @253 miles). I usually get between 20-22 on average. My last tank was 17mpg, but that was probably due to my driving habits, like said before, very conservative in driving this tank, and still bad gas mileage. Dealer wants $80 for the front O2, which is an expensive choice.
This does not mean you are running rich. Other things can cause a are to have bad gas mileage.
FU Tuning
could be your plugs, or maybe your car could use some fueul injector cleaner.
when the header was done, did you disconnect the battery so the puter resets? you do that so the puter can learn quicker from mods you've done. if you haven't, do it for 30 minutes. but dont be driving hard all the time. just drive noramlly for while
Im a Xbox 360 fanboy...and damn proud of it!!
99redz24 wrote:could be your plugs, or maybe your car could use some fueul injector cleaner.
when the header was done, did you disconnect the battery so the puter resets? you do that so the puter can learn quicker from mods you've done. if you haven't, do it for 30 minutes. but dont be driving hard all the time. just drive noramlly for while
Acutally had a Fuel System cleaner done from work, its a 3 part where they clean your injectors (the gas tank stuff), clean vaccum lines from the brake bleeder, and the throttle plate was already clean. I do have a small coat of oil on the Intake Manifold, but nothing unusual there. Plugs are new, but not to say that they cant be fubar'd already. I did Disconnect the battery the whole day i did the header, same with the catback. I did the same id say a week or two afterword when i noticed that it was sucking fuel, same result. I did fill up today, and added some fuel cleaner via advice from my boss at work (it was part of the 3 part), so we'll see. On another note, how hard is it to hook up an air/fuel gauge?
People will call me nuts... but bear with me and give it a shot, mmmkay?
Take the IAT out of your intake.... tape off the hole.... and let it hang in the warm engine bay.
Man your nutz...............
And yet your trick works on 90% of all jbodies with aftermarket intakes......
We believe this is because the air entering the engine with a stock intake is higher in temp than the air entering with an aftermarket intake.
Mileage drops because the ecu reads colder air, and injects more fuel. I notice i get better gas mileage if i run the IAT right at the very end of my short ram, closest to the TB, and measure true intake temp.
Lenko, John Lenko wrote:People will call me nuts... but bear with me and give it a shot, mmmkay?
Take the IAT out of your intake.... tape off the hole.... and let it hang in the warm engine bay.
Wouldnt there be a point when it may run lean? Also, ive had that intake since about October 05, there a reason why now it would cause issue?
I have almost the same set up and the same problem! I have a pacesetter 4-1 ceramic, magnaflow cat, custom pipes to a Weapon R muff, getting the resonator soon. I also have a reactive intake and SPEC Clutch/slywheel. Mine sputters/lags like you discribed and gets pretty bad gas mileage. It does alright if i drive conservative but it chugs the gas if i do anything spirited. A night at the track running 5 or 6 times my car will drink about 1/4 tank or more. I haven't bothered to calculate my mpg but it get between 230 and 260 if i fill it up. Which doesn't happen much with reg almost at $3 a gallon.
PSN ID: Phatchance249
You have to remember, anytime you change a parameter or piece in your engine, it affects the entire system. Basically intakes/exhausts are good when you can tune your ecm to handle the new spec's. Think of it as doing math, 1+1=2 right? Now lets say that we take one of the 1's and turn it into a higher number (as in more air flow from a new intake) lets say 1.5, the ecu is still looking for 1+1 = 2, but now it's seeing 1.5+1 = 2.5 and the information programmed on your chip tells it that a+b must = 2, so it does this.
1.5+.5=2
Lets say the .5 it changed to was a higher amount of fuel. So in essence, your engine computer sees things change, and isn't smart enough to recalulate how to change with it. To a point.
C Smyth wrote:You have to remember, anytime you change a parameter or piece in your engine, it affects the entire system. Basically intakes/exhausts are good when you can tune your ecm to handle the new spec's. Think of it as doing math, 1+1=2 right? Now lets say that we take one of the 1's and turn it into a higher number (as in more air flow from a new intake) lets say 1.5, the ecu is still looking for 1+1 = 2, but now it's seeing 1.5+1 = 2.5 and the information programmed on your chip tells it that a+b must = 2, so it does this.
1.5+.5=2
Lets say the .5 it changed to was a higher amount of fuel. So in essence, your engine computer sees things change, and isn't smart enough to recalulate how to change with it. To a point.
I see your point, but why do others with similar mods not have issues? What would suggest to be a solution to the problem? Since filling up, shes doing alright, but only about 40 miles or so into the tank. I dont really go far daily (i'd say about 10 miles round trip to work and back), would that not be much time for the PCM to want to adjust? Also, what things can i do to let the computer relearn?
Ok so lets try this then. Your flowing more air, maybe the injectors or fuel pump in some way can't keep up with the new measurements. Stock injectors should be able to, but how many miles are on it. My guess would be that maybe the stock fuel pump isn't pushing as much as it used to, or the injectors are old.
Have you checked fuel pressure, checked the lines, maybe have them all cleaned. I dunno, i without the car in front of me.
it that were true, wouldnt it run lean? I
Not necessairly. If the ecm detects that there isn't enough fuel, it will up the injector pulse. If the fuel pump is bad, it could be flowing less, but the injectors are trying to compensate.
Your best bet is to see if you can find someone with a scantool to check the sensors for readings. MAYBE it's a bad sensor also. Who knows.
