Another Gas milage thread :(

[joosdawg]

Well ive gone 95 miles and am now on the 1/4 tank mark!!! wtf, i know ive been doing some drifting in the snow and such alot but still thats like 6mpg!! Anyway heres what i see being the problems but i just need to know from some experts what i need to do ASAP to fix this. First off i have a 255 pump W/O an AFPR, 750cc injectors trying to tune those two with a SAFC is virtually impossable. Next sense the pump install my gas gauge when i first fill it only reaches 3/4 marking on the fuel gauge. so i dont know when im actually close to empty or not any insight on that would be great, or at least somone with a simular problem that could tell me that after it gets to half tank its accurate or somthing. Also just lately i think the T-stat is stuck open because the temp gauge will not go past the first tick marking no matter what i do. I do have a new front O2 and looks like its doing its job fine according to the logger. Im just thinking a mix of running so cold, and rich sense i cant tune such big injectors on the SAFC is my biggest problem. Is that my main cause for the crappy milage? if i was to put the stock 450's in and get a new t-stat and gasket for the housing until i get the afpr and dsmlink should i at least get like 15mpg? Or is there anything i can do now so i dont have to get frostbite sense i dont have a garage to swap injectors in . Any help would be awsome as ive spent about $60 on gas in one week.

-Ryan

 

[joosdawg]

another thought im having right now is replacing the stupid 750's that came in the car with some 650's so i can still use the SAFC to tune with and not have to spend a grand just to get my car to run right at this point in the dead of winter. Anyone think i should save a little gas by getting the 650's and finally being able to tune correctly sense the 750's are way to big for a piggyback like the SAFC. Its just really making me mad when i start the car in the morning and have to crank it twice because it dies out and reeeks like gas then when i start off it like bucks and acts all retarted but then once its warm its a flawless idle, perfect smooth driving ect now that i have it tuned as good as its gonna get as is.

 

[Catbox_95]

Like you said, you're probably just running too rich. I have a 255 lph, 660cc injectors, with only an MAFT and SAFC to tune it, with a Garrett T3/T4 57 trim, and if I drive it according to how the law suggests I drive it, I get about 28 mpg. I consistently get over 400 miles per tank.

Tune it. Bottom line: If you get the a/f ratio right, it doesn't matter what else you're running as far as injector size, fuel pump size, etc.

 

[xveganxcowboyx]

Swap the thermostat asap. It costs almost nothing and won't take long. That's got to be hurting your mileage.

The 650's sound like a good idea so you can tune properly. I would try to get a FPR soon as well. I don't know tons about tuning, but it seems like if you're already running rich, then in closed loop mode is a horrible combo.


*edit* I've been delivering pizza in the snow (lots of high rev corners and I've seen my mileage drop from 20mpg to 14 or 15. If I hit the local mountain trails and rally my car for even 15 or 20 miles per tank I lose about 3 mpg overall. Hitting the boost and spinning tires really hurts mileage.

 

[joosdawg]

Like you said, you're probably just running too rich. I have a 255 lph, 660cc injectors, with only an MAFT and SAFC to tune it, with a Garrett T3/T4 57 trim, and if I drive it according to how the law suggests I drive it, I get about 28 mpg. I consistently get over 400 miles per tank.

Tune it. Bottom line: If you get the a/f ratio right, it doesn't matter what else you're running as far as injector size, fuel pump size, etc.

The thing is i cant get the darn tuning right, ive been trying for the past 6 days for about 2-3 hours a day just logging while cruising, idle, WOT everything. I got all those situations with the proper fuel trims around 100% and sticking there and all seems well. Then the next morning i go to start the car and it runs like crap, like i said it dies in the morning and drives like crap until its partially warm/as warm as it can get with the cheesy thermostat in there. The tuning just seems to mess up at random, ive left it after i got it real good one night that i spent a good 4 hours cruising at 1K 2K 3K 4K and did WOT tuning from 2K-7K and idle of course. Had them all dead on, no knock, everything looked great but after the car cools off, when i start it again it just dumps fuel in and stinks bad like gas and you can just tell its running mega rich. Its almost as bad as i think theres a leak somwhere it stinks so bad BUT i know theres not because i replaced all the O rings on the injectors and checked teh fuel rail and everything sense there was a screw broken off. NO LEAKS. I think i may be having a problem with this tuning like this because of it not running at normal temps and sense its always cold i think it cools faster when i turn it off and every time i drive and the car moves it cools even more and screws with what i think the settings should be sense its a constant cycle of cool cooler ect. Im gonna replace the T stat tomorrow and see what i come up with as far as tuning after that hopfully a little better at least. Is anyone elses car like that where it runs fine when warm and on a cold start runs like junk and drives like junk for the first couple min? or is that just because of my problems?