Gas Mileage

[lynger]

Well, when I first got my truck the gas mileage sucked, so I put a bottle of injector cleaner in. I gained about 120kms with that. Then the truck starting acting up.....long story short I replaced the fuelpump,throttle position sensor and finally the computer. It solved that problem, but the fuel milage went down to 200kms a tank on a good week. Just wondering if you guys had any thoughts on why the mileage got worse....could it be that it is running better than before, therefore using more gas....???? Its the only reason I can come up with.

Thanks
Josh

[Northern Supercrew]

you're not driving more "spiritedly" now that the truck is running better are you:icon_lol: winter fuel could be hurting your mileage,change the air/fuel filters? haven't got a dragging brake? i'm outta ideas.

[lynger]

you're not driving more "spiritedly" now that the truck is running better are you:icon_lol: winter fuel could be hurting your mileage.

lol no, I changed the fuel filter and air filter. The truck has been like this since the summer when the work was done, I'm leaving for school soon and the less gas I have to put in it the better. Thanks for the ideas.

[shelbyx1]

Well, when I first got my truck the gas mileage sucked, so I put a bottle of injector cleaner in. I gained about 120kms with that. Then the truck starting acting up.....long story short I replaced the fuelpump,throttle position sensor and finally the computer. It solved that problem, but the fuel milage went down to 200kms a tank on a good week. Just wondering if you guys had any thoughts on why the mileage got worse....could it be that it is running better than before, therefore using more gas....???? Its the only reason I can come up with.

Thanks
Josh

Josh:the pcm you put in it was it a used or new part?was it for the right eng size(5.0or 5.8l)auto or man trans,have you looked at the plugs and wires(you can tell alot about how an eng is running from the plugs.:)

[lynger]

Josh:the pcm you put in it was it a used or new part?was it for the right eng size(5.0or 5.8l)auto or man trans,have you looked at the plugs and wires(you can tell alot about how an eng is running from the plugs.:)

Well the garage put it in but it was new, and I'm assuming that it was for 5.0L and standard tranny. The plugs, wires and distributor cap have all been replaced in the last 4-5 months. I'll check everything over and see what colour the plugs are.

Thanks
Josh

[lynger]

Checked the plugs today, they're a brownish tanish colour, normal I think. I'm honestly not shure what else could cause this.

Thanks for any help guys.
Josh

[Destructicon]

How's the ATF level in the tranny? And for the better question which tranny have you got M5R2 or Zf S5-42? If it's the M5R2, how's it shifting? Could it be the input/mainshaft pocket bearing seizing up?

[lynger]

Well here's the scoop guys.

Honestly not 100% which tranny but it shifts fine, doesn't seem to be acting up.

So I noticed yet another decrease in gas milage so I got off my ass and did some searching. I got the codes from the computer.
31 - PFE,EVP or EVR circuit below minimum voltage.
32 - EVP voltage below closed limit
41 - No HEGO switching detected
41 - HEGO sensor circuit indicates system lean.
42 - HEGO sensor circuit indicates system rich.


So some other symptoms are the engine lopes at idle..exhaust smells very rich..even some black smoke.

My EGR vale has been disconected since I put an exhuast on it...and the issues didn't start until at least 6 months after that...guess it could still be it though. I'm thinking the oxygen sensor is toast..or just acting up because the engine isn't running properly.

Thats all I can think of at the moment..again thanks for the continued help.

Josh

[Destructicon]

Why is the EGR valve disconnected? A stock computer will need that working in order to measure out fuel according to its programming.

[lynger]

The vacum lines and electrical is hooked up...the tube just isn't connected to the exhaust pipe. When the exhaust was done they just welded a bolt in to plug it...I always wondered but until recently havent had to much trouble with it. I'll have to talk to these guys and find out why they didn't hook it up.

[taisa899]

most mustang guys use an EGR block off plate without any issues. I get 270km out of my front tank and 200 out of the rear

[lynger]

So taisa is your rear tank 18 gallons or something close?..if it's the same tank as mine my gas mileage might not be as bad as thought...just under 200kms to a tank. Although it does make me wonder why I got about 300 when I first started driving it.

Oh btw the truck box is in surgery right now...all sandblasted, now time for some bodywork. Should go on this summer if things workout.

[taisa899]

yes it's an 18 gallon tank if I baby it I get about 230km. Glad you could put that box to use.

[Destructicon]

I was about to comment on you gas mileage being total crap, but then I realized you guys have V-8's. I've got the L-6 so my 10L/100KM average is, I guess, average for my truck. Not having the EGR tube hooked up may be throwing the oxygen sensor off.

[taisa899]

mine used to be a 6 then I swapped in a V8. I use about 16L/100km but that's mainly highway

[lynger]

well thanks for the input guys..guess it isn't so bad afterall...well its bad but normal.
Again thanks for your help.
Josh