Fuel Economy...Mine Sucks

[X2theZ3]

My fuel economy has gotten really bad after I installed a 540 HFM, new air filter, 24 injs, and a JC chip.

So my questions are: what kind of mpg are you guys getting (S50/S52)?

And what is the likely problem? A stuck open injector?

[Bennetts22@aol.com]

21-25 mpg same mods on a s52

[cheades]

Assuming you are driving it the same are you sure the HFM is operating correctly? Are the injectors new, if used maybe the spray pattern is really bad so lots of the fuel is unburned. Have you checked to make sure your injectors are all properly seated and not leaking around the seal?

[X2theZ3]

Assuming you are driving it the same are you sure the HFM is operating correctly? Are the injectors new, if used maybe the spray pattern is really bad so lots of the fuel is unburned. Have you checked to make sure your injectors are all properly seated and not leaking around the seal?

Yes, I am driving it pretty much the same. The injectors are used so I am thinking they may be the problem?

All injectors are seating correctly and aren't leaking any fuel.

Thanks.

[tonytony]

i'm sure this is a newb solution, but when i installed my 19lbs in my old m20 i dump seafoam into my tank. worked out great, it's the seafoam cure

[1990m3]

24lb injectors, 3.46 diff, daily driver...

I'm getting about 260 miles on 12.5 gallons no matter if it's highway or ripping it around the city.

[equate975]

Im getting around 23-24mpg with the same mods

s52 OBDI 24# 540hfm and 3.25lsd.

Are you s50 or s52?

[X2theZ3]

Im getting around 23-24mpg with the same mods

s52 OBDI 24# 540hfm and 3.25lsd.

Are you s50 or s52?

S50

[equate975]

Are you using s52 headers? The thing that got me for having bad MPG was the air pump block off plates on the headers. They were not very tight, after I put a new gasket on them and cranked them down I saw around a 4-5mpg increase.

[///Mpressive]

Are you using s52 headers? The thing that got me for having bad MPG was the air pump block off plates on the headers. They were not very tight, after I put a new gasket on them and cranked them down I saw around a 4-5mpg increase.

So your headers are unmodified, you just have a new gasket? I was thinking I was gonna have some work cut out for me modifying my headers..

[FredK]

I believe equate has a plate the same size as the air pump plate bolted onto the headers to block them off.

[equate975]

I believe equate has a plate the same size as the air pump plate bolted onto the headers to block them off.

Yeah, I unbolted the air pump and cut the flanges off the part that connected them to the headers. I then had the holes on them welded shut and I bolted them back in place. Better than breaking the seal on the headers

[///Mpressive]

Yeah, I unbolted the air pump and cut the flanges off the part that connected them to the headers. I then had the holes on them welded shut and I bolted them back in place. Better than breaking the seal on the headers

Cool, that was the plan. Thanks.

[equate975]

One thing though, is there was a bracket on the air pump where it bolted to the headers just to keep it in place. After you unbolt the air pump flanges off the headers just grab onto it and bend it back and fourth until it snaps the bracket. Again just so you dont have the break the seal.

[///Mpressive]

One thing though, is there was a bracket on the air pump where it bolted to the headers just to keep it in place. After you unbolt the air pump flanges off the headers just grab onto it and bend it back and fourth until it snaps the bracket. Again just so you dont have the break the seal.

The seal has been broken already. Luckily, I have an extra set of headers to perfect(or destroy) to make it right, custom. I'll cross my fingers.:D