9.2 MPG please help!!!!!

[black97mounty]

okay guys, had another thread going, but it went dead. Heres whats done to the car maintence wise. build is 05/96 if it makes a difference. vehicle is a 97 mountaineer 5.0 AWD.

new plugs- autolite platinums @ .054-.056 gap (AP764's)
new wires - napa belden premium wires
new airfilter
new fuel filter
synthetic motor oil
Fresh transmission flush- shifts fine, goes into O/D fine, and the TC locks up.
Fresh radiatior flush- car gets up to temp just fine, no worries there.
Brand new 235/75/15 Bridgestone Dueler A/T's w/ REVO technology
Brand new brakes all around from napa - no dragging
Brand new shocks from napa.
Freshly cleaned IAC and MAF

Car should get good mileage right? no. 9.2 mpg is far from good. well heres the deal. I put a new power booster as I ruined the one on the car(long story) and ever since then, the gas mileage has been terrible. The brake pedal is kinda mushy and the car is hard to stop when in open loop. Idles at like 1200 in open loop. Basically I can pull away from a stop light by taking my foot off the brake.... booster was a re-man from napa. Should I go there and get a reaplacement and say this one is defective? also note that the idle in closed loop is choppy and feels like the car is missing when sitting at a stop light. idle is around 600-700rpms. The vehicle just passed emissions two days ago....

I need some help on this as I'm getting really pissed off. I mean come on, my 98 cobra thats not stock by anymeans gets 17mpg consistantly....

PLEASE HELP ME!!!!!!!!!!!!!!!!!!!!!!!!

 

[IZwack]

About the idle, check for any vacuum leaks in the brake booster unit.

A leaky booster (or the vacuum line from the engine) forces the car to kind of sputter during idle and sounds like its going to die, or just plain old dies.

 

[black97mounty]

I looked and listened for leaks. I cant find any... someone mentioned that maybe the valve on top of the booster may be bad.....

I'm going to go the repair shop I used to work at tomorrow morn and use their scanner to check fuel trims. I bet the fuel trims are probably -25 in both banks with a vacuum leak large enough to cause 9.2 MPG.....

 

[tktrain]

Disconnect the booster and plug the vac line to it, then see if the idle problem goes away. If it doesn't, it isn't the booster. In any event always change just one thing at a time to track down a problem.

 

[black97mounty]

well, I just got back from the shop I used to work at. Used the snap on MT2500 scan tool and heres my findings.

All findings were recorded at a RPM between 700-750 (idle)

Long term fuel trim bank 1 is +3
Long term fuel trim bank 2 is -7
short term fuel trim bank 1 swings between -1 and +2
short term fuel trim bank 2 swings between -1 and +2
02s11 Swings between 130 and 800mv
02s12 Swings between 50 and 600mv but hovers around 150-200mv most of the time.
02s21 Swings between 50 and 800mv
02s22 Swings between 70 and 750mv but hover s around 100-150mv most of the time.
MAF at idle (700rpm) read 5.8 gm/s
MAF voltage was .96v
IAC was 40% at idle
TPS voltage was .89v
Load was 17% at idle

so guys, Im at a loss again. The only thing that I noticed that was off would be the IAC and load. Both seem kinda high to me. a 17% load at idle in park?

also, shouldnt the TPS voltage be closer to 1.0volts?

 

[KPT]

Or just have your foot on the brake when you start it. If the booster is working the pedal will go down further when vacuum is applied.

 

[Turdle]

Bank 1 is lean-causing 2 to go rich

egr flow problem from exhaust leak?????

 

[black97mounty]

Bank 1 is lean-causing 2 to go rich

egr flow problem from exhaust leak?????

i keep thinking I hear an exhaust leak, but then I think its just my mind playing tricks on me to find something wrong.

Theres no CEL and no pending codes. Ill have to take it back to the shop I used to work at on monday. Were going to do a custom exhaust while the cars in there anyways, so it will be a good chance to look. The only place I could think of a leak would be on the manifolds themselves.

This ones kicking my ass.

 

[Turdle]

i keep thinking I hear an exhaust leak, but then I think its just my mind playing tricks on me to find something wrong.

Theres no CEL and no pending codes. Ill have to take it back to the shop I used to work at on monday. Were going to do a custom exhaust while the cars in there anyways, so it will be a good chance to look. The only place I could think of a leak would be on the manifolds themselves.

This ones kicking my ass.

The manifolds crack-yes. actually, the welds break.
If you would like I can get you a picture of where they crack, or, just look for yourself under the heat shields--on passenger side especially. Is this the side you hear a leak? It is bank 1, most likely to crack, and contains EGR tube.

 

[Turdle]

Pics anyway
This is what is under the heat shields, note the rewelds even failing

 

[Turdle]

Also, It looks like something else is going on
I am no expert of course-am just learning this stuff myself, however, it appears the V/E ( MAF at idle) value is a bit high, Should match engine size in liters--

I wonder if the maf sensor has a glitch???

The high reading should eliminate a vacuum leak--yes???

 

[tktrain]

I had a similar problem about 3 years ago that turned out to be one of the primary O2 sensors, but I developed an OBDII code that pointed to it. I didn't notice a major fuel economy issue. I do recall having a hole get burned through a hose running to a sensor where it came into contact with the EGR tube after I installed the phenolic spacer between the UIM and LIM. (I don't remember which sensor it was going to. I'm working on pure memory here, never a good thing.) I spliced this hose back together with a short piece of metal tube

 

[tktrain]

One other thing: The TPS should ideally be a 1.0v. This gives optimum off idle throttle response. There is a little bit of slop in the mounting holes for the TPS and you can sometimes tweak this in. You will need a digital VOM to do this right. There is a good chance that you could simply use the throttle stop adjustment to adjust it in and let the idle bypass motor bring the idle back down. Ford doesn't suggest adjusting the throttle stop, however.

 

[Fredness]

+1 on primary O2's - How many miles are on them?

 

[black97mounty]

thanks for all the assistance guys!

she just turned 101k miles, almost at 102k. If the 02's were bad tho, the CEL would be tripped no? OBD2 is really good at detecting flaws.

Im going to look at the manifolds monday to see if they are cracked. I sure hope not as I dont wanna put any money into the car I dont have to. Its just a winter beater that I drive in the snow/crap weather. I already put enough mod money into my cobra.......

Ill try setting the TPS tomorrow. But i doubt that it being off .11v is enough to cause this poor of gas mileage.

Thanks again guys.

 

[Turdle]

I have my TPS set at .89 v
some say .96--euther way it should be <1 v

I think yours is set ok IMO

 

[black97mounty]

Should I bust out the BFH and just go to town?

BTW, im buying a MAF adaptor and filter http://cgi.ebay.com/ebaymotors/96-0...tegoryZ33659QQihZ004QQitemZ140058033595QQrdZ1 and cutting of the rear cats and adding high flow IMCO muffler on monday. Maybe that will help a little bit.

 

[black97mounty]

I think the manifolds on these cars have to be the worst design I've ever seen. Wow are they ****ty.

 

[Turdle]

Just wait until you see the size of the #3 port---

Did you find a leak??

 

[tktrain]

1.0v on the TPS is the point where the PCM starts enrichment during acceleration. I agree with Jon, you are probably just fine at .89v and won't see this affect milage much if at all. I just always try to optimize everything out. In any event, don't exceed 1.0v. At.96 to 1.0v it would be very hard to perceive or even measure a difference.

Those factory "manifolds" are a nightmare. You can barely get a finger into a couple of the ports. The FMS headers are a head-and-shoulders improvement, and the Torquemonsters are a major improvement on those.

I wonder if the cats are getting plugged and causing restriction?