LESS THAN 9.5 MPG CITY DRIVING!!!

[PonyGTrider]

Hello everyone

I was just wondering if any of you have any ideas about this ridiculously low MPG. ONLY less than 9.5 Miles to the gallon city driving.
I've seen many postings with much more modified engines giving much better mileage.
I was just running a small MPG study being conservative on my driving. shifting at around 2 - 2.5K
I don't consider my build radical by any means and the mileage should be much better than that.
I ran a scan and no error codes whatsoever. I've never tuned the engine but even like that shouldn't give me that bad of a mileage

My engine details are:
Production 302 block 0.030" overbored (306ci) w/ Flat top pistons
170cc twisted wedge heads with 61cc chambers,1 5/8" BBK headers,1.6 magnum rollers, and TFS stage 1 cam
65mm Throttle body and 70mm MAF tube and sensor with 19 lbs injectors, and 190 LPG fuel pump + Kirban FPR (39 psi / Vac. 0ff)
TFS upper and lower intakes and 3/8 phenolic spacer.
In fender high flow air filter,
Autolite plugs 2924 to 0.054''
MSD blaster coil and wires
Initial timing set to about 15 degrees.
UD pulleys, Griffin radiator, electric cooling fan w/Delta controller, and 200 AMP alternator
T5 Z specs transmission, 3.55:1 gears and 31 spline TruTrac differential/Mosser axles, and 245 45 17 tires all around
The two secondary converters were removed along with all the smog system. The EGR valve still working correctly

I just want to say that I'm not complaining, just it seems not normal.
.... And no, don't tell to buy a Honda, that is not the point: "THERE SHOULDN'T BE WRONG WANTING TO HAVE A LITTLE PERFORMANCE AND EFFICIENCY AT THE SAME TIME"
Right now my engine IS NOT efficient.

Thank you all for any help provided.

 

[General karthief]

Try shifting at little higher rpm like 3k- 3500, don't 'lug' the engine and maybe drop the timing a little?

 

[KRUISR]

What gear do you drive around town in? What speed are you driving?

 

[PonyGTrider]

What gear do you drive around town in? What speed are you driving?

Thank you for your comment.
1st thru 4th

 

[PonyGTrider]

Try shifting at little higher rpm like 3k- 3500, don't 'lug' the engine and maybe drop the timing a little?

Thank you for your comment,
My shifting time is fairly quick and don’t stay too long on a gear while shifting. I will start shifting at the rpm’s you’re suggesting and see how it works.
Thank you

 

[PonyGTrider]

I still running the second part of the test I just dropped the timing to the base 10 degrees. This might give me some more learning about this topic.

But still if someone has any other ideas, maybe my engine is completely off tune.

Thank you

 

[TIGGER]

What temp thermostat are you running? The cooler the thermostat the richer the car will run.

 

[Essn95]

Thank you for your comment.
1st thru 4th

Why not use 5th? Even with 3.73 I turn about 1600 at 45 around town and get 17mpg

 

[PonyGTrider]

What temp thermostat are you running? The cooler the thermostat the richer the car will run.

The Delta variable fan controller is set to be used with a 180* thermostat, and the temperature is fine tune at the controller module. Mine is set to 200 + 0 - 5 degrees (195* - 200*) and it stays there very consistent.

Thank you

 

[PonyGTrider]

Why not use 5th? Even with 3.73 I turn about 1600 at 45 around town and get 17mpg

I use 5th gear on long empty avenues (Not too many) but it is mostly stop and go thru lights and stop signs.

 

[Noobz347]

Jeeze lead foot

 

[TOOLOW91]

Need more information . Didn’t see a cam
Listed- never mind I do tfs1 . I had that on my stock block 302 with an a trim . I still didn’t get that bad of mileage

Stock ecu ? What brand maf ?

Do the 02 actually work ?

When I had a tko600 in my car I had a big bore 347 ( dart block ) same heads as you , custom cam , systemax , s trim blower , car ran 10.80s at 128 and I regularly got 20-22 on the highway and around 15 on the street . This was stock ecu , pro m maf and a Anderson pms .

I now have 205 11r heads on that same combo . Ported intake . 90mm tb , full manual aod with a super loose converter and I still get 10-12 on the street and it runs 9,50s at 3300-3400 lbs with me in it . Something is off for sure

 

[95BlueStallion]

I think your car needs a tune, the MAF cleaned, new 02 sensors, or all three. Your combo should not be netting you carbed big block drag car fuel economy.

 

[PonyGTrider]

Jeeze lead foot

Hahaha! If that was the case that high fuel consumption would be fully justified, unfortunately that’s not it.
Thank you

 

[General karthief]

A new set of plugs may be needed, what are you running now?

 

[nickyb]

A friend was getting terrible gas mileage after cam change, the cam was happy at 2,500 rpm and he was cruising at 2,000.I
What rpm is your cam happy at?

 

[Mustang5L5]

I'm leaning tune.

I have a very similar combo with TFS170 58cc heads and can definitely tell my combo is rich and needs a tune...which is coming.

 

[PonyGTrider]

Need more information . Didn’t see a cam
Listed- never mind I do tfs1 . I had that on my stock block 302 with an a trim . I still didn’t get that bad of mileage

Stock ecu ? What brand maf ?

Do the 02 actually work ?

When I had a tko600 in my car I had a big bore 347 ( dart block ) same heads as you , custom cam , systemax , s trim blower , car ran 10.80s at 128 and I regularly got 20-22 on the highway and around 15 on the street . This was stock ecu , pro m maf and a Anderson pms .

I now have 205 11r heads on that same combo . Ported intake . 90mm tb , full manual aod with a super loose converter and I still get 10-12 on the street and it runs 9,50s at 3300-3400 lbs with me in it . Something is off for sure

Thank you for the time,
Like I said stage 1 cam stock A9L ECU, the MAF is a 70mm Crown Vic for 19 lbs injectors.
In relation to the O2 sensors I haven’t physically checked their function, I’m just relying on the info from the ECU that they’re working properly.

Testimonies like yours tell me that my engine is completely out of tune

Thank you much

 

[PonyGTrider]

I'm leaning tune.

I have a very similar combo with TFS170 58cc heads and can definitely tell my combo is rich and needs a tune...which is coming.

Yep sounds like it is the general consensus.
I’ll be buying a dual wideband A/F ratio gauge to at least know what the hell is going on with my mixture.

Thank you

 

[PonyGTrider]

A friend was getting terrible gas mileage after cam change, the cam was happy at 2,500 rpm and he was cruising at 2,000.I
What rpm is your cam happy at?

My cam is around those RPM too. I guess I’ll have to change my driving habits

Thank you