I was getting 8-9mpg per city before the car was tune.
After the tune, it's getting 10-11mpg.
I smell gas coming out of the exhaust, but not as bad as before the tune.

Yoshi at Neptune Speed tune: Lo - .6bar Hi- .9bar

stock motor
Non-Seq
Apexi PFC
Apexi AVCR
Blitz cat back with catalytic mid-pipe

Things I have done:
New NGK Sparks & Wires

What should I do?
1-Replace O2 Sensor?
2- Clean air filter?

 

what are your AFRs?

comparatively, my stock FD does 15 in the city if i ***** foot around in it

how do you drive?

 

Yoshi is a good tuner, however he usually just tunes on his dyno. Unless you did some street tuning with him your cruise is going to be pretty rich. I had to lean out my cruise tables significantly on the PFC after Yoshi tuned my car. However my boost a/f were a solid 11 @ 15psi.

Get a wide band if you don't have one already, and look at your cruise a/f.. should be around 14.7 to keep the cat happy. Can go bit leaner with no cat.

-Alvaro

 

I get 12 mpg, almost all city driving. Mods in sig.

 

You should definitely change your o2 sensor, clean filters, change oil, etc before a tune. I had my car tuned before at Neptune speed and it was a mediocre tune and felt stockish with my bnrs. Those idiots put mineral oil in my dynamic seal turbos when i had synthetic idemitsu sitting in the car. Oil started to leak from the car shortly after and needed a rebuild. Anyway I did not take my car back there and got a tune at RRR and now my car drives amazingly better. My car always smelt like gas but found out my ignition coils were not firing properly. Once that was changed the car no longer smells like gas and has way better gas milage than before.

 

If you've got a PFC, you don't need a new O2 sensor....

 

the pfc still has a "O2 feedback" feature where the ECU can still go into closed loop for improved fuel mileage... it still won't do much good with city driving but it does in fact do something still.

during tuning of course i turn it off and sometimes forget to turn it back on, heh. doubt i'm the only one.

 

lmao! no you're not. i forgot the zero the TPS once, on the 3 rotor, before the trip to sevenstock. the result was a GIANT fireballs letting off the gas, i could see fire in the rearview mirror.

it actually worked well on 5 though, people respect you when you shoot fire at them...

 

i average 19mpg with no O2 sensor

 

if the base maps are tuned well enough then the O2 sensor really doesn't even need to be there, but it still serves a purpose regardless.

i get 24mpg highway without an O2 sensor.

i do the same sometimes with the microtech when i change the setup, the decel fuel cut feature is a joke on the microtech ECU's which generally causes slow speed stalling issues so it forces you to turn it off and tune the high vacuum maps rather intricately otherwise it is excessively rich(fireballs and plastic burning smell of compressed unburnt fuel) or excessively lean(loud backfiring).

 

Without a road tune or the use of a loading dyno to simulate road conditions you're not going to maximize gas mileage.

You should be able to get anywhere from 12-15mpg in the city depending on how you drive it. For a stock car they're only rated at 15mpg city using the revised EPA estimates.

 

Yeah, on my previous tune I was getting 10-11mpg if I drove aggressively (which I normally did). I think I managed 16mpg one time while I was on a decently long trip just using cruise control on the highway. My car was only tuned on the Dyno, no road tuning was done to it.

fwiw I was running sequential BNRs at ~17psi with 4x 850cc injectors, flowing at ~1000cc due to higher base fuel pressure.


I'm not sure what my MPG will be after the final tune with my single kit and 850/1680's.

 

Thanks guys, anyhow, today I just drove about 90 miles on the 91fwy. Now I avg. out about 13mpg, still bad! I do not drive aggressively, i shift around 3000-3500rpm.

I'll just go order new foam for my air filter and get new o2 sensor when i'm off work next week.

 

I wouldn't waste money on a new 02 sensor.. get yourself a wide band and tune the cruise tables as needed.. I usually get around 23-24mpg cruising with no O2 connected to the PFC, just tuned my cruise tables to about 15 A/F ratio.

 

yoshi is a good tuner but he does tune rich especially for cruising. I have horrible gas mileage as well and need to tune the cruise AFR to about 14.7-15

 

With a PFC, you should be getting decent fuel economy. When I was DD'ing my FD, I would routinely get 18-19mpg city when I was driving the car nice and easy keeping my foot out of it.

Also, with O2 feedback disabled/enabled, I get the SAME IDENTICAL fuel economy. This was tested over quite some time and is totally reliable info.

O2 sensor and air filter will have little to do with the problem.

Make sure you don't have any fuel leaks of course. Fuel pressure could be checked, if it's higher than normal that could richen things up.

What are your AFRs at cruise? With the stock PFC map it should be 14.7:1 at cruise.

Dale

 

hey trainwreck, I already paid yoshi for the tune, I believe he mention my A/F before the tune was 12 now he turned it up to 14. If I want to tune it up to 14.7 -15 cruising, that means I have to paid again to get it retune? or would a wideband solve the problem.

 

my STOCK FD got 23 on the sevenstock trip (its like 1000miles all highway), the 20B got 19.9 the second year.

 

With:
mild porting
GT35R turbo
no O2 FB and no ISC control
JDM 5th gear and 3.92 diff
self tune;
15+ around town with boost on every drive, and over 20 on the road.

Most tuners will not do idle, cruise, and boost transistion tuning as most could not afford it.
I did my own and it took many-many hours to do and it is not perfect.

 

I used to get 23mpg highway easy with pettit unlimited/stock twins/straight pipe.

 

omg, now i felt like my mpg is really bad for a stock non seq.

 

update, i just bought a aem uego the other day and install it yesterday. Ran the car,
a/f =12.9-13.0 idling
a/f= 15.0-15.7 cruising at 40m/h 4th gear
a/f = 14.3 - 15.0 stepping it slightly on 3rd gear

The aem uego bounce around too much, not constant even though speed is constant at 40m/h

Still getting 13mpg, what is going on? Is it cuz i was running rich before and my 3month old spark plugs got flooded with gas?

 

The AFR's are pretty much what they should be

How are you calculating the MPG you're getting?

 

the afr will always bounce around a little bit, that's not of concern unless you somehow set up the wb to show no decimals, just 13, 14 etc.

 

I am calculating my mpg by dumping a full tank of gas and zero out distance travel. Next, drive until it mark exactly half a tank. A full tank is 18gallon. So 120mile/ 9gallon = 13.3 mpg. Am I calculating it wrong? Cuz that 120mile distance travel is city driving plus freeway.

I am about to buy a straight mid pipe and ngk racing spark plugs to see if anything changes. Since I have a mid pipe cat and regular spark plugs (which be be flooded due to running rich before the tune)