vsmferio96

I've got a 97 ex coupe with 150k miles on it using 91 octane gas. Running the stock d16y8 with minor bolt ons header, exhaust, intake, etc.... and a p28 obd1 conversion and getting like 180-210 miles to a tank. now the way i figure it with an 11 gallon tank I should atleast be making that27-30 MPG. Any ideas on wtf it could be? Any help would be appreciated!

Paxil4x4

Don't know about the MPG, but putting in 91 octane is wasting money

Stoich EG2

why are you running a OBD1 p28?...

Fresh'86

First of all, you don't need 91 octane gas, you're wasting money. It will run the same with 87 octane gas. Since the D16Y8 motor is a very low compression motor ( I believe 9.1:1) it runs perfectly fine with 87. Now, as for your gas problem, I honestly can't help you with the amount of info you gave me. What I can suggest is swapping you fuel filter with a new one, replace your intake filter(if it's discoloured) and possibly new spark plugs/wires would do the trick. My car went from doing 21MPG(average) to 31MPG(twice, but I usually get an average of 28/29) easily from switching the items I listed above. I also seafoamed my car recently, and that was after. I still didn't measure how much MPG's I'm pulling, I doubt I can squeeze out anymore. It may be your driving characteristics also. Try shifting gears around 2.5k/3k on average. That's if your car is manual. I have a 5 speed so I regulate my acceleration.

Try doing that, and see what results you get. BTW, I have an Acura 1.6 EL (Acura version of the Civic 4 door EX, but with lots more luxurious features)

95DxSi-R2

55 mph, flat road and no a/c, do your test again

E46Kid

try a nice tune up, with new cap and rotor

divisionskate

dude, i would definally say somethings wrong. as a refrance, i get between 31-34 mpg, thats driving the **** out of it on a 106k motor. i do a lot of freeway driving, but at about 85 to 95 mph (normal speeds in cali). only thing that sucks is i drive over 100 miles a day, so eather way thats a lot of gas.

vsmferio96

Just a habbit runnining 91 I guess! As far as the tune up deal. Yes mine's a five speed and very rarely take it above 3500rpms in normal driving! Have already replace my fuel filter, plugs, wires, rotor, cap, and seafoamed it twice. still not sure why i'm getting such bad mpg! Also my lights dim at low rpm's but i think that's just a bad grounding problem. Thanks and keep the help comming!

Syndacate

Wonder if you're running rich/lean :-\.

Does it feel weaker/stronger than before you started getting shitty gas mileage?

EDIT:
PS: It's a honda, it's meant to run on cheap gas, not 91.

vsmferio96

Info that might help: d16y8 with 4-2-1 header. 2.5 apexi wsII exhaust. aem intake. ngk plugs and wires. 95 ex p28 ecu. with boomslang harness. I did the obd2- obd1 conversion because my secondary o2 sensor went out and it was cheaper to buy the p28 ecu and conversion harness than buy a new o2 sensor.

slowSOHCvtec

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vsmferio96 &raquo;</TD></TR><TR><TD CLASS="quote">I've got a 97 ex coupe with 150k miles on it using 91 octane gas. Running the stock d16y8 with minor bolt ons header, exhaust, intake, etc.... and a p28 obd1 conversion and getting like 180-210 miles to a tank.</TD></TR></TABLE>

get rid of the p28 and go back to a p2p and see what you get...get rid of the 91 octane its a waste unless you are going to do any other mods to it, it will run fine on 87

vsmferio96

YES YES i get the 91 ordeal!

blaze the chemi

Would the p28 throw a code if the O2 sensor is bad? I'm not sure since I only have a OBD2b motor. My AEM is OBD1 and it didn't throw a code when my O2 sensor failed, but threw the code when I installed my P2T.

edit: BTW the D16Y8 is 9.6:1 and olnly requires 86 or higher according to the Helms. Save your money.

vsmferio96

If I go back to the p2p i'll throw a secondary o2 code but hey it's worth a try!

Relic1

the P28 will not throw a secondary O2 code. OBD1 does not have two O2s.

It will throw a primary O2 code, all though when the O2 sensor is on it's way out it will not throw a CEL, but get really poor mpg.

when you let the car sit and idle can you smell fuel? An O2 typically dies and makes the car run richer. This will be most noticable when at idle.


drop in an O2 simulator for the secondary O2 and you can run the OBD2 ECU with no codes.

BauleyCivic

The Y8 runs with 12 degrees of timing, that ECU is designed for a motor that runs 16. Change your ECU and see what happens. That's my guess.

vsmferio96

My friend and i slightly advanced my timing so that's why I was running the 91. Back to 87 though. I "defective exchanged" my o2 sensor for a new one and car is running a lot better now. Just filled up today so i'll have to check my mpg in about 5-6 days.