okay, with all the ethanol in gas now a days, i had originally been running 87 octane in my CRX, and its been running rich and would throw a CEL afte rlike 5 minutes of driving, now that im running premium gas((93 oct) its not throwing a CEL, but one time it did, i havnt gone thru the whole tank yet, and cant judge if my MPG has gone up, but im not smelling gas as much anymore, u think its possible my motor doesnt like the low ****? lol. or do u still think my o2 sensor is going bad or something, cause i already rplaced the distributor cap, plugs, and wires.

 

When it threw the cel what was the code?
If you have over 100K and the O2 is the stock one replace it. They can last longer than 100K but it is recommended to repl after 100K.

87 should be no problem.
What year rex we talking about and with what motor?

 

1989 Honda CRX Si with a D15B sohc vtec. its got 184k on the Chassis but its from hmotors as fars as i know. But yeah its also obd1 and i dont know how to check the ECU codes on an obd1 ECU. I read up on it but i couldnt match it up with my ECU, anyway I am thinking that is is my o2 sensor or my map sensor, but it hasnt been throwing CEL today with 93 octane and its been getting noticable better gas mileage but i am sure its not getting what it should be getting.

 

When the CEL goes on the ECU doesn't respond to the sensors it goes into "limp" mode and runs off of a basic setting that is programmed into it. This is usually a rich setting and would account for the gas mileage.

Might want to search for the instructions to get the codes. It is helpful when troubleshooting. I have a D16a6 that is getting 30+ mi to the gal so you are around that range.

I have been thinking what would be affected by the 91 octane, I am still thinking about that. Might be burning better and thus not setting off the CEL.

 

im using the same engine and 87 is guuud, IM guessing your 02 is/going bad since the cell would go on once the car is warmed up.

 

well on 87 oct my cel would go off all the time, but with the 93, its not goin off hardly at all, but yeah i think it is an o2 sensor its getting alot better gas milage, so one more question since im obd-1 and its a D15B do i need a civic o2 sensor or a CRX one?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by v8Buster &raquo;</TD></TR><TR><TD CLASS="quote">well on 87 oct my cel would go off all the time, but with the 93, its not goin off hardly at all, but yeah i think it is an o2 sensor its getting alot better gas milage, so one more question since im obd-1 and its a D15B do i need a civic o2 sensor or a CRX one?</TD></TR></TABLE>

that depends on what ecu you are running. since you are running a d15b you could run 2 diffrent ecu's. a p08 is the ecu that is designed to be run with that motor. a p28 is designed to be used with a d16z6 but could run the d15b, BUT it would run rich. the p08 uses a 1 wire o2 just like you stock crx/civic one. so if you have the p08 then buy a stock o2. if you running a p28 then you will need a 4 wire o2 sensor, or a heated sensor.

in any case if you ARE running the p28 then that could also be a reason that you are smelling gas and getting shitty gas milage. i have a d15b with a p08 and i run 87 all the time and get round 30-32 mph every fill up, no problem.

 

yeah i am running a p28, but im lookin for a p08

 

You can also just have the P28 chipped to P08 specs and disable the 4 wire function so you can still run standard one wire O2. Easily done.

 

wait?? are you guys saying that if you have a CEL..the motor will not use the o2?? it will be in limp mode all the time?? are you sure? Mine is a D16A w/p28 getting a solid cel

 

Not necessarily. Why would it run in limp mode for no/bad VSS? It won't. Depends on the problem. Limp Mode is for imperative parts malfunction/failure (ie. Map Sensor, distributor parts...)

What is your Check Engine Light for?

 

ahh--well i dunno..cant jumper the ecu--this is a multi thread debate haha but im thinkin its the o2 sensor plus some kinda wiring short thats throwing the code

 

Just read up on your thread... too bad I don't live in PA. I would definitely help you out but you'd have to pay in higher-end alcohol Personally hate most beer.

 

I have the same motor in my 89 CRX but I really don't feel the difference between the 87 and the 91 octane. Maybe because i'm runnung OBD0 but I get around 25-30 mpg.

 

haha ahh yes i forgot to add that as an option as well---ps yea my motor only runs on 93--but its a jdm motor so the compression is pretty high

 

haa wanna trade your p28 for my p08

 

I might

 

Okay, well now that I have been using 93 octane, in the past 4 days i have put 140 miles on my car, and i have only used a half tank, now if i get another 140 out of the 2nd half thats about 28 MPG, so yes i have noticed a huge difference in MPG, not to mention there I havnt seen a CEL in 2 days. Also to mention, before i used 93 octane i was getting about 170 miles to a tank, and thats definately fucked up. But anyway, if anyone will please tell me where to find a p28 ECU, and also tell me if i went to advanced or pep boys to get a o2 sensor, what kinda car would i have to tell them its for?&gt; because the o2 sensor is defiantely a 4 wire one.

 

Get an O2 Sensor for a 95 Civic Si/EX (D16Z6 1.6L 4cyl VTEC)

You can't just use the gauge to calculate MPG. Your gauge IS inaccurate. The only way to really calculate MPG is to fill your gas tank to maximum. Reset your trip odometer. Drive in one manner (aggressive, granny, etc.) Go for however many miles you wish where conditions are pretty close to the same across the board (temp, humid., mph etc.). Then go to the same gas station pump you filled up at originally and let it top off again. Now take the number of gallons you just put in and divide it by the number of miles on your trip odometer. = MPG. Using the gauge will yeild false results; but so many do that for some reason (lazy?).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by v8Buster &raquo;</TD></TR><TR><TD CLASS="quote">Okay, well now that I have been using 93 octane, in the past 4 days i have put 140 miles on my car, and i have only used a half tank, now if i get another 140 out of the 2nd half thats about 28 MPG, so yes i have noticed a huge difference in MPG, not to mention there I havnt seen a CEL in 2 days. Also to mention, before i used 93 octane i was getting about 170 miles to a tank, and thats definately fucked up. But anyway, if anyone will please tell me where to find a p28 ECU, and also tell me if i went to advanced or pep boys to get a o2 sensor, what kinda car would i have to tell them its for?&gt; because the o2 sensor is defiantely a 4 wire one.</TD></TR></TABLE>

if you looking for a chipped p28 then go to rywire.com. they sell chipped p28's, which you can have them run maps for the d15b i would assume.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Coltmorris &raquo;</TD></TR><TR><TD CLASS="quote">wait?? are you guys saying that if you have a CEL..the motor will not use the o2?? it will be in limp mode all the time?? are you sure? Mine is a D16A w/p28 getting a solid cel</TD></TR></TABLE>

not really. it will look at all the sensors in the engine, and which ever one it thinks it has a problem with it will insert a generic value in. in other words if 5 out of 6 sensors are reading correctly then theres no use in not believing all of them. the computer just inputs a value into the "failed part" to "get by".