just like the title states...im getting ref'd and im getting that pesky code 91...but when i reset the ecu it goes away and only comes on when the car has been sitting...

anyways, the state ref said that the code is stored even after you have reset the ecu up until a certain point...

i want to figure out what that certain point is..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SLoWpOkECiViC &raquo;</TD></TR><TR><TD CLASS="quote">just like the title states...im getting ref'd and im getting that pesky code 91...but when i reset the ecu it goes away and only comes on when the car has been sitting...

anyways, the state ref said that the code is stored even after you have reset the ecu up until a certain point...

i want to figure out what that certain point is.. </TD></TR></TABLE>

If you cut power to the ECU for a minute or two the ECU won't remember the code.

Though with some cars (I'm not sure about OBD-II civics) you have to put a certain number of miles on the car so the ECU after you disconnect it/reconnect can gather data again. That might be the only problem you're facing.

Though if somebody else comes on here and tells you that the OBD-II ECU of the Civics doesn't require a certain number of miles after it's been reset to gather data so it can be read, then you'll be fine, as long as the CEL doesn't pop up in between the time it's reset and the time of the test.

 

its about 20-30 miles of driving for the ecu to gather data...i know that one for sure...

but the other one im not quite sure...

 

anyone know?

 

first you have to fix the prob. if you fixed it, then it won't pop up agin, but if you just reset it, it won't throw that code, untell the tank press switch is triped again. so no matter how many times u reset it, or what ecu, if the prob is still there then guess what it will pop up again. so try and fix the prob. it could be as cheap as a gas cap. heres a way to check if your gas cap is doing it's job. , after running the car, say to the store and back. turn the car off, and remove the gas cap , you should here a wossh sound, if you hear it then your gas cap is good. try that first and then get back latz

 

its not the gas cap...my car does not have the ftp sensor that the ecu looks for...only certain civics and all integras have this sensor...it stays away if i reset it and drive...i can drive all day without it going off...

it only goes off if the car has been sitting for a long time. you can do the whole ignition on, wait 10 long seconds and try to crank the car, but sometimes i dont get lucky...

i tried to use the potentiometer but for the love of me cant hone it to 2.5v...

so yea, if anyone knows how long it takes the code to erase itself from the ecu, let me know, that way i can drive that long and just go straight to the ref...

 

my guess is the next time you let the car set that long. lol in the reff. they only look for your check eng. lite on, if it an't on then you don't have to worry about it.

 

actually they use a datalogger for the stock ecu and can check old CEL's that have been recently "erased."

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SLoWpOkECiViC &raquo;</TD></TR><TR><TD CLASS="quote">
so yea, if anyone knows how long it takes the code to erase itself from the ecu, let me know, that way i can drive that long and just go straight to the ref...</TD></TR></TABLE>

its called a drive cycle. all brand new cars have to do this before they sell it. i also have to do this at work alot when a customer's car ecu has been reset or certain work was completed. just fix the cel, reset the ecu, and get the car ref'd. do it right the first time and you wont have to deal with it later.

 

If it is obd2 than it requires 40 warm up cycles and i believe on complete road test. A ecu road test needs to see all of the modules and drivers responding and giving accurate data. Some parts of the road test require going 55mph for a certian amount of time. The ecu can remeber were it left off and return to that spot on the next warm up.