Worddd,

My car keeps throwing code 45 about a day or so after resetting the ecu. Usually under light to medium acceleration or coasting/maintaining speed. It has happened twice in 2 days now. Code 45 is "Fuel Mixture is too Rich or too Lean or Possible problem in fuel monitoring system". I have a S-AFC but no correction setup at this time. The car runs very smooth, not a noticable problem if it werent for the CEL. Where should I start with this? LOL

thx in advance,
andrew

 

02 sensors possibly.

I'd use some fuel injector cleaner and replace the fuel filter.

Do you have a fuel pressure regulator? If so swap it back out for stock

 

really?

i thought it might be running too rich. had my fuel correction on the s-afc previously set to around +5%. its stock now, though. still does it with correction or without it, have tried both ways. wiring issue? o2 sensor? TPS? i find it hard to believe that it is running too lean. as long as i have owned the car it has seemed a bit on the rich side but just recently getting the CEL. could be wrong, tho. timing is advanced ~1.5 deg. also.

-andrew

 

02 going bad or injectors being dirty doesn't lock you down to lean

Injectors can get stuck open.
02s can go either way when they go bad.

 

hm good point, thanks. will try fuel inj. cleaner first. then fuel filter, then o2's.


thanks
-andrew

 

ok my car is DEFINITELY running very rich. the bumper around the exhaust is coated with carbon/soot. it isn't burning oil so i know it's not that. i just dont see what would cause this all the sudden. where can i get o2 sensors for a good price?

thanks,
andrew

 

You can pick up bosche replacements from AutoZone for fairly cheap. You have to solder them in place but that is easy enough.

 

do you have a swap and or chipped ecu?

 

well i took your advice, and it worked

no more code 45, AND ontop of that, revving from idle is a TON smoother than before + the whole general operation of the car feels smoother. doesn't surprise me since the o2 one had almost 100k on it. so, needless to say it's fixed.

sikcivic my car is pretty much stock.

thanks again to you all and also to my trusty EG shopmanual.

later,
drew

 

ok its not fixed. i do admit the car runs a LOT smoother now w/ the new o2 sensor, but, still got code 45

my two left over options are EVAP system or fuel injectors, or possibly a wiring issue. gonna take it one step at a time i guess. at least it's not a big problem.

any suggestions would be much appreciated...
-andrew

 

Did ya drop some fuel injector cleaner in the tank?

 

yup

 

Have you always had this code?

Did you just start getting the code when you installed the SAFC...even though you have it set to no correction?

Whats the setup? You say stock with a whole bunch of 's behind it....kind of like your not stock.

 

the ecu code started when i replaced the back-up fuse for the ecu. which, yes, leads me to believe that the car has always had this problem since i installed the motor close to 8 months ago. it wears out spark plugs with carbon pretty quickly, i don't think it's the evap system. it's gotta be the injectors or a wiring issue somewhere, and i have a spare set at home that are much newer than the ones in my car now. if it isn't that, then i dont know.

the engine is a d16y7 (i know woooowwww) with a y8 intake mani/exhaust mani/2.5" exhaust/hiflo cat/y8 trans, and a few other things. i honestly dont know where to start if the problem isn't the injectors....

-andrew

 

This code comes about when the ECU has reached its limit for Long Term Fuel Trim (+/- 20%). Over time the ECU has to be able to compensate for things like clogged injectors or a restrictive fuel filter. The ECU uses the O2 input to adjust the LTFT value. If the ECU sees that the O2 isn't swinging rich/lean, it'll use this parameter to try to get it to do so. If it can't within the range, you get the code.

Since you have a new O2 sensor, perhaps your fuel pressure is outta spec. I've got a 99 hatch, stock with 200k miles and my LTFT only gets to 5-6%.

Have you taken the SAFC out yet? Not set the correction to 0...but just removed its presence from the MAP wire?

 

have not tried that w/ the s-afc....will have to check that.

also sounds like changing the fpr along with the injectors and perhaps even the fuel rail, wouldn't hurt if the s-afc removal doesn't correct it. fuel filter is only a month or so old.

 

it was just an exhaust leak, heh...

the flange between the cat and the downpipe had a very loose bolt. i guess the secondary o2 sensor was seeing the car as running lean when it really wasn't because of air getting sucked into the exhaust, thus making a rich condition, causing me to waste gas and see black soot on my rear bumper.

seems simple enough....

thanks.