The check engine light recently popped out of no where on my 98 USDM R. I checked the ecu code and I recieved the code 45. Went to http://www.c-speedracing.com/faq/05.php and 45 reads: System Too Lean or Too Rich malfunction in the fuel monitoring systems . My car is bone stock, so if anyone had the same problem, please help

 

anyone?

 

i guess you could try re-setting the ECU.
Drop the backup fuse for 30 seconds.
ECU should "redraw" the fuel maps. And if there really is a problem, it will CEL again

 

Just to help you help us, we need more specifics other than the code when applicable. Such as milage, modifications, recent service performed? Stuff like that.

 

I had this exact same problem right after I bought my R.

I bought new a new O2 sensor, and checked everything else in the book. I even put my stock intake and exhaust back on while trying to daignose the issue.

It turns out that it was due to a horrible valve adjustment.
When I checked them, one side was waaaaay to tight. After doing some research, it looked like that could be a possibe cause of burning rich (it was the last thing on the list of things to check in the Helms / Haynes).

Did the valve adjustment and that solved my problem

 

I have no mods, the car is bone stock like i said. No service. Only oil changed at about 36,XXX, and it just hit 38,000 yesterday

 

Bust out your helms and possibly check both O2 sensors. Like the other guy said, try resetting your ECU.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Haleiwa-Brando &raquo;</TD></TR><TR><TD CLASS="quote">Bust out your helms and possibly check both O2 sensors. Like the other guy said, try resetting your ECU.</TD></TR></TABLE>

and check the valve clearance!

It is listed in the helms as well. When I had this problem nobody even mentioned that as a possibility, but it could be the cause for the CEL.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by erasa510 &raquo;</TD></TR><TR><TD CLASS="quote">The check engine light recently popped out of no where on my 98 USDM R. I checked the ecu code and I recieved the code 45. Went to http://www.c-speedracing.com/faq/05.php and 45 reads: System Too Lean or Too Rich malfunction in the fuel monitoring systems . My car is bone stock, so if anyone had the same problem, please help </TD></TR></TABLE>

I get this same code from time to time...I have 130,000 miles on my 97. I havent tried a valve adjustment yet. It started throwing the code after the engine was out and re-installed and Im not sure why. I had no problem before, and none of the engine componments were touched. so I am in for an answer as well. Have you tried the valve adjustment, aor did something else work for you?

 

can valve adjusment be easily done in a garage? or need to bring it to a shop?

 

you can do it yourself. the valve clearance specs are printed on a sticker on the back side of the hood.
Get a Helms manual for the directions. Download it online, or PM me. All you need is basic tools and a valve lash tool which u can get at Sears / auto parts stores.

 

Damn, I don't have my usdm hood no more. I am running on jdm front. And the hood doesn't have the specs. Is there somewhere I can get a copy of it?

 

intake .006-.007 in.....exhaust .007-.008in and also req. a tappet locknut wrench
honda p/n 07maa-pr70120 or equivelant. According to my genuine Acura manual it separates the codes.
dtc po171 system too lean; possible failure are:
1. fuel pump insufficient flow/pressure.
2. fuel feed line clogged,leaking.
3. fuel pressure regulator stuck open.
4. fuel filter clogged.
5. injector clogged.
6. gas doesn't meet oem spec.
7. primary 02 deteriorated.
8. valve clearance.
9. exhaust leak.
code po172 system too rich;
1. fuel pressure regulator stuck open.
2. fuel return pipe clogged.
3. injector leaking.
4. gas not oem spec.
5. primary 02 deteriorated.
6. valve clearance.
Hope this helps you

 

gotta check all of that. and hope i get lucky to find it on first few tries. I think im going to do valve adjustment first. Even though the check engine light disappeared by itself but im still gonna get it check. Plus, is good to just have valve adjustment done.