tech23

I had my valves adjusted by a friend and after awhile the code popped up and i even got him to readjust the valves to a looser spec, and it is still having the problems, can anyone explain to me why?

rick_rabies

same spark plugs?

Former User

Your friend may not have set the valve clearances correctly.

rehaf

Typically an ECU uses a baseline map for fuel control according to rpm, throttle position and engine temp. Once the system goes into closed loop operation it begins to look at other sensor inputs such as the oxygen sensor, map/baro sensor and the MAF sensor if equipped. The ECU uses these other inputs to more accurately adjust the fuel/air ratio. The percentage of deviation the ECU has to make from these baseline maps is called "fuel trim". Get the system running too rich and you get a P0172 (and a P0175 if there is a second bank) too lean and you get a P0171 and/or a P0174.

Look for things that can cause a too rich concern such as: excessive fuel pressure, a faulty map/baro sensor, leaky injectors etc. You may also have a contaminated oxygen sensor.

ninjasruleyou

very good explanation.....

Former User

It's a nice general explanation for fuel trim, but fails to mention that having the valve clearance out of spec can also throw this code. Considering the association of the code with the recent valve adjustment job, the first step should be to have someone more competent double check the valve clearances.

forcefedferio

x2.

I had the same exact code set repeatedly on my old 2000 DX Hatch with the d16y7 (at the time). I tried everything, tune up, fuel filter, valve adjustment...etc. Same code. Hooked up a vacuum gauge and turns out i had a burnt exhaust valve.

So that just goes to show you that a valve problem can set a fuel system code, so i also definetely believe your valve lash is wrong. What specs was your friend using? Off the top of my head i can't remember but on a b16 i think intake is between .007 and .009 and exhaust is .009 to .011

jayWknight

iTrader: (3)

use a scan code reader that has live data. therefore you can watch the stft and the ltft. If the ltft is -10 or 10+ this will set off your engine light for code p0172. then check in the service manual steps on troubleshooting the problem. good luck.

rehaf

I suppose anything that causes unburned fuel and the oxygen that goes along with it to enter the exhaust stream can cause the ecu to see the system as being too rich.

tech23

The first time we adjusted them the car would shut off and didnt want to idle, and the cel didnt pop up, so we re-adjusted them and a couple of weeks later the cel stays on. the valves are set between .007-.009 im pretty sure.

Honda_Enjineer

Don't forget to do the "IDLE LEARN" procedure after adjusting the valves on a VTEC engine.

It teaches the computer all about the new settings that it needs and must be done after any major changes like that.

Procedure

1. make sure all electrical items (a/c, audio, lights, etc) are off.

2. reset the ECM/PCM with the HDS. (or do the battery reset trick)

3. turn the ignition switch ON (II), and wait 2 seconds.

4. Start the engine. Hold the engine speed at 3,000 rpm without load (in park or neutral) until the radiator fan comes on, or until the engine coolant temperature reaches 194 F (90 C).

5. let the engine idle for about 5 minutes with the throttle closed. (NOTE: if the fan comes on, do not include its running time in the 5 minutes.)