Honda_Enjineer

Had this problem this morning with my Pilot when it was cold started:

MIL on with P0175 (rich on bank 1) and VTM-4 light ON.

I reset these codes once the engine was warmed up and so far no recurrence with the engine still warm (been driving around today).

I'm familiar with what to check for this problem (eg. fuel pressure, EGR, stuck valves etc...) but wondered if someone here could point me at the most likely cause just to save a little time (I don't get much time to play with my own car ;-)

I'm convinced that very few problems are unique to a single car - so anyone who has seen this already please comment (it's a new one on me).

Thanks for any input...

Bob.

Honda_Enjineer

Thought I'd post the resolution of this problem as it may help out someone else:

First, I meant to say:

MIL on with P0175 (rich on bank 2) and VTM-4 light ON. (not bank 1)

Also, the car has 71K miles and I have always used premium fuel.

Steps:

I linked the ODB-II port up and saw Short and Long term fuel trim values that indicated the system thought is was rich (eg. LTFT bank 2 was in the range -11% to -15% --- this looked waaay to high to me).

I read around a little and decided to take a bit of a chance and just replace the EGR valve this morning (it was an educated guess).

Problem solved! I am now seeing -1% to -2.5% values for the LTFT (long term fuel trim).

The car starts and drives noticeably better as a bonus.

Changing the EGR valve is simple (took me only about 10 mins) -

1. Disconnect the battery (have radio code handy)
2. Remove the engine cover
3. Disconnect the EGR valve wiring plug (on the front of the engine)
4. Remove the two nuts that secure the EGR valve and remove the valve
5. Scrape off any old gasket debris and clean the surface
6. Fit the new valve (reverse of above) with the new gasket (came with the new valve)
7. Replace the plug, engine cover, battery terminal etc.... job DONE!

The old valve had quite a bit of carbon buildup in it.

I hope this helps someone else save a few $$$. I hear some "stealers" charge a lot to replace the EGR valve and it is easier to do than changing a wheel.

Note: The VTM-4 light appears as a result of misfires caused by the bad EGR valve and not a tranny or 4WD problem! The PCM get's a little confused and this is a known issue.

piloteer

Thx

piloteerfrommn

In the interest of keeping useful information on the internet, I will post my updates for this issue.

I have a 2006 Pilot EX 4WD. I had the P0175 kick out starting at about 145K miles. The engine was also running a little rough. I reset the codes using a Bluetooth OBD adapter and torque app for android. It kept coming back, about 50% of the time, I would get a VTM-4 light as well, but that would go away by itself the next driving cycle. I also got a 'check fuel cap' indication about 3 times during this issue. I replaced the fuel cap (cheap/easy $15) but the P0175 kept kicking out.

The consensus on the inter-webs was an EGR valve, and also I read multiple times to do a valve clearance adjustment, so I decided to go ahead with that. Here are the values I had during my last P0175 fault prior to repair:

Freeze frame information:
------------------
Fuel Status = 0 byte
Engine Load = 32.157 %
Engine Coolant Temperature = 95 °C
Fuel Trim Bank 1 Short Term = -8.594 %
Fuel Trim Bank 1 Long Term = -7.812 %
Fuel Trim Bank 2 Short Term = -15.625 %
Fuel Trim Bank 2 Long Term = -16.406 %
Intake Manifold Pressure = 4.641 psi
Engine RPM = 733 rpm
Speed (OBD) = 0 km/h
Timing Advance = 9.5 °
Intake Air Temperature = 33 °C
Throttle Position(Manifold) = 16.078 %
Relative Throttle Position = 5.882 %
End of report.

You can see my LTFT for bank 2 is way high on the rich side. It's basically trying to do everything in it's power to lean out. Also, YouTube is a great site for finding videos that explain how engine fuel trim works if you have no clue how it works. I didn't prior to this issue, and watched and was far more educated on the system.

Anyways, I replaced the EGR valve ($55), and pulled the the stuff off the top of the motor to do the valve adjustment. The EGR was super easy once all the stuff was off. And every single valve required adjustment. All the intake valves were loose, and all the exhaust valves were tight. After all that, I put it back together, did the PCM idle learn procedure w/out the HDS (by disconnecting the battery for a while) and now my LTFTs for both banks are amazing. Bank 1 is at 0 and bank 2 is at -1.6%. I need to put some miles on it, but the difference in data was clear before and after repair. And the motor runs way smoother. All in all, the repair took about 5 hours.

Also, if you plan on doing the valve adjustment yourself (it's doable by an medium-experienced mechanic), make sure to get the angled feeler gauges if you can. I got the straight ones and had to bend them all to get them to work. It's a bastard to get that rear valve cover off under the harnesses though, stick with it, it will come off if you keep moving towards the drivers side with it.

Hope this helps some frustrated folks out there.