Monday, 31 August 2015

Trouble shooting Code P0172.. my EGR nut is loose

Just today my car threw a P0172 code

Vehicle setup

Stock setup - Honda Stream RN6 - Compact MPV
Similar engine to some Honda Civic: R18A - 1.8 L Auto
Motor Oil:  Shell Helix 5w-40
Fuel: Caltex 92
Tire: Goodyear Triple Max, Pressure between 32 to 36 PSI

"System too rich (Bank 1)"
System Too Rich (Bank 1)

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System Too Rich (Bank 1)

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System Too Rich (Bank 1)

Read more at:
System Too Rich (Bank 1)

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System Too Rich (Bank 1)

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It happened once a few months back.
I was mimicking the continental cars which had the engine switched off by the vehicle computer while it waited at the red lights. It automatically turned on again when the driver removes his feet from the brake pedal.

I think i flooded the system with fuel doing that. It threw a check engine lamp after a few repeatition of doing that on my vehicle.

Basically I erased the code via the OBD2 reader and the check engine lamp (CEL) went away.

Today is different.

The car had a jerk when the gear changed from 1st to 2nd.
I thought... its a transmission problem...oh no!

Then while i turned into my parking area, the engine switched itself off and the check engine lamp lit up on my dash.

I decided to drive on by restarting again and again.

It was quite worrying because the symptom would manifest only when the car stopped at red lights idling, but as soon as i am on the expressway, it didn't give me much trouble. I was worried because if the car switched itself off, i would loose the power steering and brakes. Thankfully the car pushed on.

I made it back to my workshop and did the troubleshooting immediately.

Its always good to have an OBD2 scanner handy to really know what happened.
Possible causes
a- Faulty front heated oxygen sensor
b- Ignition misfiring
c- Faulty fuel injectors
d- Exhaust gas leaks
e- Incorrect fuel pressure
f- Faulty Mass Air Flow (MAF) sensor

When is the code detected?
- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too large. (The mixture ratio is too rich.)

Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Excessive Fuel Consumption

Right now i am unable to remove the oxygen sensors  without tool. Yep, still waiting for it to arrive.

What I did
1. Cleaned the MAF sensor (item f)

2. Removed the fuel rail to check if it is leaky (item c).
I turned the key on several times without starting to prime the fuel pump and build the pressure up in the lines. The injectors did not leak.

No leaky fuel injectors

3. Inspect the spark plugs. Yes there is a bit of soot seen.

4. Check the EGR valve (item d)
I decided to check the EGR. I found the nuts slack. That could be the reason.

The 2 nuts on the EGR valve was slack

Well, i made my own gasket the last time. The material collapse from the heat which explained why the nuts securing it were slack. I made a new gasket and installed the EGR valve back again. This time i secured the nuts tight.

Road test
I took the car out again.
No problems this time.
I am glad it wasn't the injectors nor oxygen sensor.
They are costly items to replace!

After a long drive later, I took my spanner and tighten it again just to be safe.

Side note: It is not that the gasket is bad. It had a layered construction.
Perhaps i did not torque it enough the previous time.

Milam Mica PSS 150

This Klinger PSS150 is not al-cheapo material.
Milam laminates are suitable for use in hot, dry gas applications such as exhaust manifolds, turbines, turbo chargers and air heat exchangers.