P0172, P0175 codes, running rich (no smoke!)

[ezMatt]

Hey guys, first post here so sorry if this doesnt fit any format it's supposed to.

I recently purchased a 2010 Holden Commodore VE International. The check engine light has been on since I bought the car, so I bought a cheap WiFi OBD-II scan tool to check the codes on the engine, and the only two that show up are PO172 and PO175 (running rich in both banks). With this in mind, as far as I can see there's no obvious white or black smoke coming from the exhaust, and it only smells mildly of fuel.

Some data at idle (605 rpm):
- MAF: 4.78g/s
- fuel pressure: 378 kPa
- intake manifold absolute pressure: 48 kPa

- short term % trim bank 1: -4.69 %
- long term % trim bank 1: -27.34 %
- short term % trim bank 2: -8.59 %
- long term % trim bank 2: -40.63 %

These fuel trims vary quite a lot when I rev the car up, between around -20% to -40% each. Fuel economy tends to vary between 9L to 11L per 100km, even with heavy acceleration, which I'd think is quite good, especially given the issue with the engine shown by the code.

Anyone got any ideas what could be causing these trouble codes and crazy long term fuel trims??!

 

[uglyoldfatbastard]

Take of the oil filler cap and see if it smells of petrol in there and pull your dipstick and see if it smells of petrol.
Seen those kinds of fuel trims on a 2010 International LF1 before and it was the HPFP (high pressure fuel pump) on the rear of the engine passenger side leaking petrol into the engine which results in exactly what you are saying with the engine thinking it is running rich but in actual fact it is pulling fuel out and running lean and the petrol in the oil is damaging the bores and crank. That car now has a 2012 LFW engine in it as the engine was completely ruined.

 

[lmoengnr]

If the HPFP was leaking internally, I'd think fuel economy would be pretty lousy.

 

[uglyoldfatbastard]

If the HPFP was leaking internally, I'd think fuel economy would be pretty lousy.

Actually no it doesn't do much to the fuel economy because of the fumes getting pulled back into the engine and out the exhaust the O2 sensors read it as rich and start pulling fuel. It's well documented and been shown many times but hard to convince some people. All you have to do is remove the passenger side rocker cover and it will all be washed clean at the rear of the engine and that is when metal starts to get introduced to the engine and then it is end game for the engine and won't be diagnosed until after it is dead.

 

[shane_3800]

Actually no it doesn't do much to the fuel economy because of the fumes getting pulled back into the engine and out the exhaust the O2 sensors read it as rich and start pulling fuel. It's well documented and been shown many times but hard to convince some people. All you have to do is remove the passenger side rocker cover and it will all be washed clean at the rear of the engine and that is when metal starts to get introduced to the engine and then it is end game for the engine and won't be diagnosed until after it is dead.

Yep seen this on other brands too.

 

[ezMatt]

The dipstick smells less like gasoline, but I think the oil filler cap smells more like fumes. I'd need to smell pure engine oil first to be sure though. How many Km's do you guys think I'd need to drive it in this condition before the engine is beyond repair??

 

[uglyoldfatbastard]

The dipstick smells less like gasoline, but I think the oil filler cap smells more like fumes. I'd need to smell pure engine oil first to be sure though. How many Km's do you guys think I'd need to drive it in this condition before the engine is beyond repair??

How long is a piece of string?

 

[Marty 66]

Go to the Nulon website and order an oil sample kit. Only $45.00. This will tell you all sorts about the engine. Metal, Glycol, Water and FUEL content in the oil (and more). If the sample shows a high fuel percentage then start looking at fuel pumps and injectors. Any more than around 3.5% fuel content in the oil is abnormal noting that direct injection engines will show higher percentages of fuel in the oil as oppose to port injection engines and short trips will increase fuel percentages too as will engine age a wear (think bore and ring wear). All you need is some clear plastic tubing and a syringe and suck oil up from the dipstick pipe. Send the sample off and you'll hear back within a week. Good place to start.

 

[Marty 66]

Example of mine attached. G C (next to the fuel percentage) stands for Gas Chromatography - just the test method. Not sure if engine oil additives (lifter free etc.) that contain petro chemicals would show up in this test ? I had lifter free in mine at the time of this test. Either way sample came back as normal.

 

[shane_3800]

Imagine being the guys doing the testing.
It must be such a mundane job.
I bet they all want to be in the engineering section.