Update on Emissions

Update on Emissions 1/9/15

Only investigations on Emissions and rich running done over the last month.

Idle Fault code:

Spent some time looking at 00533-10-10 Intermittent Idle Fault code.

Cleaned Idle Actuator Valve & Tested - The valve was dirty but operated fine. Found there was a set screw which allows air to bypass the throttle valve which must sets the minimum idle. This was about 10% of the opening. When the valve activates from the ECU its opens it further to increase idle.

This was before cleaning. After it was cleaned and retested with 12V. All functions fine. Refitted but added an extra clamp as the manifold pipe appeared a little loose.

Refitted and cleared fault code. Drove to and from work trying to get the idle to faultier. But as was fine when logging with VCDS But as soon as I thought it had gone away it came back.

Managed to capture some log files when the error code happens but seems to be about 20 or so times the revs go below 850rpm. Its hard to work out why the van has always had this issue since I bought it.

Manifold Air Leak Testing

Spent a few hours trying to look for air leaks in the manifold. Used Propane blow torch without lighting and a pipe attached to the end while moving around all pipework and manifold and no increase in idle revs was found. So suspect the intake system is pretty leak free (also indicated by vacuum gauge tests)

Unless the leak is around the brake servo pipe / connections I suspect there is no false air.

There is one thing that I find odd - When I block the main air filter intake by hand it does suck but the idle is not really affected. I am expecting that the engine should stall. 

This could indicate that some false air is getting from somewhere but I cannot find it. Will look again.

Canister Valve (N80)

It was suggested on a forum that I should check the operation of the Charcoal Canister valve & EVAP system. This valve adds petrol vapor when the engine is running and up to temperature. It has a major effect on rich running and if stuck open then can cause over rich mixture.

So I removed the canister valve N80 and checked its operation. You test by applying a vacuum on the manifold side and ensure its holds. Then operate with +12V supply and see if the vacuum is gone.

The valve operates correctly and holds vacuum. So its not this. Also thinking about it the EVAP vapor causes a massive swing in rich mixture the ECU and Lambda will complain if the valve is stuck open.

Still need to test if the ECU actually operates the valve but the VCDS log files say it opens during running.

Throttle Body & TPS Sensor

I was doing some checking on the specification from the workshop manual and comparing the data from VCDS. Everything else is within specification at hot idle except the following:

It seems that the specification suggests a throttle body butterfly angle of 5 Degrees and a Throttle Position Sensor Voltage of 0.3V when at Idle.

The ECU is reporting a angle of 6.7 Degrees and 0.3V when at rest. I am not sure how the ECU works out throttle valve angle as it is only measured by the TPS sensor. So either the valve is actually open or TPS is misaligned. Did not want to adjust the TPS as its sealed on its screws.

I did try adjusting the Throttle valve angle slightly. Adjusted to 6.0 Degrees and the TPS reads 0.28V so its also out of specification. Will need to think about this a little more. Its really hard to see if the valve is actually open as access is a problem.

I will investigate this further once I am confident it could be a cause of the Idle fault code and can actually see the throttle valve.

Reset to Default (ECU reboot)

So this I am not sure about. I have read that if you disconnect the battery for a while (around 30mins) the ECU will have reset and need to "learn" new settings.

So I took some VCDS logs before disconnecting the battery and when reconnected. Looking at fuel trims etc.

The van started fine and ran the same as before. Looking back at the data it did not seem to do anything.

Maybe this is a old wives tale. I will have to look at it again but I also read that the Bosch MP9 cannot be reset unless you have a MP9 Reset software which requires a dongled connection.

Spark Plugs / Long Journeys

So we went on a very long journeys over the summer. Trip to Anglesey Wales, this was a 400 Mile trip and then to Devon a 500 Mile round trip.

So the Van covered 900 Miles this summer! She ran well but is still drinking fuel. We filled up over twice as much as our friends driving a 1600cc Carburetor bay.

I though Fuel injection was more economical!

So after getting back from Devon the engine was sounding a little blowing from the exhaust. Could be the exhaust or suspect starting to loose valve seat or sealing.

So reset the tappets and removed the spark plugs from 1 & 2 as the right hand side was sounding more noisy.

Both plugs show the "normal" tan color but they also have some carbon. It does not look that rich as was expecting completely black. The black is kind of rough textured junk not pure carbon.

Cleaned off with wire brush. 

Next Steps

So the van is off the road at the moment due to wanting to get some rust / body work on the wheel arches (Post to follow)

Whats next?

So I am stumped again to what could be causing the rich & higher than fuel consumption.

Maybe I don't actually have rich mixture?

So the plan is:

1. Fuel Pressure Measurement - Measure Fuel pressure - This will confirm the Pump pressure, Fuel Regulator and also checks for leaking stuck injectors. I have the gauge and new filter and also the "special" fuel quick release clips to replace when removing fuel lines. Will also change fuel filter.

3. Catalytic Convertor - Need to check the CAT - I have managed to find a £300 UK cat replacement or a £70 Brazilian special. Might be worth removing the CAT and have a look inside for blockage / damage. Will also try the rag over the exhaust to look for leaks or false air in the exhaust.

4. More testing / Diagnostics - I am think about running a few tests with the lambda sensor outside and see if it changes the mixture when running. I am running out of things to look for now. Also scoping ECU connections and looking at the rich / lean signals when I remove things like the MAP sensor etc.

5. Gas Emissions Test - Might be worth another trip to the garage to get another CO emissions test to see if its still rich. Removes my doubt as its only the fuel consumption.

Here is the list of what I proposed to test last time:

1. Clear fault code from ECU (TPS zero offset) - Looked into & tried to fix
2. Test for blocked CAT - Block exhaust check Vacuum / Remove inspect
3. Measure CAT temperatures
4. Test Coolant Sensor - Resistance Vs Temp
5. Measure MAP Sensor Response - VCDS & Output Vs vacuum gauge
6. Fuel Pressure - Leaky / Stuck injector / Fuel Filter replace
7. Measure Lambda response
8. Test Charcoal valve - Power & Check - DONE

Really struggling and slowly loosing interest in solving this now.......