Brazilian Kombi - Exhaust Options

Another issue! More new parts required.

OK driving home from work this evening I heard a scraping sound every wheel turn coming from the rear off-side (drivers side)

Just about to join a major roundabout the noise worsens. Oh great, my initial thoughts turned to the major works I did a few months ago (see earlier posts) so I had a mental image of a CV joint and drive shaft dragging on the road.

So went round the roundabout and back to a small side road. Pulled into a space and decided to reserve into a better space to inspect, fearing the worst.

When reversing there was a allmighty noise and loud bang.

So got out and found the exhaust final box sitting on the tarmac.

Oh.... at least its not the gearbox......

Put the rear box in the sliding door and got out the inspection lamp to inspect for any damage. NONE! Clean break at pipe. No damage.

Ohh... off I went.... sounding like a monster truck / tractor or boy racer.... took it slow on way home but made the 16 miles avoiding police cars and cruising mainly in 4th gear to keep the noise down....

So NEW Exhaust required - Been putting this off for a while (Exhaust filler and jubilee clips to hold the boxes together)

Right onto the main reason for this post - WHICH EXHAUST should I buy?

Here are the options:

Brazilian Bay

Stock System:

Stock Costings:

VW Heritage:

Stock Steel.

Silencer, Left, T2 EFI VW Brazil Aircooled 1600
Left hand side exhaust silencer for Air-cooled Brazil Kombi
Part ID 040253609
£131.95

Silencer, Right, T2 EFI VW Brazil Aircooled 1600
Right hand side exhaust silencer for Air-cooled Brazil Kombi
Part ID 040253610
£116.95

Gasket, 3rd joint, VWB Kombi

3 hole exhaust gasket joins left and right hand sides towards front of engine.

Part ID 040251509

£4.01

Total = £131.95 + 116.95 + (4.01*3) = £260.93

Cool Air:

Stock Steel.

Exhaust Silencer - Aircooled Brazilian Bay - Left, EFI

Brazilian Bay Danbury fuel injection exhaust for all Aircooled Brazilian Bay Buses.Left Hand Side.

Part ID 040253609

Price: £129.50

Exhaust Silencer - Aircooled Brazilian Bay - Right, EFI

Brazilian Bay Danbury fuel injection exhaust for all Aircooled Brazilian Bay Buses.Right Hand Side.

Part ID:040253610

Price: £114.50

3 Hole Exhaust Gasket - Brazilian Bay

Replacement 3 hole exhaust gasket which joints the left and right hand side 3rd joint of the exhaust on all aircooled and watercooled Brazilian Bay Buses.

Part ID: 040251509

Price: £3.50

Total = £129.50 +114.50 + (3.50*3) = £254.50

Longlife.

Brazilian Bay special price from Longlife Exhausts (Swansea)

Left & Right boxes + Pipes Stainless Steel

£359 Delivered.

Early system

This early system was fitted to Brazilian Kombis in the 1990s. Neat simple BUT impossible to buy in the UK and very hard to find even in Brazil! Hens teeth!

Custom Options

CSP make classic bay parts. Could use the muffler but on further investigation the flange is the wrong size and the tail pipe exits on the wrong side so the tail pipe will face upwards and clash with the valence. There are CSP parts so they could be bought in parts and a system "could be made to fit" High risk and expensive.

CSP Universal Parts:

Universal high quality CSP Python exhaust performance muffler 2,5"

Vintage Speed:

This is the heater version

This is the merged version with no heaters and also equal pipe lengths from both sides.

The vintage speed has been fitted on one other Brazilian Kombi owner and is said to pass an MOT even without the stock CAT fitted. It has the Lambda port (right hand side) so ECU and injection system will be happy.

Short and compact and trusted on many a classic bay.

Only risk is it fails the emissions test as there is NO Stock CAT.

Vintage speed prices:

Box £380-410

J Tubes £80

Options Table:

Name	Description	Price
Stock Steel	Steel 2 Boxes, rusts, stock emissions	£260
Stock Longlife	Stainless Steel 2 Boxes stock emissions	£359
Stock Header+J	Stock Header system - Steel Only available	£300
Stock Early	Single Box - Not available	N/A
Custom	Kit form s/s expensive parts, assembly costs No CAT	£300+
Vintage Speed	Simple s/s, Lambda port. No CAT, emissions unknown	£460

After considering the table my main options are Longlife (Using my older header and CAT) OR Vintage speed

Which one? I will sleep on it...............

Running Rich - Replacement ECU - Solved!

Running Rich - Solved!

Background

For those that have been following this blog for the last 2 years my Brazilian Kombi has been struggling to get through the yearly MOT.

The issue has always been High CO emissions coming at idle and also at fast RPMs.

After investigating the Lambda sensor is always running at about a constant 0.9v which indicates rich levels. The Lambda sensor should run rich / lean (0.1 to 0.9v) averaging out at about stoichiometric of 0.45v (Lambda=1)

I have checked every sensor and actuator and ran many diagnostic logs all without finding anything wrong. 

I finally concluded that the ECU system was not responding to the rich levels and not adjusting. If you inject more fuel (Propane) or ristrict air the ECU should detect this and adjust its fuel (trim) to aim for 0.45v stoichiometric.

At this level the CO emissions should be at the lowest levels.

My original ECU showed NO SIGNS of attempting to correct anything.

So I have now secured another (used) ECU...... It has travelled a 6800 Mile journey to my Kombi (contact me if you need supplier details)

It an earlier version of the original ECU but its basically the same version.

The Swap

The swap over took half a day. Removal of the old ECU was simple enough (battery & wiring disconnecting and one nut)

I then spent a few hours checking all the 25 connections from the ECU ensuring that each Pin went to the correct place compared to the wiring diagram and that all sensors and actuators where correct.

Then came the replacement ECU which was a simple plug in and secure and then reconnecting the battery.

First Start

Then came the moment of truth. First turn of the key the engine fired up first time and sat at Idle with only a little hunting.

After a few minutes everything settled down. Struggled to restart a 2nd time for unknown reason but after that it was fine.

Hooked up the VCDS Diagnostics (see Diagnostics Guide page on the right) and cleared some old fault codes.

Everything ran fine and the drive was improved. A few fault codes came up about Fuel trims but I assume that this was the ECU "Learning" the engine set-up.

The Results

So after a few longer drives I captured some log files and this is the result:

You can now see the Lambda response switching lean / rich during running.

Also of note is the Fuel Injectors switching basically off during letting off the throttle.This is what I would expect to see from a fully working ECU.

During long periods of idle the injectors period are low and the engine is running rich to lean consistently

RESULT!

Follow Up.

Now I have a functioning spare ECU to use on the bus I can now turn my thought to the orginal ECU. I have been starting an ECU repair manual detailing as much little information on the Bosch Motronic MP9 used on the air-cooled Kombi.

I have been speaking to a ECU repair company and will plan to send of the ECU to them to see what they can find.

I suspect from the repair information I suspect it could be an issue with the supply ground of the Sensor inputs not connecting or floating so it does record the right values BUT not be able to respond. Will keep you all updated on the repair.

I suspect the ECU was always faulty and even more damaged when the Engine Earth lead was found disconnected (see hot start issue)

I am SO happy to have finally resolved the issue. I always suspected it was the engine, timing or sensor wiring issue BUT never suspected the ECU to be at fault. 

I did not want to be a typical parts swapper mechanic condemning ECUs but in this case it was the ECU!

More details and information to follow!

Running Rich - Fuel Pressure Tests & Results

Further testing to investigate the rich running and high CO emissions I preformed a Fuel Pressure Test.

Set up - 8mm Female attached on fuel filter, Isolation Tap, T-Piece, Pressure gauge, Male 8mm to fuel rails.

Test 1- Static Pressure Test - Ignition on primed pressure pump runs for 2 seconds.

Pressure reads 2.5 Bar. Tap closed (isolating injectors & FPR) - 10 Minutes drops to 2.3 Bar. FPR Vacuum open (No idle under load conditions)

This confirms pump pressurises and holds without Vacuum applied (Low Vacuum, High load)

Test 2 - Fuel Pressure Regulator Test - Ignition on primed Pressure - Vacuum Applied on FPR

Pressure starts at 2.5 Bar. Tap Closed. Vacuum 24" Hg applied. Pressure Drops to 1.6 Bar and remains there.

This confirms that FPR regulator lowers pressure at Idle (High Vacuum, Low Load)

Test 3 - Fuel Pressure Regulator Test Repeat - Vacuum Applied then Ignition on primed Pressure -

Vacuum 24" Hg applied. Pressure starts at 1.6 Bar. Tap Closed.  Pressure Drops to 1.6 Bar BUT then decreases rapidly down to 0 Bar in <1 min.

This IS AN ISSUE as FPR should just lower the pressure. It seems that this test removes all pressure very quickly!

So I removed vacuum and repeated Static Pressure Test 1 and AGAIN it fell rapidly down to 0 Bar. Repeated again many time and all tests failed and static pressure was not held.

Conclusions:

So there seems to be some leak (Internal as no visual leaks found) not in the fuel pump circuit as tap was closed.

Did not have any more time to investigate but thoughts are:

1. Injector Leak - Through leak of stuck injectors - This would cause pressure to drop but not expected to be so rapid unless stuck open. This could cause excess fuel leaking causing rich mixture.

2. Fuel Pressure Regulator (FPR) - Stuck FPR spring or diaphragm - This would cause fuel to be returned. Thought if it was all being returned this would have caused a leaner mixture as less fuel pressure. Unless it sticks open and closed so increasing pressure causing rich.

Anyway I think I have found some issue.

I have ordered a FPR and also a set of 4 injectors (Not cheap! but at least I have them as spares as parts are getting scarce).

Further tests:

1. Repeat Pressure tests - Static and dynamic with engine running.
2. Dead End Pump Tests - Test pump pressure by dead end tests (turn tap & gauge round)
3. Repeat Tests above to recreate issue.
4. Isolate FPR - Clamp pipes or dead end FPR to see if pressure still decays.

I will most likely change FPR before injectors (much more work) and see if mixture returns to normal.

UPDATE:

No chance of getting injectors! Only available in South America market.

Ordered and fitted FPR - When removing FPR fuel leaked back from tank via return line which was odd.

Fitted new FPR and no difference to rich running indicated by Lambda.

Have not had time / cannot be bothered to rerun fuel pressure tests as I expect no change in rich running unless I can change injectors. 

Moved on to exhaust investigation....... See next post

Still Running Rich?

So I have gone back through diagnostic log files from over 2 years now in order to work out why my engine is running rich (Failed emissions and also poor fuel economy) and also black exhaust.

Following graphs taken at different date intervals

RPM, Lambda Regulation, Engine load and injector pulse widths

06/07/14 - Runs at around 0.8-0.9 except when de-accelerating. Still looks like its running rich but plenty of lean.

14/10/14 - Runs at around 0.8-0.9 except when de-accelerating. Still looking rich but again some lean.

05/08/15 - After fitting in March new "universal" sensor. Not really sure what's going on could be "normal" but no real regulation.

12/12/15 - Lambda Runs most of the time at 0.45v. Signal very poor stuck around 0.45v little response.

At this time the "universal" sensor response was stuck at 0.45v confirmed by unplugging and it stays at 0.45v

Decided to fit OEM Bosch Sesnor.

20/12/15 - Fitted new Lambda Sensor. Improved over previous BUT only a very few lean points.

UPDATE:

Changed FPR regulator after issues seen with Fuel Pressure tests. Re run the same trip:

No to confirm the lambda signal I removed it. Fixed it out of the way. Rerun the same drive. Very noisy from the hole left behind.

From the above graphs 2014 was before last MOT and engine seems to be have high Lambda except during de-acceleration

2015 March (03) time fitted "universal" lambda sensor due to emissions failure. at some point from then on sensor started to run constantly 0.45v

Fitting the OEM Bosch sensor on 20/12/15 the sensor has started to indicate rich at around 0.8 / 0.9v similar to 2014 at the later parts of the graph but still with not much rich / lean switching going on here.

SO in summary:

At the first traces some rich / lean cycling fitting universal sensor failed within 6-8 months.

Fitting OEM Bosch sensor improves response BUT still looking rich with little rich / lean.

I have then proceeded in using my USB oscilloscope to check the actual sensor response.

As you can see it is actually rich at 0.8v. Blipped the throttle a few times and saw the response drop from rich / lean BUT not switching enough only on de-accelerating.

So in conclusion:

Diagnostics logs & Scope of OEM sensor show rich.
Unsure if ECU actually switches rich / lean in response to o2

Things to yet to confirm / check:

1. Fuel Pressure Test - Too much fuel-Fuel Pressure regulator / Stuck Injectors - Completed - Fuel pressure decay at full vacuum - Replaced FPR - No difference. Still could be injectors. Repeat tests with FPR.
2. All Cylinders firing - One not firing - Incomplete fuel burnt
3. Find more info on ECU - Does it switch (need another Kombi / Info) - Looks like artificial lean (removed) makes no difference to Injection on time. I am suspecting that this MP9 ECU does not operate a closed loop so the Lambda is just for indication or base level of injection timing.
4. Lambda Sensor - New OEM sensor works fine out of exhaust (Lean) and Rich when in exhaust.
5. Blocked Exhaust - Still could be block CAT or exhaust - Plan is remove the CAT with Lambda in place and check signal. Inspect CAT.
6. TPS - Maybe TPS showing 6.7 degrees at Idle is causing the lack of lean at idle due to the ECU still thinking its open (foot on throttle) - Will need to reset the TPS by checking that Butterfly is actually closed and ECU detects no throttle.

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.......

Issues, Emissions & MOT Failure

6/3/15 - Fail on MOT Emissions

Had yearly MOT today. FAILED! A few simple points like rear fog lights. On major failure was the emissions. CO % Fail and Lambda Fail. CO was 0.435% Lambda was 1.807 at Fast 2500-3000rpm

Initial thoughts where the Lambda sensor. Replaced Lambda sensor. Found the old one was very black with soot. Indicates Running Rich (as does the CO readings being well out) The problem is that the Lambda is showing it really lean.

Retested and still the same High CO and High Lambda. How can I have an engine which is Rich & Lean. Too much Fuel & Too much air!

8/3/15 - Retest

Anyway manged to get it through MOT after a long warm up and pressing the emissions test at the right place so I have a years ticket but still have issues. 

Still CO & Lambda where way over but  having a Fast at 4250-4850 rpm bought the levels down if we pressed the test button at the right time.

I have also noticed that the fuel consumption is higher & exhaust (lambda sensor & tail pipe have black soot)

Investigations / Cause:

OK so I have a number of things which can cause High CO and High Lambda:

Found this table:

(Legend: L = Low, H = High , M = Moderate)

CO	CO2	HC	O2	Possible Problems
H	L	H	H	Rich mixture with ignition misfire
H	L	H	L	Faulty thermostat or coolant sensor
L	L	L	H	Exhaust leak after the converter
L	H	L	H	Injector misfire, catalytic converter operating
H	L	ML	H	Rich mixture
H	H	H	H	Injector misfire, catalytic converter not working; combination of rich mixture and vacuum leak
L	L	H	H	Ignition misfire; lean condition; vacuum or air leak between air flow sensor and throttle body (false air)
L	H	L	L	Good combustion efficiency and catalytic converter action
L		L	L	All systems operating within tolerance; normal reading

The following table lists some of the results possible when the AFR (air-fuel ratio) is sustained at conditions ranging from too lean to too rich.

Conditions	Results
Too Lean	Poor engine power Misfiring at cruise speeds Burned valves Burned pistons Scored cylinders Spark knock or ping
Slightly Lean	High gas mileage Low exhaust emissions Reduced engine power Slight tendency to knock or ping
Stoichiometric	Best all-around performance
Slightly Rich	Maximum engine power Higher emissions Higher fuel consumption Lower tendency to knock or ping
Too Rich	Poor fuel mileage Misfiring Increased air pollution Oil contamination Black exhaust

So from this information I think it could be the following:

1. Fault Code on ECU
2. CAT Not working 
3. Exhaust Blockage / Restricted / Leaking 
4. MAP Sensor
5. Coolant Sensor (Oil Temperature)
6. Dirty Injectors / Stuck Fuel Injector
7. Fuel Pressure Regulator / Too High Fuel Pressure
8. Blocked Air filter
9. Faulty Lambda Sensor
10. Faulty PCV Breather
11. Tappet Adjustment
12. Faulty Charcoal Valve

So in order to diagnose I thought I would take my time and not rush out and buy expensive parts. I have done the following investigations.

1. Fault Code on ECU - Check ECU and only one fault code which my van has had ever since I purchased it - Throttle Valve position - I think this is just the Zero setting for throttle body when installed. I ran VCDS and logged the data and compared it with a log I ran a year before. Could not see any differences.

Still to test - 
Find out how to reset throttle position to clear fault code for ever. Need to get the correct process in VCDS and try setting.

2. CAT Not working

Could be a blocked or non functioning Catalytic convertor - These are £600 to £469 which is the cheapest in the UK. They ONLY COST £60 in Brazil!

My main concern in replacing the CAT is that the Lambda sesnor was covered with soot & carbon so unless its blocked (causing blow back) it is rich from the engine pre-cat as the lambda is the last sensor. CAT function is hard to test.

Still to test - 
Measure CAT function - Temp before and after CAT.

3. Exhaust Blockage / Restricted / Leaking

A block or restricted exhaust causes issues. It basically causes the exhaust to recirculate in the combustion and even inlet manifolds. This could be the cause but ran a vacuum test on the inlet (common and useful technique for Air leaks and back pressure) this showed a typical "normal" response.

Leaking exhaust can cause issues but I cannot find any leaks or holes. Exhaust is expensive to replace so will leave this until later. 

Still to test - 
Will try the rag up the exhaust to see if it stalls and what it looks like with a restricted exhaust.

Will remove CAT & Both boxes and have a look for blockages. Need to order gaskets, new bolts & exhaust sealant

4. MAP Sensor

MAP sensor is the prime sensor for the amount of fuel to inject into the engine. If it was reading an incorrect level it "could" be the reason to run too rich. No fault codes so in range but could be giving a false reading.

I don't have the VCDS version with MAP pressure readings but plan to check against gauge.

I have been looking for the MAP sensor. Parts from Bosch are typically around £100 so not going replace this unless I am sure.

Still to test -
Measure pressure with gauge and check MAP output voltage with voltmeter.

Purchase VCDS to get access to Measurement blocks 0000 which has MAP pressure readings

5. Coolant Sensor (Oil Temperature)

The engine runs rich until up to temperature. So if faulty will constant run in open loop and rich.

Checked with Multimeter and also Logged data with VCDS and its seems to be correct values and heats up to switch to closed loop once warm. No fault codes. So not coolant sensor at fault.

One thing to note is that the oil temp takes ages to switch to closed loop (approx 80oC) short journeys could be causing to run rich for ages. I am sure the hotter climate in Brazil it does not take so long. On UK days takes a far few miles to get to 80oC.

Still to test -
Check coolant vs temp response. 

Maybe include an extra resistance to make value read 10oC hotter so goes into closed loop earlier (great for shorter journeys)

6. Dirty Injectors / Stuck Fuel Injector

If an injector gets stuck on. The engine will over fuel and run rich. The engine will sense this at lambda and I would expect the on pulse duration to be very short as the engine tries to lean out. I did not see this on the VCDS logs.

Used carb cleaner on inlet throttle body and down to injectors. Also added a bottle of Redex injector cleaner.

Still to Test - 
Test using a fuel pressure gauge (should stay at pressure for long time when pump is off - leaky injector will cause rapid pressure decay) need to restrict fuel back to pump

To test I will need to check the spray pattern (remove and spray into a jar)

7. Fuel Pressure Regulator / Too High Fuel Pressure

If the fuel pressure is too great (pump) or faulty fuel pressure regulator causing too higher pressure. This will cause the injector to over fuel so the ECU thinks its pulsed the correct amount but mixture is too rich so will back off pulse duration to lean out mixture.

I have check the pulse widths from a good emissions run done last year and after emissions failure and they seem the same nothing indicates an issue. However I have been reading about short term and long term trims. This should show if its and issue BUT I cannot find them in the VCDS log.

Checked the vacuum line to the pressure regulator for fuel (indicates a leaking regulator seal) and found none so suspect its good

Still to Test - 
Test using a fuel pressure gauge not sure what the actual fuel pressure should be but expect regulator should return pressure back to fuel tank.

Replace fuel filter and see if its causing a higher pressure. Blocked filter will cause higher pressure but reduced flow.

8. Blocked Air filter

Block air filter will cause lack of air and therefore rich mixture. Inspected the air filter and looks clean.

Still to Test - 
Will replace air filter as part of next service

9. Faulty Lambda Sensor

Faulty Lambda sensor will cause over or under fueling. The ECU should report a fault code if lambda is at fault.Replaced the Lambda sensor anyway, so its not the sensor.

Still to Test - 
Will check with scope the Lambda signal and see if the ECU is getting a lean or rich mixture from its voltage response.

10. Faulty PCV Breather

I have noticed from the HC levels of zero this could indicate a blocked or non functional crankcase breather valve.

I have noticed before that the breather does not seem to be working and pipes are always blocked with the "gunk" " Mayonnaise" from the oil / water mix. This is common place with air cooled engines and short journeys never burning off the water.

I have no managed to source a new PCV valve (211 129 101) took me ages to find one finally got one from The Netherlands.

When fitting it I noticed that all the other Brazilian engines had the breather fitted vertically. Mine was always fitted horizontally and therefore incorrect.

Now fitted a new one the right way round! Not much difference but I am sure its better and working now. Not sure what effect it will have on emissions.

11. Tappet Adjustment

The tappets will have an effect on emissions. So reset and they did not make any difference to emissions.

12. Charcoal Valve

The engine uses the fuel tank breather re-circulation via a charcoal canister and valve. This then adds an extra breather fuel back to be burnt. This is regulated via the ECU once the engine is warmed up.

This could cause an extra over fueling and rich mixture if always on. The VCDS logs show that this is functioning BUT a faulty valve could cause this to be always on but this should be measured at Lambda sensor and adjusted for

Still to Test - 
Test the canister valve to see if it functions on demand.

So in summary I have done the following:

1. New Lambda Sensor 
2. Carb Cleaner / Redex
3. New & correct fitting PCV Valve
4. Replaced Vacuum hoses 
5. Measured Inlet Manifold Vacuum - Looks normal no leak or restriction
6. Tappet Adjustment
7. Measured coolant, throttle, injector, valves etc nominal resistance - All within specifications

I have to do the following:

1. Clear fault code from ECU (TPS zero offset)
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