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
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.
Summer 2015.
Two Main Holidays - 1 Week In Anglesey and 1 Week in Devon
Here is the map:
Anglesey
Lovely Campsite in Anglesey:
dafarn-rhos-campsite
Beach is 100m from Campsite
Betty & Frank Taking the Sea Breeze
Bideford Devon
Lovely campsite on farm:
Westacottfarm
Views overlooking the sea
