Brake servo

Another friend, who was working on the air conditioning noticed an air leak on the input side of the brake servo. It was only noticeable with  the  heater fans turned off and the windows closed and door shut. The noise would go away the minute the brake pedal was depressed. This would not help our emissions (occasional EMS light coming on - long term mixture weak)  so we decided to replace the unit.

The Volvo forums warn that the front sub frame has to be dropped by 100mm. I decided to look in all places in the Haynes workshop manual for guidance. To my great delight this job is in fact covered in the manual.

Here are some images of the job.

Before showing limited access

10mm threaded rod inserted to drop the front sub frame

After dropping subframe

The biggest issue was undoing the knuckle joint in the steering column and reinserting it at the end.

The dreaded emissions test

The true test of the work done on the engine is an emissions test unfortunately we have a problem

 

 



 

The Co2 is 10x what it should be and Lambda is 0.91 where the limit is 0.97. It looks like the control loop that sets these parameters is not working. More updates to follow.

Update 22/03/16

Looks like there is problem with the EMS/ecu, the signal from the O2 sensor is being corrupted with the O2 heater power. I need to remove the EMS/ecu module first. Volvo have a special tool but it is expensive and the only ones I can find are off shore.

 

I found this design for a tool on ref: sweedspeed.com: http://www.matthewsvolvosite.com/forums/viewtopic.php?t=57066

 

I decided to make one of these:

 

 

The next issue is the EMS wiring diagram, found this on sweedspeed:

Why I think the ECU is faulty?

I have a Sealey VS925 Lambda Simulator/analyser. The purpose of such device is exactly the application we have here. The ECU monitors the O2 sensor and if the cat is to run at the correct temperature the air fuel mixture should be unity and held within very tight parameters. The O2 sensor or Lambda sensor puts out + 0.5V when this mixture is correct. However there is a control loop set up by the ECU with adjusting the fuel air mixture by measuring the Mass Air Flow and adjusting the mixture to keep the Lambda within range 0 to +1V. At idle the signal is a 1Hz sign wave crossing the 0.5V level about once per second. The tester can inject +/- 0.5V to test the ECU response.

 

 

 In the case of our V70 the O2 signal is +3.75Vand stuck there. I had to check this with a multimeter as it is outwith the range of the analyser. An error code from the ECU indicates the  long term fuel mixture is too week. The lambda is in fact too rich as indicated by the Gas analyser results. This is the ECU trying to square the impossible circle.

 

I have checked the ECU wiring and all the connections are correct. The only time the 3.75V goes away is 5 minutes after engine switch off.

 

 

 

 Unfortunately I cannot identify the ECU part number from the outside, the label is unreadable however I hope this image may identify the part.

The internals of the ecu electronics look factory fresh despite the outside can being corroded slightly.

Update 27/03/16

The purpose of todays measurements was to see if the 3.75V was a signal from the ECU or some noise generated within or without the ecu. In my mind it could be caused by noise from the O2 heater (possibly) if it were pulse width modulated. Some manufacturers of ECU do this trick.

I connected up an old oscilloscope I had in the workshop to the O2 signal and there is no noise just a constant 3.75Vdc. So the incorrect signal must be from the ecu and in fact must be a blown input stage.

I will phone the ECU repair man (The ECU Doctor) in the morning.

 

 Update 12/06/2016

Well I had to give up on my home diagnostics the ECU is not available on ebay (with lock and key) and neither is any repair service available at a reasonable cost. I am not entirely sure the ECU is in fact faulty. We decided to get the help of an expert The Krypton Garage in Blackburn. Krypton (Steven) has all the Volvo approved diagnostic kit.

The key issue was the O2 sensor. The one I obtained from ebay was not the correct one. You must use an O2 sensor matched to the ecu there are several different types for that model year. The incorrect O2 sensor did not deliver obvious symptoms and Steven did a good job tracking this down. It appears Volvo use a current driven wide band sensor that does not give a voltage variation at the input to the ecu, hence my confusion.

Also replaced during the diagnostics was the MAF sensor and VVT solenoid in an attempt to get better performance although I am not convinced it has made that  dramatic a difference. However good enough for a Rome adventure.

Another issue is was the persistent oil leak which returned and caused intermittent sparks from the coil packs. I finally nailed that, the rocker cover bolts were loose.

All in all this is a lesson in what can go wrong with a modern car when they get older and fail the emissions test. I spoke to a garage friend and in normal circumstances this car would have been scrapped as the time spent and cost would normally be prohibative.

Summary so far

The repairs have gone well, the car is now reliable if a bit lacking in power. All the Engine Management issues have been resolved. It now requires us to customise it for the trip and change the fluids.

Here are the issues resolved so far

Description

EMS problems requiring multiple fixes (O2 sensor, coil pack and MAF sensor)

Oil leak rocker box (cheap fix using washers and glue)

Corroded exhaust section (new section from low cost source)

Replaced front discs and pads

Fuel filler flap hinge (ebay to rescue)

Spare key sourced

Courtesy light drain on battery 9 x 21W (changed to LED's)

Cup holder jammed (simple fix)

Battery condition, added bataid for now (still could still be a problem)

Power steering noisy pump (known Volvo problem)

Nearside front flasher intermittent (new bulb and adjust holder)

Timing belt change (standard kit)

Power steering noisy pump

When the car has been running for a while and driving it hard the power steering pump makes the most awful groaning noise when you attempt to turn the steering wheel. The cap on the reservoir spits out oil when you try to remove it and the contents are all frothed up. The sides of the reservoir are bulging.

The Volvo forum described these symptoms exactly:

http://www.volvoforums.org.uk/showthread.php?t=110646

"Quick and easy fix if your pump steering is noisy, feels wrong, froth in reservoir. Look inside the Power Steering Reservoir to were the inlet pipe is and if you see a brass pipe approx 40mm long this is your problem as it should be covered by a "L" shaped plastic pipe. Fish around in the bottom of the reservoir , retrieve it and refit. It is secured by removing the inlet pipe and pushing in the 20mm or so of brass pipe till flush with flange. If this is to fiddly purchase a new reservoir. It is caused by the high pressure from the pump gradually pushing the brass pipe back into the inlet pipe causing the L piece to drop off thus causing the froth which your pump then tries to pump."

 

We decided on a slightly more robust but cheap approach. After doing the above we added a second pipe to keep the original pipe in place and secured with a jubilee clip.

 

Plastic internal pipe

Additional pipe

Original pipe now kept in place with additional pipe

 

 

 

 

 

More progress on MAF etc

The good news: The new MAF sensor arrived today from Bulgaria. The bad news: It is the wrong one. I have emailed the vendor with the VIN/EngineNo/Part no and they are going to check if they have one. A proper Volvo part is £70.

On a brighter note I did a few repairs including the old MAF sensor. I managed to get a pencil light source down the MAF sensor tube and examined it with a magnifying glass, it was full of crap despite my last attempt to clean it. I put cellulose thinners down it this time and all the carp is gone.  I measured the platinum wire resistance against the new part that arrived today and they are both the same. It also appears to work, dare I say it, I have been a couple of runs in it of at least 30 miles and the EMS light is still off but It is too early to tell as it is the Long Term Fuel Trim that is going wrong, here's hoping.

I repaired the cup holder today in true R2R style using an earth tag and a screw to act as a latch.

 

I repaired/bodged the rear lock on the tail gate. I did not fix the solenoid (way too complicated) so I disconnected it. If we get time we can investigate further but at least we will not unlock it by mistake (an accident waiting to happen esp with migrants looking for a free ride).

 The next task is to get those bulb alarms to go off, I am waiting on the rheostat to investigate these alarms  further.

The gearbox is making some odd groaning noises and so is the power steering pump. I checked the tension on the aux belt but it is tight enough.

If the EMS remains off, I am planning to take the beast to a friendly  MoT station and get the emissions measured  and see if they have any ideas re steering pump.

 

Test drive - more EMS light woes

After the extensive work done so far:- new timing belt, front brake discs, rocker box oil leak, oxygen sensor, coil pack No2, exhaust mid section, fuel filter, fuel filler cover and brake fluid change it is time to give it attest run. All is now well with the work done so far except the EMS light has returned.

The latest code to be thrown up is P0171 -  Generic System Too Lean(Bank 1). This has been reset a couple of times but keeps returning. Also the car is gutless could not pull the proverbial skin off a rice pudding. The warnings about this problem are all on the web and it cannot be run to Rome with this defect  without damage to the engine.

We have various bulb failure messages including one real one indicating  the offside front flasher bulb has failed. I had a brief look and it is a bu..er to get out.

Forum/google wisdom says (*)

Reported error on the Gendan code reader: P 0171 Generic System: Too Lean (Bank 1).

Freeze frame data for above

LT FTRM (%) - 22.6

* The short fuel trim is derived from the computer trying to keep the engine at a perfect 14 to 1 fuel gas air ratio. It uses the signal from the o2 sensor and the map sensor and the mass air flow sensor. to come up with long fuel trims and short fuel trims. The short fuel trim is what is happening right know. The long fuel trim is what is happening over a long period of time. The goal for driveability  is the long fuel trim to be within 10% of 0
MAP (in.hg) - 17.1
* Manifold Absolute Pressure
1 Bar = 29.4 in. vacuum at idle is always high and typically ranges from 16 to 20 inches Hg in most vehicles.
Engine (RPM) - 709
* Normal tick over type revs so MAP is ok
CALC load (%) - 37.2
* I guess at the point of failure the engine was under some sort of load
COOLANT TEMP - 189
* 189degF = 82deg C quite normal
ST FTRM1 (%) -3.1
* As per previous note this is actually within range so the oxygen sensor loop, MAP and MAF  must be doing something.
Fuel Sys1 - CL, using H02S
* Closed Loop = Good , using oxygen sensor = Good

In summary the long term fuel trim is in error 22.6% it should be less than 10%, at the point of failure (freeze frame data) the MAP(in.hg) absolute pressure was in range. Most of the forums indicate the MAF (Mass Air Flow) and MAP sensor sets the fuelling from the ECU to the injectors.

I have therefore ordered a MAF sensor as the most likely cause of the problem based on the data and reading the forums.

The other likely cause is a leak in the inlet manifold but I have checked that with a butane aerosol and I cannot find a leak (like I did on a previous car).

Acronyms

FUEL SYS1 – Fuel System 1
•CL – Closed Loop
•OL – Open Loop
•Using HO2S – Using Oxygen Sensor
•FUEL SYS2 – Fuel System 2
•COOLANT TEMP – Engine Coolant Temperature
•ST FTRM1 – Short Term Fuel Trim, Fuel System 1
•LT FTRM1 – Long Term Fuel Trim, Fuel System 1
•ST FTRM2 – Short Term Fuel Trim, Fuel System 2
•LT FTRM2 – Long Term Fuel Trim, Fuel System 2
•Engine (RPM) – Engine Speed in Revolutions Per Minute
•VEH SPEED (MPH) – Vehicle Speed in Miles Per Hour
•IGN ADV (DEG) – Ignition Advance in Degrees
•IAT (°F) – Intake Air Temperature in Degrees Farenheit
•MAF (lb/min) – Mass Airflow in Pounds Per Minute
•ABSLT TPS (%) – Absolute Throttle Position in Percent
•O2S11 (V), (%) – Oxygen Sensor 1 Bank 1 Voltage and Percent
•O2S12 (V), (%) – Oxygen Sensor 1 Bank 2 Voltage and Percent
•O2S21 (V), (%) – Oxygen Sensor 2 Bank 1 Voltage and Percent
•O2S22 (V), (%) – Oxygen Sensor 2 Bank 2 Voltage and Percent
•OBD2 Stat – OBDII Standard Vehicle Conforms To

Fuel filter

As the fuel filter looked original I think this needs changed (good old Arnold Clark service).

New filter in place