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Topics - Kevin Wood

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91
http://www.pistonheads.com/news/default.asp?storyId=24438&utm_source=newsletter&utm_medium=email&utm_content=html&utm_campaign=2011-10-3

 :-[

Hope the injured guy pulls through. :(

Still, Elite Pete will be pleased to see another couple of BMWs off the road. ;D

92
Maintenance Guides / Fitting variable intermittent wipe
« on: 14 July 2010, 10:49:56 »
This HOWTO has been compiled based on valuable contributions to the forum from NickA, BigAL, Ken T and Welung666 amongst others for which we are grateful.

Later facelift Omegas came with two options regarding intermittent wipers. An optional rain sensor at the top of the windscreen provides variable intermittent wipe automatically. Unfortunately, on cars lacking this option, only a fixed delay intermittent setting was provided.

The manually variable intermittent delay fitted to older Omegas was dropped. The fixed delay is never quite right for the level of rainfall, so it is a worthwhile modification to add variable delay functionality. There are two options, as described:

Retro-fitting a variable delay stalk from an earlier model

This is not too difficult to do. It requires a small modification to the wiring around the stalk and swapping of the intermittent delay timer module.

The first job is to obtain a wiper stalk and timer module from a car with variable intermittent delay. The stalk has an extra thumbwheel in the arm to adjust the delay. This is in fact a variable resistor. On a fixed delay setup, the positive supply is switched via terminal "J" of the stalk via a wire (black with yellow stripe) to the delay module which contains an internal resistor to set the delay. On a variable setup, the variable resistor is inserted into this connection, making the delay variable. The timer module in this instance has a smaller resistor to set the minimum delay, hence the requirement to also swap the timer module to get the correct adjustment range.

To remove the stalk first the steering column cowling must be removed. This is achieved by removing the 3 posidrive screws in the bottom of the cowling and then the 2 countersunk screws in the front of the cowling that are accessible when the steering wheel is turned to the "90 degree" position each side. Unscrew and remove the steering column height adjust lever and remove the upper and lower halves of the cowling.

The stalk can be removed by squeezing the two levers at top and bottom of the switch body and withdrawing it sideways, then withdrawing the electrical connector from the switch body.

93
Maintenance Guides / Repairing a Central Locking Motor
« on: 29 May 2010, 18:58:34 »
Central locking motor failures are a common and irritating problem. Whilst the motors are not too expensive on Trade Club  they aren't exactly cheap either.

The majority of failures are actually caused by the failure of a microswitch inside the motor assembly (it's actually a motor, not a solenoid), and this is cheap and relatively easy to change.

Firstly, the motor must be removed from the car by following the appropriate maintenance guides:

http://www.omegaowners.com/forum/index.php?topic=90504.0
http://www.omegaowners.com/forum/index.php?topic=90543.0

Once the motor is on the bench the black plastic cover needs to be removed, as follows:

Ease the rubber seal around the actuating lever off the motor body and lever.
Pull the actuating lever out to the fully extended position and remove the protruding part of the white plastic lever from the section that extends into the motor body by sliding it sideways.



Punch out the 2 roll pins by the lower end of the motor body and carefully prise the black cover past the four lugs surrounding the roll pin holes and off the motor body.



This is what you should see:



In the following picture you can see the silver motor in the centre with gearing to the left. To the right of the motor is the white microswitch that causes problems. Note that it may not always be white!



In the following picture the mechanism has been stripped down to show the two microswitches in position. Note that passenger and rear doors do not use the second (black in this case) microswitch, and it may not be fitted to the unit at all. The repair procedure is the same. however.



Here is the mechanism that was removed to show the microswitches. A rack is turned by the motor which winds a plastic sled up and down. This sled sits inside the internal part of the lock actuating lever.



Here is the assembly as it sits inside the motor:



The sled has 3 positions:

It can be wound fully down towards the bottom of the motor whereby it will take the actuating lever down with it and lock the door.

It can be wound fully upwards, taking the actuating lever with it, and unlocking the door.

It can be at a central "parked" position where manual control of the actuating lever is possible, allowing the door to be unlocked and locked manually. When the car is deadlocked, the sled is parked in the fully downwards position, which makes it impossible to manually lift the actuating lever to unlock the door.

It is the microswitch which senses the central position of the sled which causes problems. The purpose of this switch is to cut the supply to the motor as the sled reaches the central position from either above or below. As it wears the contacts become intermittent, and then fail completely, meaning that the supply to the motor is disconnected and the door does not respond to the central locking system.

The microswitch can be tested with a multimeter in-situ at this stage, or one or both of the switches can be replaced as a matter of course. If the rest of the device looks clean, there is no evidence of water ingress or other damage and the mechanism moves freely, it is a fair bet that a microswitch failure caused the problem.

So, on to repairing the motor. To achieve this, the microswitch needs to be removed. It must be desoldered from the connections that are moulded into the body of the motor. The body material has a low melting point, so care must be taken in desoldering to ensure it is not damaged. You will need a desoldering iron or a fairly fine tipped soldering iron and desoldering pump to achieve this.







Once all of the pins have had the solder removed and are free in their holes, ease the body of the microswitch out of the plastic retaining moulding.

The microswitch is a Cherry type DB2 with button actuator and straight PCB pins (not the solder bucket connections).

RS part number 290-0463, 1.26 at the time of writing looks a direct replacement, as does Farnell part number 1519007, 1.38.

Similar pattern switches are available from Rapid components (78-2410 @ 47p). Note, however, that these do not have the high 10A current rating of the original Cherry switch so might well have a shorter life in this application!

94
Having completed installation of an LPG system, care must be taken in checking correct operation of the system and calibrating it to suit the engine before it is used.

The following is a suggested procedure for commissioning a Stag system installed in an Omega. It assumes as a starting point a completed installation which has not yet been filled with LPG and where the LPG system has not yet been powered up.

1) Check the vehicle still runs on petrol.

With the vehicle completely assembled but the LPG system 12v permanent supply not yet connected (remove the fuse, for example), try to start the engine.

The engine should run exactly as it did before installation, on petrol. If there are any problems at this stage the following should be considered:

  • Have all items disturbed been re-connected correctly? (hoses, electrical connections, etc)
  • Could an air leak have been introduced into the induction system during removal of the manifold?
  • Have the LPG nozzles been connected to the LPG injectors? (otherwise there is an air leak!)
  • Have the petrol injector piggy-back connections been made correctly? (no injector signals swapped between cylinders and all injectors connected)
  • Have the connections to the Petrol ECU been made to the correct pins and are the cable colour codes as expected?

If anything is wrong, back-track your work until you find the problem. If there is a problem running on petrol there's no point proceeding further with the LPG setup until it is resolved.

Now is also a good time to check for leaks in the plumbing to the vapouriser, to ensure that the vapouriser gets hot to the touch, indicating healthy coolant flow, and to top up the coolant level if required.

2) Install the diagnostic software and connect a PC.

The Stag "AC Gas Synchro" software and USB driver should be installed on a laptop. It is better to download the latest version from http://www.ac.com.pl than to rely on the CD that is supplied with the kit. Note that the software version required depends on the exact ECU model fitted.

Connect the diagnostic cable to the 4 pin connector that emerges from the Stag loom, and plug into a USB port on the laptop. Allow the driver to find the USB device.

Load "AC Gas Synchro" software.

Insert the fuse or connect the permanent 12v supply to the LPG system (there may be a small spark due to the inrush current).

Switch on the vehicle ignition and then attempt to connect to the LPG ECU using ACGasSynchro.

At this point, the latest firmware can (and should) be installed onto the LPG ECU.

3) Check the LPG controller configuration using ACGasSynchro.

The ACGasSynchro software should be showing a screen similar to the following:



Note that the above shows the parameters for a Stag 300 ECU. Other variants such as the Stag 300+ and Stag 4 will have variations but the basics (which is all we're currently interested in) are the same.

Set the Car Parameters to suit your vehicle. In all Omegas converted according to this guide, the settings shown will suit, except that the Number of Cylinders and Number of Cylinders for coil should be set according to the number of cylinders on the engine.

The LPG Controller Settings shown should be a good starting point except to note that the Calibration Parameters are automatically set during calibration and should not be edited manually.

Ensure that the Injector Type is correctly set for your LPG injectors. The Valtek Type 30 injectors with red coil housings normally supplied in Teilo's kits should be configured as "VALTEC/RAIL/AC 3 Ohm". Other injector types will require different settings and damage can result from an incorrect setting!

4) Start the engine on petrol and check live parameters using ACGasSynchro.

Verify that the engine still starts and runs normally on petrol.

Check the live data displayed on the right hand side of the screen when ACGasSynchro is running and connected to the LPG ecu.

With a fully warmed up engine running on petrol the following typical values should be displayed:


ParameterTypical value
LPG PressureNot Important
MAP PressureAround 0.30
Injection Time (all cyls)Around 3 ms
LPG Tempshould match ambient temperature of engine bay
RED TempShould match coolant temperature
Lambda VoltageShould cycle between 0 and 1v (0 and 5v for X20XEV)
Battery13-14.5 volts
RPMShould match engine RPM


If the temperature and pressure readings are incorrect it could be that the ECU is configured for the wrong type of sensors. Open the Settings tab and check these match the sensors supplied in your kit.

Injection time should be visible for each of the cylinders in the engine. On a V6, it should be obvious that the injection time for the two banks are varying independently (for example, if the 1,3,5 bank is connected to channels 1,2&3 of the ECU, these should be showing the same duration whereas channels 4,5&6 will be slightly different). This can be useful in identifying injectors that have been cross-wired by mistake.

If the engine RPM is wildly inaccurate check the setting for Number of Cylinders and RPM Signal.

Make sure that any issues are resolved before proceeding further.


95
Maintenance Guides / Fitting LPG - Electrical Connections
« on: 06 April 2010, 10:02:11 »
Connections to the engine ECU and battery

The LPG system needs the following connections from the car's electrical system to supply power to the LPG system, in order to determine the engine operating conditions and also to allow the Lambda sensor output to be available during system calibration:

  • Permanent 12v supply
  • Ignition switched 12v supply
  • RPM (Tachometer) signal
  • Lambda sensor output(s)
In addition to this, the LPG system needs to intercept the signal to each petrol injector in order to determine the time and duration of the injection events and to allow the petrol injectors to be disabled when running on LPG.

For the switched 12v supply, RPM and Lambda sensor signals, the most convenient place to intercept these is probably where the wiring emerges from the engine ECU in the triangular plastic box next to the battery.

An easy way to find the connections is to dismantle the connector(s) which plug into the ECU and to find the numbered pin corresponding to the signal of interest. On the X25XE, X30XE and X20XEV engines it is reasonably easy to solder additional wires to the pins in the connector. On the Z22XE, Y26SE and Y32SE engines, the pin pattern of the ECU electrical connector is too dense and it is better to identify the wire by finding the connector pin, but follow it a few centimetres up the loom before stripping the wire, soldering a connection to it and protecting with heat-shrink sleeving.

The following table indicates on which connector pins these signals can be found for each of the petrol engine options and the colour coding of both the vehicle wiring looms and the Stag LPG system looms:


Engine TypeY26SE/Y32SEX25XE/X30XEZ22XEX20XEV
Signal NameLPG Loom Colour
Switched 12vRed(thin)X86 Pin47 BlackPin27 BlackX84 Pin64 BlackPin17 Black
RPMBrownX86 Pin35 GreenPin43 GreenX84 Pin62 GreenPin20 Green
Lambda Sensor 1VioletX85 Pin28 BluePin28 Brown/BlueX83 Pin57/8 Black/GreyPin36 Yellow
Lambda Sensor 2Violet/GreyX85 Pin44 BluePin47 Brown/BlueN/AN/A

On the Z22XE, Y26SE and Y32SE engines there are two connectors on the ECU and we indicate above which connector is applicable. On the Y32SE/Y26SE X86 is the connector where the loom emerges and heads through the bulkhead into the car interior. X85's loom runs across to the cable tray on the engine.

On the Z22XE, X84 heads to the bulkhead while X83 heads to the engine.

The permanent 12v feed (the thicker of the two red cables in the Stag loom, with an inline fuse holder near the end) can be taken directly from the battery positive terminal. Ensure all other electrical connections have been made before connecting this (or leave the fuse out until you are ready to test).

The ground connection for the LPG system emerges on a thick brown wire next to the permanent 12v feed. this can be connected to the battery negative terminal.

96
LPG injectors such as the Valtek type 30 usually supplied with the Stag kits are designed to work with a wide range of engine power outputs and so a way to calibrate the rate of fuel delivery to suit the engine is required.

Fuel flow from an injector is controlled primarily by the time for which the ECU holds it open during the induction stroke of the engine and the pressure of LPG vapour with which it is supplied.

If the injector is delivering fuel too fast for the engine, it becomes impossible to achieve a short enough injection time to accurately control the mixture and the engine will idle poorly and emissions will suffer.

Conversely, an injector what is not able to flow fuel fast enough might end up open 100% of the time as the engine approaches maximum RPM at full throttle, and be unable to supply any more fuel. The engine may have a lean fuel mixture as a result and, at full throttle, this can cause burnt out valves and piston crown damage due to excessive combustion temperatures.

In order to calibrate the injectors to the requirements of the engine a small brass nozzle is fitted at the outlet of each injector valve. These nozzles should not be confused with the nozzles installed in the intake manifold to inject the fuel into the intake. The brass nozzles can be drilled out to various sizes and in so doing the rate of gas flow through the valve is set.

This can be regarded as a coarse adjustment of the fuel flow. Finer adjustments can be made by adjusting the pressure of the vapouriser output, and by adjusting the injector opening time by adjusting the map in the LPG ECU.

The nozzles are normally supplied with very small drillings and it is necessary to drill out the nozzles before installation to achieve sufficient fuel flow on all Omega engines.

The Stag manual contains a table of nozzle diameters against horsepower output per cylinder. In practice, it has been found that a 2.5mm nozzle diameter is a good starting point for a 2.5 or 2.6 V6 engine and, for all others, 2.8 - 3.0 mm works well.


97
Maintenance Guides / Battery, Charging and Starting diagnosis
« on: 03 November 2008, 14:54:59 »
Questions regarding battery, charging and starting problems are frequently asked here, expecially this time of year, and diagnosis is straightforward provided the correct approach is taken, so I thought a guide was in order for future reference:

From a practical point of view it is useful to know that the battery terminal voltage under various conditions can tell us almost everything we need to know about the state of the battery and charging system so accurately measuring the terminal voltage is key to fault finding in this area.

A cheap digital multimeter the like of which is available in Maplins or at most motor factors is the perfect tool for the job. Set it to a voltage range of around 20 volts DC if it has manual ranging, ensure that the test leads are inserted in the connectors marked "common" and "V" and connect them across the battery terminals, ideally with crocodile clips so you don't have to hold them conencted while you perform the tests. DO NOT connect a multimeter on the Amps range across a car battery, and make sure the test leads are not left in the "common" and "A" connectors.


Battery condition and charging curcuit


Obviously the circumstances in which you find yourself with a starting or charging problem can vary, but in an ideal situation, when faced with a problem, I like to take the following sequence of actions to diagnose the fault:

1) Try to charge the battery, ideally using a mains powered battery charger for a couple of hours, to ensure it is likely to be fully charged.
2) Allow the battery to settle for perhaps 15 minutes after charging so the terminal voltage reflecs its' true condition.
3) Measure the terminal voltage of the battery.
4) Apply some load (e.g. car headlights) and watch the terminal voltage for a minute or two.
5) Switch off all loads, start the engine, and, ideally, have someone watching the battery voltage while cranking the engine.
6) Measure the terminal voltage with engine at a normal idling speed.
7) Increase engine speed to a fast idle (2,000 RPM) and measure the voltage.
8) Add some electrical load (headlights, blower fan, heated rear window) and measure the voltage at idle speed.
9) Increase engine speed to a fast idle (2,000 RPM) and measure the voltage.
10) Check electrical connections to battery, starter and alternator and also all chassis ground connections in the engine bay for heat.


I interpret the readings taken above as follows:


3) Normal reading would be 12.5 - 12.8 volts indicating a healthy battery fully charged. Suspect battery if it has failed to reach and stabilise at this voltage after a charge.

4) Expect the voltage to drop to perhaps 12.2 - 12.5 volts due to internal resistance but to remain stable for a minute or two. If voltage continues to gradually decline below this level, and certainly if it reduces to 12.0 volts or below within a minute or two, and was previously fully charged, suspect battery.

5) While cranking, battery voltage will fall significantly. If it falls below 10 volts or so when battery was previously fully charged, I'd suspect the battery. If it's also cranking the engine rather slower than usual, it adds more weight to this diagnosis.

6) Expect 13.5 - 14.5 volts. Greater than 14.5 volts indicates battery is being overcharged (voltage regulator failed within alternator). If it's significantly greater than 15 volts do not drive the car until resolved as the battery could be damaged or even explode and other electrical accessories in the car may be destroyed.

7) If the voltage didn't make it to at least 14 volts when idling it should do now otherwise alternator suspect, or perhaps wiring from alternator to battery or chassis and engine block to battery negative terminal connections. Should remain under 14.5 volts, as before.

8) Expect perhaps 13.0 - 14.5 volts. voltage may well have dropped due to load on the alternator.

9) Expect 13.5 - 14.5 volts. Most of the drop with load in the previous step should recover at normal cruising RPM. If not, suspect alternator or wiring fault.

10) Electrical conductors may become slightly warm to touch with electrical load, but any conductors, or particularly crimped connectons, that become hot to the touch have a high resistance (loose crimp perhaps?) and are reducing the effectiveness of the charging system. It doesn't take much voltage drop before the battery is not being adequately charged so rectify poor connections before they leave you stranded.

It may not be practical to perform the whole sequence above if you are stranded in a rainy layby. However, the battery terminal voltage will still give you some vital clues as to what's going on:

Engine stopped
No load: < 12.5 volts : Battery not fully charged or defective
Dropping to < 12 volts under load :  Battery flat or, most likely, defective

Engine Running:

< 13.8 volts: Battery not being charged adequately. Ideally expect to see 14.0-14.5 volts at cruising RPM with normal levels of electrical load



98
Maintenance Guides / How to fit line level outputs to a CCR2006
« on: 21 March 2007, 22:17:31 »
The CCR2006 stereo as fitted to many Omegas at the factory is quite a nice unit in many respects. The 4 CD changer is handy, the radio works nicely and it has nice integration with the MID to update the clock to RDS time. The steering wheel controls are very useful and it has decent support for connecting mobile phone car kits.

Unfortunately, whilst it sounds reasonable at low volumes I find that the power output is not quite good enough for  enthusiatic listening, especially at motorway speeds. In addition, the sound gets pretty harsh even at modest listening levels.

As with many car head units, the CCR2006 is let down by its' power amplifiers. Packing four channels of audio amplification into a DIN size case forces many compromises (although double din, the CCR2006 is built as two separate single DIN units, a radio/cassette and a CD changer bolted together). There is insufficient space for anything other than a couple of small chips to form the power amplifier, the unit is physically too small to dissipate the heat that is generated by more powerful amplifiers and, constrained by a supply voltage  of only 12-14 volts, the power output is limited to a theoretical maximum of 18 watts RMS per channel into 4 ohms with a bridged amplifier.

The solution to the power amplification issue is to use a good quality external power amplifier, of course. Less constrained by space, these have large heatsinks and good quality amplifiers, and have the space for additional power supply circuitry to step up the car battery voltage to a higher voltage, making much higher power levels possible. They also allow the head unit to run cooler.

Ideally amplifiers should be driven from "Line Level" outputs from the head unit, as this bypasses any deficiencies in the power output stage of the head unit. Unfortunately the CCR2006 doesn't have any line outputs available. Whilst it is possible to drive some amps directly from a speaker output, I was concerned that the CCR2006 power amplifiers would still degrade the sound and the amplifier I purchased on EBay didn't have speaker level inputs.

Some would say that a new head unit would be the best choice, and, indeed, it probably is the easiest option. However, there's a limit to how much I was prepared to spend for a line output and I like the way the CCR2006 integrates with the rest of the car and, most importantly, doesn't look anything special to the passer-by. Take away the nasty internal power amplifier and the performance of any CD player / Radio is adequate in a car environment as it's not exactly an environment suited to critical listening.

The following procedure describes how to fit Line Level outputs to the CCR2006. Note that it does require some dismantling of the unit and soldering small components. It should only be attempted by someone who is competent at working inside electronic devices.

99
The following table gives the expected air temperature at the face vents for an air conditioning system in satisfactory condition for various conditions of ambient temperature and humidity. The following conditions should be established in order to achieve a consistent measurement:

Engine running
Climate in Auto mode
Right and Left temperature : "LO" selected
Air distribution to face vents
Recirculation OFF
Front and Rear doors open
ECO mode OFF
Run engine for 15 minutes with bonnet closed
Increase engine speed to 1500 RPM for 5 minutes
All air vents open
Measure flow temperature at central face vents

All temperatures quoted in degrees Centigrade



Ambient TempHumidityFlow Temp
1550%5-10
2050%6-11
2090%9-14
2550%8-13
2580%11-16
3040%10-15
3070%15-20
3540%13-18
3570%19-24


100
The following plots, kindly provided by 2woody, show the effects on gearing of an Omega with the available diff and gearbox options:

















Plots are of road speed in MPH along the X axis against engine speed in RPM on the Y axis in the available gears.

101
Fuel Trim Malfunction codes (0170 and 0173) and Cat Efficiency problems (0420 and 0430) have been mentioned a few times recently, particularly with reference to LPG conversions. I've also chatted with a few members via PM who have been interested in what's behind it and the following explanation evolved, which I thought probably deserved to be available in public.

Fuel trim codes can be a common problem where an LPG system hasn't been tuned accurately or where another malfunction of the engine or associated systems has had an effect on the tuning of the engine. So, first things first. What is fuel trim?

The petrol engine ECU has a number of inputs to tell it about the engine operating conditions and from these inputs it looks up in a calibrated table (called the "MAP") how much fuel to inject into the engine. This results in the petrol injectors being opened for a precisely controlled length of time during each engine cycle called the "injector duration". Since the injectors flow petrol at a constant rate when open, the volume of fuel is directly controlled by the injector duration. This typically ranges from 3 milliseconds (0.003 seconds) at idle to perhaps 15 milliseconds at full load.

The above describes an "open loop" fuel injection system, of the type that were common before catalytic converters were mandatory. The map was calibrated for a given combination of engine, injector flow rate, induction and exhaust system, cam profile, etc. Provided none of this changed significantly the engine remained in a reasonable state of tune, with only the odd mixture adjustment required at MOT time to keep the emissions at idle within specification. Crucially, the ECU is operating "blind" in an open loop system. It delivers fuel to the engine, but has no idea if the fuel mixture turns out to be correct.

With the advent of 3 way catalytic converters the fuel mixture burnt by an engine became more crucial. A catalytic converter will only clean up the exhaust emissions successfully when there is a chemically correct mixture of fuel and air being burnt in the engine. This means tighter control of the fuel mixture. Lambda sensors are the mechanism by which this control is achieved. They give the ECU feedback on the actual mixture burning in the engine.

The most common type of Lambda sensor, and the type used on all Omegas, is termed a "narrow band" sensor. This is because it measures the fuel mixture over a very narrow operating region centred around the chemically correct mixture. Such a sensor can be viewed as indicating whether the mixture is "lean" (too little fuel) or "rich" (too much fuel) with respect to the chemically correct mixture. Basically, the petrol ECU will use the output of the lambda sensors to adjust the quantity of fuel injected (the injector duration) so that the lambda sensors are always at the point of switching between "lean" and "rich", so the average mixture is correct.

It does this by maintaining a variable called a "fuel trim" for each bank of the engine (on a V6 - just the one on a 4 pot). If the lambda sensor reads "lean" it will increment the fuel trim periodically. If it reads "rich" it will decrement it. The fuel value from the map is multiplied by the fuel trim before calculating the injector duration so the fuel trim has a negative feedback effect, adjusting the injector duration read from the fuel map to keep the mixture correct.

The fuel trim is used to compensate for variations between engines, fuels, injectors, etc. to ensure the mixture is always right for the catalytic converters. However, it has a maximum range based on how much trim would normally be expected. If the fuel trim exceeds a threshold programmed into the ECU, a fault code is stored and the EML comes on.

Many ECUs take this a stage further and store a "long term fuel trim" value based on the long term average of the fuel trim that is in use. This variable is often stored in non volatile memory so it is available from start-up before the Lambda sesnors have warmed up. It is also often applied to areas of the map where the closed loop correction is not active, for example at full throttle where the mixture is too rich for the Lambda sensors to provide useful feedback.

Many ECUs also store long term fuel trims in a so-called "block learn table" which effectively stores separate fuel trim values for different areas of the fuel map, as the fuel trim required when idling is often different to that in use when motorway cruising, for example.

Add LPG to the equation and the LPG ECU is watching the injector duration in use by the main ECU and using it to calculate the LPG injector duration required. The tuning of the LPG ECU relates these two durations, and also applies corrections for the temperature and pressure of the vapour being delivered to the engine so if, for example, the petrol ECU uses a 3ms injector duration, the LPG injector duration might be 5ms for the same amount of fuel. If this is done correctly the fuel trim remains roughly the same as on petrol and the main ECU is happy.

Now, let's say for a 3ms duration the LPG ECU only injects 90% of the fuel required, due to a fault in the LPG system or to bad calibration of the LPG system. The fuel trim is increased by the main ECU until the mixture is right. This will require a fuel trim of +10% to correct the situation. So, it is straightforward to see that, if the LPG ECU is not correctly tuned, the main ECU adds fuel trim to make the mixture correct again, and if that trim is too large, the EML comes on.

Incidentally, you can watch this process happening on a Tech 2 or, on later engines, using an OBDII compatible reader. It allows you to view the variables inside the ECU in real time.

102
Omega Electrical and Audio Help / Re: Bose By-Pass
« on: 08 November 2010, 11:28:19 »
You will need to change all the speakers for 4 ohm ones!.

You should be able to disconnect the Bose loom in the driver's footwell, install a loop-back connector from a non-bose car, remove the fuse for the Bose amp feed and that should be it.

Kevin

103
OK. I did it the obvious way on my Omega and it works nicely.

Here's the guide to recap:

http://www.omegaowners.com/forum/YaBB.pl?num=1279100997

One of the things I want to add to the Westfield is an intermittent wipe - it doesn't have one at all, let alone variable!

Anyway, I've been rersearching ways to do this and came across a VW part which implements variable intermittent wipe in quite a neat way.

This wiper delay timer "learns" the wiper interval in the following way:

It starts drizzling, so you flick the wipers once. It keeps drizzling so, when the screen is in need of another wipe, you flick it onto intermittent. The wiper delay timer sets itself to the time interval between your initial "flick" of the wipers and when you switched it to intermittent, and carries on using that interval thereafter.

So.. No need for a stalk with a variable setting and, the best part, this relay is pin compatible with the non-variable timer module already fitted in Omegas without variable intermittent!

The upgrade simply involves lifting the bonnet, pulling out the old timer module and plugging in the new one.

I should stress that I haven't tried this in an Omega as I've already changed the stalk on mine however I have obtained a timer module, tested it on the bench and I can't see any reason why this wouldn't work on an Omega. It behaves exactly as my old non-variable timer module except that you can set the time interval. 8-)

If anyone wants to try this, you will need the timer module which is VW part number 357 955 531. Also referred to on the net as the "99" relay as it often has a large number 99 printed on the case. This site suggests that there are some equivalent parts but I can't vouch for its' accuracy.http://wiki.seloc.org/a/Wiper_Variable_intermittent

I ordered one from ebay seller stevens_vw_dismantlers mid-afternoon yesterday and it was on the mat waiting this morning when i got up (OK, I had a lie-in). :y

I stress that I haven't tried this on an Omega but if someone would like to volunteer to try it out I will agree to buy back their relay if it doesn't work, such is my confidence that it will. Once it has been verified I will add the info to the guide.

Kevin

104
Omega Electrical and Audio Help / dndservices.co.uk
« on: 13 January 2010, 15:39:12 »
http://www.dndservices.co.uk/

Closed due to staff illness.  :(

Hope everything is OK, Dave.  :y

Kevin

105
Omega Electrical and Audio Help / Central locking motor
« on: 18 January 2008, 09:55:21 »
My driver's side central locking motor plays up occasionally. It seems to go through a phase of being lazy for a week or so at a time. It moves the button up but not quite far enough to unlock the door, so I have to nudge it round with the key to open the door.  

As I say, it'll d!ck me around for a week then work faultlessly for several months before playing up again.

I have to remove the door card at some point to change the speaker and I'm wondering whether to lube everything up or just change the C.L. motor.  :-/

Anyone know how much a motor is, what the normal failure mode is, and what my likelihood of success will be on just lubricating it?

Also, what's the best lubricant? White grease? Silicone? Something waterproof that doesn't go too thick in the cold, presumably?

Cheers,

Kevin

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