FLASH CODES/SCAN TOOL/ EXHAUST GAS ANALYSIS

when you turn your ignition on the engine check light should come on and then turn off after one or two seconds, if it remains on it means the car has found an internal fault with one of the sensors or actuators it monitors. To find out what the code is for you will need to find the diagnostic plug and bridge(connect with a wire) two of the terminals in it, you should consult the manual to find out exactly which ones. Once they are bridged start the car again and the engine check light should flash this time. there is a link to this happening below.

FLASH CODE

Once you have got this happening you will need to read the flashes. The code starts at a space of about five seconds, and ends at the next five second gap and between them there may be one or more separate codes. each separate code is separated by a gap of two and a half seconds. To read the individual code count the flashes till the first one and a half second gap and then count the flashes till the two and a half second gap, the first count is the first digit and the second is the second. Once you have this number find the cars manual and look up the number and it will tell you what area has had a fault.

the code in the video was 31 which was for the MAP sensor, on closer inspection I found it was not connected correctly, So I reconnected it and checked the engine check light again by starting the engine and the light was no longer going.

I with the problem with the MAP sensor the ECU would not of had enough data to get the fuel ratio right and would of probably run rich.


SCAN TOOL

Below are images listing the live data that I retrieved from my 328i at idle, this information is very useful as it can give you an overview of how the engine is running.

Below is a list of the fault codes that were stored in the ECU when I first connected the scan tool.

At a first look a list like this might seem bad but once I cleared the list most of them did not reappear, this is because the errors had been stored from when they have had problems earlier.

Once the existing errors had been cleared I had an intentional error put into the engine and rechecked the errors. as you can see above there are two errors, the first said there was a problem with the IAT sensor, upon my initial visual inspection I noticed a connection that was lose so I reconnected it cleared the fault codes and rechecked them. The only one that was left was the tank vent valve that was not introduced so I will have to inspect that at some stage.

the scan tool is really good for helping find problems with a car, it can give you a direction to look in when there is a problem, but it needs to be remembered that the scan tool can only give you information it knows i.e. it may say that there is an error in a temperature sensor, but the problem could be in the wiring anywhere between the ECU and the sensor or it could even be the ECU itself sometimes a faulty earth on the ECU can make the scan tool register an error in another system so you still need to test the unit before replacing it. Also with the live data option you can compare voltages and other sensor readings easily.

EXHAUST GAS ANALYSIS

Above is the display of the exhaust gas analyzer, it is currently displaying the readings for normal air, the CO(carbon monoxide) level is almost non existent CO2(carbon dioxide) is at .22% O2(oxygen) is 19.38% HC(hydrocarbons of fuel) are 27PPM(parts per million) and NO(oxides of nitrogen) are 3PPM and Lambda is not registering. as this is only reading normal air al these readings are telling us is what state the air is in before it enters the engine. The reason Lamda is not bringing anything up is because lambda is the fuel ratio of 14.7:1 so there is nothing in the normal air to read.

Above are the readings as the engine is warming up, the CO is high as the catalytic converter has not warmed up so is not converting into the less harmful CO2 and that is why the CO2 is a bit low. It is also not separating the oxygen from the nitrogen so the NO is high. Also this car has a vacuum leak so the lambda is above 1 meaning it is running lean.

above is the vehicle at idle and warm the CO and the NO are low because the catalytic converter is stripping the oxygen off the NO and attaching it to the CO to create CO2 which is a far safer gas.

above is the engine running at 2500 RPM as you can see the CO2 and NO are higher as the engine is   running richer which is also means the O2 level is down.

above is the engine under acceleration. because it is being given extra fuel the HC has risen so has the NO and CO as the gases are traveling through the catalytic converter to fast to be converted.


If I was to make the engine run rich the HC would raise from the excess unburnt fuel. the CO2 would go down and the CO would go up because the fuel isn't burning properly and the O2 would go up as it will be all burnt.  And lambda would go below 1.