If the AMM (MAF) fails completely the engine ECU reverts to an in built guess of air flow. The pink EGR actual trace on the graph roughly follows the EGR specified trace. So the EGR actual trace should look similar to the EGR specified trace. You are expecting 300-400 mg/stroke at idle and 800-900 mg/stroke at high revs. The EGR actual trace shows you the Mass Air Flow into the engine recorded by the AMM (MAF) sensor. You need the EGR specified trace on the graph so that you can compare it with the EGR actual trace. This hardly surprising as the faster engine must suck in more air. When the accelerator is pressed the specified EGR rises rapidly to 800 mg/stroke at 1400 rpm. The EGR specified value at idle is 300-400 mg/stroke so the blue line starts low at 1300 rpm. I have not included EGR duty cycle on the graph. Use Excel to produce a graph of your log. Log the four EGR sections as you accelerate through the gears up to 4000 rpm. 3, Exhaust Gas Recirculation (actual)Ġ03. (The EGR measuring block values are MAF values)Ġ03. To evaluate Air flow you need to look at EGR (exhaust Gas Recirculation) and MAF (Mass Air Flow).Īs far as VCDS is concerned, these are the same thing because most engines can only log data for the AMM (MAF) sensor. So if the ecu thinks the temperature is below 89 degrees C, it will not run on it's optimum economical settings. (Coolant temperature if fuel temperature sensor fails)Īdjustment temperatures are approximately: The over riding factor for adjusting these maps is Fuel temperature. The engine ECU may be relying on 6 Duration maps and 10 Beginning of Injection maps for Injection Quantity. The Fuel and coolant temperatures are far more important than you might think. If the air intake temperature is considerably different to ambient temperature, change the Air Intake Sensor. If the fuel temperature graph looks odd or goes too high/low, change the fuel temp sensor.Īir intake temperature should be similar to the outside temperature on the day of test and should stay constant.
#VCDS MEASURING BLOCKS LIST CODE#
Pre CAN vehicles like the B5 passat cannot self diagnose a cooling problem so you have to do a test like this.ĬAN vehicles like the B6 passat will flag a fault code if the engine ECU detects that the warm-up graph is incorrect.Ī Fuel temperature graph should look the same as the coolant graph.
I have only included Coolant temperature to make it easier to read. The excel graph will look something like the one below. You need to turn this log into an excel graph. This will be a very long log which has Time Stamp as one of the columns. When you get back, save the log you have produced. Go for at least a 20 minute drive to bring the engine up to working temperature. Start the engine from COLD and select log START.
#VCDS MEASURING BLOCKS LIST HOW TO#
This assumes you know how to engine measuring blocks.Ī good, first check, is the engines coolant, fuel and air temperatures as these are very important for fuelling.įind the block that displays temperatures. It is advisable to fit a new air filter and fuel filter before running any checks. Injector diagnosis (You can't diagnose injectors using VCDS)
The following measuring block checks will help you investigate an engine problem that hasn’t logged a fault code. Pre CAN control engines tend to need more diagnosis while CAN control engines do more self diagnosis. The information here is only a general guide as there is variation between engines. It is a good idea to log your engine when it is healthy so that you have something to use for comparison when your car is not healthy. This guide applies to most VAG pd tdi engines.
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