1) Frequently asked questions are here 2) Also a great video showing how to trim fuel at idle for best mpg using vagcom here 3) VAGCOM GUIDE: CHECKING MAF (MASS AIR FLOW METER) AND MAP (MANIFOLD ABSOLUTE PRESSURE) SENSORS... A quick look at what we are doing here... I'll be talking in absolute pressure, this reading includes atmospheric pressure within the reading, atmospheric pressure is around a bar at sea level so on an absolute pressure sensor you will see a bar pressure without the engine running...so basically, take your reading, minus a bar from it and that is the boost level you are getting in the inlet manifold... The MAF is an Mass Air Flow meter which measures the amount of air being sucked in by the turbo...The MAP is a Manifold Absolute Pressure sensor which measures the amount of pressure within the inlet manifold (connected to the ecu via a slim pipe from the inlet manifold as the MAP is within the ecu)...the two are linked as the amount of air a turbo sucks is dirctly relatable tot the amount of air it can push into the engine So, to recap, without the engine running, the MAP will read a bar shown as 1000m/bar The following vagcom vagscope image shows readings from my car with a healthy turbo, healthy maf and a sealed boost system Its healthy because the maf peaked at near 850mg/st and the map sensor peaked at just shy of 2.2bar absoulte meaning 1.2bar of boost, this is the peak, the hold is around a bar of boost (2000m/bar on the gauge) The follwoing image is from my mates car with a healthy turbo, a healthy maf and a boost leak You can tell this by the fact that the maf reading is near 850mg/st so the turbo is sucking enough air for 1.2bar as before but the manifold pressure (map) is only 1.5bar absolute (0.5bar boost)...down 0.7bar on my car (the boost leak was traced to a cut in the flexi boost hose between the plastic pipe and inlet manifold) Both cars were run up to 3k rpm in third gear To get these little gauges you do the following select engine select measuring blocks (then choose the ones you want, for this you want the ones in 'air supply', i'll add the block number later) select vagscope once the scope comes up you'll see coloured squares beside each block, right click on each colour square to display the gauge as shown below right click again on the displayed gauge to check or select your options ...you can have up to 12 gauges at once by using three rows of four meauring blocks, all of which keep peak readings if selected If you are getting the top readouts then you could quite safely assume that everything from the MAF to the MAP in the ecu and all pipes inbetween are in good health, so a well worthwhile test Please note, both cars have had the egr's electronically turned off hence the 450mg/st+ readings at idle, none egr deleted cars float around the 380mg/st mark 4) VAGCOM GUIDE: DELETING EGR ELECTRONICALLY Firstly, What's an EGR? EGR stands for Exhaust Gas Recirculation which is generally a vacuum controlled valve that sits between the exhaust and inlet manifold, at preditermined times, mainly at idle and cruising conditions, the egr is opened and exhaust gas is sent back into the inlet manifold...this reduces NOx emissions... WHY DELETE IT? Well, the above is all well and good for manufactures to reach their emission targets but the offshot is soot in the inlet manifold restricting the engines ability to breath, lessening mpg and performance. In severe cases, a costly de-coke is required as the soot has backed up on the back of the inlet valve and the inlet ports in the head. CAN I JUST BLANK IT OFF? Yes, you can but the ecu is still looking for a reduction in MAF readings when the EGR is supposed to be open, this is how it checks the egr is still doing its job. Delete it electronically and the ecu knows not to be looking for a MAF change anymore. You can do both electronic and mechanical blocking if you like HOW DO DELETE IT? using vagcam do the following Select Engine Select Login Enter 12233 to activate special adaptations Select Do It! Select Adaptation Enter channel number 3 In "new value" put the highest value possible, usually 33768 or 188 for older ecu's Select Test Observe the "test value" field to make sure the adaptation setting is acceptable Select Save and you are done 5) VAGCOM GUIDE: CHECKING INJECTION TIMING WHY IS THIS IMPORTANT? Out of the three cars i have tested using this, only one was where it should be, the other two saw power and mpg improvents so well worth doing WHAT WILL I GAIN? More mpg, more power and less smoke WHEN IS IT WORTH DOING IT? If you have never had it checked before then get it done. Also, whenever the cambelt has been changed it needs doing again. The timing belt will slightly stretch over time so it's worth checking periodocially HOW DO I CHECK IT? Your engine has to be warm (coolant above 85C) so take it for a spin before attempting the check Go to Engine select Measuring Blocks Switch to Basic Settings select tdi timing on the righthand side to see the following graph appear select your engine type from the tab on the lower right hand section of the graph and check your timing Specification is between the red and green lines but ideally you want to be between the blue and green as shown above with the timing result reporting 'timing within spec but advanced' Setting is done mechanically, slightly rotating the pump shaft once its three screws have been loosened (replace these as early bolts were one use) on cars with vernier pulleys on the pump....older cars require the pump body to be moved upon it's mountings It is strongly discouraged to set your timing outside of the specification! Some videos i made for reference [YOUTUBE]7zET8soUlow[/YOUTUBE] [YOUTUBE]__eoHl_ZxdU[/YOUTUBE]
these diesel things are amazing, just wait till you start stripping, and setting up/altering VEP pumps using vagcom! it's one tool i can't live without outside work!
Excellent info there. Having had the dis-pleasure of de-coking and removing the soot / oily tar like build up from the inlet manifold and inlet ports of a few engines in the past, EGR delete has got to be a worthwhile modification.
one for the research, I have been running EGR delete the mk4, with no software adaption/remap - my fuel consuption isn't great for a diesel - shes happier and burns less being driver at higher revs (above 2K) I think I'll have to start taking logs on gentle drives to work (same route/speeds) mainly the EGR duty cycle and the MAF reading, then the same with the plate out
Is your mk4 a ve tdi or pd?? If ve, then i would do the software adaption and see if you have an improvement? On my own mk3 i have done the egr software adaption and have the timing spot on and know that the turbo/maf and map are all working fine....i am currently averaging 53mpg My idle injection quantity is a little high at 5.3mg/str at the moment....i'll soon be updating all the seals in the pump to viton seals (the pump head seal and shaft seal are not viton in bosch rebuild kits) along with viton fuel return line kit to make the fuel system more suitable for veg oil. I'll adjust the idle injection quantity to 3-4mg/str after that has been completed...this should lead to slightly better mpg, throttle response and reduce full load smoke
I was trying to turn my EGR off electronically at the weekend, and followed the 'How To' on the Ross-Tech site using adaptations. However, instead of the 5 figure code for the EGR value on their site (Group 3) mine shows a starting value of 128, and gave me an error when I tried to adjust it. In fact, 128 seemed to be the starting value for all the groups I tried. Also, I'm seeing inconsistent readings in VAG COM when I look at measuring blocks. The car has a lumpy idle (and has had since I've owned it) and is juddery at very light throttle openings (on tickover - see the lumpy idle - and just as you come off tickover). I was planning to adjust the injected quantity at idle, but it jumps around all over the place. I've started wondering if there's a more basic problem here - power feed to the ECU / ECU relay or something similar. I took a short video to show the movement in the values. I'll upload it later. I'm getting the injection quantity jumping around all over the place, and the RPM signal is inconsistent between the two readouts. I wonder if that's because the reading is being taken at different points in the engine's cycle, or from different sources. I thought one of the sources could be the third injector, but when I unplug it, it makes no difference. Could the pump be a source of an RPM signal. or is it all from the crank sensor?
Is it possible the ecu has suffered minor water damage, my starting issue has been solved by trying a friends ecu (with imobiliser delete). Worth taking a look, you can solve a fair few ecu problems just by sticking the ecu in an airing cupboard over night (assuming the damage is water ingress and not perminant)
Maybe, but other than idle control and the odd readings above (which could just be something I'm doing wrong), the car runs fine. I'll have a look at the ECU and see if there's any sign of water marks on it. the cover over the scuttle looks in good nick, so no obvious gaps for water to get in.
Mine drove fine too. Dont forget with the freezing weather any slight water ingress gets worse due to the expanding ice. Worth a look just in case
Older ecu's need the value changed from 128 to 188 as listed in my guide above mike Have you checked for air ingress at your clear feed pipe?
Thanks for that. I'd been looking at the TDIforum version of that FAQ. I can't see any air bubbles or anything like that in the clear pipe, or leaks from the pressure pipes (which would be pretty obvious). I assume that's what I'm looking for. The car starts within a few turns of the engine from overnight, even in the cold weather, and almost instantly at other times. condition of the glow plugs is unknown, but they seem to work. Pump timing is at the advanced end of the spec, but within the lines. I've tried different settings but it doesn't cure the idle issue. Fuel and air filters are only a few months old (5k miles, ish) VAGCOM registers no fault codes
Maybe... but short of pulling them all out and sending away for cleaning, I'm not sure how I'd tell. I was thinking of trying some injector cleaner additive, but I don't really believe in most of that sort of stuff. Someone I know used BG engine additives in his Audi 80 TDI recently, and reckons it's a bit quicker and more economical now. The conflicting RPM readings still makes me think it might be electronic rather than fuelling though.
I have sold BG and used it alot, its very abrasive and can cure large build ups, can also do damage as well if not diluted properly. Millers is the best all round stuff and actually works. Have you tried the injector union nut break off test?
