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Discussion Starter #1
Audi A8/D2 2.5TDI V6 132kW tiptronic FWD facelift (year 2000)

ESP/ABS warning lights come on and off. Before it was occasionally, but now it starts a while after I start the car for the first time a day.

It doesn't have some specific on/off pattern.

When ESP/ABS lights come on, the engine changes how it sounds and when I put the Auto-transmission into D it is one very brutal engaging. But, in R it is normal. Just in D is very rough.

I was trying to figure out what was the culprit, and finally I think I have found it. When I disconnect injector needle motion (INM) sensor cable, warning ESP/ABS lights generally stop turning on. They can still light on at some point, but not constantly turning on/off.

The resistance of the sensor is 125Ohm while hot, and it is less (118Ohm) when it gets a bit cooler.
The voltage measured at the connector coming from ECU is 10,9Volts. Are these value readings ok?

What to do next in order to fix the problem? Can I drive it with INM sensor disconnected for a while without risking the engine getting damaged? Is ECU the actual problem?
 

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First posts normally go in introductions else you could get a free fix and we never see you again!!!

Forum Rules and Guidelines


This is a new forum layout which is owned by a company last year that doesn't give a dam with loads of bugs which have been reported in the new thread. There is no TDI Wiki at the moment or original similes which they refuse to install. It doesn't show the car spec/location.

Add your car specs to your signature that will show on every post you make.

We Are Live - Community Feedback

This has been talked about many times.

I've made a poll which no one has posted in, there are a few votes and comments.

Do you like the new forum features?

Wiki pages have been restored as of 7th December, I asked where is the link it should be on top of the main forum.

You need to get your motor scanned (preferably with VAG-COM\VCDS) for any error codes logged in the ecu and post them, that will save a lot of guessing and check systems out.
 

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Discussion Starter #3
Mister Moderator, this is actually useful for all those who had the same or similar problem. I generally know what is the problem with my car and I don't actually really need this, but people who would join this thread/discussion would learn something here and improve their knowledge along with helping me to clarify what was going on with this particular engine. I am not a mechanic, just an enthusiast and I know some things, not everything. I can help people here by giving my opinion only about car issues that I have experienced or resolved. Even if I come here occasionally we would all benefit from it.
 

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Discussion Starter #4 (Edited)
Ok, here is the answer. Might be useful for some of you. I had to readjust timing of the high pressure fuel pump for about 2.75° (it is 5.5° at the crankshaft) counter clockwise (advance direction) to achieve 0.5° warm engine idle timing. I suppose that the ECU sends pump command to advance/retard injection for some angle (+0.4° factory setting) and injector needle movement sensor sends back the signal that it has much different angle achieved than commanded, then ECU activates limp mode, disables turbo. It tries to set correct timing continuously but cannot and so you get ESP/ABS light on/off again and again.

So, incorrect IP timing will activate ESP/ABS warning lights to come on. No other warning signals, just ESP and ABS.

Be careful, there are other issues that set these lights on. For example, failing boost pressure sensor can also cause problem with timing. Broken MAF wire for intake air temperature signal also. Whenever ECU realizes that there is something wrong about timing, or that there are not enough valid data or incorrect data or anything that prevent ECU to precisely calculate timing angle you will get warning.
 

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Interesting. It seems your ESP/ABS acts like the glowplug light on others.
 

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Discussion Starter #6 (Edited)
Interesting. It seems your ESP/ABS acts like the glowplug light on others.
Glowplug light was flashing when there was a problem with fuel supply and the other time when I had problem with brake pedal switch being screwed a bit less than needed.

About brake switch. It has two NC contacts (contacts are closed at rest position). They may have slightly different moments of closing/opening so one should be careful about that. You may have brake lights off (contact open) and the other contact that gives information to the ECU that brakes are applied may be on. Since ECU checks brake lights, it will be "confused" about that. This is what I suppose there was going on, I am not quite sure about this.

About fuel supply. Tank has a baffle housing inside which must always have fuel in it. If not, the ECU will realize that and activate glow plug light flashing. Usually the culprit would be a tank fuel pump failure or its electrical connections, wiring etc.
 
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