Strange idle connected exhaust vibration

[newsh]

To check for shorts, unplug both ends (the ECU and the ISV) then meter between the pins on the ISV connector. (If there are 4 pins you have to meter all the different combinations!) There should be no connection anywhere (ie. infinity or very high resistance in the megohms region). If you get 0 Ohms or a few ohms or even a hundred ohms there is a short circuit between the wires.
Repeat for the TPS connector.
Repeat for the Temp sensor on the back of the block

[220bhp]

I will do my best and report back.
Many thanks.

[twoqu]

The output test in Vagcom would be the thinking man choice to check the operation of the ISV! You just go through the individual injector tests and onto the ISV.
At least you would be able to identify whether the ISV was working by either the clanking of a fitted one or the operation of a spare connected up. The clicking of the carbon cannister and the wastegate valve is also pretty clear which would also prove the power supply was ok as they are fed off the same fuse and therefore the fuel pump relay.
However if it was not heard/observed working, then you would still have to methodically check all the wiring to find out why.
Had a bit of trouble after the output tests reconnecting Vagcom, even though I could connect using the same interface straight away on the A6. On one occasion the ISV continued to clank even after the interface was removed!
Took a few goes to re-establish a connection. I guess thats the first time in 20 years the ecu has been instructed to perform that task!

[Greg_S]

What was the outcome from the plug testing?

[220bhp]

What was the outcome from the plug testing?

I have been so busy at work,almost 24/7 and have not had the time to do anything.
I need to find a couple of hours to go through every thing systematicly, and log all my results
as twoq suggested.
Hopefully I can get to it this weekend.

[220bhp]

Managed to do some tests this morning.
pin 6 on tps to pin 52 on ecu connector.continuity ok

pin 4 on tps to pin 10 on ecu connector.continuity ok

pin 4 on tps to pin 2 of isv conector continuity ok

pin 4 on tps to small earth on im.continuity ok

pin 52 on ecuconnector to pin 10 connector on ecu continuity ok

Then | tried to test for shorts and found that Ihave a reading of 00.9 ohms on pin 6
of the tps to ecu.that I think is short.
Then from pin 4 on the tps to pin 2 on the isv there is no connection.
I do not no what these two problems, will cause but I need to trace the wires to find out.

[twoqu]

Lou,

I am a bit confused on the pins!
If with the tps connected there is continuity between pin 52 and pin 10 of the ecu connector and continuity between pin 10 of ecu and pin 4 of tps (earths) then the idle switch circuit is intact. That leaves the ISV control circuit.
The power side is fuse S24 to ISV pin 1 and ecu pin 4 to ISV pin 2. So there should be continuity on those connections.
I think you have put tps when you should have put ecu! I don't think that pin 4 of the tps is connected to pin 2 of the ISV, the ecu pin 4 should be!

[220bhp]

Robin I tested the wireing again as you say above and all was ok. I did test the wireing between 4 on the tps and 2 on the isv as well and found no continuity,but i am not sure if that is the correct thing. however dispite the fact I found continuity between pin 6 of the tps to pin 52 on the ecu connector,I also when testing for shorts as John said,and found that between these pins it regestered a short,showing 00.9 ohms on the mm.
I also tried bridgeing between 4 and 6 0n the TPS with the engine running, but there was no change in the idle,it stayed at 1050.
I also have change the ecu,fpr and injectors back to the rs2 package this weekend as I need to return them.

[twoqu]

Still confused to be honest!
Why are you testing between pin 4 on the tps and pin 2 on the ISV?
If we accept that the idle switch circuit is ok, thats ecu pin 52 and pin 10 have continuity (through pins 4 and 6 of the tps) and that pin 4 of the tps and pin 10 of the ecu have continuity and are earthed, we can look at the ISV circuit.
The ISV needs 12V from fuse S24 with engine running on pin 1 of ISV and continuity between pin 2 of ISV and the ecu connector pin 4. So do you have both of those?
If you do then the only other possibility is that its the ecu circuitary that controls the ISV. The ecu controls the ISV by switching it to earth using a duty cycle so its not earthed all the time.
I have quickly tested mine. The ISV pin 2 is not connected to the TPS pin 4 with everything connected which is what I expected. I think you are confusing pin 4 of the ecu with the tps. It is the connection of the ISV pin 2 to ECU pin 4 we need to check for continuity not the TPS. The tps tells the ecu that the throttle is closed. The ecu controls the ISV to idle using pin 4 of the ecu.
So do we have 12V on pin 1 of the ISV with the engine running?
Do we have continuity betwen the ecu connector pin 4 and the ISV pin 2?

[220bhp]

.I gess I was confussed, and checked between 4 on tps and isv,mistake on my part.
Yes I do have continuity between pin 4 of the ecu connector and pin 2 of the isv connector.

[twoqu]

Ok!
Still need the answer on the power!
Find a good earth and test the connector for the ISV pin 2 and the ecu connector pin 4 for continuity. If that connection was shorted to earth then as soon as the ISV was powered, it would open fully and not be controlled by the ecu.
This is certaintly the long winded way. The output test in Vagcom would have been easier!
Basically it comes down to how the ISV is being controlled. If its not powered then it will not function and be at the default stop - idle 1050. If its powered but not being controlled by the ecu via earthing, then the same result. I am not sure what the effects of a powered but earthed permantly ISV would be other than the rotary valve would be fully open. Whether that would allow the car to idle higher than the default 1050 rpm or not I don't know! Clearly it would be the absolute maxium possible.

[220bhp]

Robin,I have continuity between pin 2 on the isv and pin 4 on the ecu connector.I am sorry but I do not what you mean when you say find a good earth.
I placed one probe of the multy meter in the pin 2 on the isv, and the other in pin 4 of the ecu.I then turned the meter to the resistens setting and it reads oo.3 ohms,

[newsh]

By a good earth he means a clean place on the engine or chassis of the vehicle, like the Inlet Manifold. Neither of the ISV pins must connect to chassis.

Have a look at this. http://www.s2central.net/images/3B_ECU_Schematic.jpg

Up the top you can see the fuel pump relay, the ISV, WGFV and Carbon Can' valve are powered from a pair of contacts on this relay via fuse S24 10A. These contacts also power the fuse for the injectors so they must be ok because your injectors are firing.

So you should have power to the fuse S24 when the engine is running.

1/ Make sure the fuse is good. (It's one of the extra fuses on the front lip of the fuse box)
2/ Disconnect the ISV and the WGFV and the Carbon Can Valve.
3/ Start the engine so that the Fuel Pump relay is closed. (alternatively you can pop the top off the fuel pump relay and close it with a rubber band, if you do this then pull the fuel pump fuse, S13 so the fuel pump doesn't run, this is a good alternative if you have to work indoors!)
4/ With the multimeter set to 20V DC, measure between chassis and the pins on the ISV connector, you should have have 12V on one of the pins, (The other pin goes to pin 4 on the ECU connector)
5/ Still with engine running, now measure for voltage on the WGFV connector, one of the pins should have 12V. (The other pin connects to pin 23 on the ECU connector)
6/ Now repeat for the Carbon can Valve, one of the pins should have 12V(The other pin goes to pin 5 on the ECU connector)

7/ Stop the engine and disconnect the ECU connector.
8/ With the multimeter set to Ohms measure between the 2 pins on the ISV. There should be no connection (infinite or several Meg Ohms)
9/ With the multimeter set to Ohms measure between the 2 pins on the WGFV. There should be no connection (infinite or several Meg Ohms)
10/ With the multimeter set to Ohms measure between the 2 pins on the Carbon Can Valve. There should be no connection (infinite or several Meg Ohms)

Let us know your findings at stages 1/,2/,3/ etc!

[twoqu]

Robin,I have continuity between pin 2 on the isv and pin 4 on the ecu connector.I am sorry but I do not what you mean when you say find a good earth.
I placed one probe of the multy meter in the pin 2 on the isv, and the other in pin 4 of the ecu.I then turned the meter to the resistens setting and it reads oo.3 ohms,

Lou,

If the ISV wire back to the ecu was shorted to earth, perhaps by having chaffed on the car body, which would open the ISV fully as I understand it, then it would also have continuity with earth. By touching one probe on say the battery neg terminal or an earthing strap, you should be able to tell that.
Just trying to work through the conditions that would allow the ISV either not to function or function incorrectly.
I would think that by connecting a spare ISV to the connector and leaving the other ISV in situ, you would be able to observe whether that ISV wire back to the ecu is shorted to earth. If it is shorted the ISV will open fully and stay there with the engine running as it will be powered.
As John has said, it would be useful to know if the ISV is getting power.

[220bhp]

Thanks Robin, and John for your help today,but I have let you down. I just snaped the Hollow nut that connects the fuel pipe to the fuel railIn my attempt to change the injectors etc.What a prat I am one step forward ,and two back.
I have had this ecu and fpr on lone for to long now, along with your pressure test kit John.and felt that is time to return them to there rightful owners. so I have been at it all day with this dam car,then I do something stupid like this.
No way I am going to get a replacement around hear for a few days at least.
I take it its an audi only part.

LOU, pissed of and very frustrated