From Audi 100 to urS4 in a week

[newsh]

Dave will be along to show you where the "Motor" fuses are then. On the S2 they're in a little red 2-wide fuse holder at the front of the fuse box.

[hunker7]

I used the sticker on the cover, doesn't say anything that could be "motor" Sure Dave will know

[UrS4boy]

20vt compression testing protocols

So bought a compression tester today, just to try it out, I tested first two cylinders. What I did, I disconnected the 12v that go to coils, and removed one cylinder at the time, and when I turned the engine, in both cylinders I got a loud "pow" sort of noise. Could it be that valves won't shut properly and therefore the compression is so low and it won't run right?

No it could be that you didn't remove all the spark plugs as per the protocol in the AAN manual that I know that I have pointed out to you before.

Here is summary are the protocols for SAFE compression testing:

To start, remove *ALL* the spark plugs, as detailed in this Spark Plug Replacement post.

To disable fuel going into the cylinders during this exercise, pull No. 17 fuel pump fuse *AND*pull the injector connectors off OR remove the injector fuse in the brown S72/116 fuse holder above the ECU, as shown in this AAN above ECU fuse call-out post (equivalent S2/RS2 fuse is No. 28 in the fuse box under the bonnet )

From a previous kinderutz post:

Compression pressures
New: 9-14 bar (131-203 psi)
Wear limit: 7.5 bar (109 psi)
Max. permissible pressure difference between all cylinders: 3 bar (44 psi)

Check page 42 of 93 in the pdf linked below:



http://s2-audi.co.uk/workshop/aan/aan.pdf (also works for ABY and ADU)

[newsh]

[hunker7]

No it could be that you didn't remove all the spark plugs as per the protocol in the AAN manual that I know that I have pointed out to you before.

Here is summary are the protocols for SAFE compression testing:

To start, remove *ALL* the spark plugs, as detailed in this Spark Plug Replacement post.

To disable fuel going into the cylinders during this exercise, pull No. 17 fuel pump fuse *AND*pull the injector connectors off OR remove the injector fuse in the brown S72/116 fuse holder above the ECU, as shown in this AAN above ECU fuse call-out post (equivalent S2/RS2 fuse is No. 28 in the fuse box under the bonnet )

From a previous kinderutz post:

Compression pressures
New: 9-14 bar (131-203 psi)
Wear limit: 7.5 bar (109 psi)
Max. permissible pressure difference between all cylinders: 3 bar (44 psi)

Check page 42 of 93 in the pdf linked below:


http://s2-audi.co.uk/workshop/aan/aan.pdf (also works for ABY and ADU)

What is meant by "new" and "wear limit"? As I thought 9bar is minimum compression allowed

[UrS4boy]

http://12v.org/urs/DaveTsRS2FuseBoxS...osticPlugs.jpg

Number 28 in that photo.

For the UrS4/S6s, it is the fuse in the yellow fuse holder in the rack above the ECU. OR just disconnect all the injector electrical plugs (probably easier than digging down to the AAN ECU).

[newsh]

New is when the car is new.

Wear limit is the point at which the engine should be rebuilt or refreshed.

[UrS4boy]

What is meant by "new" and "wear limit"? As I thought 9bar is minimum compression allowed

I don't know why the "new" low limit so low. That is just a quote from the AAN manual. I presume that the manual's writers knew what they were talking/writing about.

[hunker7]

New is when the car is new.

Wear limit is the point at which the engine should be rebuilt or refreshed.

That's good then. First one showed 9bar, second was 9.5, but will recheck them tomorrow "the proper" way. I was planning engine rebuild, as I thought 9 is the lowest it could be before engine should have a rebuild. Good news there.

[newsh]

I don't know why the "new" low limit so low. That is just a quote from the AAN manual. I presume that the manual's writers knew what they were talking/writing about.

Probably depends how well the rings are bedded in, the compression usually goes up during the running in period.

[hunker7]

Probably depends how well the rings are bedded in, the compression usually goes up during the running in period.

So, as long as compression is between 9-13 engine is completely fine?

[newsh]

That's the idea!

[hunker7]

That's the idea!

Well then I am a happy chap. I do have to do the head if I am keeping the car, so that could improve it.

[Majorcina]

Some good news i see

[hunker7]

Some good news i see

Indeed. Made my day this

See what comes up when I check compression by AAN manual