Timing pull on only one cyclinder

[rsmith]

Hey Peeps,

Looking for suggestions to my problem that is doing my flippin head in.Over all the car is running great, everything is as it should be but i cannot go any further with tunning untill i get this problem sorted.

I get timing pull(CF's) consistently on cylinder 2, all other cylinders will log 0 CF's where as cylinder 2 will consistently read 5-6 CF's starting at about 3500rpm.

So far i have swapped coils, new plugs(colder again), tried different gaps, 0.028 and then 0.024 and swapped injectors over and its still them same.

Any suggestions, i am not running crazy timing and i am basically stuck.

All and any comments welcome.
Thanks for looking.

 

[Pyro]

subscribed sorry i know its no help but im interested

 

[DaNnY_LaD]

You done a compression test rob?

Too rule out the compression..

 

[rsmith]

You done a compression test rob?

Too rule out the compression..

No,
What would a compression test tell me about the cyclinder?
Any guides?

Thanks

 

[Murdered LCR]

Compression tests are easy take the spark plug out starting from cylinder one screw the compression test in turn the car over for a few seconds until you get a reading on the gauge any where over 10 bar is fine any thing less then your loosing compression

 

[DaNnY_LaD]

A compression test would tell you that something is wrong in that cylinder is the readings are .5-1bar of each other then there fine...

Takes 20mins todo and you can rule out the mechanic of the cylinder...

 

[rsmith]

I have a compression test tool alright, what's the exact proceedure do you know?, I read different ones on the Internet.

 

[rsmith]

Looks like this is the one i need:

http://forums.audiworld.com/showthread.php?t=283328

 

[rsmith]

Compression test results are in, they appear to be in the 10% + - range.

Cylinder 1 = 11.2 bar / 162psi
Cylinder 2 = 10.9 bar / 158 psi
Cylinder 3 = 11.6 bar / 168 psi
Cylinder 4 = 11.8 bar / 171 psi

Cylinder 2 is defo down but not massively out of spec.

Now i am utterly confused

 

[LEE69]

Only just in the 10%, maybe where your problem lies?

 

[DaNnY_LaD]

Stick a teaspoon of oil down cyl 2 and test again..make sure its new oil

 

[rsmith]

Only just in the 10%, maybe where your problem lies?

True, the highest figure being 11.8 and the lowest 10.9, thats a 0.9 bar difference where the 10% threshold is 1.18bar.

What would cause the pressure to be lower in this cyclinder?

Stick a teaspoon of oil down cyl 2 and test again..make sure its new oil

What would that do? no being smart just trying to learn.

Also is it normal to hear popping when doing the test?

Thanks lads

 

[LEE69]

The oil will seal the rings so if the compression goes up, it points to the rings.

 

[LEE69]

Sorry if the seal of the rings is poor it will be a lower compression.

If the oil makes no difference, it might be the valves leaking.

Popping might be just the other 3 cylinders because they have no plugs in them?

 

[rsmith]

Cheers lads, i just finished putting the car back together about an hour ago, fitted new coilovers so i have enough oil and dirt on my hands for one day, i will get to it tomorrow.

Here is more good info straight from the bentley manual, just for future peeps.

http://forums.vwvortex.com/showthread.php?3521125 Step 5. should be fuse 28 for our motors.

 

[LEE69]

44 psi that says you are well with in that.

 

[rsmith]

Yeah, some guides are saying 10% others 20%, but i would trust the Bentleys manual for sure.
I wonder would carbon build up be the problem, i might run some injector cleaner through the system and see if it improves.

Edit, i run water and methanol & octance booster sometimes, surely my engine should be squeeky clean.

 

[DaNnY_LaD]

if you put oil in too the cylinder and the compression raise its todo with the rings...If it stays the same points toward the valves/Seats....

Me Personally i think 11 bar is rather low...Mine was 13 bar on 1,2,3 but 4 was 11bar which was the one that i had sysmtoms with...

 

[carlossus]

It's worth checking that the knock sensor for cyl 2 is properly fixed.

 

[rsmith]

if you put oil in too the cylinder and the compression raise its todo with the rings...If it stays the same points toward the valves/Seats....

Me Personally i think 11 bar is rather low...Mine was 13 bar on 1,2,3 but 4 was 11bar which was the one that i had sysmtoms with...

Thanks for the tip, reading around some of the peeps are getting different reading with different compression testers, but whats more important is the consistency between the readings, i.e if you have a tester that reads low, it will read low for all the cylinders, same goes for high readings.

But then again this is just from reading around, i have an extensive lack of knowledge in this area.

I would love to know what a new LCR reads.

It's worth checking that the knock sensor for cyl 2 is properly fixed.

I must check this too, i have had the connection off for knock sensor 1 several times and its all caked in crap, i must check the voltages in vagcom.

I could also swap knock sensor around as a test.


Edit, further internet research and people are saying cylinder 2 is considered the loudest on the 1.8t because of the block design, if i can confirm this, i might get it desensitised if you know what i mean.
Logging the voltages on the knock sensors at idle suggests this too, all cylinders sit at or below .5 volts, cylinder 2 is always .9 or 1 volt,, hmm interesting.