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  #61  
Old 25th November 2016, 09:36 PM
MatthewH MatthewH is offline
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Quote:
Originally Posted by Mechcanico Lee View Post
The vaccum is not as good as it should be Matthew , like i said back there you need to check cam timing first port of call .

If cam timing correct next would be to have a look at variators to see if foot has worn through or fell off .......and the inlet cam timing mark
Cambelt drives exhaust cam ........ exhaust cam drives inlet cam with internal chain .

Cam / crank correlation codes .......... sometimes you get them .....sometimes you dont .....if the cam that is off does not have a cam sensor the ecm does not know that it is out , it can only reference from the cam that does have the sensor ......does inlet and exhuast have cam sensors ?? .

I seen chains stretched to death on vauxhall engines putting cams out loads and still not had cam /crank correlation codes .

In some cases the ecm can only see cams that have gone retared (chain stretch) it can not always see cams that are advanced .....as in someone doing cam timing incorrect whilst doing the cambelt job
Hi Lee,

I will try to get the timing checked. Is the manual way the only way to check the belt is correct (Audi camshaft locking tool)? Cambelts are one of the maintenence jobs I've no real experience with yet!

Thanks
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  #62  
Old 26th November 2016, 10:27 AM
Mechcanico Lee Mechcanico Lee is offline
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A manual check with the correct pins and line up bars is the only way to check the timing properly , there are places where you can hire tools from ive heard .

There are a few utube vids showing you how its done , or perhaps one of the guys on here can send you a pdf of the online workshop procedure for it .
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  #63  
Old 26th November 2016, 01:34 PM
ainarssems ainarssems is offline
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Timing tools are not that expensive for 40V engine compared to 32V, I would definitely buy my own, after all I even bought tools for my 32V which are a lot more expensive. You can always sell them for not much less than you buy them for when you are done anyway.

Camshaft timing would effect fuel consumption a bit but should not be too much unless it's way out in which case inlet valves would meet pistons.

I have seen single front brake caliper sticking to cause fuel consumption to double, brake disc was glowing red in dark after drive. Did not feel it much driving, just felt like a bit down on power and needd to press accelerator a bit harder, also pulling a bit to side if you took hands off steering wheel.

So it could well be a combination of several issues on your car.
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  #64  
Old 21st January 2017, 02:10 PM
MatthewH MatthewH is offline
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Update:

I rebuilt the rear brake calipers last weekend as they were seizing as mentioned earlier in the thread. Both calipers are now moving freely. This made a slight improvement to MPG as expected but nothing major. The front brakes are fine.

The car also had an MOT this week. It passed with no advisories and the emissions tests were good. Here are the results from the print-out:

Fast Idle Test
Engine Speed: 2500-3000 RPM
CO: 0.00%
HC: 1ppm
Lambda: 1.01

Natural Idle Test
Engine Speed: 450-1500rpm
CO: 0.00%

According to this, the engine is running well in my view. I would assume this rules out any engine problems causing my low MPG (unless the problems only happen under load?). If cam timing was out, I think it would show up on the emission test.

If it's not the engine and it's not the brakes I'm not sure where to look next! The transmission module also shows no error codes.
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Last edited by MatthewH; 21st January 2017 at 02:12 PM.
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  #65  
Old 22nd January 2017, 01:15 PM
Mechcanico Lee Mechcanico Lee is offline
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Hello Matthew just been looking back at the posts , I'm still not sure on the vaccum readings at idle , most modern engines with higher compression ratios and the volumetric efficiency they run most of em can pull 20 inches Hg of vac .
I test vaccum in engines quite a lot and I normally see on good engines 20 or 21 inches Hg .

Yes the emissions test looks good , but sat still whilst on test at a certain revs is not the whole picture of the engines map , when ecm sees road speed things change ..load changes , cam timing had to be ruled out .... I know this is a bit of a task stripping it down .....but what's the option .....buy some more parts on a whim and hope they fix it ( like I see near enough everyday in the workshop )

My next tests as I have said before would be cam timing checks with the correct tools , if all other possibilities of inlet manifold leaks have been ruled out its the next step , very often with diagnosis it's a case of rule it out then move to next step .
If this shows to be good then my next step would be pull all the injectors out and flow and pattern test them .

On vcds on the camshaft position actual and camshaft postion phase position , actuator duty and so on data block page , could you screen shot it , take a picture or whatever and post it up , one at idle one at say 3000 Rpms .

Another possibility.....could your next door neighbour be sneaking out in the night and syphoning a couple of gallons out of your tank for his scooter .......

Last edited by Mechcanico Lee; 22nd January 2017 at 01:18 PM.
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  #66  
Old 22nd January 2017, 02:04 PM
MatthewH MatthewH is offline
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Thanks Lee. Yes, I thought it may have been a problem that occurs under load only - I just thought bad cam timing would cause rough idle (and bad emissions) so I was hoping that was not the case! It's still worth checking as you mentioned. I'll get a photo of the timing-related VCDS values you mentioned later on today.

People have also mentioned the hydraulic camshaft adjuster valves as these can be a common problem on this engine - I think the plastic "shoes" wear down and cause the chain to become loose. This uses causes a loud rattle though which I don't have.

I actually have a spare fuel rail with injectors so I'll probably start with these. I was planning to rebuild the injectors with new seals and microfilters. I tried to remove my injectors when I had the intake manifold off but the fuel rail wouldn't lift off (with only the injectors holding it in place). It felt like I was going to bend the rail if I pulled any harder so I ended up leaving it attached.
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  #67  
Old 22nd January 2017, 03:44 PM
Mechcanico Lee Mechcanico Lee is offline
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Iirc the cam timing actual and cam phase position should be as close to 0 kW as possible ...kW just means degrees of cam rotation , so if these data blocks are off it sort of proves that cam timing is off ......and the low engine vaccum supports this also ....yes this could also be a fault with the cam chain variator units ( yes known issues on these ) but you also have to know that your base cam timing position is correct also .
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  #68  
Old 22nd January 2017, 06:44 PM
MatthewH MatthewH is offline
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Photos of all cam-timing related values attached.

Photo #1 is idle
Photo #2 is ~2000 RPM
Photo #3 is ~3000 RPM

I think the "phase position" values relate to the hydraulic camshaft adjusters but there's not much info about it online. The info online mostly seems to be related to TDI engines.

Also, I checked fuel trims again today. They're both at +7.0% (partial), 0.5% (idle), so still within tolerances. Replacing the main fuel pump fixed my P1128 lean code but didn't improve MPG.
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Last edited by MatthewH; 22nd January 2017 at 06:58 PM.
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  #69  
Old 22nd January 2017, 09:16 PM
Mechcanico Lee Mechcanico Lee is offline
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Mmmmm ....phase position not doing what I thought it would be doing , actual timing is advancing with speed as I thought it would ......we could do with another member looking at there settings to compare readings on that phase position , just in case we are going up the wrong pathway .

The idle reading fuel trims are spot on , you would think if injectors where over or under fueling you would see it at the idle fuel corrections , on the partial throttles there's some correction but not so bad .
If you watch short term fuel trims on the road is there any areas of throttle where they go widely out of range .

What would be interesting.... the camshaft position sensor on the drivers side bank ...the easier one to get at , looks like it's held in by two 10 mm head size bolts , if they are slackened is there any movement clockwise or anti clock ...like turning an old type distributor , I just want to see if moving it what it does to the phase position kW readings and in turn what that does to the partial throttle short term fuel correction values .

For how heavy it is on fuel you would expect the trim values to be showing a rich condition or is it a case of its leaning out and the engine becomes in efficient and that's using the fuel , do the spark plugs show any signs that's it's rich ....bit dark in colour ?
Interesting one this
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  #70  
Old 22nd January 2017, 09:46 PM
MatthewH MatthewH is offline
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The phase position always seems to stay the same regardless of RPM, when not moving at least. I've not testing while driving but I'll record a log tomorrow.

Back on post #36 on this thread I checked the phase positions and they were almost the same as they are now (-5.0 and -9.0).

If I get chance tomorrow I'll also remove a spark plug as you mentioned. I changed them around 12 months ago.

I'll also have a look at the camshaft position sensor - it's fairly easy to access from what I remember. What would you expect to see from turning it?

Thanks
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