Transporter T5 1.9 TDI AXC

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Transporter T5 1.9 TDI AXC

Postby Technician » Sun Dec 25, 2016 8:20 pm

Van is what appears to be under powered when driven, not sure at the moment if the cat is seriously restricted causing high back pressure. The van starts OK and engine runs OK, free revs to governed speed OK. VCDS pulls back no codes based on an auto scan. I did collect some data using Snap On equipment and if I can load it, here is some graphical data from the injectors. The injectors fitted to this van are the solenoid PD unit injectors. Observations from the graphical data appears to suggest that one injector is not functioning correctly, I could be mistaken on this.I have a graph of a PD injector operation from VW, front door, that suggests by visual comparison an injector may be reading incorrectly, but the graphical data does not make it clear which injector relates to which cylinder. I have not tried scoping the injectors at the front door at this time.

http://imgur.com/tgoTQxI
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Re: Transporter T5 1.9 TDI AXC

Postby grunf1976 » Mon Dec 26, 2016 12:35 am

Hi,
from what I saw in your scope data injectors seem to be ok. You would get better readings using VCDS mvb 013. On idle rough running values below 1 are considered ideal. Also you can see maf in mvb 003. It is measured under load in 3 gear on 3000 rpm everything from 800 mg/str is super. And you can see turbo charging in mvb 011 also under load 3-rd gear at 3000 rpm. Max. deviance should be 100-150 mbar.

Hope this helps,
Mickey
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Re: Transporter T5 1.9 TDI AXC

Postby Technician » Mon Dec 26, 2016 3:00 pm

Thanks Mickey,

Very much appreciated for your time and valued advice. I had looked at measuring blocks 013, I must confess that I didn't like what I was reading. The values were - 1.91 mg/str, - 1.81 mg/str, 2.99 mg/str and - 1.69 mg/str.

The reading 2.99 mg/str caused me to look back at the data I had previously recorded using the scanner, I wasn't really happy about one of the solenoid valve response time graphs, looking back at the graphs if I am reading them correctly, from the Y Axis, the valve commencement of activation occurs, and each graph records similar data for the first 100 data frames, then, again if I am understanding the Y Axis values correctly, I am reading them as current (amp) readings and not "The current" reading displayed.

Out of the four injectors graphical data displays, at the point of 100 data frames, each injector, at what I think is the beginning of the injector period, shows three injectors according to the Y Axis values, where the current values increase, however, one injector seems to have a decrease shown in the vertical axis current value, and the horizontal line increases vertically upwards where the remaining three injectors horizontal lines decrease downwards. I was thinking the injector reading 2.99 mg/str was the injector in the graphical data with the vertical increase with the horizontal line, which I read as a fault condition?

The engine had seriously amounts of carbon buildup to the extent that in the inlet manifold air intake port number 1 cylinder was completely blocked off with sticky carbon, the cylinder head was the same. The only concern now besides the graphical data showing an odd injector along with the MVB 013, is whether the cat has a restriction of flow present?

Thank you for your advice.
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Re: Transporter T5 1.9 TDI AXC

Postby grunf1976 » Mon Dec 26, 2016 6:29 pm

Hi,
you are welcome. I'm glad to help if I can. Carbon build up can be one of causes of lack of power since it is restricting intake ports so engine cant breath. If you have negative readings than ECU is taking fuel away because those pistons are moving faster, and positive value means that is adding fuel to the piston that is moving slower in order to balance the engine on idle. Reading of 2.99 is maximum value and you should focus on that one first. What I would do is to do a relative compression test to get an idea of what is going on. If you have that much carbon build up on intake there is a god chance that there is a build up on intake valves and thus a lower compression, that could result in those readings. I have done a lot of those engines and rarely had a situation where I had to change injector ( not saying that this not the case) Most people rush in and when they see readings like that , they change injectors but the fault is mechanical i nature.As for cat restriction that one you can see looking at MAF on load. If it is restricted readings would be extremely low. because engine is not breathing right. And turbo readings wouldnt be right for the same reason. They would be low as well.
I hope this is of help. I dont want to confuse you but my method always is to eliminate mechanical stuff first.
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Re: Transporter T5 1.9 TDI AXC

Postby Technician » Mon Dec 26, 2016 8:02 pm

Thank you for your advice. The engine has been rebuilt and is now exceptionally clean, the breathing problem through the inlet manifold and cylinder head eliminated. The cylinder compression's were uneven before the engine was rebuilt as I remember, the built up of compression's were also slow. I did not complete another compression test after the rebuild. On road test the engine did not seem to have much power after about 50 MPH. Having built the engine I did not notice any splits in any hoses when reassembling, however I failed to mention (Sorry my fault completely) that when I put my foot down on the accelerator to demand power, the turbo kicking in I could then hear what sounded like a pressurized air leak, giving me the impression that a restriction is present, but with your advice I will check the readings of MAF and Boost on road test later, and let you know my findings.
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Re: Transporter T5 1.9 TDI AXC

Postby grunf1976 » Mon Dec 26, 2016 8:51 pm

I wanted to ask about that one but I forgot :D . That sound can mean two things. Bad cat or cracked hose. If there is a lot of smoke on the tailpipe when you put your foot down than it looks like boost leak. Otherwise it could be the cat.
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Re: Transporter T5 1.9 TDI AXC

Postby Technician » Mon Dec 26, 2016 10:04 pm

Based on this graphical data from the VW it seems that it is more than likely the cat has a serious restriction?

http://imgur.com/a/ttQE2
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Re: Transporter T5 1.9 TDI AXC

Postby grunf1976 » Tue Dec 27, 2016 12:13 am

If I'm reading this right rpm 3444, Maf 855, and boost 1887, than I think it is the cat. Your MAf maxed out at over 1000 at
one moment so that is ok. But 1877 of boost at 3444 rpm is low. at that speed it would be 2000-2015 mbar at least. the simplest way of confirming cat is to release the bolts for EGR return from cooler an see what happens. It is not scientific but it is the simplest way of eliminating back pressure .
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Re: Transporter T5 1.9 TDI AXC

Postby Technician » Tue Dec 27, 2016 1:21 am

With reference to the MIN/MAX boost pressure readings, i.e. 989 - 2040 and the current value being 1887, are the min/max readings not what are programmed into the PCM so that the PCM can have a monitor that knows when the actual reading goes outside of the operating parameters ?

If I do actually have a boost pressure leak from what I can hear when I put my pedal down hard, I am kind of thinking that the loss up to 153 could be because the back pressure (nominal) has been exceeded, hence the leak and results in a lower reading under full load?
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Re: Transporter T5 1.9 TDI AXC

Postby grunf1976 » Tue Dec 27, 2016 8:56 am

The way it works on VW is that you have requested value and actual value. You can see it in VCDS mvb 011. ECU is requesting some calculated value and then it monitors turbo pressure response over MAP sensor. both values shoud be within 100 mbar of each other. If it went over requested for than it would go in to safe mode deactivating turbo.
And if you have a big back pressure than you would have turbo boost loss by o rings on the hoses those 153 mbar
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