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1.9Tdi MAF Sensor Help

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mike1978 View Drop Down
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    Posted: 22 Jul 14 at 21:11
Hi,

The van i bought recently has a 1.9TDI conversion in it. Its been running really flat and just doesn`t pull well at all.

I took it to a local garage i know and we spotted the problem with his computer hooked up to it. The monkey who fitted the engine didn`t bother fitting a MAF sensor for some unbeknown reason.

Now i`m going to be converting it to a subaru engine, but not for a few weeks yet. The thing is we were meant to be travelling into france in it in 2 weeks time, but i can`t go with it running like this. We`ll have to travel in our mk4 golf instead.

I`d much prefer to go in the van, but need to sort this problem.

Has anyone else fitted a 1.9TDI into their van? Which MAF sensor did they fit and how - most importantly, how did they wire it into the ECU? I don`t even know where to start with that!

The engine is from a 2000 Skoda Octavia and is the 90bhp engine. with the flyby wire throttle.

Any help much appreciated!

Thanks, Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote youthy giblets Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jul 14 at 21:39
If you don't have a MAF fitted it can cause poor running and lack of power. The MAF itself is only 5 or 6 wires. Is the ecu loom easy to get to? It wouldn't take much to solder a bit of 6core cable on to the the loom and the MAF plug to get you away. We're there any other fault codes present? Seems strange that someone would connect up the diagnostic plug and not connect a MAF. Any pics??
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jul 14 at 21:50
yep - i can`t beleive they went to all the trouble and didn`t fit one. You could see on the computer, as you revved it up, the air flow stayed constant (at 550 i think, whatever that is!)

The whole loom is there with the ecu and dash clocks aswell. The odbc connector is there and shows 4 codes - can`t remember exactly as we checked at the garage - the most significant though was vehicle speed sensor.

The ecu is very accessible - i`m trying to find a wiring diagram online somewhere at the moment.

I `ll see if can get some pics in a min. The air intake is a K and N airfilter which connects down the to the turbo area. There is a boost monitor there - let me see if i can get some pics.


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mike1978 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jul 14 at 22:33
Managed to get some pics  - its a bit dark. There is one sensor in the intake - i`m not sure if its a boost sensor or maf (or map?) sensor.

The ecu is easily accessible as is the rest of the loom etc.

I also found some notes about the ecu wiring that came with the van - it mentions -

4 - MASF (brown)
25 - MASF (Brown/Blue)
50 - MAFF (Red/Green)

there`s a whole bunch of sensors tied up (you can see in the pic)






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mike1978 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jul 14 at 22:37














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mike1978 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 08:09
I think i have located the plug for the MAF sensor - 

In the tangle of wires, i found this which looks like the plug on a skoda how to page - 


and also seems to roughly match the wires mentioned in the notes i`ve got.

Might see if i can get hold of a maf sensor and see what happens if i plug it in. What bugs me, is why they didn`t fit it - did the engine run worse fit it fitted possibly?
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syncroandy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote syncroandy Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 08:49
That's a shockingly poor TDI install you've got there. Your N18 (EGR valve) and more importantly N75 (turbo boost control valve) don't appear to be doing anything. I'm guessing the turbo isn't even the right one for the engine, possibly a JX one ??

Without the MAF the ECU wouldn't know the turbo was wrong as it can't see the airflow. With the MAF, it'll probably start complaining about inlet air pressure deviation as it'll realise summat isn't right with the turbo.

What sump is fitted ? AFAIK the JX one won't fit to that later block. If the original sump is still there god knows how you're getting any oil into the engine reliably with it sitting at 55 degrees instead of 15.


Edited by syncroandy - 23 Jul 14 at 08:50
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mike1978 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 08:57
Yes - its not the best!

I think its got a JX turbo fitted, but not 100%. I`m thinking they did a MAF originally, but then ran into problems because of the other things you mention.

Which is the turbo boost control valve? would that normally connect to the turbo?

The EGR valve - where would that normally go?

I `ve had it less than a week and already had a turbo pipe blow off due to bad conenctors and clips and one of the main rubber connectors to the front radiator pipes just randomlly popped off while sitting there idling!

I `d just like to get it running reasonably for the couple of months until i can get the wiring for the subaru sorted by richard at rjes (he has a waiting list!) Smile

Here` s a link to the last subaru conversion i did a few years back now to an LLE i had if anyone is interested.

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mike1978 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 09:01
oh - yes, the sump is hand made - all lots of plates welded together. I`ll get some pics of that tonight when its a bit more light.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jim potter Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 09:10
WOW ..

as has been said you are missing important things that should be connected .

if your using a jx turbo and no maf i'm surprised it drives .
you will probably have a load of stored fault codes .

can you read any part no's from the turbo ..

have you got a boost gauge fitted ? what does a jx turbo push 6-8psi ?

i hope you get it all sorted .. sounds like you have good plans for it .

Full vcds ,vag tacho,
immo removal ( postal service avalible ), ecu remapping , spanners and a garage for anyone that wants any help, kettle always on.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote syncroandy Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 09:47
Ah right.. apparently you can get away with the JX turbo on an MTDI, but on an eTDI the ECU is wanting to control things with more precision. Which is the whole point of eTDI really.. I suppose you could try running the JX turbo wastegate from the TDI N75, might be better doing this than leaving it uncontrolled.

Re. valves, in your pic, the N75 has the metal body, the N18 has the plastic one. Most folk don't fit the EGR system to TDI conversions, so the N18 valve is left connected (to suppress a fault code) and hidden away somewhere or else replaced with a resistor to keep the ECU happy. Re. plumbing, there will be good diagrams out there, just make sure its correct for your engine.

Interesting link to VWKD, I've used it as well, did my EJ25 conversion a few months after yours in late '08. I did my own wiring, obviously.


Edited by syncroandy - 23 Jul 14 at 21:27
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mike1978 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 09:51
Hi - yes, I can check the part numbers.

There is a boost guage actually which tops out at about 8psi.

When the turbo hose came off the other day, I noticed because the guage was no longer showing boost - the performance was hardly affected!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jim potter Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 10:05
Have you got the ecu part no. Can you post it here.

Edited by jim potter - 23 Jul 14 at 10:28
Full vcds ,vag tacho,
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Post Options Post Options   Thanks (0) Thanks(0)   Quote syncroandy Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 10:37
ECU looks like 038 906 018 GM, the 'latest' version used on the Octavia AGR, it's 80-pin possibly with Canbus as its late.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 11:34
thanks guys for the help - i`ll see if i can also grab the ecu number tonight.

I`ll also have a good look at the turbo to see what i`m looking at and if its possible to connect up that N75 to the JX turbo wastegate.

I`ve also ordered a ODB2 bluetooth connector which will give me any codes, etc. It`ll come in handy for my subaru conversion anyway.

I don`t really want to spend any money getting going given that i`ll be replacing it, but will see if i can get somewhere by trying to get the plumbing right.

cheers, MIke

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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 12:54
I found this diagram with the EGR valve removed - 



And this one with everything including a N239 - 



In the first diagram where the EGR and N239 are eliminated, he routes the turbo control valve to a vacuum with a one way valve - wheres best to take this on the T3?

Also, what is the N239 - do i have one these or need it?

Guess i`ll be off to our local scrappy on saturday morning to find an airbox and maf sensor!

Cheers, Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 12:57
I also found this diagram which is pretty good too - 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote syncroandy Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 13:16
No, they're no good, your wastegate turbo is operated by pressure, not vacuum.

Edit: From the manual:



Edited by syncroandy - 23 Jul 14 at 13:43
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike1978 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 13:25
Ah - ok, i`m all a bit new to TDIs, turbos and wastegates!

So the Skoda (it an AGR by the way) turbo is operated by vacuum while the JX turbo is operated by pressure (air or mechanical?)

Sorry for the questions - Thanks Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote syncroandy Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jul 14 at 13:47
No, wastegate turbo control uses inlet manifold pressure, VNT's use vacuum. Your 90hp AGR is a wastegate system. The JX is also a wastegate turbo controlled by boost pressure, but uses simple negative feedback, not ECU controlled like the TDI.
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