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A3 1.6 to 1.8t engine conversion complete, now no throttle response!

Discussion in 'A3/S3 Forum (8L Chassis)' started by Lingo89, Oct 6, 2012.

  1. Lingo89
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    Lingo89 Member

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    Hey guys,

    I recently carried out a complete 1.6 (AVU) to 1.8 turbo (AUM) engine conversion and all has been going completely fine, except now when I'm finally at pretty much completion, I start the car, it starts fine and idles perfectly but when I try and throttle it doesn't respond at all!

    I should note another issue I have is that the fuel pump for some reason has no live to it, I bypassed that temporarily so I can get the car running and fix all the niggles in my own time (as I work full time and ideally need the car running ASAP) and made a connection through the fuse box which means the fuel pump is now working.

    Could these two problems be related? is there anything I should be doing to get the throttle working again? I'm going to post up a complete VCDS log from the scans at some point soon but because my laptop isn't with me I can't at the moment. One of the errors that I have got that are actually worrying me is:

    01314 - Engine Control Module
    013 - Check DTC Memory Intermittent

    I'm unsure as to whether this could also be related but I had a guy come over and do an immobiliser bypass as the wiring for the clocks in my car wouldn't fit the clocks from the donor we used (my clock wiring had two plugs, the clocks from the donor engine used has 3)?

    If anyone could please give me some advice as to what I can do to get the throttle working I would be extremely grateful!

    P.S The T.B is plugged in!
    #1
  2. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Did you use the AUM loom? I would imagine its a wiring issue and tbh its gonna be difficult to suggest anything considering the work you have done as there is nothing really std about this...

    Need more info realistically... did you use the AUM ECU? wiring loom? sensors etc? I can't imagine too many people have taken on this type of conversion before for so many reasons so other than checking the wiring not sure what else to suggest..

    Have you immo defeated the ECU?, using the AUM clocks?

    More info needed really as its neither a 1.6 or a 1.8 at this stage..

    <tuffty/>
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  3. 16Klappe
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    16Klappe Princess Slayer

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    This can be a symptom of a faulty crank position sensor I think.
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  4. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    no throttle = no power or wiring mismatch
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  5. Lingo89
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    Lingo89 Member

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    Yes you're right, it's quite complicated to explain. I'm really hoping there's a genius on here that can help though. I'm using the ECU and the complete engine loom of the AUM 1.8t, however the interior loom is still from the AVU. Basically, we assumed with the clocks, key and ECU from the 1.8t we wouldn't have an issue starting the car but when we went to start it it kept coming up with the key signal on the dash and it would turn over but never start, so we had a local key guy come and immo defeat the ECU and we now use the original clocks.

    @Badger5, it's not as if the car is struggling at all, it's idling perfectly fine, it's just as if the throttle is not connected to the car, you can press it to the floor and nothing will happen. The AVU was a drive-by-wire system too, so we've not even changed anything there. Do you have any pro tips as to what to look for in a wiring mismatch here?

    @16Klappe, wouldn't a faulty crankshaft sensor come up on a VCDS scan? the only significant and possibly relative error code that I saw would be the one I posted in the original post, I will post up the complete log when I can though.

    Is there any way to reset the DBW throttle?
    Last edited: Oct 6, 2012
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  6. Prawn
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    Prawn My other car is a MINI!!!!

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    haha :laugh:
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  7. 16Klappe
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    16Klappe Princess Slayer

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    Don't laugh fat boy, it's true.

    That's what my car did when the crank sensor went, it would idle fine but it wouldn't rev. It just sat at 800RPM and wouldn't move regardless of throttle position. We had to drive it home in first at idle RPM.

    Com'd it, changed the sensor and it was fine.
    #7
  8. Lewis583
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    Lewis583 Active Member

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    Have you checked the AVU throttle pedal is compatible with the AUM ecu? Checked part numbers etc pin outs.
    Is it possible to perform an output test on the throttle body with VCDS?
    #8
  9. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    log throttle pedal and throttle plate in vcds

    you will see whats occuring there..
    also basic settings it in engine, block 060 and see what it does
    #9
  10. phil miller
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    phil miller Member

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    easy i had this at work, go into live data (messuring blocks) now go to throttle pedal % now you show see a figure maybe 2% at idle, now press the throttle pedal and you should see that figure go up until it reads 100% WOT, now i expect the figure you will see is 0% even when you press the throttle, this points to the pedal (unlikely) or the ECU as the ecu has been taken off a car and then refitted its likely the ECU has gone down (we had a 1.8t AUM with this a few weeks ago)

    i wouldnt rush in to checking all the wiring because all the sensors on the engine go to the ECU the the needed dash stuff and fuel pump stuff joins the care loom, TBH to get the engine to run all you need is a couple of earths and lives, yours runs to check messuring blocks, if the reading is 0% next do a continuety test of the wiring from the pedal plug to the ECU making sure you have pure contiuety on them all, if you do then try another pedal if still the same its the ECU, id try the pedal first mainly because if you can borrow one then its a free test

    Hope this helps sort your problem dude
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  11. Lingo89
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    Lingo89 Member

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    Thank you for the responses guys. I found out about a pretty major error on my part yesterday though, so I ended up working on that. Basically, I (wrongly) assumed that the engine loom only went from the engine up to the ECU, when actually it also goes from the ECU up to a set of coloured that connect to the interior loom that sit underneath the clocks/ steering wheel.

    I already had wiring that went from the ECU into the car but obviously my 1.6 one was wrong for the 1.8t engine (even though it plugged in the same, lots of things were wired up in the wrong way). Now, I have changed all of that so now the engine loom completely matches the engine all the way up to the interior loom but I've hit another bump in progress.

    Looking at the picture below (which is not my own), if you look at the part of the picture that shows the five coloured plugs that are labelled by the number "1" those five plugs are exactly what I've got on my AUM 1.8t engine loom. However, my old AVU 1.6 engine loom had a sixth plug which is green that connected to the interior loom that this new engine loom doesn't have. Therefore, I have one empty socket where the green plug would have plugged in.

    [​IMG]


    I tried to start the car after swapping these parts of the engine loom over but now it won't start as the car has no spark and I'm sure it's down to this sixth plug not being plugged in. Can anyone enlighten me as to what the plug did, so I can attach the wiring from the green socket to the appropriate parts of the other plug/ plugs?

    Thanks in advance for any help you guys can give me!
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  12. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Hang on, I thought you had this running? How can it have run if you hadn't connected the engine loom to the car?

    The missing plug is more likely the DBW / Throttle peddle plug.
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  13. Lingo89
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    Lingo89 Member

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    Byzan, I DID have it running. Let me try to explain this better. There are two sections to the engine loom, one goes all the way throughout the engine and connects all over the place and runs up to the ECU. I've had this fitted the whole time (correctly so).

    The second part of the engine loom is the main plug which connects to the ECU and then runs into the car up to the interior loom. I had the main plug from my 1.6 connected before which is when I got the engine running, however this is wired up completely wrong (if you pressed the brake switch the radiator fan would turn on!) so once we realised this I removed this wiring and replaced it with the one from the 1.8t.

    However, of this part of the wiring, the 1.6 had 6 coloured plugs which went into the car where they connected to 6 coloured sockets. Now on the AUM part of this wiring, there are only 5 plugs which all go to the same coloured socket but the green plug is not in the 1.8t loom so nothing is plugged into the green socket, as a result now the engine won't start at all (there's no spark, and there's still no power to the fuel pump). I'm certain that once I get this issue resolved the car will start and run properly but I need to know which wires from the green socket need to be connected to the other coloured plugs.

    Does anyone have the wiring diagram for the 1.6 engine code AVU and 1.8 turbo engine code AUM?

    Thanks again!
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  14. phil miller
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    phil miller Member

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    save me re reading it all again, have you used the 1.8 clocks, key and the like? if you havent then its an immo problem, you said something about the fuel pump, what was wrong and how did you fit it?
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  15. Danio
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    Danio AUDI-MANIACS.COM

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    You can fit any clocks you want you. It doesn't matter whatever engine it comes to 1.6 1.8 1.8T - doesn't matter as long as the match pre and facelift model. Yours are facelift so leave old clocks.

    Regarding the wiring just go by cable colours every Audi A3/S3 has got same colours plug on to the under scuttle body so match that and should be ok. You don't have to change anything else.
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  16. Lingo89
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    Lingo89 Member

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    Forget the clocks, I am past that issue, the car has had an immo defeat.

    But Danio that is the exact problem I am having, all plugs match and I have connected those but the interior loom has a socket for a green plug for which the AUM engine loom has no green plug for!
    #16
  17. Danio
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    Danio AUDI-MANIACS.COM

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    Can you tell me what cable colour left in that green socket inside the car and in AVU green socket??
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  18. Lingo89
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    Lingo89 Member

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    Hi Danio, I sure can, there are 7 small wires in total and the colour of the cables going from that green plug are:

    1 Yellow/Blue wire

    2 Solid Yellow wires

    1 Yellow/Red wire

    1 Red/Blue wire

    1 Blue/Green wire

    1 Black/White wire
    #18
  19. Lingo89
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    Lingo89 Member

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    Hey guys, I've managed to get it running and revving! strangely enough, I've done virtually nothing on it. Had it sitting on the drive for a few weeks as I got busy with other things, went to start it today, unplugged and plugged the crankshaft sensor back in, removed the battery and checked all connections, unplugged and plugged a big plug by the headlights and it turned over and started straight away. Great stuff!

    Now I'm running the fuel pump via a by-pass in the fuse box, how how can I get it sorted permanently? the fuel pump live must be in one the plugs right? is it in the elusive green plug that's not connected?
    #19

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