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T3 Audi flip box and afn TDI - cruise control prob

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jeff lawrence View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jeff lawrence Quote  Post ReplyReply Direct Link To This Post Topic: T3 Audi flip box and afn TDI - cruise control prob
    Posted: 06 Apr 14 at 20:52
I have been installing an Audi a4 gearbox into my TDI van so far this year. It's taken forever.

Saturday I wired up the Audi Vehicle Speed Sensor (vss) but cruise control is very erratic. When I set the speed it surges and sometimes cancels itself right away.

Other times, at lower speeds it is fine until you hit a hill or try to increase the speed with the resume button. It drops out of cruise.

I also have an issue with the van dropping into limp mode when I'm overtaking especially if going up hill. I have a boost control indifference fault code logged.

I suspect that my ecu is looking for 4 pulses per revolution, but getting 8. Can I change this with VCDS?

Please, any advice welcome.

Edited by jeff lawrence - 07 Apr 14 at 07:23
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jim potter Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 14 at 16:10
whats the fault code.. overshoot ? positive deviation ?
what is the engine code of the tdi engine ?

i suspect you cant do this with vcds , more than likely requires ecu reprogram .

i take it you had no issues before the cruise  was fitted .
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 randolph57 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 14 at 16:17
is the engine at 50 degrees? (turbo re indexed?)

is the error code 00575 control difference?

is the boost sensor in the ECU or induction pipework?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jeff lawrence Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 14 at 18:27
Thanks for the replies.

It's an AFN code motor. It is at 50 degrees, and I don't think the turbo has been re indexed.

As far as the limp mode issue goes, it drove fine back from Germany 5 years ago, then fine for 12 months, then was off the road for two years whilst I was repairing and having it painted. The limp mode thing started when I got it back on the road and seems much worse in the cold.

Cruise control worked too when I bought it back from Germany, but packed in soon after I got back. It was intermittent at first with an implausible speed signal code, but that was from the speedo mounted (rather home made looking!) vss, then gave up altogether.

Ross tech mentions a speed limiter function. Is it possible that the the vss is causing the limp mode if it is significantly over reading?

Boost sensor is in ecu. I'll try to dump the codes tomorrow and post them here. I fight with a lot of old stuff everyday and have limited patience when my own stuff is broken!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jim potter Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 14 at 22:52
from what i remember you do not want to touch the speed limiter function on vcds.. as once its lowered that's your lot .

any saved codes will point you in the right direction .
 bar that id say check and recheck all vac hoses . plus operation of the stuff its attached to .
has the sensor failed in the ecu ?

i take it the cruise is wired to the ecu and vss ?

Good Luck .. i reckon it will be time consuming hunting it down .

 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote randolph57 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr 14 at 23:21
My money is on a vnt problem which is usually the sticking of vanes in turbo but could also be vacuum hoses a dodgy N75 or Ecu Bourne boost sensor- start with the cheapest option- hoses.
Sensor in ecu could be full of oil but in the absence of any codes it,ll be the turbo vanes. Turbo is surely re- indexed if at 50 degree as oil return would be crazy
Worth checking if actuator can be moved by hand(about 10mm-12mm) and also at rest actuator arm is deffo on the stop screw. If its not I would split turbo casing and free vanes before trying again.
When you crack the limp mode it's loads more smiles
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jeff lawrence Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 14 at 07:54
Bringing laptop home tonight, so will dump codes and check turbo. Oil drain is fairly low from memory.

The cruise control is wired in and I can see the switch operating in VCDS. I'm guessing I have wrong number if pulses programmed for the vss. My motor was over revving a lot on my old gearbox so I wondered if it was some rev limiting function.

I guess I need to log some data and see what's going on. Could the MAF be on the blink?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jeff lawrence Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 14 at 10:22
this is the typical list of codes I find when I plug my van in!

3 Faults Found:

00625 - Vehicle Speed Signal

        27-10 - Implausible Signal - Intermittent

00575 - Intake Manifold Pressure

        17-10 - Control Difference - Intermittent

17978 - Engine Start Blocked by Immobilizer

        P1570 - 35-00 -   -

Will re-scan this eve and re-post codes. Sometimes the immobiliser plays silly beggars, other times it is fine. I'm guessing I will have a fresh Speed sensor code, given that I have swapped VSS type and now have different cruise control issues.

Edited by jeff lawrence - 08 Apr 14 at 10:24
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Post Options Post Options   Thanks (0) Thanks(0)   Quote youthy giblets Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 14 at 20:56
Have you got the round multiplug between the engine and wiring loom as fitted to golf sharran engines? I found mine to be not plugged in correctly and had a very similar list of fault codes to what you have there. Just a thought as after 2nights of head scratching I clicked it into position correctly and all was well
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jeff lawrence Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 14 at 00:59
Originally posted by youthy giblets youthy giblets wrote:

Have you got the round multiplug between the engine and wiring loom as fitted to golf sharran engines? I found mine to be not plugged in correctly and had a very similar list of fault codes to what you have there. Just a thought as after 2nights of head scratching I clicked it into position correctly and all was well


I painstakingly soldered and heat shrunk every one of those buggers when I broke the multi-plug two years ago! They can be really difficult to get apart.

Been out tonight in van, with laptop plugged in. The only code on ecu is as follows.

00575 - Intake Manifold Pressure

        17-10 - Control Difference - Intermittent

The specified and actual MAF values are way off, The actuals are consistently around 200mg/s above the specified. I will try to log boost requested vs actual tomorrow too, but it was getting too late for any more tinkering.

Does this shed any light? I'm on a roll now, so anything else I should log if I go for some by-pass road testing tomorrow?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote timmythedog Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 14 at 08:18
I spent a lot of time and money trying to eradicate the 00575 code. Had the turbo reconditioned, new n75 valve, split the ecu and changed vacuum, and on and on.
 I finally discovered I had wrongly connected the vacuum tube to the brake servo take off. Swapped that over and it all went away. 

My turbo was never reindexed. I'm not sure you can on a vnt. It did need the biggest available bore for the oil return however, though this was not causing any code issues, just  a little blue smoke on pullaway. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote randolph57 Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 14 at 12:41
I refer you to my previous comments regarding Turbo vanes:- if it was running previously with no limp mode problems it will be most likely the vanes that have stuck/are sticking somewhere in the range of operation. limp mode with the 0575 code followed by 17-00 indicates the ECU is sensing either too high /too low manifold pressure for a given period of time at a certain throttle position. it was possible on my conversion to drive 'through' the speed in 4th/5th gear by varying the throttle ie flooring it and then reducing-obviously a crap way of driving!!
My turbo vanes were sticking and being held off the stop screw (this was by a tiny amount)
Carbon build up or corrosion/seizing of the actuator arm is a possibility and this has been addressed by others by administering a 'oven'type cleaner into the VNT part of the turbo! Preferred to strip and clean mine to ensure correct operation as I obviously didn't do it well enough when I re-indexed (yes you can)mine.
The operation of vnt arm/actuator can be checked with a mity-vac direct to the actuator can as a functionality check.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jeff lawrence Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 14 at 14:02
Thanks guys. I now have a list of things to re-check, so will get busy this weekend. It@s a shame as the van makes great power when it is behaving, but it lets itself down far too often and can be a bit scary when overtaking.

Any thoughts on the MAF values being so skewed?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote youthy giblets Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 14 at 21:12
Could be a faulty MAF but as said I don't think it will cause a limp mode or check engine light, as said above get that VNT looked at. I havnt actually stripped one before but I watched a video possibly on YouTube or another forum and it didn't look to difficult. I have heard good reports about using oven cleaner also so you best get looking in the dildo cupboards. I suspected mine to be tight but I removed the actuator and the arm was quite free to move, there is quite a bit of resistance on my actuator when connected to the arm on the turbo. i would try and get rid of the limp mode and then check MAF values after that's sorted.

Edited by youthy giblets - 09 Apr 14 at 21:14
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Post Options Post Options   Thanks (0) Thanks(0)   Quote youthy giblets Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr 14 at 21:17
Just out of interest if you cycle the ignition off and straight back on again when it drops into limp mode does it pick up again on full boost straight away? Be carefull when doing the above u wouldn't want to end up with the steering lock coming on.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jeff lawrence Quote  Post ReplyReply Direct Link To This Post Posted: 10 Apr 14 at 11:12
Yup, just a blip of ignition and it's fine again. I've gotten quite good at it. A botch would be push to break switch in ecu power feed, but I hate it when things don't work right...and botches always cause more trouble in the long run...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote youthy giblets Quote  Post ReplyReply Direct Link To This Post Posted: 10 Apr 14 at 12:54
My money's on a turbo fault- sticky vanes/crap pipe work/bad n75
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Post Options Post Options   Thanks (0) Thanks(0)   Quote busbuddy Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 14 at 07:41
Originally posted by jeff lawrence jeff lawrence wrote:



Any thoughts on the MAF values being so skewed?


is there a leak in the pipe between the maf and turbo, even the smallest hole/split will cause the maf to have a panic attack
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jeff lawrence Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 14 at 14:20
Today I checked that the lever for the turbo vanes moves freely and returns. This seems ok, but I guess the vanes inside could still be sticky. So, before pulling turbo to bits I plugged her into VCDS and can report that the requested boost and actual boost values are very close, so I think turbo is ok.

Changed vac line from N75 to turbo. It looked tired, but wasn't leaking.

Checked all inlet pipe work from Air mass to turbo. Replaced a load of clips. All seems ok.

Air mass values were still very high. Fitted new MAF. Actual values still high. Argh. Thinking it may be wiring issue now as values still too high with MAF unplugged!

Is it possible that my ecu has been remapped? How would I tell?

This is beginning to p1$$ me off...

Edited by jeff lawrence - 12 Apr 14 at 14:21
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