limp mode after aggressive acceleration

I am curious that the over boost has not triggered errors. Because of that I am more inclined to go for the intermittent cam position sensor. When that plays up it gives the same symptoms as limp mode. Other possibilities are fuel filter, injector loom, injector(s) or tandem pump.
 
Catnip64 said:
Fault code 17965 relates to overboost which is leading to limp mode:

17965/P1557/005463 - Ross-Tech Wiki

wiki.ross-tech.com wiki.ross-tech.com

I'd suggest checking the hoses that connect to the N75 valve as a starting point.
Click to expand...
Is this the N75 valve at the right?
N75valveposition.jpg
and hoses that connect to the N75 Valve one at the front and two at the back?
N75valvefromfront.jpg
N75valvefromabove.jpg
N75valvefrombelow.jpg

If so all connections, seem to be connected. I can't see where they go to though, do I need to check the other end of them?
 
audifan said:
I am curious that the over boost has not triggered errors. Because of that I am more inclined to go for the intermittent cam position sensor. When that plays up it gives the same symptoms as limp mode. Other possibilities are fuel filter, injector loom, injector(s) or tandem pump.
Click to expand...
I understand that the cam position sensor is behind the plastic cambelt top cover. Would it be easy to get at and replace without removing anything else?

Now I am wondering what to try first.
 
Au2ro said:
Is this the N75 valve at the right?
View attachment 53555

If so all connections, seem to be connected. I can't see where they go to though, do I need to check the other end of them?
Click to expand...

The N75 valve has the green hose connection so is on the RHS, further details in this thread:

N75 / Boost Pressure Regulator Location

Hey guys, I am going to have a look and see if I can find out what is causing this limp mode problem after I get to 70mph later and it seems the biggest culprits are the N75 / Boost Pressure Regulator and the MAF. The MAF I can see easily (and will clean it) but where should I be looking...
www.a2oc.net
You need to check the other ends of the hoses, although access to these is more difficult.
 
Au2ro said:
I understand that the cam position sensor is behind the plastic cambelt top cover. Would it be easy to get at and replace without removing anything else?

Now I am wondering what to try first.
Click to expand...
The cam sensor is a bit fiddly to change if needed to,main thing is to use magnic sockets on the bolt head under the cam cover or blue tack,as if you drop the bolt on removal it goes just where it's not wanted.(I have a brand new crank sensor if this is needed )

Thanks
Pete
 
Check the cam sensor wiring and clean the contacts. If no improvement I would change the CAM position sensor. Just take heed of Pete's warning about dropping the bolt. If it was overboost then there would be errors even on a basic reader. Is possible it is a combination of both but CAM sensor or its wiring a higher chance of curing the problem. Have you done a full auto scan yet?
 
audifan said:
Check the cam sensor wiring and clean the contacts.
Click to expand...
I can't see any wiring from the outside of the plastic cambelt top cover, do you have to remove that and unbolt the sensor to check the wiring?
audifan said:
Have you done a full auto scan yet?
Click to expand...
https://www.a2oc.net/community/inde...ter-aggressive-acceleration.40204/post-358727 was the result of an autoscan in VCDS-Lite.
I was looking for a "Read Fault Codes" option but I guess the autoscan is the right option in VCDS-Lite. I found a "Control Module Finder" option which took ages and found some controller codes but I am not sure what use that would be? I guess that with the codes I could use the "Select control Module > Direct entry" and enter a code there to see what happens?
 
Au2ro said:
I can't see any wiring from the outside of the plastic cambelt top cover, do you have to remove that and unbolt the sensor to check the wiring?

https://www.a2oc.net/community/inde...ter-aggressive-acceleration.40204/post-358727 was the result of an autoscan in VCDS-Lite.
I was looking for a "Read Fault Codes" option but I guess the autoscan is the right option in VCDS-Lite. I found a "Control Module Finder" option which took ages and found some controller codes but I am not sure what use that would be? I guess that with the codes I could use the "Select control Module > Direct entry" and enter a code there to see what happens?
Click to expand...
Cam sensor plug is circled(rhs) as is the point the wiring passes into the belt housing(lhs). Fairly straightforward swap assuming you don't drop the bolt.
IMG_20190706_183353.jpg
 
Au2ro said:
I can't see any wiring from the outside of the plastic cambelt top cover, do you have to remove that and unbolt the sensor to check the wiring?

https://www.a2oc.net/community/inde...ter-aggressive-acceleration.40204/post-358727 was the result of an autoscan in VCDS-Lite.
I was looking for a "Read Fault Codes" option but I guess the autoscan is the right option in VCDS-Lite. I found a "Control Module Finder" option which took ages and found some controller codes but I am not sure what use that would be? I guess that with the codes I could use the "Select control Module > Direct entry" and enter a code there to see what happens?
Click to expand...
If your just checking the wiring before removal,unclip the top cam belt cover and remove it,then use a mirror to look at the sensor that is behind the timing belt,follow the wiring it goes though a grommet and along the engine head into a plug on the right hand side

Thanks
Pete
 
Unplug the cam sensor connector, and clean both male and female with contact cleaner, and allow to dry. Reconnect, and cross your fingers ... Mac.
 
Just had a quick visual check of the contacts on the cam sensor connector:-
cam sensor connector.jpg
Does that look like a little corrosion, the white powdery residue?
 
Au2ro said:
Just had a quick visual check of the contacts on the cam sensor connector:-
View attachment 53569
Does that look like a little corrosion, the white powdery residue?
Click to expand...
Difficult to be certain, I'd be surprised if poor connection was the issue looking at the photo. I fitted this one(not generally a fan of cheap sensors though... )
www.ebay.co.uk

NEW POSITION SENSOR IMPULSE SENDER CAMSHAFT VW AUDI SKODA SEAT 045957147B | eBay

Find many great new & used options and get the best deals for NEW POSITION SENSOR IMPULSE SENDER CAMSHAFT VW AUDI SKODA SEAT 045957147B at the best online prices at eBay! Free delivery for many products!
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And when the cam belt cover is off check the condition of the cam belt. All your other question have already been answered. Those female contacts look pretty good more likely now the sensor itself has had it. Was hoping there was something in the plug ( engine oil or water ).
 
For info, main function of the cam sensor is to identify which cylinder is on the compression stroke to allow the ECU to synchronise the fuel injection sequence.
If the sensor fails, the ECU utilises the crank sensor signal but on start up the engine may need several revolutions to work out when No1 cyl is on compression.
Usually the only indication of a failed cam sensor is the extra cranking time when starting

Not related to the issues in this thread but if the cam timing has slipped and is out by a tooth or two, the engine may not start due to a mismatch / conflicting signals from the cam and crank sensors. The engine however may run if the cam sensor is disconnected

Cheers Spike
 
spike said:
Not related to the issues in this thread but if the cam timing has slipped and is out by a tooth or two, the engine may not start due to a mismatch / conflicting signals from the cam and crank sensors. The engine however may run if the cam sensor is disconnected
Click to expand...
Do you mean if the engine is not starting and cam timing has slipped and the cam sensor is disconnected the engine may run as there won't be mismatch / conflicting signals between the cam and crank sensors?
Also, If I do have a cam sensor issue and repair it that I would potentially not be able to start the engine if cam timing has slipped?

I think that my engine starts fine, but if I disconnect the cam sensor and try starting the engine with it disconnected, then I should not notice any difference in starting if the cam sensor or its wiring is faulty?

However, what I really want to know is, could this cam sensor issue have anything to do with loss of power on aggressive acceleration in your opinion, spike?
 
audifan said:

19463/P3007/012295 - Ross-Tech Wiki

wiki.ross-tech.com wiki.ross-tech.com

From the fault code provided by VCDS.

How old is your battery and what is its voltage?

Yes the cam sensor can produce a limp mode effect, loss of power.
Click to expand...
The battery is a couple of years old. I have not got a voltage meter but should get one I suppose.

I have just tested by disconnecting the cam sensor and starting the engine with it disconnected - it had to be cranked over for a while before it started whir whir whir whir whir whir whir.... fire. With the cam sensor connected it started straight away - whir whir, fire, just like before and I disconnected and after I reconnected it yesterday.

I will re-set the fault codes and give it a drive and check again.
 
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