Intermittent Throttle Issue + various other issues.. (1.9TDI Leon)

[Riften]

Hello.

Cutting straight to the topic at hand; at random, my throttle will stop working altogether, and the engine goes into 1200RPM limp mode in the process. Restarting the car fixes the issue. A guy I know plugged in VAGCOM and saw that it was bringing up a "Throttle Sensor - Implausible Signal - Intermittent" error. The software he had allowed him to view throttle input from 0% (not depressed at all) to 100% (fully depressed) and all the travel between that, and even when the engine went into limp mode and throttle stops working, the computer is still registering complete operation of the throttle from 0% to 100%. I took off the plug at the top of throttle pedal itself in the driver's foot well, sprayed it with some electric wire cleaner and plugged it back in, and it still did not fix it. I have cleaned more or less every sensor possible, also. I checked the connections to the ECU and found them to be great.

I am having a boost issue at high speeds in a high gear coming from a low speed and pushing the RPM all the way to 4000-5000, to which it drops off the boost and the turbo itself goes into a very low-boost mode until the ignition is switched off and back on again and the engine started back up. This is either a problematic vacuum hose, piping or most likely sticky vanes, to which I am looking into a full Terra Clean - the car has done 134,000 miles now. I have also ordered a new fuel, oil and air filter, and will replace all the vacuum piping with some brand new piping to rule out possible leaks regarding the piping itself.

Another big problem I am having is that when the guy I know plugged VAGCOM into the Car, he found that the Driver and Passenger side-air bags had been disabled, as well as the Passenger's air bag (not turn-off-able via key or button in the car itself on my model, seemingly). Linked to each air bag is an error saying "Implausible Signal - Intermittent" (which within the message said something like "low signal" or "low current".. something like that.. my memory isn't perfect, and this was some time ago since the reading). As a result, my airbag light is constantly on, and knowing that my airbags are disabled or have possibly been disabled by someone (possibly?) is worrying.. especially when it was put as an 'advsory' on my PASSED MOT.. I know, right? Serves me right for buying a car without properly inspecting it first

At this point, I would really appreciate thoughts and pointers on where to go next regarding this all, particularly the throttle issue. I've had the throttle go right on a roundabout, and when that happens, it has been god damn hairy every time.

Thanks!

 

[sockpuppet]

I expect the sensor in your accelerator is knackered, I did read a post where someone had used electrical cleaner and got it working, but if you are getting an implausable signal then the best solution is probably to replace the accelerator unit.

Check that all your boost pipes are secure as well as one of mine blew out and that seemed to cause an issue with my accelerator when I first started the car. I put it down to the ecu trying to work out boost and throttle and getting a bit confused.

The other thing to check is that your EGR isn't blocked as that is common and if you have access to vagcom, flex the turbo vanes using Group 11 and basic settings.

 

[Riften]

I expect the sensor in your accelerator is knackered, I did read a post where someone had used electrical cleaner and got it working, but if you are getting an implausable signal then the best solution is probably to replace the accelerator unit.

Check that all your boost pipes are secure as well as one of mine blew out and that seemed to cause an issue with my accelerator when I first started the car. I put it down to the ecu trying to work out boost and throttle and getting a bit confused.

The other thing to check is that your EGR isn't blocked as that is common and if you have access to vagcom, flex the turbo vanes using Group 11 and basic settings.

I will look into the accelerator unit. Saw some used ones going for £20-25 on ebay, so not too expensive.

My EGR currently has the vacuum pipe disconnected and plugged so that it isn't active, which apparently shuts the EGR off (closed) altogether so that it no longer recirculates unburnt fuel. Correct me if I am wrong; it's just what I read on here in other threads.

Thanks for the pointers!

 

[Riften]

An update: I bought a used throttle pedal to replace my current one, hopefully bringing this throttle issue to a close. Hopefully I will have VCDS sorted out soon so I can check fault codes and what not.

Regarding my airbags, except for the steering wheel air bag, they have all been disabled (shown by a VAGCOM scan). I plan to re-enable them with VCDS, although we did see that each airbag also had a 'Intermittent' error pertaining to it also, something along the lines of 'Low resistance' or something like that. Could this be because they are disabled, or possibly even unplugged?

Lastly, I was thinking of getting my engine Terra cleaned soon, to which they also provide the option to inject a special foam into the EGR valve area straight into the turbo so that it declogs and removes any soot and dirt and all that good stuff. This is a professional service and one that has a plethora of great reviews and feedback on their page, and are highly reputable overall. I wanted to know if this 'special foam' really is a special foam or not just some Mr Muscle - I have heard horror stories about this killing turbos (not everyone's, but a handful).

Thanks!

EDIT: What diameter piping do I need to replace all the vacuum lines/pipes on my ASV 1.9 TDI engine? Thanks!

 

[sockpuppet]

The piping is variable sizing, some is 3 - 3.5mm and other pipes are 6mm. I would recommend buying the proper pipe that goes on the turbo actuator as it is shaped. All the other n75 and n18 piping can be bought off ebay by the meter.

 

[Riften]

Thank you, sockpuppet. I've seen some say it's 3.5mm & 7mm. I'd rather not buy a diameter that isn't correct, so i'm not so sure which number to trust.

 

[sockpuppet]

It could well be 7mm as I only wanted to replace the 3.5mm pipe and didn't pay much attention to the other pipe work when I checked.

 

[Riften]

Okay. Thank you again for your input. The vacuum pipe going to the turbo actuator looks to be 6-7mm - thicker in appearance and feel than the rest of the other vacuum pipes. I guess I will gamble on 3.5mm/7mm.

I will be replacing my throttle pedal unit with a used one to see if that fixes the issue I am having, to which I have also bought some Redex and Wynn's Diesel smoke treatment for a general engine/injector cleaning. Anyone have anything to say about these two products from experience or knowledge?

Thanks!

 

[Rich-I-Am]

Is it safe/ok to disconnect the vac pipe from the EGR valve to keep it shut?
Any problems (ie setting off the eml)?

 

[Riften]

The 2001 MK1 Leons don't get an EML when disconnecting the EGR valve (as far as I have read many times throughout the forum, anyway. I certainly didn't get one). Disconnecting the vac pipe means it is closed permanently as far as I know and why others recommend doing it. Plug the vac pipe you just unplugged with a snug bolt and off you go.

An update on my situation; I replaced the throttle, not 100% sure if it completely fixed the issue or not - it functions, at least. I am slowly but surely discovering more and more problems with the car, one of which is that I have lost all communication with the engine control module, which has been confirmed with VCDS-Lite-1.2 and a permanent SEAT Leon ESP warning light on the dash - the engine refuses to turn over as a result. I have had this problem intermittently up until recently when it decided to became a permanent thing. The search now begins for what wire is causing the problem. which would seem to be the most probable issue.

I am suffering from huge water problems on the floor of my car inside, and I think this has caused a great deal of issues. The wiring loom that runs down under the carpets inside to the bag are soaked, for example. More updates to follow.