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Discussion Starter · #1 ·
Hi.

I've a 02 PD130 (ASZ) and just posted a longish 'hello' message on the 'into' page. To business, the car has developed an oddity, which is annoying, frustrating and could be a bit dangerous. At seemingly random times the car's power output drops. It's happened ~10 times since probably early August and appears as a lack of acceleration or the car drops out of cruise control generally on a big hill. I then have to drop down the gears and even with the revs ~2500k there's much less power. It doesn't happen on every trip and it might happen during warm up or while a long way into a journey. If I stop and then restart the engine (in a lay-by) or while driving the car's power is restored, but doing this on the move isn't ideal (and could presumably damage the turbo, too).

No warning lights come on and my initial thoughts tended towards the MAF sensor. I tried cleaning this (with brake cleaner, sadly) and all seemed fine, but it's an intermittent problem. Yesterday I replaced the MAF sensor and also put in a new air filter element as the old one was quite dirty. This combo seemed to be good as the car had plenty of oomph on a long uphill drag but quite a few miles later the same fault occurred, maddeningly on another long rise.

I don't think it's mechanical as all seems fine after being turned off and on, but I need to get this fixed.

Presuming that the new (Delphi) MAF sensor is fine, and I've no reason to thing it (or actually the original BOSCH one) are the problem where do I start with solving this one, please?

Cheers
 

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Discussion Starter · #3 ·

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Does sound like limp mode from the turbo over speeding with sticky vanes. Very common problem with the TDI, I've been getting it for the last 10 years on my car. Normally when I've done too much town driving. The TDI likes to be given a good run on the motorway, ideally running at 4k revs under load every so often.

You can try getting the turbo to self clean, that's how I've managed my limp mode. If it's happening going up hill, that's the ideal place to clear the vanes. Drop a gear or 2 and go up the hill with your foot to the floor. The longer you hold the revs at 4k+ the better. If the turbo isn't too clogged that'll sort it, otherwise it's time to get the oven cleaner out. The last resort is taking the turbo off to clean it since there's a lot of work involved.
 

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Top tip: never clean a MAF sensor. Solvents kill them.

Check for codes. If it's underboost, it's a got a leak. If overboost, it's sticky vanes. Do not guess and do not allow the internet to buy parts for you.
 

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From my understanding it'll go into limp mode if it's over boosting to prevent any damage.

The Mr Muscle clean doesn't take long at all and costs a few quid.

Get the car scanned to see what codes are stored.
 

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Discussion Starter · #7 ·
More thanks to you all. Been doing some more research and now know about the N75 (boost control valve) and turbo actuator, plus the mechanical side of things. Didn't even realize these engines had a variable boost turbo. Among others, this video has been useful
Not looking forward to a turbo clean and rebuild if that's necessary, but it doesn't look too daunting. Car doesn't use oil and it's ~130k miles so should have plenty of life there. Might also investigate the 'Revive' type clean but also the self-cleaning option, vroom, vroom. Much of the recent mileage has been dual carriageway and motorway but there's clearly something not quite right.

Can anyone recommend a good code scanner in sw Devon (around the Plymouth area), or Exeter? Definitely wish I'd got the garage in Scotland to do this when they did the belt. Ah well.
 

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Your post has been moved.Always ask technical questions in the relevant technical section.This site is well enough laid out to make them very easy to find.
 

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Discussion Starter · #10 ·
Ta. First post and clearly I don't know how this site is arranged. I can see there are some highly-related posts to mine in this part so if I'd found this section I might have been able to get the info without my message.
 

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Discussion Starter · #11 ·
I've got VCDS scan tool which you are free to use if you can get to Wellington near Taunton.

I've got the same vehicle so pretty sure it will work ok.

Let me know.
Cool, thanks. I've some relatives near there so it's a possibility, but further away than should be necessary. Hopefully, I can get something sorted more locally. Finger's crossed!
 

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For what it's worth,

I had a 90k mile pd140 Jetta, similar engine to the pd130, except it's the slightly newer 2.0 litre engine found in Mk5 cars.

That car developed overboost issues too
I got used to clicking the engine off and on even on motorways to reset the limp mode.

Anyways ,

A garage did the revive thing. Which didn't do anything.
I bought another bottle of revive and did it myself. That still didn't cure.

I did the Mr muscle thing 3 times down the egr hole and moving the pushrod. That did nothing .

I took the hot side of the turbo off 2 times from underneath the car and sprayed and held Mr muscle in there whilst activating the push rod thing . That did nothing .

In the end we sold the car anyways, but for our car the Mr muscle no revive could cure the limp mode.
Ideally would have needed to remove turbo and clean it properly to make that car run normal again .
 

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Discussion Starter · #13 ·
For what it's worth,

I had a 90k mile pd140 Jetta, similar engine to the pd130, except it's the slightly newer 2.0 litre engine found in Mk5 cars.

That car developed overboost issues too
I got used to clicking the engine off and on even on motorways to reset the limp mode.

Anyways ,

A garage did the revive thing. Which didn't do anything.
I bought another bottle of revive and did it myself. That still didn't cure.

I did the Mr muscle thing 3 times down the egr hole and moving the pushrod. That did nothing .

I took the hot side of the turbo off 2 times from underneath the car and sprayed and held Mr muscle in there whilst activating the push rod thing . That did nothing .

In the end we sold the car anyways, but for our car the Mr muscle no revive could cure the limp mode.
Ideally would have needed to remove turbo and clean it properly to make that car run normal again .
Hello and thanks for your post. Sorry to hear of your woes. I am hopeful that my problem isn't so intractable and general advice is to get the codes scanned so I know what to tackle. The MAF sensor swap might have been a blind alley, but I now feel much better prepared to get to grips with this. If there is wear in the turbo or damaged parts elsewhere then cleaning out my system won't improve the situation. I've been doing a lot of motorway miles recently and there it's possible to run ~2k revs for hours on end. This might be good for some sort of cleaning but perhaps not for others; better than purely round town driving but not high revving cleaning. The fault is quite intermittent, which might be a good thing, perhaps I can get it to disappear with cleaning, 'wiggling' or there's something up with a solenoid or vacuum hose. I've trawled through the list of those with VCDS on that part of the forum and will message a few people who are local, but my initial look suggests these few members haven't been active for a while so will see. Alternatively can see about the cost of suitable software and cable for myself. My neighbour, who worked in the motor trade for many years and has a VW T5 might be able to help, too. Anyway am too busy to do much before the latter part of the week. Cheers
 

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The £10 Ebay/Amazon VCDS cables work on the MK4 Golfs. That's all it cost me to read codes and enable my cruise control. You need a windows laptop and to download the free version of VCDS from their website.

If you're doing a lot of motorway miles, the problem may go away if you use the full rev range. Don't have to do it every trip but once every week or so.

Was getting limp mode for a few years then my commute changed to 65 miles of motorway a day. The car ran a lot better after that.

Most of the time I'm on cruise control around 70 but give it a boot full once in a while. Uphill motorway on ramps are ideal for that.
 

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Discussion Starter · #15 ·
The £10 Ebay/Amazon VCDS cables work on the MK4 Golfs. That's all it cost me to read codes and enable my cruise control. You need a windows laptop and to download the free version of VCDS from their website.

If you're doing a lot of motorway miles, the problem may go away if you use the full rev range. Don't have to do it every trip but once every week or so.

Was getting limp mode for a few years then my commute changed to 65 miles of motorway a day. The car ran a lot better after that.

Most of the time I'm on cruise control around 70 but give it a boot full once in a while. Uphill motorway on ramps are ideal for that.
Hello buddy. Thanks.

I've been taking a quick look at the VCDS family of software and cables, which is quite bewildering with so many different variants and prices to match. I don't mind spending a few £ more, if necessary, to get something that'll read codes, clear errors, and also log the input of sensors. Looking at the YT video for the PD Tdi overboost (turbo cleanout) video I linked to yesterday it seems that having the ability to log the sensors is quite useful. Here, to see if the expected boost pressure vaguely matches the observed. I'm looking at a ebay site that sells cable and software (for £30) where they ask you to send your reg so they can check compatibility. It's this one (https://www.ebay.co.uk/itm/Diagnostics-interface-FOR-VCDS-VW-AUDI-SKODA-SEAT-VAG-COM-MULTI-COMPATIBLE/202953470227?hash=item2f40f83113:g:3MIAAOSwIBJehR0I). CD, too - how quaint! Think I can still read these! Without this post turning into a VAG-COM / VCDS discussion is this logging feature available on even the most basic varieties?

I've downloaded a few different software packages, too; in case they disappear from sites and have a suitable laptop, also in case I don't get responses from those I've reached out to.

general. Got a response from Bristol, but possibly a bit too far. Prob makes sense to try local or spend the travel money on the kit.

There are a few big hills around here so probably time to put the foot down, too. I want my hp back.

Cheers
 

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You're welcome, VCDS (or VAG Com as it was) can be a maze of car, software and cable compatibility with a range of prices to match.

The equipment and software first used on the MK4 platform quickly got updated and became incompatible with the newer cars. There's a number of options available for us DIY's still using the MK4 based cars. Guess it depends on your view of using cloned hardware and software that's well over 10 years old.

Not sure if VCDS Lite allows you to log items but I doubt it . I needed to check/adjust the fuel pump timing which it wouldn't do. I spent some time researching the problem and sourced a copy of the software that would work with my cloned cable.
 

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Discussion Starter · #17 ·
Right.

Still no ability to read codes. Got a response from PMs out, but that's in Bristol so quite a hike, plus that above in Wellington (thanks, both), which is nearer but am tempted to spend the fuel cost in being able to read codes (and log sensor outputs) myself. On this theme I asked the logging question to an ebay cable seller, but the reply was my questions were too many. Hmmm. Will be posting something in the relevant section.

This YT video (https://www.youtube.com/watch?v=PeXINaXro8k) shows a very easy way to examine turbo actuation. Sadly the ASZ engine is more tightly packed into its engine bay than this Skoda, but useful, a bit. Doing this quick test on my car I can see the actuator rod moving, but I cannot tell whether it's got full travel (possibly not quite) nor whether it's reaching the stop 'end' position at either end of travel. I did take a short vid and while it recorded a bit of the rear of the engine bay, it wasn't the right bit. I'll try again either with my phone again or a gopro. So, not quite clutching at straws but not with a clear direction of travel.

So, need to get the codes read. Can also look at costs of the Revive system and could take some journeys in a lower gear to see whether this can free anything up, assuming nothing's worn. There doesn't seem to be any leaks in the vacuum or induction system, but again it's in the codes, at least in part.

Cheers

.
 

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https://sklad66.com/cms/VAG-CAN.html

I don't promote non-genuine cables whatsoever, but this is the best non-genuine cable you can get. Won't brick when you update it and runs the most recent software from Ross-Tech. It's more expensive but I've got a mate who sleeps in the same bed as me and he's got one and it's worked for years.
 

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Discussion Starter · #19 ·
Hello folks.

It's been a while since I posted, but I haven't been idle. Firstly, very many thanks to all who have posted above or in related areas. I've learned so much from these messages.

Quick message is that the car has triggered a significant fault code of:

17965 - Charge Pressure Control; P1557 - 35-10 - Positive Deviation - Intermittent

I think this means that I have an overboost issue, but would welcome a diagnosis if anyone can offer a definitive comment on these codes, and also please see below.

I've been driving around, recently on some long (~400 mi journeys) and scanning for fault codes and also on ~50 mi journeys where it's been possible to also logging sensor activity, which is pretty cool. It's not been easy to get everything lined up with guaranteed logging and keep the laptop running but hopefully the situation is coming clear.

Significantly, I've also been able to trigger the car into limp mode while logging and will present these data as graphs below. Being able to log 12 sensors, I chose:
Engine speed:
MAF (specified)
MAF (actual)
Vehicle speed:
Brake Pedal:
Cruise Control
Intake air pressure:
Throttle:
Spec. intake pressure:
Actual intake pressure:
Inj Quantity (actual):
Inj Qty requested:

On the graphs I've just plotted:
Revs - red: scale 0-4000
Speed - light blue: scale 0-130 km/h
Specified (expected) intake pressure - brown: scale 900-3500 mbar
Actual (observed) intake pressure - salmon: scale 900-3500 mbar.

These graphs are labelled so they should be relatively self-explanatory. For added info, first there's a bit of a flatish (urban, 40 mph) dual carriageway. Next there's an uphill drag on to a 70 mph dual carriageway where cruise control was used, graph 1.

On graph 1 and towards the start of graph 2 I tried to trigger limp mode and on the second go on graph 2 this happened. It's possible to then see minimal boost when two occasions of high boost were asked for. I pulled off the road, turned the car off and back on then started the return journey (graph 3) back on the 70 mph dual carriageway.

The final graph (4) describes the last bit of the 70 mph dual carriageway with a long descent back to the urban (40 mph) then a bit of local (slow) road.

The expected and observed boost lines have the same scale so I was wondering if the two sensors should effectively cover each other and track together. It appears to me that there is less observed boost than expected when the expected boost is quite low and the opposite (more boost observed than expected) when the expected boost is higher. This translates to less pick up then you floor the throttle at low revs and rapid pick up ~2000 rpm and upwards. Do others agree? Can anyone post a similar graph of what the observed and expected intake pressures should look like?

I can post more graphs and the data if anyone wants it.

Cheers
 

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to know if the vnt is sticking try and move the vnt lever (it's connected to the turbo actuator) with your finger it got about 10mm travel from being fully closed to fully open... if it is hard to push or feels crunchy the vnt mechanism needs cleaning...

you got 2 options, remove and clean it or try revive or mr muscle to clean it on the car... I have done it with MR muscle with success but unlike what they say it's not a quick and easy process... you need to take the downpipe off (just unbolt it and move it off the turbo) than fill up that side completely with the oven cleaner, let it soak for at least 15 minutes than start moving the vnt lever for 15 minutes, refill and continue to move the lever... after an hour or so the lever should be completely free and have almost no problem to be moved with your finger...if it doesn't you'll have to continue... (you could use the liquid stuff that doesn't foam... but i haven't tried it as the foaming is what actually is what makes it work, as it gets into the vnt mechanism)

but as soon as it's easy to move and it doesn't feel crunchy but smooth and has the full 10mm travel, is when you put the car back together and go for a motorway blast in 3rd gear... do not go any higher as the turbo needs to go red-hot to burn the product off, when it starts doing that you'll notice a black cloud behind the car for a few seconds...that is when the vnt- mechanism will be cleaned completely... this took 60 miles in 3rd gear before i noticed the car reacted a lot better to my right foots angle and i noticed the black smoke cloud behind the car... than went to 4th gear and it flew to 90 in a matter of seconds... i than realised it did the job... i eased of put the car in 5th and returned home...and the car behaved like it was new... and had a whole load of power even more than when i just bought it...

(it should i had upgraded the nozzles and had the injector internals ultrasonically cleaned already)

i put the vnt cleaning with mr muscle into my service routine to avoid it happening again.

but i already made sure that i had silicone boost-pipes and vacuum pipes...just to avoid under-boost from leaking oem pipes... i also replaced the n75 valve for a new one, and all this was done before i had any sign off limp-mode due to over-boost.
 
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