1.9TDi Turbo cutting out Error P1557

gabhan16

I have seen some threads on this about cleaning the VNT valve? Is this easy to do and how would I go about it? No mechanical experience with any cars

It's a VW Passat

gabhan16

To elaborate, my turbo cuts out when I get to about 3000 revs in 1st 2nd or 3rd gear or earlier sometimes in 4th and above.

If I restart the car it's fine, no error was and when one did I knew someone who ran the diagnostic with this error. The diagnostic machine must have reset it coz it worked for a day or two but then cut out again.

George Dalton

Have you checked the actuator on the turbo to verify that the VNT is sticking?

gabhan16

I haven't to be honest, how would go about that? Cheers.

George Dalton

The easiest way is to operate the VNT with a hand held vaccum pump and see if it moves freely.

To be honest with you from your description of the problem it doesn't sound to me like a VNT problem.

You say it sometimes happens in first gear, does it only happen under hard acceleration or can it also happen on light throttle?

Which shape Passat is it?

gabhan16

Hard acceleration and its a saloon 100bhp.... Took her out there a while ago and it seemed fine but no doubt it'll show again

George Dalton

Which model? B5.5 or B6?

gabhan16

George Dalton wrote: »

Which model? B5.5 or B6?

B6 I think, it's a 03

gabhan16

Anyway for me to check for sure?

gabhan16

actually looks like it's a b5.5 due to the year after a look at wikipedia

George Dalton

2003 would be a B5.5.

The reason I asked was because the B6 models have a common problem with the wiring that can lead to the overboost fault code.

In your case with the B5.5 it is likely to be either a faulty MAP sensor or a sticky VNT.

gabhan16

George Dalton wrote: »

2003 would be a B5.5.

The reason I asked was because the B6 models have a common problem with the wiring that can lead to the overboost fault code.

In your case with the B5.5 it is likely to be either a faulty MAP sensor or a sticky VNT.

Can the map sensor or sticky valves be pricey?

George Dalton

The MAP sensor is cheap enough, around €60. The VNT is expensive to sort out properly because it is built into the turbo. The only 100% way to sort it out is to replace or recondition the turbo.

gabhan16

George Dalton wrote: »

The MAP sensor is cheap enough, around €60. The VNT is expensive to sort out properly because it is built into the turbo. The only 100% way to sort it out is to replace or recondition the turbo.

Lets hope it's the sensor, the Passat just cost me 3k, if it is the VNT would it be worth repairing?

George Dalton

Sounds like you bought a Donedeal special. Whoever sold you the car probably knew about the problem and decided to sell the car rather than fix it.

Worth fixing alright but will still cost you a good bit of money, to get a garage to remove the turbo, send it away for reconditioning and then refit it you would be looking at around €900 in total. If you can DIY it you will get away with spending less.

gabhan16

Thanks for the advice anyway

gabhan16

How much would it cost just to fit one roughly if you don't mind?

George Dalton

We would be charging about 5 hours labour so €250 + VAT. Don't forget that as well as the replacement turbo you also need to allow a few quid extra for oil and filter, air filter, turbo oil feed line, seals, gaskets, nuts, bolts etc.

gabhan16

I have cleaned the actuator rod with WD40 but still seems to be happening, you mentioned you don't think it's sticky VNT vanes? Why do think that?

George Dalton

Usually a sticky VNT won't lead to limp mode until you are in 3rd, 4th or 5th gear. It would be unusual for it to cause limp mode in 1st gear as yours is doing. Did you try to move the actuator rod up and down when you were working on it?

gabhan16

I got a fella to do that for em so I din't to be fair. Could I move it with my hand to see? And if so what kind of response should I get from it?

gabhan16

ive tried to replicate it in 1st and 2nd but couldn't last few days only 3rd and 4th maybe i was mistaken. i need to drive it a bit more to find out i need to get it to someone who knows more than me i guess

George Dalton

If it is happening more in 3rd and 4th then it is more likely to be a sticky VNT.

Anybody that is familiar with the setup of a VNT turbo should be able to diagnose it in a very short time to be honest. Where are you located?

gabhan16

Cork City

MidlandsM

George Dalton wrote: »

2003 would be a B5.5.

The reason I asked was because the B6 models have a common problem with the wiring that can lead to the overboost fault code.

In your case with the B5.5 it is likely to be either a faulty MAP sensor or a sticky VNT.

Yeah, any i'v had it nearly always turns out to be the map sensor.

cork city ehhhh, you are approx just 1hr.40mins from George

gabhan16

ill see if i can get up but i know one or two guys here in cork that are supposed to be handy with VW, if you were nearer id be up to ya in a shot george

George Dalton

I'm sure there are plenty of places in Cork that will be able to get you sorted, hopefully someone will be able to suggest somewhere for you to try.

gabhan16

Good call, anyone here know any vw mechanics in cork city?

gabhan16

I've seen a new turbo on ebay for 330E, 2 years warranty. For that price would it be better that a recon of the engine? I'll check the MAP sensor first of course, just preparing for the worst.

http://www.ebay.ie/itm/TURBO-CHARGER-VW-PASSAT-3B-3B3-3B6-1-9TDI-1-9-TDI-ATJ-AJM-/380600281724?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item589d8b6a7c#ht_7022wt_1162

George Dalton

That is a cheap chinese copy of the proper Garrett turbo. Literally not worth fitting if you got it for free.

gabhan16

Cheers, good to know.

Bean_Flicker

gabhan16 wrote: »

I have seen some threads on this about cleaning the VNT valve? Is this easy to do and how would I go about it? No mechanical experience with any cars

It's a VW Passat

Have a read of this:

http://www.audi-sport.net/vb/a4-a4-cabriolet-s4-forum-b6-chassis/177333-1-9tdi-sticking-turbo-vanes-fix-pics.html

Hope this helps, I know it's on an Audi but engine is the same.

gabhan16

I would not be able to do that myself, but thanks

gabhan16

I found a very extensive post on another forum about this issue that may help others.

"i just want to share this hope that this may help you all,

Diagnosing and Fixing Limp mode for A4 1.9TDI
By Canadian Grizzly

Read the entire post prior to jumping to conclusions.

This is a general overview on how to diagnose and fix a A4 1.9TDI that goes into “limp” mode due to an overboost of the turbo. While I’m by no means an expert I’ve gleaned this information through information on this forum and my own experiences.

Limp mode happens when you are accelerating, often up a hill, or passing and the car suddenly seems to lose all power. Power is immediately restored when you cycle the ignition. What has happened is the computer has sensed that the turbo has created too much boost and the computer shuts it off and goes into safe mode.

There are a number of different reasons why the car may overboost… some being very simple to verify and fix and others more complex. The majority of overboosts are created by:

Bad Maf (Oxygen Sensor)
Leak in the vacuum system
Faulty N75
Bad actuator
Dirty gummed up turbo causing variable vanes to jam or stick

Some members have experienced overboost due to coked up intakes as well. This is a maintenance issue. See below for links.

If it only occurs occasionally try to find a long uphill slope on the highway and try to accelerate and reproduce limp mode. This will help later to see if the problem is resolved when you try again with similar circumstances.

Bad MAF
One of the easiest to check...but you will get a CEL (Check Engine Light). All you have to do is disconnect the MAF and give it a test drive. If power is same or improved, replace. Read this thread for one example... P1556 Limp Mode Diagnosis Problems - TDIClub Forums

Vacuum Leaks
Most problems with the turbos are simple leaks in the vacuum lines. It is hard to see on the cloth covered stock hoses and if your car is past warranty it is best to simply replace all the lines. Here is a link of what you need… http://forums.tdiclub.com/showpost.p...7&postcount=30 Note to Canadians... mcmaster won't ship to us so I recommend sourcing the lines (and any other necessary parts) from Brian at Roseland Volkswagen Parts from Roseland Technical Services for A4s
Be very systematic. Remove one hose, cut new one to length and replace that one hose and so on. That way you won’t screw up. When removing lines carefully work them off with a screw driver or carefully slice them with a razor and then slide off. Be especially careful if its cold. When you encounter a check valve ensure that it is also working correctly.

Also check the large vacuum line on brake booster…if you have experienced any hard brake pedal situations that will likely be the culprit. Ensure that the hose to the bottom of the airbox is plugged in as well, this one is commonly overlooked. If you haven’t replaced the hoses and think you have ruled out a leak… start checking again as this is the single most common reason for most overboost situations.

The top line on the N75, labeled 'vac' is where unregulated vacuum is drawn. Regulated vacuum is pulled through the larger 5mm ID line labeled 'out` The 5mm ID line opposite the other lines is the vent which vents the regulated line to atmospheric pressure.

Even if the N75 is good, it it doesn't have solid vacuum getting to it (top hose 'vac' ) it will not send vacuum properly out the 'out' port just below the vac port. It is also important that the vent port is clear. It's on the same side of the valve as the connector.

2 test options posted by Anut:

1. disconnect the 'vac' hose. Connect a mighty vac to the hose. Start the car. You should get >25 inHg vacuum.

2. connect a vacuum hose directly from the rigid brake booster vacuum line to the 'vac' port on the N75. You'll get an EGR code, but your turbo oughta work great.

If 1 doesn't occur, of if 2 fixes the problem; find the vacuum leak. Vacuum is drawn from the rigid line. The line splits twice such that you have 4 unregulated vac lines. One to the N18 (EGR), one to the N75 (turbo), one to the vacuum reservoir and one to the N239 (anti-shudder valve).




Faulty N75 solenoid
The N75 is the solenoid that adjusts the vanes on your turbo. On your car it will be on the firewall just to the left of the airbox. It has a grey top and some vacuum lines attached to it. If it is not working then you would be getting an overboost situation.

You can also check that the N75 is working and moving the actuator on the turbo. This is a little more difficult. Remove engine cover… use a mirror and a flashlight and watch or feel the actuator as another person puts the ignition key on. It should cycle and move properly. As in diagnosing many things on these cars a vagcom comes in very handy as you can ask the computer to cycle the N75 while you watch the actuator. With the engine running, in VAG-COM go to Group 011. Down in the lower left of that VAG-COM page is "basic settings." Click this on. You'll see the N75 go "off" and "on." Then, put a light down against the lower firewall (just in front of where the passenger's feet would be) and position a mirror so you can see the back of the turbo. As the N75 cycles, you'll see the VNT actuator rod move up and down, about 3/4" each way. If this test is ok, you can assume that the N75 is working ok.


If it doesn’t seem to work then swap the EGR solenoid, N18 (same looking part just to the left of the N75 and with black top not grey) with the N75 and try again.

Faulty Actuator
If this doesn’t solve then you either have a faulty actuator or stuck vanes in the turbo. If you can get your hands on a vacuum pump attach it to the actuator and see if it holds vacuum. If not then purchase a new actuator. Dealers normally don’t carry the actuator as a separate part as they want to sell you an entire turbo. These can be purchased by a number of vendors in the states and through Roseland in Canada.

Test the adjustment of the VNT actuator. It should start to move at 3-5 inHg, and be on the stop (fully open) at 18 inHg. Less vacuum necessary, and it will spike. More, and it takes too long to make boost, and drivability is poor.

Here is the TSB from VW on swapping and testing the actuator. http://pics.tdiclub.com/data/500/Actuator_TSB.pdf

Jason has a couple videos of a actuator in action. Video showing proper VNT movement - TDIClub Forums

Sticking turbo vanes
Now failing all of the above it might be the hardest job which is cleaning the actual turbo. Note I said clean not replace. Here is the link thanks to Drivbiwire on how to accomplish this task… VNT Repair Procedure - TDIClub Forums

PLEASE NOTE: If you take it to a dealer they will diagnose a blown turbo and replace what is probably a perfectly good dirty turbo. If you are daunted by the task find a TDI Trusted Guru, look at the sticky in TDI 101 or go to a local GTG (get together) general discussed and planned the regional forum areas.

Other power sucking maintenance that should be performed.
Snowscreen cleaning… http://forums.tdiclub.com/showthread...00#post1344400 For Beetle Lower Air Box / Snow Screen Removal for NB - TDIClub Forums
Intake Manifold cleaning (just do it…really) http://pics2.tdiclub.com/gwillie/VW/...AKEMAN101b.htm"

gabhan16

Brought car to a mechanic and he couldn't find the problem as he couldn't recreate it. The problem is intermittent so where does that leave me?

MrFrisp

gabhan16 wrote: »

Brought car to a mechanic and he couldn't find the problem as he couldn't recreate it. The problem is intermittent so where does that leave me?

You could google the "Mr Muscle" treatment for sticky Turbos..

Easy enough to do if your any bit handy at DIY ... The "fix" may only last a few months though and would need to be repeated.

The Briskoda Forum is a good one here..

https://www.google.ie/search?q=mr+muscle+treatment+for+sticky+turbos&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a


Also this one..More expensive,,but seems to be easier to do..

http://www.spdiagnostics.com/index.php/products/workshop/revive-turbo-cleaner
.

gabhan16

Update on this one guys. Got some error codes and brought it back to my mechanic.

He seems to think it may be the throttle body, he said drive it some more until an another error comes up so he can has more info.

Finally looking like we are making headway