Fault Code 00550

[Scorpiorefugee]

I originally thought this problem was to do with the turbo and it still may be. However, I am now learning how to use a newly aquired VAG interface and the only code I can get is....

 

00550 - Start of injection regulation

 

17-10 control difference intermittent

 

This comes up every time on engine start.

 

There were no other historical codes.

 

The problem, now almost permanent, is that the engine sounds like an old tractor and has no apparent turbo action aalthough it revs freely to the maximum. The full power returns occasionally in short busts and the engine note reverts to a happy buzz.

 

I have read (in Haynes) that excessive 'rattle' can be caused by one or more faulty injectors. The suggestion in the manual is to slacken the injector unions one at a time to check for a change in engine note.

 

I've searched for this code with no results so my plea for help continues.

 

The engine is the 110 bhp '98 with 220k of otherwise exemplary performance.

[Scorpiorefugee]

The saga continues.........

 

I now have codes 1262 and 1265 - no information but I did a test drive with the vacuum reservoir disconnected. It behaved exactly as before. i.e. fault both on and off.

 

I have since removed the boost control solenoid and another almost identical unit and, testing with a piece of hose and blowing, neither seems to change with or without 12v applied although both click (on and off).

 

the boost control solenoid seems to have a much more restricted air flow from the input and the other seems identical but with a white bottom end.

 

Questions - are these identical and how should they react to being on or off?

[turk90210]

might be worth a look at the bottom pully for the 00550 code this usually means that the timing is altering for some reason and iirc the bottom pully is a good starting culprit after that check the other pully's that the timing belt touches

[Scorpiorefugee]

Thanks TURK90210,

 

That's useful but worrying at the moment. I have lots of bits out of the turbo control system out at the moment and my immediate concern is to try to establish what is actually working because out of 3 valves, none seem to be behaving as valves and it would help if I could find out what the rest condition of the EGR valve and the turbo vane control is.

 

Re code 550, I had assumed from the description that it was to do with fuel pressure and possibly associated with the need to crank the engine for a few seconds to start when warm or due to wear and tear after 220k miles, possibly supported by the fact that the code appears after the engine is warm.

 

Life was never this complicated with side valves and downdraft webers. ;)

[Scorpiorefugee]

This now looks serious.

 

I've put everything back together and it's no better but according to VAG thingy the diesel injection timing should be adout TDC but actual is about 25 degrees before. :o

 

Diesel pump c

[seatkid]

Life was never this complicated with side valves and downdraft webers. ;)

Yes it was......the plugs were always fouling with side valve engines making them a pig to start. And decokes were a binnaual ritual.

And weber carburetors - you could never get them running quite right, the automatic chokes always stuck closed, they were....how should I describe them?.....complicated....italian quality...crap

 

I've put everything back together and it's no better but according to VAG thingy the diesel injection timing should be adout TDC but actual is about 25 degrees before.

 

Not sure what you've been doing - have you had the pump/cambelt off?

 

Bottom timing pulley slippage is a known problem. The key shears and it moves between two positions depending on what the engine is doing.

 

Check the camshaft TDC position agrees with actual Piston no.1 TDC

 

IIRC theres a flat bit on the end of the cam furthest from the belt end that should align with the cylinder head - for use with a locking tool.

Edited September 27, 2008 by seatkid

[Scorpiorefugee]

Life was never this complicated with side valves and downdraft webers. ;)

Yes it was......the plugs were always fouling with side valve engines making them a pig to start. And decokes were a binnaual ritual.

And weber carburetors - you could never get them running quite right, the automatic chokes always stuck closed, they were....how should I describe them?.....complicated....italian quality...crap

 

Ahh, but you could always fix them with bits and pieces left over from other scrappers, irrespective of make or model.

 

And anyway, I never had a moment's trouble from the weber in my Mk1 cortina GT.

 

Speedo and rev counter kept in line all the way round to 5 o clock.

 

65 bhp of great fun - until I flew it upside down into a ditch - OUCH!

 

But then, that wasn't a side valve.

 

My old Standard flying 14 was though. Aluminium head and oversquare pistons. State of the art from 1947.

 

But what about my poor old Gal?

 

Just found out that if, once warm, I switch off and restart quickly, I get full turbo boost for about 30 seconds or so and then it starts to sound like an old taxi and the power just drains away.

 

I think I'll check the intercooler for blockage. The rubber pipe to the inlet manifold was swimming in gunk when I took it off so the intercooler may be in the same state.

 

Re the pulley/timing, I've been reading about that and it does seem a likely candidate.

 

Thanks again for your input. I'll keep updating this until one of us (me or the Gal.) gives up

Edited September 27, 2008 by Scorpiorefugee

[Scorpiorefugee]

This is getting silly. I have a single repetitive fault code 550 - injection timing, and when faulty, (most of the time) VAG COM reports injection timing approx 24 deg before tdc and it really rattles.

I have found, since stripping and rebuilding the pipework around the boost ctl solenoid, that the fault seems to clear for a variable period if I switch the engine off and on again while moving and without disengaging the engine. i.e. normal sound and performance.

Just now, after I've been for a 3 mile round trip, the fault seems to have cleared and VAG COM now reports a timing error of only about 8 deg.

All of this supports SK's suggestion that the pump drive sprocket is slipping but that will have to wait for a few days. In the meantime, I am wondering if there is any possible electrical or engine management cause of such a large error.

[f0ster]

it sounds like it might be overboosting and going in to limp home mode, switching off the ignition resets the ecu and you are away again, once the boost goes past 2.2 kpa the ecu goes in to limp home mode and the ignition has to be switched off, on the early ones (1995) all you have to do to reset this fault is to back off the throttle and that resets the ecu, you need to check the turbo waste gate for it being siezed, if that is ok you need to replace the vacume pipes that feed the ecu and the turbo waste gate, also the n75 valve might have to be replaced along with the vacume pipes that feed it, oil gets in to these pipes and prevents the ecu from getting the correct reading, by the time the ecu has got the reading, the boost has gone critical and so the the ecu shuts down in to limp home to prevent damage,

[Scorpiorefugee]

fOster,

 

Thanks for your reply. I agree with your reasoning apart from the fact that this thing actuallt starts from cold with the fault before I even get above 2000 rpm and the Injection timing also registers the 20 deg error on start up.

 

All very confusing. Unfortunately, I can even reason against the pulley slip possibility on the ground that all sorts of varying driving doesn't cause it to change but just switching off and on whilst not disengaging gears can correct the problem.

 

Another thing - The secondary symptom of severe knocking comes and goes, even with the input to the inlet manifold removed.

 

Just one question this time. Is the N75 valve the turbo boost control?

 

Other than that...AAAGGHH!!! :( :wacko: :wacko: :wacko: :wacko: :wacko: :wacko:

Edited September 29, 2008 by Scorpiorefugee

[bofus]

Not sure, but I was reading an article on the VeeDub diesel prior to the PD family, use a 'needle lift' sensor in one of the injectors to accurately set and control the timing. If the sensor fails it falls back onto basic timing.

 

 

Have a look at this

Edited September 29, 2008 by bofus

[seatkid]

Yes Mk1 Tdi uses a needle lift sensor - IIRC its fitted to No.1 injector. I wouldn't have thought that its capable of inducing a 25 deg error but it may be worth disconnecting it to see if the fault becomes permanent. Edited September 29, 2008 by seatkid

[Scorpiorefugee]

Thanks Bofus and also, for the umpteenth time, SeatKid.

 

Yes, it does have a needle lift sensor, on pot 3, and Haynes gives some blurb on it. I shall have to re-read it and have a play.

 

I wandered down to my friendly garage to ask them to check the bottom pulley but thay seemed reluctant to take my money and recommended a local specialist. I don't really have the facilities to tackle the job myself these days so I may have to take their advice. In the meantime, I shall investigate and report.

 

Thanks again fellers.

[Scorpiorefugee]

Just a quick update. I've found some text in theTIS disc which states that if the injector(presumably the one with the needle lift sensor) is closed, the injection timing is fully retarded, if it is open it is fully ADVANCED...

 

There are also some notes about a 'start if injection sensor' which I am having some difficulty in making full sense of.

 

However, you have given me something else to check over although I suppose that this will have to be limited to electrical checks.

 

One thing I have just remembered. A couple of times shortly before the fault hit with a vengence the poor old thing suffered a momentary loss of power after swinging left onto a roundabout and when it did hit hard, I had just completed one of those 270 tight left turns on a motorway access. Could this be a clue? :wacko: :wacko: :lol: :wacko:

 

At least, this all sounds less drastic than some of the other possibilities. ;)

[Scorpiorefugee]

And more....

 

The fuel injection timing control, i. e. the selection of the correct time for the start of fuel injection, is calculated by the Powertrain Control Module (PCM) (A147) using information from the needle lift sensor (B83). The Powertrain Control Module (PCM) (A147) compares the actual start of fuel injection with the set values from the map for the start of fuel injection and provides the appropriate signal to the injector (Y114). If the injector fails, the start of fuel injection remains fixed, dependent on the valve position. If the injector (Y114) is closed (e.g. due to an interruption of fuel supply), a maximum injection advance is performed. If the valve is stuck in an open position, injection is retarded.

 

Quoted from TIS disc. I got the open closed bit back arsewards but it is a very revealing statement if a littlelacking in detail.

 

It appears the only way to test the injector or the start valve is by replacement so now it looks like checking prices and tossing a coin. I might just try connecting my ancient oscilloscope up if I can find somewhere to connect it. It would be nice if I could find some way of making sense of this and pass it on so I am going to try to get something useful out of it.

[seatkid]

If you disconnect the sensor, you'll get a fault on the VAGCOM and it'll go into a limp mode for sure, but if you no longer get intermittent variable performance it would probably eliminate the pulley theory and point the finger at the sensor. Edited October 1, 2008 by seatkid

[Scorpiorefugee]

And yet more... Today I went to the local Bosch injection specialist and spoke to Les - very helpful and knowledgable.

 

Re the pulley - He looked with a torch and said it wasn't wobbling but explained that the problem here was usually caused by people who changed the timing belt and slackened the nut that holds this on when it wasn't necessary and then not retightening it to the 180 or so thingies (bl00dy tight!) and then for another 180 deg. so that it relied on the bit that was only ever intended for location guidance to keep it in place. The mechanic who has changed the belt twice since I have had it is a VW fan and I would not expect it of him but it should have been changed 2 or 3 times before I got it so, who knows? He added that if it had really become loose then the crank would be scrap. :wacko:

 

He pulled off the connector for the needle valve sensor and the figure for actual timing went to 0 which indicated that the sensor was ok. It generated another fault code and the glow plug indicator started to flash - expected.

He then explained thus... The start of injection valve is controlled as a result of a comparison between the flywheel sensor and the needle valve sensor (obvious when you think about it). Its rest position is fully retarded so I assume that it either jams fully activated or is being over driven because of a fault on the control panel. :wacko: Either way, if I can find a way of getting at the connection, I may yet be able to make a logical diagnosis, even if that takes me back to the pulley. The trouble is that, having driven home with the timing permanently at about 13 deg. adv., I cleared the codes and the damned thing is running perfectly but I don't suppose that will last. However, it might just give me a chance to take some measurements for reference.

 

Sorry that this is not yet a success story but I am updating it on the basis that my experience may help someone else.

 

P.S. Thanks to Bofus for that link to what is the most useful description I have found so far. I am going to settle down to read that tonight over a glass or two. (Beats a screwfix catalogue any day! :wacko: )

Edited October 1, 2008 by Scorpiorefugee

[seatkid]

This is turning into War and Peace, the sequel......

 

 

;)

[Scorpiorefugee]

SK,

 

Dead right! WAR! No bl00dy surrender! ......... for a bit longer at least.

Oh! And thanks for your last post which I missed 'cos I was fumbling over my keyboard.

Edited October 1, 2008 by Scorpiorefugee

[seatkid]

Dead right! WAR! No bl00dy surrender! ......... for a bit longer at least.

I was refering to the length of the book rather than the content...... ;)

[Scorpiorefugee]

O.K. I can take a hint. ;)

 

However, I should like some thoughts on the next chapter as I think we're getting to the chase.

 

I tested the operation of the start of injection solenoid thus..

 

Timing seems to have settled at about 8 deg adv. for the moment and the solenoid has about 90% duty cycle. I.E full on.

 

I chopped a wire and the timing went to 28 deg adv. so the solenoid seems to work.( Fault generated - solenoid o/c)

 

Assumption

1 - electronic adjustment range about 20 deg.

2 - problem caused by a mechanical timing error in the region of 15 deg.

 

Nasty thought - that has got to be pretty close to a wrecked engine. :o

 

Will our hero be in time? :o

 

Sorry! War andpeace is supposed to be serious. :P

[seatkid]

He pulled off the connector for the needle valve sensor and the figure for actual timing went to 0 which indicated that the sensor was ok. It generated another fault code and the glow plug indicator started to flash - expected.

 

I chopped a wire and the timing went to 28 deg adv. so the solenoid seems to work.( Fault generated - solenoid o/c)

 

Make your mind up Sergei, was it 0 or 28???

Edited October 2, 2008 by seatkid

[Scorpiorefugee]

O.K. to summarise....

 

Yesterday - went to Bosch centre and Les (expert) disconected needle valve and VAG COM lost signal so timing > 0.

--------------When reconnected all back to stable but slightly faulty - Timing = 8 adv.

Performance quite reasonable and stable for the moment. Still a bit rattly and didn't feel quite right.

 

Today, having re-read all of the info available decided to attack.

 

Checked control to start of injection control - 90%ish pretty well fully one way.

 

Start by checking injection timing again - stable at about 7.5 deg adv.

Disconnected start of injection control valve (cut wire) - VAG COM indicated timing 28 adv.

Reconnected and timing returns to 8 deg adv. - assumption control working over a range of 20 deg. and that control is at max to attempt to retard back to near TDC. but out of range.

Assume normal range to be centred around TDC so there must be a mechanical timing error of about 15 - 20 deg.

 

Now assume needle valve OK, timing control OK, so back to your suggestion - pulley slipped, but this does seem to be a way of diagnosing the fault with some certainty.

 

Not having recent experience of what things look like down there I am having difficulty visualising the way this can happen but from the tests above I can see no other possible cause. It seems from what I have been told that the crank and cam shafts are now offset by the same 15-20 deg unless there is another cause for the mechanical drift - possibly the injection pump drive.

 

I think I have done as much as I can. It's back to the friendly garage.

Edited October 2, 2008 by Scorpiorefugee

[seatkid]

Some light reading for you

 

here here and here

 

There may be more out there waiting for a search....

[Scorpiorefugee]

Thanks SK. Just what I needed to go to bed on. :lol:

 

You DO go to bed, don't you?

 

It will probably soon be time for you to send "Q.E.D."

 

Just hoping that the crank ain't wrecked.

 

Again, thanks for your attention.

Edited October 2, 2008 by Scorpiorefugee