How to tell if a turbo has been cleaned

[Ibiza2000]

Right ok had my vag com reading today, it has brought up codes:
Coolant sensor
Maf sensor

It originally had brought up loads but after a clear and a run it just brought up those, I don't know what to do now as can a maf really affect a turbo that bad it don't work? Could it be a mechanical failure,.. Ie the turbo not correctly put back together? What are signs of mechanical failures on these?

Mech a worryingly, is inconsistent

And another quick question are ALL maf sensors the same or do they vary?

 

[Muttley]

Your MAF is showing all the signs of having failed. An exchange unit replacement is about $60-£80 I think? Never had to do it myself. Go for an OEM part, cheap e-Bay repalcements have proved to be very unreliable according to many who've posted here. The MAF will be common to all TDI engines.

MAF failure causes the ECU to fall back on a more conservative map with a consequent loss of power.

CTS (Coolant Temperature Sensor) failure causes the ECU to fall back on a fixed, low value for coolant temperature i.e. it assumes the engine is cold.

If it was me, I'd be getting a new MAF, clearing the codes and seeing if any new fault codes get set.

I don't think your turbo has been taken apart. I think it has had a cleaning solution poured into it via the exhaust downpipe connection or the EGR connection.

 

[Ibiza2000]

It probably has as long as its cleaned at this point is better than nothing, I'm just a bit pd off for being lied to by mech a :/

My mate says he has a maf I could try out so Ill do that and see what comes of it then I'll take the plunge if all is well, I'll post up my results, thanks for all your help do far

 

[Ibiza2000]

Iv been looking into this issue now finally my mate came round with hea maf we plugged it all in and boom the turbo is kickin, it was the maf stoping the turbo from working, however, it's still got a positive charge pressure code and does do the whole limp mode thing I I kick it to like 2800 revs,

What can cause the positive boost pressure fault just sticky VNTs? - it was scanned on the vag com, it just has the coolant sensor fault code and the charge pressure deviation - positive

Also anyone know a part no for dealers on a maf for seat? My mate can sort a discount out, failing a crap discount wheres best to get a maf sensor from?

 

[Muttley]

Ibiza2000 wrote

Iv been looking into this issue now finally my mate came round with hea maf we plugged it all in and boom the turbo is kickin, it was the maf stoping the turbo from working, ​

Not exactly, MAF failure causes the ECU to fall back to a map that assumes a low, fixed air mass, which limits the boost. The turbo is still working.

however, it's still got a positive charge pressure code and does do the whole limp mode thing I I kick it to like 2800 revs,

What can cause the positive boost pressure fault just sticky VNTs?​

Sticky vanes or the EGR valve sticking open are the usual suspects.

 

[Ibiza2000]

Tht sounds about right lol

So I'm intrested to see what are the causes of positive charge deviation? Just vnt and egr valve? Can the egr be removed to go for a straight pipe? Or is my turbo relying on that? What may mech a blame the charge pressure on now as he's told me the vnt's are clean...

 

[Ibiza2000]

Also forgot to post looking at mafs and I got a good price on one called inter motor or something like that, apparently it's ment to be exactly the same as a Bosch one quality wise, just wondering if anyone's used that make and what they think of it?

 

[Ibiza2000]

http://www.intermotor.co.uk/?p=smpeurope/intermotor&SESSID=7ihvc43kjuhgrmm2grpoqson47

http://www.intermotor.co.uk/?p=smpe...=intermotor&SESSID=45m47fqq8bkjbcic7nu897b1p1

Theres two links one about intermtor and one with the maf link, what u guys reckon?

 

[Seatmann]

Hi man, I'd go for the bosch one myself, read a lot on the tdi sites about useless mafs. I think the one on my car is one of them but it was already on there when I got it. It's not going above 550mg in vagcom though which suggests it's lacking a bit. I can still hit 100mph but it just doesn't seem to have the little extra kick of the previous car.
Regarding your over boost, that's usually the vanes in the turbo sticking a bit or the actuator spring is knackered. The turbo uses vacuum to pull the actuator which moves the vanes which ups the boost. I would try moving the vnt lever by hand and see if it moves properly, it should move a good inch anyway. It'll be tight with the actuator still connected but it should still move smoothly.
Another method is to get the car warmed up and get the revs upto around 4200 or so, a good old italian tunes up. It'll probably hit limp mode but just restart it and try again a few times. It's worth a shot anyway, I've read of a few people having success with that method.
For anyone using innotec, you have to disconnect the boost pipes and the downpipe for the exaust, blank it off and pour the stuff in. I haven't had to use it myself but if you google it you'll find the instructions.

 

[Ibiza2000]

Just got a good price from Gsf on the Bosch one so will go for that

As for the positive boost deviation, the mech who cleaned the vnts said it was a map sensor surely this would have shown on the vag com reading?

Can positive deviation on boost pressure charge be caused by a map sensor?

 

[Seatmann]

Just got a good price from Gsf on the Bosch one so will go for that

As for the positive boost deviation, the mech who cleaned the vnts said it was a map sensor surely this would have shown on the vag com reading?

Can positive deviation on boost pressure charge be caused by a map sensor?

If the map sensor is faulty it could cause problems, the ecu uses the info from sensors like the map one to make adjustments but if the sensor's wonky then the info it sends to the ecu is wonky and yeh, it should've shown up with vagcom but sometimes you do get flukes that slip through. I have read of people solving limp mode with a new map sensor even though they didn't have a code for it.

 

[Ibiza2000]

I could just b playing a guessing game here map sensors arnt cheap either r they?

Is there no way ican test if it's the map?

 

[Seatmann]

£20 - £30 there abouts, not sure how you test it personally but I'm sure the info must be out there somewhere

 

[Ibiza2000]

So my map sensor is it a digital sensor or a anologue? Again my engine code is ALH, I'm asking this because there are different testing methods :/

 

[Seatmann]

It's analogue but a very fast response one, somewhere in the region of 500 samples per second. Straight from the mouth of my brainy guru lol

 

[Ibiza2000]

Lol so in right in saying analogue sensors can be tested with a voltmeter? What sort of voltage current should I expect? And I should unplug the sensor and test the voltage from the plug?

 

[Seatmann]

Haven't got a clue, never had a map problem so never had to research it. Have you tried googling how to test them?

 

[Ibiza2000]

Yeah tried it but everyone is comin up with how to re invent the wheel when ur only lookin for a simple step to test the damn thing, lol just need a voltmeter, where to put it and what readings u should get, but they put it in about 50 steps lol