VR6 Pinking

[Dan_Storm 0]

When I disconnect my MAF i get no change......but I still assumed it was dead so bought a new one. I installed the new one expecting more power/smoother delivery but it drove exactly the same (yes I reset the ECU).

 

I also read posts from a couple of people on here who have found the same.

 

Found a post by dr_mat on this thread that seems to backup this theory:

Funnily enough, very late VR MAFs don't have this effect on the engine if you disconnect them. There's no noticeable difference to idle on disconnect, but the engine hiccups slightly when you reconnect it, that's all.

[Roger Blassberg 0]

I disconnected the MAF and the idle became unsutainable, so it must be doing something, even if its not doing it exactly right.

 

So.

 

I'll reset the ECU and take it out for a tutoring session.

 

Best wishes

RB

[Guest]

Not even putting the MAF on an Oscilliscope will tell you for sure. It is without doubt the most difficult component to monitor and test.

 

Utter rubbish, a DMM and a clue is all that's required. A digital scope is more than capable of producing a real-time trace and saving it.

 

If only the ECU monitored and reported MAF volume in CFM per minute/second or what ever.... that's the only way to be sure.

 

It's an Air MASS meter not an Air VOLUME meter. Since when has the cubic foot been a unit of mass? :roll: Mass is measured in kilograms, grams, pounds, ounces, etc. In this context, MASS airflow is measured in grams/second and a standard ABV VR6 at peak power would have a mass flow rate of 140-150g/s.

[Kevin Bacon 5]

Well that's me told then!

[Roger Blassberg 0]

Finally, finally!! It is cured.

 

It turned out to be the front knock sensor, which had cracked. I had both replaced just to make sure. Front 75, back 45 pounds.

There's a fair amount of dismantling necessary to get at the front one - inlet manifold, oil cooler etc., and my garage man will have a very happy Christmas on the money I gave him to do it.

 

I might even put the modified chip back in the ECU, just to see if it makes a noticeable improvement, now that I'm not in danger of blowing holes in the pistons.

 

Thanks to all who took the trouble to make suggestions. I hope this is of use to others.

 

Now then, what else can go wrong......??

 

Best wishes

 

RB

[Kevin Bacon 5]

Did the knock sensor not show up as faulty on VAG-COM / VW1551 then?

 

They are pretty fragile things those knock sensors. How much were they as I have a feeling this might help some others with pinking issues?

 

Glad you've solved it at last 8)

[Roger Blassberg 0]

Kev,

 

No fault shown - I suppose the continuity remained but the function was compromised.

 

See my previous post for costs -

 

Best wishes

 

RB

[tonytiger 0]

No fault shown - I suppose the continuity remained but the function was compromised.

That's what I hate about these cars (or rather the ecu). So many faults are not reported when I'm sure it should be easy for them to be. I realise the ecu can't always know exactly what's wrong, but using certain sensor values for example as a substitue to others should always be reported as a fault. Similarly, it should be possible to monitor the values from all sensors - especially the MAF. I just don't think the ecu was particularly well designed - I know it's over 10 years old, and there will have been cost considerations, but why allow some values to be monitored and not others. :mad:

 

 

From Bosch, MAFs are £150 + VAT recon (new guts in existing housing) or £200 + VAT new. That was last year's pricing, so they may be cheaper now - or more expensive!

 

And meanwhile Corrado owners are still being kicked in the teeth by the dealers charging us £300 for one, whereas R32, 4Motion etc people get them for less than £100 exchange with a 2 year warranty.

 

Shall we put together a petition to send to VW UK? Might be worth a go....

 

This is where I feel the CCGB should get involved - especially being as no dealer that I know will provide parts club prices. It's not as if it costs anything to join the parts club, as it's free to all in the trade, so I don't understand why VW won't let CCGB members have the discount. The CCGB should speak to VW UK again and try to renegotiate this - even if only for more common service parts (some of which have a 30% discount). This would actually get VW more money, as less people would go to ECP/GSF.

[dr_mat 0]

No fault shown - I suppose the continuity remained but the function was compromised.

That's what I hate about these cars (or rather the ecu). So many faults are not reported when I'm sure it should be easy for them to be.

 

Yep, good points, and I agree. Unfortunately the knock sensor is one of the impossible to quantify ones. If electrically it's got a connection, but it's not picking up any knocking, does that mean it's failed, or does that mean the engine isn't pinking? Impossible to tell, without being able to artificially generate pinking (which I suppose would be possible, but not a good idea).

 

But it would be good if we could read off MAF values, and so on. We can read off lambda values, but it's a little impractical when you're driving along, and OBD1 doesn't really give you enough bandwidth to get a decent granularity of reading anyway, unfortunately.

 

Hey, imagine how tricky it's going to be to keep one of the current generation engines running when they're 10 years old and suffering all the same problems? Jeez, it will only get worse as they make the engines more complex.

[stevemac 0]

less people would go to ECP/GSF.

Cheers m8..

 

Most of the MAF sensors that we buy (for all the makes of vehicles that we cover), we get direct from Bosch... :wink:

[tonytiger 0]

stevemac, I wasn't particularly trying to reduce sales for GSF (or ECP) but personally I prefer to buy genuine parts for my car when possible (never bothered with any cars prior to this though) - and naturally this is easiest if bought from a dealer. I've never had any dealings with GSF (as it would have to be mail order which puts the cost up), but certainly when getting genuine parts from ECP they're usually only slightly cheaper than the dealer, and after the usual 10% dealer discount ECP usually end up more expensive (and never have the parts in stock anyway). Even buying the same make as the original part doesn't guarantee it to be the same as far as I'm aware.

 

Didn't mean to cause offence, and if you're not fussed what make the part is (just want to keep the car running at a low cost) then obviously GSF (and to some degree ECP) are great. 8)

 

Hey, imagine how tricky it's going to be to keep one of the current generation engines running when they're 10 years old and suffering all the same problems? Jeez, it will only get worse as they make the engines more complex.

 

Yes I know - it took ages for me to convince myself the Corrado wasn't going to be too bad (I mean at least it doesn't have airbags in the UK) and part of the reason I decided it was okay was because of vagcom (and the support this forum provides). If I'd known how poor the ecu diagnostics were I may not have bought one. Still, at least it's better than my parents 5 year old Saxo VTS - have to take it to the garage everytime for the diagnostics and that doesn't always show everything.

[emax 0]

Mine's been pinking for a while and, most tellingly, during the winter months too. It doesn't last long (1 to 2 secs) and only between 3,000 and 3,500rpm (when the Schrick kicks in).

 

Last fill up, I put some Octane Booster in with the usual Optimax and the pinking cleared up alltogether. Is there any long-term issues with using Octane Booster on every fill up?