Sometimes fast, sometimes slow...

[jamiehamy 0]

Hi all,

 

I've decided to post and ask the question as I'm pretty certain the 'symptoms' are not just a figment of my imagination.

 

Basically, sometimes I drive my VR and it feels great. Fast and willing to rev. Happy to sit at speeds above 70 without effort and sounds really happy.

 

However, some other days, it feels slower and less eager to rev - it's more of an effort to get her revving about 4k. I've (in my head) analysed this for a good few months and can't find any logic to it. Outside temperature doesn't seem to make a difference - there is no pattern. Only thing I notice is that sometimes if i switch the engine off and back on, it improves performance.

 

I know that the ECU adapts, but sometimes the car is 'fast' straight off.

 

Final point - MPG seems to match this performance chance. When she's running 'faster', the MPG is better (unless i'm booting it).

 

Any thoughts from anyone? I've done recently plugs, VAG leads, blue sensor, cleaned MAF, new air filter.

 

Last time i ran VAG COM, it gave me the old 'Control limit not reached - intermittent' fault.

 

I'm thinking MAF or lambda but wanted to check in case there's something else that could cause this. Has anyone else experienced this before?

 

Thanks, Jamie

[easypops 8]

Not sure if you have done this?........not sure personally how good it is but i remember one of the guru's on here writing about how important it is to do this procedure

 

http://wiki.the-corrado.net/vr6_ecu_reset_procedure.html

 

I've not needed to do as yet but plan to once i bring the c out of hibernation

[Kevin Bacon 5]

VR6 ownership is like Golf: Striving for consistency is a long, tedious and expensive path.

 

I don't think I've ever owned a car that performed exactly the same from one day to the next. It would be nice if they did!

 

This control limit not reached VAG-COM error. I'm guessing that was Lambda related? Is the part throttle performance off, or full throttle?

 

Full throttle is not managed by lambda, it runs just from the MAF and throttle position. If both conditions are down on power, then I'd look at the MAF since that can throw both out of kilter, especially the part throttle. The lambda will have to do more work to get the fuelling right and moan about it, hence the VAG_COM error.

[jamiehamy 0]

This control limit not reached VAG-COM error. I'm guessing that was Lambda related? Is the part throttle performance off, or full throttle?

 

Full throttle is not managed by lambda, it runs just from the MAF and throttle position. If both conditions are down on power, then I'd look at the MAF since that can throw both out of kilter, especially the part throttle. The lambda will have to do more work to get the fuelling right and moan about it, hence the VAG_COM error.

 

Thanks Kev - My cheapy cable gave up the ghost, but yeah, from memory it was 00537 11-00. So lamba related.

 

I'd say the issue is an overall rev range issue, less noticable lower down, but still there. My whole problem is that I want it to run perfectly everyday...lol I'm thinking I'll have to save up for a new MAF. I reckon it's the original on it tbh and that'#s at 174k.

 

It's annoying, there are some days when running well and you think ' Gawd, she just wants to go' and other days you really have to 'work' to get momentum (still fast, just not as willing).

 

 

Easypops - I don't have the proper VAGCOM cable, so never been able to perform the basic settings. I've done about 10k since the last reset. :(

 

Cheers, J

[Kevin Bacon 5]

Yeah I know what you mean. Mine was like that when it was standard, but to be fair, when a car is used every day, you notice any lack of performance immediately.

 

Have you done any basic checks like dragging rear calipers, low tyre pressures, someone putting 20 paving slabs in your boot.... that sort of thing?

 

It would also be handy to do another VAG-COM check if you can. A dead cam sensor can causee the symptoms you describe, although peformance and economy would be woeful all the time, not occasionally.

 

Another thing it could be is the VR6 rot has set in. In other words, you're used to the power and just finding it a bit slow now :D

[Roger Blassberg 0]

Maybe your cam position sensor/trigger is failing intermittently.

 

Best wishes

 

RB

[Yandards 0]

Any of the usual sensors failing will put the ECU into limp home mode, this will give you noticably less go and less fuel economy as the engine is no longer on full adaption and is using safety defaults.

 

VAG-COM checking should highlight areas to look into although I always find it is worth doing that, clearing the codes and doing it as soon as possible after you think the car has been down on power; that way at least you can prove to yourself you are not going mental!

 

Although as Kev says you do just get used to it after a while, I find a run out in my wife's Passat TDI soon reminds me that the nugget is not slow, not going to work too well when the new VR arrives on Thursday to replace the Passat though...