le shed has a tiny turbo( ECU controlled boost ? we dont all drive VAG's you know
)
of course the wheel is going to be spining at idle , just not enough to produce positive boost. I think you'll find the vacumn reading on a NA car woudl be more than on a forced induction one.
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ECU's do not "request" boost, they just deal with the reprocussions of having boost, some also limit boost.. Whether you get boost or not is defined by whether your pushing enough exhaust gasses to spin the turbine fast enough create positive boost - nothing to do with the ECU at all.
Your assuming that a all car's turbo system are confugured in exactly the same way as yours. Theyre not. You don't get full boost at 1000rpm - do you?
Butuz
I didn't say anything to contraryOriginally Posted by Moby-Dick
le shed has a tiny turbo
of course the wheel is going to be spining at idle , just not enough to produce positive boost. I think you'll find the vacumn reading on a NA car woudl be more than on a forced induction one.
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Actually VAG ones do - in fact it's literally a parameter of the ECU you can see with something like VAG COM (there is also a parameter for 'actual' boost too) - sure mechanically you're limiting pressure in some way but that's not something I made any such statement about. Aside from that I see nothing there that I disagreed with or othewise implied
No, I'm assuming that you'll not having a positive boost at idle on _any_ turbo charged car - your reply suggested to the contrary so what exactly is your issue? lol. I'm making no 'assumptions' about 'all car's' - we're talking about a Passat are we not? Sheesh.
Last edited by dangel; 22-09-2006 at 12:27 PM.
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The VAG units have a solenoid for boost control in the same way I have one for my aftermarket boost controller ( Infact a one of the aftermarket ECU's available uses a VAG solenoid for its boost control function )
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Yup, it's usually the N75 valve (I think this is true on the passat from memory). My boost controller runs directly off the ECU on the Leon - had it put on the same time as it was remapped.
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If it's a noticeable 'drop' in power delivery, the most likely culprit is the MAF sensor - a VAG special Achilles heel... it'll show up on a diagnostic, so get to your local dealer and persuade a spanner monkey (no offence intended) to take the hand held device out and plug it in (under a panel on the lower dash somewhere) - it should pull all the way through to 4/5k before dropping off
cant remember the last time i saw a diesel go past 4.5 k tbh then redline...If it's a noticeable 'drop' in power delivery, the most likely culprit is the MAF sensor - a VAG special Achilles heel... it'll show up on a diagnostic, so get to your local dealer and persuade a spanner monkey (no offence intended) to take the hand held device out and plug it in (under a panel on the lower dash somewhere) - it should pull all the way through to 4/5k before dropping off
er, my golf does tbh
err my golf doesnt, redline after 4.5
and on other deisels i have seen i have only ever seen the same.. strange
go see some more then
you can get kits to clean them, which might provide a short term solution, or a replacement (recon) part should be £60-80+fitting... (mass airflow meter)
The dreaded MAF... ho-yus. Very easy to kill these with oily air filters/induction kits etc and yes, it dies all by itself too. Can't you unplug the MAF, drive it and see if the car pulls better? I seem to remember you could - but correct me if i'm wrong? It should peak fairly early in the rev range and then gradually tail off (compensated by engine power somewhat) although it can be a fairly quick tail-off on a standard map (chipped cars generally hold boost at a higher level for longer) but it does sound like somethings wrong in this case to me. Also check pipes/clips to see they're tight - sometimes they work themselves free. If you're brave, put the handbrake on and load the car in first gear (control it with the clutch) whilst someone listens around the engine bay for hissing sounds (leaks). Any VAG specialising garage should be able to read off fault codes from the ECU (if any) too giving you an idea of what's wrong. I had an intercooler pipe work loose once and although I quite liked the 'whooshy' noise it didn't half drop powerIf it's a noticeable 'drop' in power delivery, the most likely culprit is the MAF sensor - a VAG special Achilles heel... it'll show up on a diagnostic, so get to your local dealer and persuade a spanner monkey (no offence intended) to take the hand held device out and plug it in (under a panel on the lower dash somewhere) - it should pull all the way through to 4/5k before dropping off
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4700-rpm redline Passat TDI..
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i've heard that too, but never tried it... the power delivery in my tdi is fairly linear once it's kicked in (1.5kish), tailing off past 4k(ish)...
It should feel that way to the driver - it's only really on dynos you see it. Def think his car sounds unwell tho
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