GolfGTIforum.co.uk
Model specific boards => Golf mk5 => Topic started by: mrlapou on 10 September 2008, 16:09
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No idea if this is a test which means anything, so bear with me.
Since from when a pipe (not sure which, as stealer fixed under warranty) blew off in engine bay, the car seems to be suffering from what appears to be like throttle lag. Seems to be a slight 1 second response to throttle inputs Also down shifting in DSG tip mode, the engine / gear change baulks. Taken it in twice now, but stealer says it fine..
Today I tried this against a MK2, 2.0T Audi TT with DSG. Both engines warmed up & are stock with no mods.
From idle (box in Park) , as fast I could, blipped throttle to WOT then released immediately. Did this a few times.
Results:
TT (1.5k miles on clock) : rev up to about 2850 rpm.
GTi (21.5k miles on clock, new Plugs, PCV, DV, Air Filter, oil changed 2k miles ago) rev up to 2100 rpm.
Any thoughts?
Could you check your car, see how it relates to my GTi results.
Tks
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No idea if this is a test which means anything, so bear with me.
Since from when a pipe (not sure which, as stealer fixed under warranty) blew off in engine bay, the car seems to be suffering from what appears to be like throttle lag. Seems to be a slight 1 second response to throttle inputs Also down shifting in DSG tip mode, the engine / gear change baulks. Taken it in twice now, but stealer says it fine..
Today I tried this against a MK2, 2.0T Audi TT with DSG. Both engines warmed up & are stock with no mods.
From idle (box in Park) , as fast I could, blipped throttle to WOT then released immediately. Did this a few times.
Results:
TT (1.5k miles on clock) : rev up to about 2850 rpm.
GTi (21.5k miles on clock, new Plugs, PCV, DV, Air Filter, oil changed 2k miles ago) rev up to 2100 rpm.
Any thoughts?
Could you check your car, see how it relates to my GTi results.
Tks
What does "WOT" mean? :huh:
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Wide Open Throttle
i.e pedal mashed to the floor
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Please do NOT try this - unless you want to fcuk your turbo! :shocked:
Revving an engine under "no load" conditions creates aggravated wear, both on the piston, and in the valve train - considerably more so than under load. :sick:
Furthermore, blipping, or reving the throttle on a turbo engine is a sure-fire way to dramatically reduce the life of the turbo. Whilst the engine revs may rapidly drop to tick-over speed when you close the throttle, the turbo will still be spining at around 180,000 rpm (and that is NOT a typo), with very little oil flow through its' bearings. :sick:
The reason that the GTI and TT can not rev beyond 3,000rpm under no load is simply because VW/Audi specifically programme their ECUs to prevent such stupid behaviour. :smug:
I noticed this very same question was posted over on ukmkivs, where you will know-doubt get a completely different answer from their resident bully/net-nanny - who is expert in . . . . . er . . . . . IT. :rolleyes: For once, trust the stealer, because they are exactly correct. :wink: :smiley:
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Classic response TT - I was waiting for this :grin:
Cass
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Well you learn something every day :grin:
Didnt know that was the case with turbo cars... so I guess sitting at the lights in launch control mode is probably no good for them either?
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Didnt know that was the case with turbo cars... so I guess sitting at the lights in launch control mode is probably no good for them either?
Not really a problem, because (a) the revs are held at a constant speed, and (b) the revs are limited by the ECU to a safe level. :smiley:
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Sorry to spoil the party but both the GTi and TT will happly rev up to red line under no load i.e DSG in P.
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Sorry to spoil the party but both the GTi and TT will happly rev up to red line under no load i.e DSG in P.
Really! :rolleyes:
Well you carry on f**king up engines and turbos, but please don't encourage others to do so, and please, when you come to sell your car, advise new owners of how you treated it. :sick:
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The OP isn't trying to rev the nuts off his engine, he's just concerned that the throttle response isn't what it should be and is testing by comparing a short 'foot to the floor' blip against another car... during which short time it wont over-rev anyway. Not the most scientific test but a decent benchmark nonetheless.. and with a 750rpm difference I'd say there's something not quite right there.
In days gone by disconnecting the battery for a while caused the throttle body alignment to reset.. not sure if that applies to anything after the MK4 though.
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The OP isn't trying to rev the nuts off his engine,
Soryy, but can't agree with that. He is pressing the loud pedal to the floor, thereby requesting the engine provide maximum airflow, maximum fueling, and therefore maximum revs. Just because modern engines have "rev-limiters" and the like, it still doesn't mean it is safe, or advisable to rev a car to high revs without any load on the engine. This was fully explained, and painfully (to the owner) demonstrated to me by a Ferrari engine technician at Grey Paul. :nerd:
he's just concerned that the throttle response isn't what it should be and is testing by comparing a short 'foot to the floor' blip against another car... during which short time it wont over-rev anyway. Not the most scientific test but a decent benchmark nonetheless.. and with a 750rpm difference I'd say there's something not quite right there.
Like I said, "foot to floor", or indeed any "blipping" of throttle is a very bad idea on a turbo engine. How would you like to be trussed up naked like a chicken, and then spun around at 180,000 rpm on your bare butt cheeks without any lubricant? :shocked:
If the OP is concerned about actual throttle response, then his method certainly aint an appropriate method. VAS505*, or VAG-COM, and/or a RR session would help/tell. :smug:
Regarding the difference between the TT and the GTI - well do they have identical engine maps? Even if they both have "OEM" maps, there can still be differences, and the manufacturers are known to release revisions to standard maps, which can noticeably alter many "traits". On my RS, the revised engine map dramatically altered mid-range throttle response, but also altered the operation of the exhaust valves - so going back to the specific concern of the OP, this perceived difference may actually be perfectly OK. :nerd: :smug:
In days gone by disconnecting the battery for a while caused the throttle body alignment to reset.. not sure if that applies to anything after the MK4 though.
I'm sure that on all the later Bosch MED ECUs, the throttle body was re-aligned every time your turn on the ignition. I can hear, and feel the throttle body doing just that on both the GTI and the RS. So I doubt the battery method would add anything further - though, providing you have the audio sec code, there would be nothing to loose by trying. :smiley:
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Yes but the engine isn't reaching high revs at all is it :tongue: and it's nothing to do with a rev limiter.. it just doesn't get there.
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VCDS (Vagcom) did not pull up any codes. Have carried out the throttle re-alignment, but this made no difference.
When doing a rolling road test upto max revs, how do they know what load to put on the driven wheels to simulate the car tyre and wind resistances as they change at any given speed??
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Yes but the engine isn't reaching high revs at all is it :tongue: and it's nothing to do with a rev limiter.. it just doesn't get there.
But the actual revs arn't the issue. The engine is still being reved with zero load, and with WOT, the turbo will get max boost, and spin upto heady revs. :tongue: :smug:
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VCDS (Vagcom) did not pull up any codes. Have carried out the throttle re-alignment, but this made no difference.
OK, thanks. Do you know if there are any differences in ECU software revisions?
When doing a rolling road test upto max revs, how do they know what load to put on the driven wheels to simulate the car tyre and wind resistances as they change at any given speed??
Ahhh, the actuall rolling road is fundamentally a dynomometer. This means it actually puts a specific load, or static resistance on the road wheels (or hubs, if it is a hub dyno), and is meant to mimic a straight and level "normal" road. This is where the term "brake horsepower" orginiates - the engine/car was tested against a load provided by braking the rollers. Don't forget, all the driveline transmission is being used on a RR, in exactly the same way as normal driving.
Regarding wind resistance, you have a valid comment, but not completely important. Afterall, when accelerating from a standing start (unless there is a big headwind), then wind resistance isn't an immediate concern, just the loading through the wheels and transmission. The BFO fans used in rolling roads are simply to assist in cooling.
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VCDS (Vagcom) did not pull up any codes. Have carried out the throttle re-alignment, but this made no difference.
OK, thanks. Do you know if there are any differences in ECU software revisions?
Thanks for informative info on rolling roads.
I do not know ECU software revisions. Suspect there may be as the cars have a 3 year age difference...
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max boost at < 3k rpm ? maybe on a diesel..
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max boost at < 3k rpm ? maybe on a diesel..
On the standard 200PS GTI, the turbo is "on song" therefore spinning at virtually max speed at 1,750rpm. The Ed30 is a little higher (about 2,200rpm from what I gather), because it has a larger turbo. The actual boost pressure is dependent on other variables too, and not just engine revoulutions. :nerd: