Turbo Lag?

[ponkusjr]

hi guys, i am new to this forum and hope that you can shed some light on my problem. i have a Audi A4 2.5 TDI v6 avant and i have a problem with the power. when i rev hard through the gears and change up into 5th or 6th the engine power just dies on me for a few seconds and then picks up as the revs go down, this is a real pain when you are overtaking someone at high speed only to loose power and have to pull back. i have only had the car a few weeks and its a 1998 model, the power is great when its there and the car is very sporty. a friend said that it may be that i have whats called turbo lag ?. have you heard of this and could this be my problem. if you can help guys i would be most greatfull. another idea was that it may be a rev limiter? again i have not heard of this hapening to others. does it need a crypton tune>. HELP!!!!!!!!!!!!!!!!!

[giago]

I don't know.
It could be a turbo lag. but i don't remember that the v6 Tdi was turbo.
and by what you said it isn't turbo lag because in the lag it only makes the car feel slower before the turboi kick in. It doesn't stop the power abruptly.

[bhvrdr]

Originally posted by ponkusjr
hi guys, i am new to this forum and hope that you can shed some light on my problem. i have a Audi A4 2.5 TDI v6 avant and i have a problem with the power. when i rev hard through the gears and change up into 5th or 6th the engine power just dies on me for a few seconds and then picks up as the revs go down, this is a real pain when you are overtaking someone at high speed only to loose power and have to pull back. i have only had the car a few weeks and its a 1998 model, the power is great when its there and the car is very sporty. a friend said that it may be that i have whats called turbo lag ?. have you heard of this and could this be my problem. if you can help guys i would be most greatfull. another idea was that it may be a rev limiter? again i have not heard of this hapening to others. does it need a crypton tune>. HELP!!!!!!!!!!!!!!!!!

The problem on your turbo diesel does not sould like lag because it sounds like once you are on the boost your car cuts out or stumbles. This can result from a bad MAF, overboost if your car has been chipped, detonation, and probably a host of other things i cant think of, but the bottom line is that it sounds like its time to have the car vagged to diagnose the problem. let us know what you find. cheers! mike

[ponkusjr]

thanks for the speedy reply guys,
the car has not been chipped , could it be that it needs tuning and do they have a rev limiter to stop you giving the car some stick so to speak.

[bhvrdr]

Your rev limiter is close to the redline on your tachometer. I assumed you were not boucing off this when shifting into fifth, but if you are winding out the tach all the way up to redline, than yes your car will finally bump the rev limiter. cheers! mike

[ponkusjr]

i was about 3.5000 revs aprox i would say. it sometimes happens when i want to pull away to pass traffic in 5th at high revs. i realy have to look into this at a garrage cos there is something not right. please dont think that i hammer my car everywhere, i do drive carefully but you do need that extra power in trafic to pull out and when it dies for a second or two it can be embarasing

[bhvrdr]

yeah, i kinda figured you werent hammering it hard enough to bounce of the limiter all the time...that would be me :) Good idea getting the car looked at. Have them do some datalogs while driving the car so they can see what is going on real-time. cheers! mike

[Mark]

doesn't sound like lag to me. reduced power in higher gears makes sense, and you might just be out of the power band of the engine. the 2.5Tdi is known for great low and mid torque but doesn't have great top-end horsepower at all. torque is what really makes the car go at lower rpms, while the HP is what really matters at higher RPM's with turbocharged cars.

is it bucking when it happens? slamming the transmission, etc? pinging when WOT at higher rpm's? diesels are tricky business with their high compression ratios. how does it run at higher rpm's in lower gears?

[ponkusjr]

it does not buck or spit and spurt its as if the engine has died, nothing there, no power at all for a second or three then off she goes, if you change down a gear she picks up. its that quiet you think the engine is not running, its realy wierd. i will check the rpm today and get back to the forum with some numbers. as you can see guys i live in north wales in the uk so the time difference is about 7hrs. thanks for your help and i will be back online later.

[aussie_s4]

Originally posted by ponkusjr
i was about 3.5000 revs aprox i would say. it sometimes happens when i want to pull away to pass traffic in 5th at high revs.

Correct me if I'm wrong guys--we don't have any TDi Audi's in the USA (only VW's), but Audi is thinking of importing them next year?

Anyways, just wondering---what is the redline on this diesel engine? About 4000 rpm?

[Mark]

Originally posted by aussie_s4
Correct me if I'm wrong guys--we don't have any TDi Audi's in the USA (only VW's), but Audi is thinking of importing them next year?

Anyways, just wondering---what is the redline on this diesel engine? About 4000 rpm?

VAG said that they didn't want to import the Tdi's because our Diesel fuel was too high is sulfer content and therefore would create more polutents then they wanted. Marketing ploy . . . who knows . . . they brought the 1.9Tdi (VW's) over a while back but not the 2.5TDI. Such a shame, as they probably thought it would cut into 1.8T sales. Over in Europe the 1.8T is higher up on the engine selection. They have all sorts of other options with much lower HP and Lb numbers, but also get great mileage.