prizrak

Good morning everyone,

I was searching the internets and the only thing I found that was somewhat related is this

It doesn't fit my situation a 100% though. So let me explain the issue and hopefully someone can at least point me in the right direction

Setup:
2004 A4 1.8T Tiptronic Q, Stage 1 APR tune.

Issue:
In rain/humid weather the car does not seem to be making much power. In fact I don't even hear the turbo spooling or feel the boost come on. It basically feels as if it's running in "stock" mode even though the car is set to Stage 1 (I double checked).

The car hasn't had any major work done, the latest that happened to it was a speaker wire repair by the dealer.

Bolo

Is'nt it that if weather conditions are very wet or slippery....the ESP (traction) control regulates abs brasking and engine output to prevent slippage and maintain traction on the road.
maybe your feeling some of that....Try Driving on wet conditions with the ESP off, see if there's any difference.

cheers

prizrak

I'll try that thanks, It was a bit drier yesterday and it was running about same as it normally does so I think it might just be that it was too wet outside.

Rob.S4

hello everybody,

im new to audi scene( 2001 audi s4 bone stock... 85XXX) but a have a interested in cars and work on the little things on the cars in the household...oil change, brakes...so on

I realized the same situations as prizrak but only a couple days ago that my car seemed to be a bit sluggish and def noticed that when i first got it it was a lot more peppy and boost kicked in harder in first gear than it does now...i assumed it was the down weather but it still seems to have have more motor than turbo power.... i checked some tbbs for any leaks or tears and so on....The car is bone stock and not sure if putting 92( didn't know that existed) from Getty may of been the culprit or should i be worried of more severe issues. such as one of the turbos going....

Some observations noted:
no noticeable difference to the sound of the car just the loss of power...

that "stock" whistle the dv gives off is there but sometimes it just isnt there(mainly when trying to pull in first gear..and this was present before)

i dont feel them kick in like they used to in (mainly first) gears..

help me out guys as i plan to obtain as much information possible to help me maintain this beauty..

PDX04a4

ya i experience the same problems when the weather is crappy up here in portland. one thing to consider is that when its raining the air temperature is usually significantly cooler and the humidity is significantly higher. this results in denser air being drawn into the turbo. cooler denser air results in a slight loss of power. the ecu learns how you drive over a given period of time, when there is a sudden change in weather after a period of warm nice weather than the ecu may not be able to compensate for these changes quickly. not sure if thats completely true or not, something to think about.

its more than likely a whole bunch of things contributing, cooler denser air, slicker roads and the car compensating for that, other things...

prizrak

Actually cooler and denser air will give you more power because you are adding more air into your combustion chamber. The MAF measures air density as well as other things so your ECU will compensate.

From all my research it seems that the issue here is humidity, basically the car sux in water vapor and as water is not compressible you end up with less boost.

gimik

not to take away from PDX04a4's point about general weather changes affecting boost, but in particular cooler air will usually result in *more* boost. when the air is colder, heatsoak will take longer to set in and will dissipate more quickly (so the turbo can run harder and longer than in hot temps). denser air also means more oxygen to combust, so if you've got larger injectors that can support the fuel demand, more air will give you more boost. that being said, i think the wet factor is more likely the root cause of any symptoms you're seeing.

this may or may not have anything to do with your issue, but for what it's worse i once lost boost entirely after parking for a few hours with my front end getting drenched by a sprinkler head. mechanic had no idea, but boost was back after troubleshooting with a broom up to the wastegate. this sounds different than your issue of just losing "peppiness" as when the car has no boost at all you will feel like you are towing a horsetrailer behind you. aside from that i've always driven in rain with no problems, but i live in temperate southern california and we don't get a ton of it usually.

greg

ps - premium is 91 octane in california so i don't think that's the issue either, although crappy gas *will* have a noticeable impact.

prizrak

Shouldn't make that much of a difference unless you have a tune. The stock ECU has maps for 91 and 93 octane because of CA. If like me you have a chip for 93 octane you can actually blow the motor.

Rob.S4

definitely soaking in the info guys....
Thanks again

Im still not sure what to do im hoping its because of weather...and not sure if i was able to take it to a experienced Audi mechanic to see if there's any reason for a diagnosis "loss in power" but no engine lights or anything...

do you guys recommend any injector cleaners or so? or anything of that nature

also... on a side note
is it just me or does the motor get so hot to the point when your driving if you don't crack a window it will make you sweat?

gimik

crazy! didn't know that..

rob.s4: the turbo will glow red under normal usage, but you should not feel any heat from the engine unless you are running the heater.. you sure it's not the sun beating down on the black interior?