Warm weather=massive hike in performance

[deanski]

What could cause this? My A4 has never been quite right despite numerous garages looking at it and its always a bit lethargic until the engine gets properly hot. The last few days though as its been pushing 20c, the thing is absolutley flying from the get go! What could cause such an obvious increase? I dont mean its running slightly better, I mean it's like it's had a new engine jammed in.

 

[stu_m]

oil too thick when cold stopping the turbo spooling up properly?

 

[AlexGSi2000]

Engines usually perform better using colder air.
It sounds like an issue measuring the temperature of the air to me which is making me think it would be an issue with the MAF sensor.

To the response above, oil would not stop the turbo from spooling properly. - if the turbo has an issue with oil then the turbo would most likely be dead.

 

[deanski]

It has had a new MAF but i suppose there's always the possibility of a dodgy new one?

 

[666markyboy]

Prawn over in the A3 8L section bought 3 or 4 brand new MAF's for his track car before getting one that was right so yeah it could be MAF

 

[Andi25th]

What about the water temperature sensor ?

If it is faulty it could effect performance and economy.

 

[deanski]

it had a new one not long ago.

 

[JAS11N]

Maf measures mass air flow (amount of air) not it's temperature.

 

[murran]

Maf measures mass air flow (amount of air) not it's temperature.

mafs on these do both jobs actually.

 

[quattro tony]

mafs on these do both jobs actually.

Yes this is correct, What brand maf did you fit? I only ever fit a genuine bosch one to these, the cheap ones can cause problems, Have you had the ecu scanned?

 

[deanski]

yeah it was bosch. only fault showing on VCDS is the engine mount. it's in the garage so we'll see what happens.

 

[beachbuggy]

Maf measures mass air flow (amount of air) not it's temperature.

Maf's measure air flow by temperature so air temperature is a factor. Therefore faulty maf, wrong temp, wrong airflow. There are correction maps in the ecu for temp, so warm air will cause ecu to increase boost to compensate for lower air density. Could be your ecu is just providing more boost. You shouldn't notice this though as the aim of the correction map to maintain the same power/performance regardless of weather/air temp.

Its still cold at night, so take it for a spin then and see if there's any difference in performance. Do some logs if possible when it's both hot and cold to see if there are any Maf differences.

 

[marktdisport]

ive noticed my mpg as improved with the warmer days as for power mines far better on a damp cool morning than warm

 

[JAS11N]

 

[marktdisport]

????? how

 

[JAS11N]

How what ?????
It's a joke, I was wrong about the MAF.

Hell this forum has a serious lack of humour

 

[murran]

this forum has a serious lack of humour

ah i thought it was just me that had noticed.

 

[marktdisport]

well it followed my post.....

 

[deanski]

garage are thinking its and injector problem. doesnt sound good.

 

[beachbuggy]

garage are thinking its and injector problem. doesnt sound good.

Did they explain why or how it could be a problem..

 

[deanski]

not yet, they're delving into it and letting me know. my mate runs it so I trust him completely. I've had this prob for ages where it will vibrate and rumble at 2100rpm, and they think its an injector fault causing that and causing the engine to rock at idle when it's warm. it doesnt do it when its cold.