If I change intercooler, eg to a large front mount, will I need to change the mapping on my car?

 

It may cause overboost (depending on the boost control method).

 

would it cause overboost?

I would have thought if anything the fuelling would need to be altered to add extra fuel to compensate for the extra airflow etc???

or am i barking up the wrong tree?

 

You will need more fuel if you run a more efficient IC. Cooler charge = more air in combustion chambers = leaner A/F ratio.

 

will a bigger intercooler adjust the air flow at the airfilter side then? If so i can see how the maf would compensate?

Otherwise i would have thought its just a case of better cooling of existing pressurised air and hence denser. I would have thought fueling would be leaned out slighly but on a standard "rich" ecu its probably fine. I would be curious/cautios though if the car was already tuned to run leaner.

Cheers

Paul

 

Yes, if the pressure drop across the intercooler is lower the flow for a given compressor outlet boost pressure will be greater which the MAF sensor will see.

 

I was thinking possibly reduced pressure drop across the intercooler? - the feedback source to the wastegate is usually the compressor outlet before the intercooler, and certainly on Imprezas uprated intercoolers sometimes cause overboost. If the fuelling is MAF based (on the VAG 1.8T?) then the fuelling should cope, but worth checking.

[Edited by john banks - 7/11/2002 11:34:27 PM]

 

That is what the MAF sensor is for

[Edited by john banks - 7/12/2002 11:57:38 AM]

 

just for the uninitiated:

MAF = Mass Airflow Sensor

Keyword, Mass, meaning it will measure the airflow regardless of density. Fuel ratio is done on a mass basis, as density of fuel is fairly constant.

Paul

edited for speiling mistakes

[Edited by Pavlo - 7/12/2002 3:06:27 PM]