Drilled Airbox = Poor MPG??

[MikeVR6 0]

I recently drilled my airbox, following the instructions on the Scots CCGB site. I'm still using the standard airfilter (can't source a K&N locally)

 

Before I performed this mod I usually got between 29 - 32 MPG on my 16 mile journey to/from work. :)

Since drilling the airbox, I've been getting 19 - 23 MPG :mad:

 

Even on a long, easy drive I'm now getting 26 MPG where I used to get 35 MPG or so :(

 

Does this sound right to other peeps who've done this :?: :?:

[Scott 0]

Are you sure your not prodding the pedal more due to the extra noise? *:)

[MikeVR6 0]

Knew someone would suggest that :D

 

No, it's been 3 weeks now and the "driving with my ears" phase is well over :wink:

[CazzaVR 0]

I've done the mod (without the ducting- couldn't be arsed). I've got a K & N in and I can honestly say there has been no difference to the mpg. I still get up around 40 mpg on long journeys and 25-35 on shorter ones.

[20valver 0]

Yeh i'm the same....

 

had it drilled for about 3 months now. This last month I got my best MPG yet! I think it's because when you are trying to save petrol you know if you hear that rumble :lol: to back of the throtle.

[G60Jet 1]

Have you reset the MFA??

[MikeVR6 0]

Hmmm :?

 

If you mean "reset the mfa" as in zeroed the settings on both memories...

Yes, I do this everytime I fill the C up.

 

It's not possible that I may have upset one the the connections onto the airbox whilst removing them? Would this have that effect?

 

All connections seem fine and secure. :?:

[MikeVR6 0]

A fellow Club GTI member who's a mechanic has now given my car a full going over.

This included, timing belt, gearbox oil, coolant flush, fuel filter and fully tuning the engine.

Turned out I had a dodgy throttle microswitch.

Now it's been replaced and the car's been correctly setup it is running like never before.

MPG has returned to the 35-40 mark on a long run.

8) 8)

[marksvr6 0]

chuffed for ya mate :wink:

[cheesy 0]

Happy for ya mate.

 

Dodgy throttle microswitch! How much did it cost ?

Thats what affected the ammount of fuel u used?

 

cheers chris

[Rams 0]

Mate, you could turn your question around for it to be a good point. The more air you feed in the better. You cant have more power and less fuel!! Have you noticed a difference in the pic up at all? We all want the most power these machines can produce and with 40 MPG, NOT HAPPENING!!

[MikeVR6 0]

Cheesy : Don't know how much the switch was, he pulled one off an old 16v Golf in the scrappies and said nothing ;)

 

He reckons this would've made it difficult to set the engine up correctly since the switch let's the ECU know what position the throttle's at and it references the mapping accordingly. This would have knocked the engine right out.

 

The car was really slow moving up the revs below 4000rpm before. It's now more smoother and responsive.

Also, had a poblem with really lumpy cold start (like it was firing on 3 cylinders) this has now disappeared.

The car seems run slightly higher revs for a few minutes when started from cold now. It never did this before.

 

Anyway, car's much improved and according to my calculations and the MFA reading, my MPG has improved to an average of 32 with higher figures achieved on a long motorway run.

[Henny 0]

mmmm 32mpg.... I can only dream... I really need to get some lighter shoes :lol:

[cheesy 0]

Cheers Mike

[willmason 0]

Everyone seems to be gettin good MPG but me I get 13-16 MPG around town and no higher than 24 MPG on the motorway!

[markTTC 0]

I drilled my airbox a few weeks ago, and I'm getting roughly the same MPG as before (about 25 around town, 35 on motorways)- and that's with me flooring every time I hit a nice stretch of open road :wink:

 

Cheers

 

Mark