straight piped my TDI and milage dropped 150Km

[albertaTDI]

As the above reads just wondering WTF is going on? the only mods I have done are a smoothed airbox, k/n filter and no muffer. and it just started happening after I put in the straight pipe. I thought my milage should have gotten better not worse. could it be the MAF Sensor? when i say im down 150Km that means im only getting 650KM to a tank before the light comes on.
help me out please TDI drivers

[nephilim]

Re: straight piped my TDI and milage dropped 150Km

Sounds like you had not so great mileage before you did the pipe. The pipe shouldnt do that much to it either way so I would look at the air filter and then back at the MAF first.

[Kor]

Re: straight piped my TDI and milage dropped 150Km

How many tanks have you tested?

I am not sure while mileage would go up, generally power goes up, mileage goes down. In a Diesel more power means more fuel so this should be even more true?

[NeonGTI]

Re: straight piped my TDI and milage dropped 150Km

How many tanks have you tested?

I am not sure while mileage would go up, generally power goes up, mileage goes down. In a Diesel more power means more fuel so this should be even more true?

While this is true when at full power it is not true during mid-throttle operation.

The supposed effect of the straight pipe is to increase the breathing efficiency of the engine by reducing the power required to push the exhaust out of the cylinders.

If pre-straight pipe the car required 20 HP to cruise at 100 km/h and that 20 HP was obtained at 10% throttle then the supposition is that post-straight pipe to travel at 100 km/h would require that same 20 HP, but the throttle percentage might only be 9.75%

One must also remember to try and clear the computer of it's adaptations following a mod as well as the driver needs to try to clear their own habits otherwise they can be a little more heavy footed than required and thus use more fuel.

Removing an obstacle in the exhaust path will generally increase peak power but reduce low throttle and low RPM power. This can lead to the engine requiring more throttle at low RPM's to supply the same required power than before the mod.

[albertaTDI]

Re: straight piped my TDI and milage dropped 150Km

I have ran 2 tanks through now and it has been the same both times 650Km. I understand what you are saying Neon but I find it hard to belive it would make that much difference. I couls see maybe 10 to 15 km per tank but not 150. when i say 800km per tank that is 100% city driving. does that still sound low?

[Stonewall]

Re: straight piped my TDI and milage dropped 150Km

I am not sure while mileage would go up, generally power goes up, mileage goes down. In a Diesel more power means more fuel so this should be even more true?

Diesels are weird in this respect. Add a chip: +3mpg, injectors (.205): usually +- 4mpg but I have never heard of a mufflerectomy causing such a lose. If you get 800k in town you are doing better then my 700-750ish I would give the ecu some time to settle itself into the new parameters but if you have ran 2 tanks through there might be another problem.

[albertaTDI]

Re: straight piped my TDI and milage dropped 150Km

yea i figured maybe i got bad fuel on the first tank but when it happened again i started to think it could be something more serious. wood a MAF be covered under waranty

[TDi_Steve]

Re: straight piped my TDI and milage dropped 150Km

I'm still getting 1000+k per tank
without a muffler....

[James]

Re: straight piped my TDI and milage dropped 150Km

in town 1k / tank?! Wow...Im with Brent on the 750 city

[Boy Racer]

Re: straight piped my TDI and milage dropped 150Km

Stupid question, but are you revving your car more? This may not be something you notice yourself doing but with the extra/different noise, you may be just be holding onto the gears just a bit longer. This makes a big difference to economy.

[TDi_Steve]

Re: straight piped my TDI and milage dropped 150Km

Most of my Driving is from Okotoks into downtown.

[albertaTDI]

Re: straight piped my TDI and milage dropped 150Km

I always try and shift around 3000rpm. i even factored this in when i ran my first shi**y tank through. I thought well maybe cause its sounds cool i was on the gas more, but my next tank i made a consious effort to drive normal

[NeonGTI]

Re: straight piped my TDI and milage dropped 150Km

I always try and shift around 3000rpm. i even factored this in when i ran my first shi**y tank through. I thought well maybe cause its sounds cool i was on the gas more, but my next tank i made a consious effort to drive normal

Damn dude I don't shift my 1.8t that high most of the time! With the monster torque you TDI guys have I can't see much cause to shift past about 2200.

Try this: Shift at the RPM that your car sits at at about 65 MPH (105 km/h). The gear boxes are often 'tuned' to keep the engine at peak efficiency at normal highway cruising speeds.

[albertaTDI]

Re: straight piped my TDI and milage dropped 150Km

what im getting at, is that I am not driving it any different than I was before the straight pipe, so something has gone wrong

[Kor]

Re: straight piped my TDI and milage dropped 150Km

what im getting at, is that I am not driving it any different than I was before the straight pipe, so something has gone wrong

Well, fuel does not mysteriously disappear! If its being burned, then you are going to be going faster in a diesel no matter what as far as I understand. If its not being burned, then you are spewing it out as smoke/unburned fuel and this should be measurable and noticable?