1.9 Boost Issues

[polo_spec_d]

Hello all,

Ive noticed since I have got my 2.5 turbo back exhaust my 1.9 doesnt peak at 19psi as it did before and now im lucky if I get 12 or 14psi peak.

I have a Oettinger tune, Seat intake, provent and the exhaust are the only engine mods I have made. Could this be the tune not using the exhaust to full effect? Would I need to look at a custom tune to get full effect from the exhaust?

Thanks in advance

[Jarred]

I'd look for a boost leak first, before I started worrying about the tune.

can you put it down to an exact time you noticed the boost missing? was it after you picked the car up from the exhaust shop, or 'sometime' after that?

[polo_spec_d]

Well it still goes as hard as it did before and have done a search on the car but cant find anything, Ive had the exhaust on for about 8 weeks now.

[Tim]

Is your boost gauge a mechanical one? If the car still goes just as hard it may be the tube for that leaking?

[polo_spec_d]

Yeah mechanical VDO, yeah ill give that a look, cheers fellas

[polo_spec_d]

Gave the boost gauge piping a pressure test, No leaks on the pipework. hmm now im stumped.

[geoff_gti]

It's a fair bit cooler today, see if that make a difference?

As the engine output is still the same, could it just be the exhaust pressure will be a bit less now that you've change the system? That's just a random guess...I could be way off being non-tech :|

[gldgti]

hey mate.

if you are only making 14psi now, theres almost no way the car is going as fast as before.... are you sure your butt dyno is calibrated properly???

as suggested, very important to know for sure that your boost reading is accurate.....i would suspect a leak somewhere still. if the boost reading your getting really is accurate, is it possible that there is a sensor in the exhaust (exhaust gas recirculation) that was disturbed when the exhaust was fitted?

hope to help - i wish i had more experience on the newer oilers and their systems....

**edit** 2000 posts for me

[h100vw]

I think you need to log it with VAG-COM and see what boost it is producing, as far as the ECU is concerned.

Gavin

[Greg Roles]

A larger exhaust will decrease backpressure, which is what you want. I don't care what anyone says, in a boosted engine there is no such thing as good back pressure. No scavenging effect with a turbo / blower in place! You should have "felt" quicker spool / response times when it was fitted, now the pumping efficiency of the engine has been raised. Since there is less restriction to pump against, the turbo doesn't have to boost as hard to develop the ECU determined power level. Remember the ECU is simply pushing the boost as hard as it needs to, given the throttle, load, temps etc. I'd expect the less restrictive exhaust I have planned for my TDI to drop the boost pressure, but the overall power output to be the same. Your drop is a bit bigger than I'd expect, but if the power "feels" the same, and your 0-100 times etc feel the same, then start looking for ways to make the most of the additional boost you can now run!

Allows more ceiling in the turbo, and thus more room for a more aggressive tune.