Nick Gustas

in the air intake, after they had achieved _positive_ pressure in the intake the car was compensating for the increased flow.

"And with the better brew in the tank? Yes, it was better - but then I noticed that boost was always lower! Aaaahhh! The ECU appeared to be dropping boost to keep the power the same, ignoring the benefits that could be had from the new high-flow intake system and better fuel! I was going around in circles while the Audi ECU thumbed its nose at me."

From <a href="http://www.autospeed.com/A_0663/P_4/article.html">page 4 of part 5</a>

Also check out the pressure chart at the top of that same page.



interesting series of articles...


<A HREF="http://www.autospeed.com/A_0629/P_1/article.html">Eliminating Negative Boost - Part 1</A>
<A HREF="http://www.autospeed.com/A_0637/P_1/article.html">Eliminating Negative Boost - Part 2</A>
<A HREF="http://www.autospeed.com/A_0646/P_1/article.html">Eliminating Negative Boost - Part 3</A>
<A HREF="http://www.autospeed.com/A_0652/P_1/article.html">Eliminating Negative Boost - Part 4</A>
<A HREF="http://www.autospeed.com/A_0663/P_1/article.html">Eliminating Negative Boost - Part 5</A>

frank

but by and large I think the hardware makes the diffrence


I know Bob Hamme's avant, was running stage 3 MTM

he swapped the ECU for an Abt 551M stage 1, and the car felt a bit stronger


so that tells me that the hardware makes the bigger difference

a lot of the Hoppen/MTM kits, seem to be "eye-candy" to help you justify the exhorbiant price

like the Samco hoses for instance


does that make sense?

Nick Gustas

"Part way through the development of a new pre-turbo intake system for my Audi S4, I realised that the factory electronic boost control was causing boost variations that were making a greater difference to acceleration than the intake mods. For example, no matter how much I improved the intake, the power gain wasn't consistently there - the ECU simply kept dropping boost pressure further and further at high revs. While I didn't want to increase the max boost developed, what I did want was to have boost that was not varying on the whim of the ECU."



<a href="http://www.autospeed.com/A_0670/page1.html">Boost control article</a>



so... it would seem that a ecu tweak may be needed. shrug.

Nick Gustas

The performance changes that occurred as the intake system was being modified indicate that the boost control logic takes a signal from the mass airflow meter, dropping boost if mass airflow increases, so as to retain the same performance level. This is probably also the mechanism by which the boost varies with the temperature of the day.


I'm just a cut-n-paste machine today...

frank

well there is also an Intake air temp sensor

Tostao

Hmmmmmmm piggyback module to cheat readings uhhhh?

ihavenoaudi

u know it!! came stamped "JDM APROVED"

DarinS4Turbo

If you piggyback it to fool the car into thinking less air is flowing in, then the car will inject less fuel and run LEAN, which can burn engine parts. But hopefully it would correct that in time based on the resulting high EGTs!

Nick Gustas

naah, just tell the ecu to request more torque.

Sander

With better breathing (both inside and exhaust) a turbo charged car (even one as tightly controlled as ours) can reach it's max capacity faster. This would result in more torque and HP at lower rpms, something you will notice in timeslips and daily driving.

Good question! I think that the influence of the ECU over the engine is sometimes underestimated or misunderstood on this forum. Like you indicated it has a -lot- of control. More than my Eclipse or Merkur ever had for example.

Sander