I was talking to a motorhead friend who knows a good bit about cars in general, but perhaps not enough... Anyway, he says that the EVO already has the equivalent of an EBC built in in the ECU, could this be true? I thought that the boost could still be more finely tuned or controlled with an EBC or MBC.... Am I mistaken? Is a EBC superfluous in the EVO?... I'd be most appreciative of any enlightening answers....

Thanks,

Manuel

 

I could be mistaken, but I don't think the Evo's ECU regulates the boost pressure. Either way, the Evo definitely benefits from an EBC or MBC.

 

i always thought the 16g turbos had a wastegate built into them...am i wrong?

 

All modern turbochargers have a wastegate to control the boost. Most are internal and some are external. All the wastegates get a signal from the manifold that causes the waste gate to open and relieve pressure once a preset boost has been achieved. The question is, how the signal is delivered to the wastegate to cause it to open. Most turbos that I know of, suffer from a condition where the wastegate begins to open ever so slightly as soon as the turbo starts making boost, so it's a self defeating design. As I understand, the EBCs have solenoids or stepper motors that maintain the signal completely off the wastegate until the desired (dialed in) boost is reached, thus the boost is achieved sooner and held longer (?) or higher, so more power is made...

My question is, does the EVO already have an EBC or similar device, or does it have the typical wastegate actuator that begins to open the wastegate as soon as the boost begins to build........

 

From what I can tell from analyzing the ECU and the wiring, there seems to be a "Boost Control Solenoid", However it looks like its not variable or programmable, in other words, it seems to open only to bleed off boost to drop it to that 16.5 level, it appears to be either open or closed. I"m fairly certain that the solenoid is just under the air box (Airflow sensor), it appears to have two vacuum lines into it (maybe a third, I didn't see if it had a bleedoff connector, but it wasn't to the airbox if it was.. and a wiring harness.. Has anyone else noticed that? Or disconnected it? I'm not inclined to trigger my CEL if I disconnected it.

 

silverEVO8-

Well, I am not Shiv or a "tuner", but I have owned 10 turbo cars, and understand the components pretty well.

The EVO VIII does have an electronically controlled boost solenoid that is driven by the ECU. The ECU is reading data from the factory MAP sensor, and then holding or bleeding through pressure accordingly to achieve the desired boost requirement programmed in the ECU boost map.

On most EVO VIII's it ramps to and holds 19psi until higher rpms where it tapers to 16-16.5 psi. ECU tuning can provide different boost characteristics across the RPM range and can allow more boost than the factory parameters.

An aftermarket EBC provides a standalone replacement for the "FBC" and includes a new solenoid, map sensor, and boost management logic controller (the actual display headunit).

So the short answer is the EVO does have an EBC, but unless you have access to change the ECU maps, you cannot dick with the settings.Alternatively an aftermarket EBC gives you boost control management capabilities, potentially better solenoids(the dual solenoid types), and less spiking than an MBC type set-up.

Edit: The actual connection for the FBC is more like a "y" connection. One leg to the compressor outlet nipple, the other leg the WG actuator, and then the third leg connects into the FBC. The FBC bleeds off pressure to bring the boost up while maintaining the boost constant back at the WG/compressor "Y". I couldn't see real clearly, but the FBC bleed vent is probably plumbed back into the low pressure intake. Sorry for the confusion on how I wrote that up originally.

Again sorry for the long post.

 

Hey, no problem with that at all, Shiv is very knowledgeable but other people can contribute too

So the short answer is the EVO does have an EBC, but unless you have access to change the ECU maps, you cannot dick with the settings.Alternatively an aftermarket EBC gives you boost control management capabilities, potentially better solenoids(the dual solenoid types), and less spiking than an MBC type set-up.



Sorry for the long post. [/QUOTE]

Not at all, the long post was very informative. In one respect my friend was right... The EVO does have a built in EBC.. On the other hand, perhaps the aftermarket EBC can be a worthwhile add-on because of several reasons. Thank you very much, I appreciate the help.

Now, I had a TurboXs MBC in my WRX along with their POS Unichip, the boost seemed to spike at times, but people told me that my cheapass Autometer boost gauge was not to be trusted and was worthless Oh boy, what the hell is one supposed to buy anyway? This is one reason to get the Blitz SBC i-D.. I think it does display the boost as well as other information. I know it's a little expensive, but if it works as a boost gauge plus an accurate boost controller, it would be worth at least the combined price of each item...

 

When I installed my Hallman boost controller, I was told to bypass the stopck electronic boost solenoid, but leave the harness plugged up to it, but no vacuum lines going into or our of it. Basically just let it chill there, plugged in.

 

I was told the same thing.. Obviously it makes sense whether its just a bleedoff or a true ECU boost controller, you don't want to add a second variable to your MBC or EBC by leaving that in place. And about the comment about the accuracy of the autometer gauge.. whoever told you that it was innacurate is incorrect, there are several inexpensive versions of autometer gauges that aren't as accurate as the sport-comp, or pro-comp gauges (Autogage is a good example) but there's a reason why autometer gauges are used in a majority (of american) race cars and street cars, in all forms of racing.

 

The Evo doesn't have a MAP sensor, so that would be quite a trick.

 

hehe.. Give him a break.. I think all of us have used MAP/MAF interchangably over the last few posts..

 

A MAP and a MAF sensor do very different things, though. The Evo has a MAF, but it doesn't measure boost. It measures mass-airflow.

 

If you wanna be nitpicky, its a Karmann Vortex sensor.. THBBT.. I always assume a mass airflow sensor used a hot wire.. or was that speed density?

 

yeah you have to leave it plugged in, the second you take it out you will throw a check engine light.. i know because the for the last three days mitsubishi has been trying to figure out what the hell is wrong with my car, and that was one of their little dummy checks, to see if the solenoid is operating corrrectly. The mitsu engineers were about to take the damn car into their own hands and send it to japan, because the car is only boosting 10 lbs.. but the tech (who is my buddy) finally narrowed it down to a broken wastegate actuator arm.. what kinda BS is that?!? anyways

 

Um, then how do you think the ECU measures boost then? It does have a MAP (Manifold Air Pressure) sensor - it just doesn't use it for fuel metering, that is what the MAF is used for.