I'm what you could call a complete newb to the world of standalone ECU's. Ironically enough I bought an EVO IX over the summer that is using an AEM ECU with the boost solenoid to control boost. Now that the weather is getting colder, the thing is spiking like mad. I have no clue how to turn it down, or other means of correcting that. I know that it is running in closed loop feedback mode, that is about it. What parameters do I adjust? If you are interested in helping me, I'd be more than willing to PM the calibration to you.

Thanks in advance,

Ryan

 

What kind of boost controller are u using?

 

As I mentioned, the AEM boost control solenoid valve, with the ECU controlling boost.

 

I would just look at your base wg duty cycle table and pull some duty cycle out where you are overboosting. Even easier just reduce the whole table by a percentage to compensate for the cold until you get your boost where you want it. It's really easy just highlight the entire table and hit the + or - key. You can also right click after you have the table highlighted and adjust it by a percentage.

Of course this assumes you know how to connect to your ecu and save your changes.

The only thing I am not positive of is whether raising duty cycle raises or lowers your boost. You will have to experiment a little.

 

Well see that's the thing. It's overshooting so hard that I'm hitting load cut and the thing shuts down as soon as I start boosting. And If my boost error duty cycle graph is any indication, high duty cycle = high boost. So do I start pulling the duty cycle as soon as 3500 rpm?

 

I would just pull it everywhere, but if you are hard set on not doing that then I would start at least a few thousand rpm before max boost and cut more aggressively as you get closer to max boost. Cutting it everywhere might hurt your spoolup a bit, so it will be a balancing act of trying not to kill your spool, but not overshooting your target. If you are hitting fuel cut I would just kill 15% 1000rpm before max boost and up and see what happens. The worst thing that will happen is you still hit boost cut.

BTW, make sure to backup your current file before making changes. Just click save as and save it somewhere on your laptop you will remember. This way if you FUBAR it you can always go back to the original setup

 

you should post a log...preferably an internal log.

 

I'll try to get one tonight. Thanks for the help.

 

OK, I got it figured out last night. the Boost VSS function is enabled so it was just a quick reduction of that across the whole vehicle speed that brougt it down. I also figured out that my O2 sensor is shot, it starts going lean about half way into a pull. Knock volts are low and it's adding fuel, so it's not a tune problem. I've had the sensor in there about 6 months so it probably needs changed.

One other question, and this may be related to the O2 feedback, but the boost spikes pretty good and then settles down and oscillates between 19-21 psi in a very consistent manner. Is this the ECU compensating for what it thinks is a lean condition?

 

If your feedback is setup right, you shouldn't be using it under WOT. Unless you have been using leaded fuel your O2 sensor should last a lot longer than 6 months, but reading false leans are how they fail. BTW, boost by speed is usually only used for extremely high horsepower vehicles that can't get traction in the first few gears, so the boost is reduced until you hit a speed above those gears.

 

So it's NOT in closed loop mode when under boost? I'm confused. The engine load oscillates when in the upper ranges, get what I'm saying?

And the boost by speed thing I'm a little baffled on. That is the way AMS set it up though. Gotta believe they had a reason for that, however I'm not sure what that reason was.

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Well the boost by speed could be used to prevent overboosting in higher gears, since high gear = more load and higher boost generally.

Your oscillations probably imply that there is a closed loop feedback going on. There are usually values you can tweak with feedback (Proportional and Integral) that will help keep the oscillation down.

Besides the Boost Target Speed and Boost Error Duty tables, are there any other tables under advanced that are being used?

Also which FB options are checked in the advanced section: Boost WG FB, Boost FB on VSS, Boost FB on Error, Boost FB on P & I?

To simplify your boost setup you could just ditch the VSS boost table (zero it out) and just adjust your base table, but if they only made slight trims in that table it might be fine to leave it. My guess is they raise/lower your duty cycle as speed increases (whichever one opens the wastegate more).

BTW from your log it looks as though you need to adjust your fuel as well, your O2 values don't look flat at all.

 

There are many ways to skin this cat, with regards to o2 set-up / feedback...i have my o2 working during wot, however i dont allow it too much control, +/- 0.8%, this way I see the error & dial my fuel map in.

boost control, i eventually went away from using the p.i.d. to just getting my base duty map close & use Boost error duty table for finer control + setting up your target boost vs tps tbl.

 

The O2 values look like crap because the O2 sensor is shot. I ordered a new one last night, after I install it I'll pull another log. Fuel adjustments should be fine. AMS did the tune and Buschur gave it a once over after I purchased the car. Everything checked out. As far as options, Boost WG FB is On, Boost FB on VSS is On, and Boost FB on Error is On.

I did notice the oscillation in the higher gears a few months ago before it got really cold. Shortly after that I found a vacuum hose that popped off the EGR. I thought that took care of it but I guess not (the hose is still good, checked it last night).

The feedback is set up for O2 during boost with Knock control enabled as well. How do I tell, as you said Aby, how much my O2 is controlling, % wise. What is that value called? Is that O2 feedback lean and rich limits? If that is what you are talking about it's + or - 10.2%.

 

You should not be using O2 feedback while WOT. You should only use O2 feedback during part throttle/cruise and idle. I believe there is a few options you can set for throttle position and boost to choose when to activate O2 feedback. As far as your boost oscillations go, I would mess with the pro/int values, although if you don't have the Boost FB on P & I checked, it might not have an effect.

All I know is that when my part throttle O2 values were oscillating really bad, I messed with the pro and int settings to get the oscillations down.