new boost spike
 

My car recently began getting more boost than normal and hits over boost at 185kpa. Under hard acceleration I get to 188kpa. A couple weeks ago the car would max out at 171kpa without hitting over boost. I would like to get it back down there.

Attached are a log and tune from today. In the log I hit over 180 at 546 seconds, 549, 624, 948, and 1252(188kpa, max).

I also attached a tune and log from a month ago when 171kpa was my max.

If you are using open loop, you're going to have to revisit your tune as the weather changes.

If you would like to use closed loop, there's a sticky that tells you how to do it.

Sorry, can't open your msq for some reason.

I am running in open. What parts would I need to re-tune to get it under control? I do not have an EBC installed.

I've actually read that several times over the last year. Do I need to just re-tune the boost duty targets again?

If you are using open-loop only, then yes, you need to adjust the duty cycle targets as the weather changes. That's a pain, which is why the write-up shows you how to implement closed-loop (but you need a TPS to do closed-loop).

I've got closed-loop implemented and my boost goes directly to target and doesn't waver, Winter or Summer.

Thank you. I do not have TPS either...

I tried to tune the boost duty today, but I had a bit of a problem. After a few pulls I realized that the car was not obeying the boost duty table, no matter the value. I even put zero across the whole table and still hit 170kpa at 3500rpm.

I went back looking at my tunes and logs. The most recent tune I have where it was acting normal is from 2013-04-09 and the first time it was not acting correctly was on 2013-04-24. I included tunes and logs from those dates.

I did a compare on the tunes and the only difference I found was in the VE table.

I also included a log from today when boost duty was set to zero.

Looked at your logs. When you look at them, make sure you graph "BCDuty3." That is the output to your EBC solenoid.

I don't see very much difference between the 4/9 (looking at ~885 seconds) and 4/24 (looking at ~1284 seconds). In both cases, I see a bit of boost overshoot at the beginning as follows:

4/9: Overshoots to 163kPa @ 4212RPM. EBC DC is 23%. Settles to ~150-155kPa with EBC DC decreasing to 12% at the end of the pull (5800RPM).

4/24: Overshoots to 183kPa @ 4500RPM. Again, EBC DC is 23%. Settles to ~155-160kPa with EBC DC decreasing to 11% at the end of the pull (5900RPM).

The above two pulls are consistent with environmental changes and open loop control. I would recommend that you start dropping the EBC DC at a bit lower RPM to smooth out the overshoot.

As for your 5/4 test, EBC DC stays at 0% throughout the log. Looks like you made a WOT pull around 5959 seconds but knocked it off at 3600RPM or so. The MAP line is starting to bend over indicating that the wastegate is kicking in. So, the 0% is working. Recommend you do a real pull at that level to see what your wastegate-only baseline is. Perhaps your wastegate can has a leak or is getting weak.

Remember that EBC can only increase your boost from the wastegate-only level. It cannot lower it below what the wastegate does naturally. This could be your issue.

Hornetball, I have a question about EBC. The previous owner of the car gave me an EBC solenoid kit that he bought but did not install . He said the EBC was so he could run closed loop if I remember correctly.

Here is a link to the EBC - Electronic Boost Control Solenoid Kit BEGi

So I am not exactly sure if I currently have EBC. I have not seen anything similar connected to any of the boost lines.

I will make a few more runs this afternoon to test 0 boost duty again.

I took at look at BCDuty3 and I can see where it is pulling the data I entered in the boost duty table.

Thanks!

Interesting.

Yes, the linked device is an EBC solenoid.

Take a look at the small line connected to your wastegate actuator. Does that line go directly to a nipple on your compressor outlet or somewhere else along your intake? Or is it interrupted by some other device (like the EBC solenoid from the picture)? If there is no interrupting device, then your boost is only being controlled by your wastegate. You can set EBC values in MS all day long, and it will make no difference whatsoever.

The wastegate signal line runs directly from the actuator to the IC pipe, post IC. There is no device between the two.

I checked the signal line and it looks ok.

So, that being said, is the culprit of the new boost spike the actuator/wastegate? How could I tell or what can I check?

About two months ago I moved the signal line from a nipple on the throttle body to just after the IC.

If you have a way to pressurize the actuator, you should see that it holds pressure and position and doesn't leak. If it's leaking, you would need to replace it. I don't think there are rebuild kits (might ask BEGI).

Usually, the length of the actuator arm is adjustable (has a threaded end with a locknut). If you extend the length of the arm (so that the wastegate at rest isn't held shut as tightly), it will lower the boost you achieve.

Unfortunately, I am away from the car the next 3 days and I have an autox next weekend. Even if I did adjust the arm, that doesn't really fix the issue, right? Wouldn't still be a fault in the actuator causing it not to work properly?

I understand that having the signal line pulled off the throttle body can damage the actuator. And that was the way it was setup for several years until a couple months ago.

Would it make sense to purchase a new actuator? BEGi has "Chinese" 10PSI actuator for $35 plus shipping. BEGi

Ok, so I just read about adjusting the actuator arm. Is that a common way to adjust the amount of boost? I know it did not change recently. The last time it was off was around December. But if this is normal then I can adjust it and skip buying a new one.
https://www.miataturbo.net/prefabbed...ustment-23673/
Thanks again!

Adjusting the arm would just cause the wastegate to be a little more open across the board (lowering boost). That little bit of overshoot (which basically corresponds to a slow actuator) would still be there most likely, but the peak would not be as high.

Normally, I hate to buy new parts without first doing a thorough diagnosis. But if you're on a time constraint and the replacement can is so cheap, why not? Worse comes to worse, you'll have a spare.

I called Stephanie at BEGi and talked to her the issue and my setup. She said she has seen only a couple actuator failures and suggested I take a look at some other things first: catalytic converter, maybe air filter, etc. Places that might be causing it to get more boost.

I also asked about the Chinese actuator they sell. She said they are fixed 10 psi and not the best. They come with the Chinese turbo kit they order and they usually send a different actuator out to the customer. She gave me an extremely great deal on one, so it is on the way.

Once I get back to the car in a few days I will see if I can see anything wrong with the cat. I will try adjusting the arm on the current actuator. And install the new one if needed.

In the meantime, does anyone have other suggestions on the issue?

Thanks!

edited - nevermind

I got back to working on my car again tonight.

I adjusted the actuator arm and lengthened it about 1 to 1.5 rotations. I took a drive to test it and the logs and tune are below.

First and second gear still hit too much boost too fast. Around 708 seconds I hit 201kpa in second gear. That's quite high considering I usually max around 170 and I have the over boost set for 185.

Third and fourth gears seemed ok. I was not building boost as fast in these gears and I guess that gave the actuator more time to open the wastegate.

There are several third and fourth gear pulls around 1083 seconds. These maxed out around 171 and fell to 160 in higher rpms.

Tomorrow I can try and extend the arm a little further to see if that helps out with first and second gear accelerations.

The actuator is a Garrett 7 - 11 PSI actuator. Is adjusting the arm to fix this just a band aid and should I purchase a new one? Or is it ok since it is adjustable?

PS - The Chinese actuator BEGi sent me for an extremely low price does not fit with my system. The actuator arm is about 3 inches too long when adjusted all the way down.

I created a chart showing kpa vs. rpm.
Green = before actuator issue
Blue = during actuator issue
Red = today after adjust actuator arm