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

Something is fucked up. Its not keeping closed at lower rpm but its not opening enough at high rpm.

Are you using ecu controlled wastegate or is it the standard internal wastegate?

Internal wastegate. I'm going to lengthen the arm today and try again.

Why are you messing with the boost control in megasquirt then?

Yeah, now I know. I have been extremely confused as to why people keep telling me to tune the boost control even after I mention I do not have EBC. But several high ranking members over the last year kept insisting that is what I needed to do. I'm still learning.... obviously.

And about the chart I made. I don't think you can really draw a lot from them. They were in different conditions, different roads, and possibly different gears and maybe not all at WOT. Maybe if I put all of my long pulls together I could determine more from them.

You should set the wastegate this way and dont fuck with it.

I'm very much against using the adjustment arm to increase or lower boost. Its not made for that. Its strictly made for preload and preload only. To increase or lower the boost you'll need another wastegate for the boost you want. In your case you should check the line going from the intercooler to the wastegate, It either has a hole in it or the wastegate it self is fucked.

Thanks for the video. I do have a question though about adjusting the arm. The actuator is advertised as being adjustable from 7 - 11 PSI. Assuming everything was working as expected, isn't that how I would adjust when wastegate starts to open. I'm just asking because I am not 100% sure.
Thanks!

You see they can advertise them as much as they want.. Theoretically you can adjust it from 0ish psi to all of it. Here is the problem with that theory. There is a set psi spring in the wastegate. Its suppose to open when it reaches the configured psi.

So to make this easier, let me give you an example. Say the wastegate is set for 10psi. Theres 3 scenarios.

Scenario 1. The preload is set correctly, the wastegate opens at 10psi and stays open to keep the turbo at 10psi and everything is correct. 10psi all across the rpm range.

Scenario 2. You want to run less pressure (say 8psi) so you adjust the wastegate looser to lose pressure. In this case the wastegate will actually be halfway open because its too loose. Theres no preload to keep it shut therefore you will lose a lot of middle rpm boost since the flapper is open. So in this case you get low pressure in the middle rpm that slowly increases to 8psi by redline.

Scenario 3. You want to run more pressure (say 12psi) so you adjust the wastegate tighter. Now theres too much preload so spool up is normal however when it reaches 10psi, the wastegate starts opening and as the exhaust flow increases the smaller tighter opening limits the maximum flow so you get up to 12psi. In this case you get 10psi in the middle rpms and then slowly increase to 12psi from there.

triple88a,
That makes sense. I will check the signal line.
The wastegate does open and close. I could move it freely with the actuator arm disconnected or connected.

I can try and move the signal line back to the original location on the throttle just to compare.

Take off the line and check it. Bend it in all directions inch by inch to ensure its not cracked.

That won't make any difference.

You could try a test with the signal line connected to the compressor outlet nipple. What you are looking for is the disappearance of the spike. If it doesn't disappear, then the can is bad (not reacting fast enough/leaks). If it does disappear, then the signal line has a problem (clogged or has a leak).

Note that the disadvantage of connecting to the compressor outlet nipple full time is boost sag at high RPM (not compensating for IC pressure loss). But that won't make any difference for this particular test.

Ok. So I did a test before I read the latest replies from triple88a and hornetball.

First, I adjusted the arm as shown in the video above. I shortened it 3 full turns from where it just fits easily.

Then I moved the line back to the throttle. I did a 4th gear pull and a 1-4 pull. I maxed at 161 kpa.

Then I moved it back to the IC pipe. I did a 1-4 pull, 4th gear pull, and another 1-4 and 4th. I maxed at 157 kpa and the MAP graph looks ok (to me :) ).

The logs are attached below.

So, what was the cause? The signal line was tight on the IC pipe connection. The actuator arm did not change until I started playing with it yesterday. Currently it is a couple rotations tighter than it used to be.

So I'm not sure what the issue really was. Do you think the issue is resolved? It seems ok to me now.

Thanks everyone for your help!

My guess is that your wastegate actuator is sticking when fully relaxed. By adding the preload, you moved its resting position to an area that's free.

Guess, mind you. I've never heard of this happening before, but I can't explain it any other way. So, you're looking good. Keep an eye on it.

Thank you. So in continuing my education, I have another question.
Is it possible to increase boost beyond my current level without installing an MBC or EBC? I'm guessing the answer is no. And I have the EBC from the previous owner that I could install ( EBC Electronic Boost Control Solenoid Kit DIYAutoTune.com ). However, it looks like I need this boost control mod kit too: PCBv3 and v2.2 -- Boost Control Mod-Kit DIYAutoTune.com

Ways to increase boost:

1. Tighten the actuator arm . . . add preload. Will only go so far and subject to the issues mentioned by Atanas in Post 27.

2. Add external helper spring (search -- several examples on the site).

3. Change wastegate actuator to a unit with a stiffer spring (will be rated for a higher PSI).

4. Add MBC.

5. Add EBC. The solenoid you have is all that you need. The MSPNP already has the EBC circuitry inside of it. Reference the MSPNP documentation here: MegaSquirtPNP by DIYAutoTune.com.

Add a MBC from ebay and move on.

I was looking forward to start installing the EBC today, but on the way home from work I had a problem. While accelerating I hit over boost at around 12 PSI. It happened one more time after that when I was just checking to see if it would happen again.

The actuator is still set like last week. It is tightened 3 full turns from fitting comfortably on the wastegate arm.

I can pull the actuator arm and move the wastegate. I disconnected the actuator and moved the wastegate around. It does hang a little bit when it is completely open.

I have four pictures below.
1 and 2 are how the actuator is currently connected to the wastegate.
3 is the wastegate hanging closed
4 is the wastegate stuck open as wide as possible

The wastegate moves smoothly up and down except for when it reaches full open. It is not difficult to close though. If the actuator pushed it that far, and I am not sure it even can, then it should easily close it too.

Picture 1... why is it crooked? Is the rod all crooked going in the wastegate too?

Are you referring to the area highlighted in the attached image? If so, I don't know why it sits like that. Maybe I can turn it...
Or the actuator arm itself?
This is the actuator I have: 7 psi Turbo Actuator, 48009-9 BEGi

Yes take a pic of the arm entering the wastegate too pls. Look at begis image, even though the arm is crooked the part of the rod entering the wastegate is straight. Thats what you want. If the arm entering the wastegate is on a large angle it will not function properly.

Here are some more pictures.

Wow, that's really crooked.

Looks like the stud on the wastegate arm got bent. Straighten that out.

If you can, also adjust your can a bit in towards the manifold so the arm is as perpindicular as possible to the stud.

After all that, readjust your preload.

Angles = Binding = Bad

Uck. Fix that right there. Bend the rod or get a new straight arm.

https://www.miataturbo.net/attachmen...517_171617-jpg

Ok. I was able to rotate the actuator arm to get a better angle. It is not perfectly straight, although it looked good from my point of view.

I took a drive and did a few 1-4 gear runs and it never went over 8 PSI according to the gauge in the car. I did not log it.

See the pictures below.

That looks perfect.

I recently installed EBC and I wasn't sure it was working properly because I was getting too much boost and over boost was kicking in.

I reconnected the wastegate signal line like before, directly connecting it from the IC pipe, post-IC, and to the actuator.

I still over boosted. I disconnected the actuator arm from the wastegate arm. I moved the wastegate up and down without any problems. I pulled the actuator arm a few times. It seemed ok.

I reconnected the actuator and wastegate and the arm is tightened three revolutions.

I took another drive and still the boost shoots up until over boost. The hose is brand new; I just bought it for the EBC.

The last two times I was over boosting I was able to adjust the arm properly to correct it.

I think your actuator is finally dead.

Do you have a way to pressurize the wastegate line? Small pump of some sort? You only need 5-10psi (basically, the boost the compressor makes). You're trying to see if the wastegate actuator opens with that pressure.

I thought u said it was working few days ago without the MBC?

Take a pic of the MBC installed for me pls.

It was working before. This is the third time in the last couple weeks that it stopped working.

I do not have MBC. Before I started working on the EBC a few days ago the car ran on actuator pressure only.

I can try and blow on the line to see if that moves the actuator.

So, blowing in it real hard did not do anything. Although, I'm not really sure if it should be possible or not.

LOL. Unless you're a real blowhard, I don't think you can generate the pressure required.

What we're trying to detect is whether the diaghragm in the actuator has a leak. I'm thinking that applying vacuum with one of those hand pumps and seeing if the vacuum is maintained would accomplish this -- but I'm not sure if that's a correct test. Maybe try searching for "wastegate actuator testing" or something like that. Or call BEGI.

Did you rotate the actuator arm relative to the actuator when you were trying to get things lined up better? That's a no-no -- can tear the diaghragm.

Yep.

Although, it had obviously rotated away from the preferred position at some point.

Blowing with ur mouth you wont be able to generate even 1 psi. You need to use a pump.

So is it working with actuator pressure only? Few days ago you said it was after you fixed the angle.

Let me get this right, it was working properly after you fixed the angle just on the actuator pressure and then you added an EBC and its not working any more?

It was working after I fixed the angle. hornetball now says that rotating the arm in the actuator like I did is bad. But it had to be rotated at some point for me to need to adjust it. I probably did it at some point in the last few months by accident.

A few days later I started working on the EBC. Even though the EBC was open, I was still overboosting.

I connected the signal line back the way it was before, directly to the actuator. The EBC is not involved at all right now. I am still over boosting.

I disconnected the actuator arm and wastegate arm. I confirmed that the wastegate can move up and down. I pulled the actuator arm a few times to see that it moves. I connected the actuator and wastegate. The actuator arm is 3 tightened three revolutions.

I am still over boosting. The actuator is not opening soon enough, or at all.

I will see about hooking up a pump.

Well man i'd get a new wastegate and call it done.

wastegate, or actuator ?

Actuator. Might as well get one for the correct psi you need. Get one made for 10 psi or whatever you want... not one made for 6 psi that will work for 10 psi by extending or shortening a rod like the ones begi sells.

gotcha, thanks again!

I put my new actuator in tonight and it seems to have solved the issue with the wastegate not opening.

Below is a log of a few pulls and it holds pretty steady under full throttle between 152 - 154 kpa.

Now I can get back to the EBC!

Wow! What a difference.

Yeah, a big difference. I put two runs together into one image.

The top half is when I thought the actuator was still working correctly. The bottom half of the image is from tonight after installing the new actuator.

No sag and nice and straight.