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Yes I've tried the stock filters. Cleaned all the oil from turbos, intake tubes and as much of the intake and tb I could. The k&ns I've cleaned and have no oil should get my green filters this week.
Wow interesting the rod length is different which I guess doesn't matter much as long as the pull length is the same open to close. Thank you for the picture! Was there any ports for boost reference on them? Also can you measure the intake side diameter?
Did you found out what was wrong? Im having the same issue, I have a non-S and im boosting a max of 10-11 psi, im missing 4...
Well I kind of narrowed it down. For one the QT gas I was using wasn't helping. I had/have a bad motor mount on my drivers side this allowed it to torque over further than usual which lead to denting the Exhaust downpipe on the cross member which ended then lead to an exhaust leak at the flange. The fuel trims were off pretty bad. After tightening both flanges the fuel trims improved a lot which seemed to help my boost issue. Another thing that I see that effects boost is the iat temp. After making a direct on/off switch to my Intercooler pump allowing it to run full time, the Iats will be just about ambient temp on the hwy. In the winter with lets say 60 degree (f) temps it seemed to make less boost but added more timing. The same applies to when I didnt turn the pump on letting the iats get over 100 it made more boost (about where it should 18psi) but would pull timing. The boost is controlled by the vacuum controlled actuator that is doing what it is told by the ecu and which map its on. I bypassed the boost pressure regulator with a manual controller and it would make whatever boost you wanted it to but the ecu would pull timing accordingly. I also installed a boost gauge so there was no sensor telling me the boost. only the physical boost telling me that. My car doesn't have an ecu tune so the tune may help make the same boost consistently but I dont know if they mess with the maps or not. hope that helps
Now I really wonder if an ECU tune solves all of the above problems, especially with IATS and intercooler operation.
Anybody know about a tune affecting this?
I do know that the intercooler pump (at least on the 14+) is turned on and off by the computer. It turns it off until it reaches somewhere above 100 maybe 115 or so then turns on cools to about 90 then turns off. It seems like it tries to keep iats in that range. Thats why I put mine on a switch. Hasnt thrown any codes doing that.
I do know that the intercooler pump (at least on the 14+) is turned on and off by the computer. It turns it off until it reaches somewhere above 100 maybe 115 or so then turns on cools to about 90 then turns off. It seems like it tries to keep iats in that range. Thats why I put mine on a switch. Hasnt thrown any codes doing that.
oh that's good to know. Luckily I have a 14, but I'm guessing since it's tuned it may cause it to heat up faster than stock when driven hard.
Seems like you and alexdou111 have the same problem I have, which is a 2016 M278 pulling a ton of boost. Stock is supposed to 13psi, but I'm <8. It varies so usually it starts ~7.5 when I first floor it, then tapers off to ~5 at full rpm.
This all started maybe a month or so after I got an OE tune, and with the tune in it's psi is more like 11.5 and tapers down the same way from there. So I'm guessing the % diff may be the same % if it were working normally, and tune or not it's ~40% low.
It's being commanded to that psi, which sounds like what yours is doing. No codes, no other issues I can find and this started when the car had ~29k miles on it so it's not shot out or anything. It was, and is, bone stock except for K&N filters, and the tune which I remove and reinstall now and then while troubleshooting. The K&N filters did not leave any residue like was mentioned here. The airbox and intake tubes are squeaky dry, which I again checked yesterday because I did an oil change and cleaned the filters while I was in there. Kinda weird it's that clean in there so all I had to do was clean the grime before the filter. I don't have a MAF so I can't see how oil would matter anyway.
So we may all be in the same boat with the same mystery whatever killing our fun. I've mentioned to others that there are no other symptoms and power is comparable to a "normal" car so Joe Blo could drive the car for life and never know it. Meaning there may be lots of cars with this issue but only some of us are aware.
It's commanding the low boost because I put a dash cam under the hood and watched it. And it'll spike beyond command psi if it hit just right so it makes boost faster than it can control it back down. I've had it as high as 17 with the tune in it, but a split second later it opens the wastegates and brings it back to the lower boost. So it's there, as is my power, it just won't me have it for more than a microsec. So you could tinker with the rods but it won't do anything, it's not like a regular pressure controlled wastegate. The ECU will simply command more until it's at the psi it wants. My thought is to make a circuit to directly control the wategates and tell the ECU to fukoff. Command away, won't do squat. I'd prefer to find the actual cause because whatever reason it's doing this may be real (I doubt it) but I also worry I'll go through the trouble to make the circuit and the ecu will go limp mode on me. I kinda doubt it but it's possible.
I've looked it over with Autel and Xentry, can't find anything wrong, but still looking for clues. I've talked to some shops and they say without codes they wouldn't have a clue what to do and won't even look at the car.
So lets stay in touch, especially if one of us finds the cause!!!
I know this old post is likely dead, so I'm really posting for alexdou111 and others that have, or will have, this issue.
I bought HP Tuners and I can now program in my lost boost... Never found the problem, I'm just overriding it.
When I look at the data, using the HP Tuners Scanner program, it said it was making the oem torque and HP, which I guess explains why it was pulling boost because it thought it was doing what it's supposed to do. You see, the car doesn't work like old school at all, it works based on programming and it drives to xx torque based on a bunch of values programmed in and a bunch it reads from sensors. So anything in the ecu that is wrong, or a sensor not reading right, which screw it all up. Since it seems all my hardware and sensors are right I think my power chart is off. What goes into that chart, or where it is, I have no clue. All I know is it thinks it's making full power when it is not. So my band-aid fix is to request much more power, even than the eng can make, and it balances out. Sorta. The more power you request the more problems I run into. There's all kinds of things going on in the ECU and HP Tuners won't tell you squat. No instructions. Plus there are errors in the program. So it's like picking a lock written in a dead language and some of the numbers are wrong and some numbers are not there at all.
Since my power is down about 40% I'm having to ask quite a bit to get it back, which is why I'm running into problems. The less psi you need the easier it'll be. Bumping it by 3psi should be super easy. Like picking a 3 digit lock compared mine with 10 digits.
Fyi there is no boost selection. You have to request more torque and it'll make more boost to get there.
The HP Scanner setup cost me $720. It does have a very nice scanner program to record your data, far better than any I've seen. If you just want that it's $400. Permission to program the car is another 300. So you could buy it for $400 and see what it's doing, then decide if you want to program it.
Programming over other tunes is not a good idea. In some cases it'll wipe the program you had, gone, forever. If you have a tune via USB, like my OE Tune using MyGenius, then once you tune it with HP you can't go back to the OE Tune, MyGenius simply won't allow it. So to get around that I used KESS (or KTAG works) to copy my ECU with the oem file loaded in the ECU, then I used the HP Tuner. Nobody told me this, I'm just paranoid and wanted to copy/save it before I messed with it, and I'm glad I did. Actually I went a step further, I wanted a spare ECU to do all this HP Tuning on and KESS is how you program a spare ecu. So now that I have the files saved I can use KESS to revert back to before I used HP and MyGenius will work. If you use the HP before you copy it with KESS, you're screwed. Apparently a MB dealer or maybe someone else can program the oem file back into it, but you're still talking time and $. Do yourself a favor and get KESS or KTAG and copy your ecu first. It's ~$80 or so on Aliexpress or wherever, and I can explain how to do it. Do NOT follow the instructions that come with the KESS/KTAG, at least not on my ECU. I think any MED17x ecu they have wrong, so just ask me and I'll save you a massive headache.
And when I say use HP I mean use it to program your ecu. You can use the scanner and you're ok. When you want to use the HP software to get into the ECU and see what's inside it needs to apply a patch first, which is what screws you from using the MyGenius again. Apparently this patch is for MED17 ECU's, not sure about others. Basically if it asks you to apply a patch, that's a line you're crossing, so back it up first! Not sure if that patch hurts other tunes, like bench tunes, or not. Considering how much having the MB dealer wants for a new ecu, or a tuner wants to reload your ecu, it seems like cheap insurance to KESS it either way. My spare junkyard ecu was $200.
Also, when I used KESS to copy my ECU while it had the OE Tune in it, it copied the OE Tune too. So I'd imagine even a bench tune will be saved as well? My guess is it copies everything, like cloning a hard drive. I'd also imagine a KESS or KTAG is what many bench tuners are using in the first place. And yes, to backup your ECU, or reload it via KESS, you have to take it out of the car and take the cover off, like a bench tune. Not that hard if you know what do to. If you don't, or follow the KESS instructions, good frikkin luck! Maybe I'll make a how-to post on it, but meanwhile just ask me
I wanted to add what I found recently: Low voltage will kill boost!
I've had issues of late with charging voltage. Voltage varies from >14 to 12, and when under load it drops another .5 to 1V. Not sure why but the point is the boost solenoid runs off voltage, the less you have the less boost you have. For me an mine it seems if voltage is 13+ under load I'm good, but somewhere ~12.5 I can start to see a loss in boost. If it drops to 11V boost drops to <8 psi.
I may have mentioned previously that the boost solenoid is a crude device so they don't all act the same, some work better than others so if you want peak boost you need, imo, a good solenoid. The vacuum pump check valve is also sketchy so you may not have the vacuum you need. Point being that if either is not ideal then no doubt you will be more sensitive to voltage. I was able to increase the solenoid duty cycle to 100% and it's substantially better, but most people can't do that. So check voltage while driving and especially while under load to be sure it isn't doing stupid stuff like mine.
If anyone had thoughts about my low voltage, the only clue I have so far is disconnecting the battery will allow it to make >14V 100% of the time. This only lasts for maybe an hour of run time where it reverts back to varying all over the place. I installed a new battery, no change.
That's how I discovered they're crude and not the same. I bought a new one chasing my mystery low boost issue from over a year ago and the new solenoid was worse, a lot worse. So I'm still using my oem solenoid. New one is the same make/model, but imo too crude to be consistent, and this one is a dud.
The only way I'd know how to check the solenoid is how I did it, which is to check vacuum after the solenoid. Assuming vacuum before it is good which I think 25" is what I had. I forget exactly what vacuum I had after the good solenoid but certain it was 20 or more. The new solenoid was 15, and 15 is not enough.
I added the vacuum gauge just after the solenoid and ran it to inside the car so I could watch it. It'll vary as the ECU adjusts, but when warmed up and decelerating it should read as high as it's going to get.
I also lost boost when the vacuum check valve on the vacuum pump fell apart. I lost boost, can't figure out why, and traced it to low vacuum from the pump. Sheeze, so many bs things to go wrong.
The vacuum and solenoid in my car are likely both as good as it gets and it can make more boost than stock, but it doesn't take much loss in either, or voltage, to ruin that. This may be why some people here were talking about adjusting the tension on the wastegates, so it can hold them closed with less than ideal vacuum.
I wanted to add what I found recently: Low voltage will kill boost!
I've had issues of late with charging voltage. Voltage varies from >14 to 12, and when under load it drops another .5 to 1V. Not sure why but the point is the boost solenoid runs off voltage, the less you have the less boost you have. For me an mine it seems if voltage is 13+ under load I'm good, but somewhere ~12.5 I can start to see a loss in boost. If it drops to 11V boost drops to <8 psi.
I may have mentioned previously that the boost solenoid is a crude device so they don't all act the same, some work better than others so if you want peak boost you need, imo, a good solenoid. The vacuum pump check valve is also sketchy so you may not have the vacuum you need. Point being that if either is not ideal then no doubt you will be more sensitive to voltage. I was able to increase the solenoid duty cycle to 100% and it's substantially better, but most people can't do that. So check voltage while driving and especially while under load to be sure it isn't doing stupid stuff like mine.
If anyone had thoughts about my low voltage, the only clue I have so far is disconnecting the battery will allow it to make >14V 100% of the time. This only lasts for maybe an hour of run time where it reverts back to varying all over the place. I installed a new battery, no change.
Have you replaced the vacuum lines?
Cracked vacuum lines were the bane of the twin turbo set up on the RX-7. The heat / age usually meant needing to replace all the vacuum lines. Also, some thinner wall lines were prone to kinking.
That's how I discovered they're crude and not the same. I bought a new one chasing my mystery low boost issue from over a year ago and the new solenoid was worse, a lot worse. So I'm still using my oem solenoid. New one is the same make/model, but imo too crude to be consistent, and this one is a dud.
The only way I'd know how to check the solenoid is how I did it, which is to check vacuum after the solenoid. Assuming vacuum before it is good which I think 25" is what I had. I forget exactly what vacuum I had after the good solenoid but certain it was 20 or more. The new solenoid was 15, and 15 is not enough.
I added the vacuum gauge just after the solenoid and ran it to inside the car so I could watch it. It'll vary as the ECU adjusts, but when warmed up and decelerating it should read as high as it's going to get.
I also lost boost when the vacuum check valve on the vacuum pump fell apart. I lost boost, can't figure out why, and traced it to low vacuum from the pump. Sheeze, so many bs things to go wrong.
The vacuum and solenoid in my car are likely both as good as it gets and it can make more boost than stock, but it doesn't take much loss in either, or voltage, to ruin that. This may be why some people here were talking about adjusting the tension on the wastegates, so it can hold them closed with less than ideal vacuum.
What is the 'proper' vacuum you should be seeing after the solenoid?
Have you replaced the check valves? Aside from vacuum lines needing to be replaced, I have (on other cars) needed to replace check valves that have gone bad.
Is there a WIS PDF on here somewhere that explains how the wastegate control system actually works? I understand there is a vacuum pump (with an important check valve), a PWM "boost solenoid" and vacuum lines that go to the wastegate actuators. But the exact control theory I'd like to read up on.
Cracked vacuum lines were the bane of the twin turbo set up on the RX-7. The heat / age usually meant needing to replace all the vacuum lines. Also, some thinner wall lines were prone to kinking.
Vacuum, if I recall was 25? It's been a couple years and I'm going from memory but pretty sure 25.
The solenoid is just a vent to let air in to the turbos. So with the eng off the solenoid opens to let air in and the diaphragm springs open the wastegates wide open. With vacuum from the pump and a closed (powered 100%) solenoid it will give all the available vacuum to the diaphragms to overcome the springs and close the wastegates.
This does not mean it can hold them closed under high exhaust flow, but for the most part they're closed. The solenoid only allows 100% vacuum when it's fully closed 100% of the time, but that's not the norm. On mine for example the oem max duty cycle is 90%, which means the electrical power to hold the solenoid closed is 90% on and 10% off. I forget the frequency but the solenoid opens very fast and the freq is slow enough that 90 vs 100 is a big difference when it comes to boost psi. So normally it's letting some random % of air in to reduce vacuum and that's as good as it gets. Any kind of issue at all will reduce vacuum to the diaphragms, which is saying something if there's isn't enough to begin with. When the ECU wants less boost, it simply lowers the duty cycle powering the solenoid so it lets in more air. Like you might imagine, the less voltage the solenoid sees the less power it has to close, so it lets in more air, a lot more air.
The ECU is constantly adjusting the duty cycle so the wastegates open/close a lot and this causes wear at the hinge to the point the wastegate cannot close properly and you lose power. So I have mine basically locked closed and only exhaust flow, once high enough, can open them. So in my case it only adjusts how firmly it is held closed. This is done by raising the minimum duty cycle, which in my case I set it to 50%. Oem min was 10%. At 50% duty cycle I can only make ~10lbs boost, any more and it just blows the wastegates open more to self regulate. To give you an idea how much difference the voltage makes, going from 12.5 to 11V at 90% duty cycle netted me 8psi.
So both the voltage and duty cycle can very quickly kill boost because the hardware is set to just barely work as-is. A 10% difference in voltage can kill boost, so why wouldn't a 5% less effective solenoid make a huge difference in power, which is exactly what mine did. If you look at it, and how it works, I'd say 5% error would be easy. I doubt you could expect 5% accuracy in the spring they use.
All my oem vacuum lines are good.
Yes I changed my check valve on the vacuum pump. It didn't break as they usually do, but instead it fell apart. So I put it back together and to keep it from coming apart again I melted the plastic to sorta weld it together. I wanted a new one just in case, since mine was ~6 years old with 40K on it so who knows when it would break. Finding a good new one is apparently not so easy. It seems they only come with the pump, which is of course a scam to force you to buy the pump. You can buy a Ford valve separately that fits but most, maybe all, are made in china and of course they cut corners and make a crappy one. It won't make as much vacuum because the actual flapper valve inside is crap, which translates to less boost. I ordered one on ebay that noted it had the good valve inside, not the "cheap black chinese one", but of course, like anything from china, it was a lie and was the cheap black chinese one. I had a new pump on hand so I pulled the good valve from that and am still using it. Otherwise I don't know how to find or buy the good valve other than buying a whole pump.
The only way I know to get around any these issues with parts and settings that when working 100% are borderline good enough, is to take some tension off the wastagates. Imo they have far too much tension, completely unnecessary. Imo a classic case of the mfg being overly cautious. I'll likely do that anyway since even with full vacuum I know the wastegates still leak.
Fyi a screenshot I stole from somewhere. It gives the gist of the system it but not quite accurate, especially the solenoid. Close enough I spoze, just don't go trying to brain it out using that pix.
Vacuum, if I recall was 25? It's been a couple years and I'm going from memory but pretty sure 25.
The solenoid is just a vent to let air in to the turbos. So with the eng off the solenoid opens to let air in and the diaphragm springs open the wastegates wide open. With vacuum from the pump and a closed (powered 100%) solenoid it will give all the available vacuum to the diaphragms to overcome the springs and close the wastegates.
This does not mean it can hold them closed under high exhaust flow, but for the most part they're closed. The solenoid only allows 100% vacuum when it's fully closed 100% of the time, but that's not the norm. On mine for example the oem max duty cycle is 90%, which means the electrical power to hold the solenoid closed is 90% on and 10% off. I forget the frequency but the solenoid opens very fast and the freq is slow enough that 90 vs 100 is a big difference when it comes to boost psi. So normally it's letting some random % of air in to reduce vacuum and that's as good as it gets. Any kind of issue at all will reduce vacuum to the diaphragms, which is saying something if there's isn't enough to begin with. When the ECU wants less boost, it simply lowers the duty cycle powering the solenoid so it lets in more air. Like you might imagine, the less voltage the solenoid sees the less power it has to close, so it lets in more air, a lot more air.
The ECU is constantly adjusting the duty cycle so the wastegates open/close a lot and this causes wear at the hinge to the point the wastegate cannot close properly and you lose power. So I have mine basically locked closed and only exhaust flow, once high enough, can open them. So in my case it only adjusts how firmly it is held closed. This is done by raising the minimum duty cycle, which in my case I set it to 50%. Oem min was 10%. At 50% duty cycle I can only make ~10lbs boost, any more and it just blows the wastegates open more to self regulate. To give you an idea how much difference the voltage makes, going from 12.5 to 11V at 90% duty cycle netted me 8psi.
So both the voltage and duty cycle can very quickly kill boost because the hardware is set to just barely work as-is. A 10% difference in voltage can kill boost, so why wouldn't a 5% less effective solenoid make a huge difference in power, which is exactly what mine did. If you look at it, and how it works, I'd say 5% error would be easy. I doubt you could expect 5% accuracy in the spring they use.
All my oem vacuum lines are good.
Yes I changed my check valve on the vacuum pump. It didn't break as they usually do, but instead it fell apart. So I put it back together and to keep it from coming apart again I melted the plastic to sorta weld it together. I wanted a new one just in case, since mine was ~6 years old with 40K on it so who knows when it would break. Finding a good new one is apparently not so easy. It seems they only come with the pump, which is of course a scam to force you to buy the pump. You can buy a Ford valve separately that fits but most, maybe all, are made in china and of course they cut corners and make a crappy one. It won't make as much vacuum because the actual flapper valve inside is crap, which translates to less boost. I ordered one on ebay that noted it had the good valve inside, not the "cheap black chinese one", but of course, like anything from china, it was a lie and was the cheap black chinese one. I had a new pump on hand so I pulled the good valve from that and am still using it. Otherwise I don't know how to find or buy the good valve other than buying a whole pump.
The only way I know to get around any these issues with parts and settings that when working 100% are borderline good enough, is to take some tension off the wastagates. Imo they have far too much tension, completely unnecessary. Imo a classic case of the mfg being overly cautious. I'll likely do that anyway since even with full vacuum I know the wastegates still leak.
FWIW as mentioned the vacuum lines can look fine, but when pressurized / (-)ve or (+)ve you may have a crack that you cannot see.
This was/is a real issue with many vehicles.
I replaced my vacuum lines on my RX-7, and found that 2 were cracked, and this was only noticeable after removing them and carefully inspecting them. I had intermittent issues with my boost pattern on the sequential turbos and this was all sorted after replacing the lines.
There was a supplier of one way valves that were very well regarded (Viton check valves) that are about $5/each and were the replacement for the OEM check valves.
When I check the lines they hold vacuum.
Interesting they made the check valve from Viton, My first thought is that would be too stiff to work, or unable to survive, but if people like them I'd give it a shot. I don't suppose you recall the name or source?
As for vac line part #'s I'm sure konigstiger will have it. I'd post your info so he can pull it up. I'd imagine all M278 use the same lines?
11-08-2016, 12:01 PM
