No primary boost for a while after hard acceleration
09-02-07, 12:12 AM
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No primary boost for a while after hard acceleration
Hey guys, I tried searching but didn’t find anything definitive.
Basically I temporarily don’t have primary boost anytime after secondary boost is engaged. I will be driving and hit the gas and primary boost hits hard to 12psi then secondary boost hits at 4500rpm (everything normal). But then for 30 seconds or so if I am below 4500rpm I get no or very little primary boost but if I stay on the gas I get full boost above 4500rpm. After a short while everything returns back to normal and primary boost works under 4500rpm. Everything will be fine until I floor it again and the secondary turbo hits. Then again I have no primary boost for a short while.
If when everything is working fine and I floor it but never go above 4500rpm (I.E secondary turbo not engaged) then the primary will always work.
If when everything is working find and I downshift to 5000rpm and floor it I get the problem as stated above. What I am saying here is that the transition doesn’t have to happen for the problem to occur. It seems that all that has to happen is the secondary turbo be engaged.
Any help would be appreciated.
PS, Check valves are new and I looked for any lose/torn vacuum lines.
PPS, during searching I found one thread that described my problem and the solution was a bleeder valve to trick the car into thinking I am not boosting above 10 psi. I will try this but have my doubts since the car has been working fine all summer.
Regards, Jason
Basically I temporarily don’t have primary boost anytime after secondary boost is engaged. I will be driving and hit the gas and primary boost hits hard to 12psi then secondary boost hits at 4500rpm (everything normal). But then for 30 seconds or so if I am below 4500rpm I get no or very little primary boost but if I stay on the gas I get full boost above 4500rpm. After a short while everything returns back to normal and primary boost works under 4500rpm. Everything will be fine until I floor it again and the secondary turbo hits. Then again I have no primary boost for a short while.
If when everything is working fine and I floor it but never go above 4500rpm (I.E secondary turbo not engaged) then the primary will always work.
If when everything is working find and I downshift to 5000rpm and floor it I get the problem as stated above. What I am saying here is that the transition doesn’t have to happen for the problem to occur. It seems that all that has to happen is the secondary turbo be engaged.
Any help would be appreciated.
PS, Check valves are new and I looked for any lose/torn vacuum lines.
PPS, during searching I found one thread that described my problem and the solution was a bleeder valve to trick the car into thinking I am not boosting above 10 psi. I will try this but have my doubts since the car has been working fine all summer.
Regards, Jason
09-02-07, 06:56 AM
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When it works the transisiton seems to be fine... something like 12-9-12 on low boost and 13.5-10-13.5 on high boost. Then for the next little while it will be 0-12 or 0-13.5 (no transition since only the second turbo kicks in at 4500rpm).
One thing I should mention is that I noticed the nipple on the Double Throttle Solenoid was broken so I capped the tube both on the front and the back of the UIM to basically disable the Double Throttle (read to do this). The problem started right after I did this.
One thing I should mention is that I noticed the nipple on the Double Throttle Solenoid was broken so I capped the tube both on the front and the back of the UIM to basically disable the Double Throttle (read to do this). The problem started right after I did this.
Last edited by NTIMD8; 09-02-07 at 07:04 AM.
09-02-07, 01:22 PM
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UPDATE: So I started trouble shooting and noticed that when I test the Charge Control Actuator, the rod would not stay in when I turn the car off. If I understand correctly the rod should stay in until I remove the vacuum line. So I then tested the actual charge control actuator by unplugging the vacuum line pushing in the rod and plugging the nipple with my finger. The rod stayed in until I removed my finger.
So now I am thinking it must be a vacuum leak. So I test the vacuum chamber and it was fine, looked at the lines and replaced them with silicon ones and changed the Check valve (even thought the old one seemed fine). Basically I found no vacuum leak. Started the car and the rod went in, turned the car off and the rod popped back out right away again.
Anyone have any advice on what to do next to figure out why the actuator arm is popping out when I shut the car off?
So now I am thinking it must be a vacuum leak. So I test the vacuum chamber and it was fine, looked at the lines and replaced them with silicon ones and changed the Check valve (even thought the old one seemed fine). Basically I found no vacuum leak. Started the car and the rod went in, turned the car off and the rod popped back out right away again.
Anyone have any advice on what to do next to figure out why the actuator arm is popping out when I shut the car off?
09-02-07, 05:11 PM
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I tried to edit my post above but I guess I waited too long. Anyway, ignore what I wrote above. I am a moron and didn't realise that when I shut the car off the key has to be in the accessories position. So when I do the test an KOKO the rod does stay in with the car off and the key on.
So I went for a road test and the only thing I can think it can be is what I had mentioned in my original post..
So I turned my boost down to 10 psi and guess what, everything works fine and I do not get the problem I was having. I only get the problem when running over 12.5psi. I thought this couldn't be the problem since I was running 13.5psi all summer with no issues but I guess I was wrong. Here is a post that describes my problem and has the solution...
https://www.rx7club.com/showthread.p...+control+valve
Here is a quote from the post..
I will try it and let you guys know if it fixes my problem.
PS, sorry for all the long posts but I figure maybe this will help someone in the future.
So I went for a road test and the only thing I can think it can be is what I had mentioned in my original post..
PPS, during searching I found one thread that described my problem and the solution was a bleeder valve to trick the car into thinking I am not boosting above 10 psi. I will try this but have my doubts since the car has been working fine all summer.
https://www.rx7club.com/showthread.p...+control+valve
Here is a quote from the post..
Hey everyone, I think my solution will solve this problem. My local Rotary Shop (Rotary Power, Gardena CA) put on a regulator from the turbo's to the pressure chamber. If the turbo control system sees more than 10 psi and the gate starts to stick. What you need to do it add a regulator and set it to 10psi tricking the system into thinking you only are boosting 10lbs. This is for cars that are on seq-turbos boosting more than stock levels. This solved my issue. I'll post pictures later.
PS, sorry for all the long posts but I figure maybe this will help someone in the future.
09-02-07, 07:36 PM
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I don't think you have a problem. What you're describing sounds like normal twin turbo behaviour.
The 1st turbo works alone until 4500rpm at which point the 2nd turbo boost is added to the 1st to maintain boost levels. Once this transition has occured, you will be locked in non-sequential (both turbos on at once) mode until rpms drop below ~3000 rpm, at which point everything resets to sequential mode.
Try accelerating past 4500rpm, then letting off until you're back at 3500rpm. If you floor the car now, you're going to be spooling both turbos (which takes a good 500rpm or more) to get full boost. The only way you can get out of this condition is to drop the revs below ~3000rpm at which point the 2nd turbo will go offline and you'll be able to spool quickly again because you're only using the 1st turbo.
Mazda designed the system to be the best of both worlds. Good acceleration from low rpm by using the sequential system and the predictability and consistency of a big single after transition. You can actually learn to use the system pretty effectively by chosing when to switch from sequential to non sequential modes. Personaly, on the track, I prefer to keep both turbos going to avoid the nasty transition spike mid corner and only reset back to one turbo mode for coming out of slow speed corners.
The 1st turbo works alone until 4500rpm at which point the 2nd turbo boost is added to the 1st to maintain boost levels. Once this transition has occured, you will be locked in non-sequential (both turbos on at once) mode until rpms drop below ~3000 rpm, at which point everything resets to sequential mode.
Try accelerating past 4500rpm, then letting off until you're back at 3500rpm. If you floor the car now, you're going to be spooling both turbos (which takes a good 500rpm or more) to get full boost. The only way you can get out of this condition is to drop the revs below ~3000rpm at which point the 2nd turbo will go offline and you'll be able to spool quickly again because you're only using the 1st turbo.
Mazda designed the system to be the best of both worlds. Good acceleration from low rpm by using the sequential system and the predictability and consistency of a big single after transition. You can actually learn to use the system pretty effectively by chosing when to switch from sequential to non sequential modes. Personaly, on the track, I prefer to keep both turbos going to avoid the nasty transition spike mid corner and only reset back to one turbo mode for coming out of slow speed corners.
09-02-07, 09:08 PM
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Hi Will. Thanks for the input. I actually knew about this but unfortunately this is not what I am experiencing. I get no boost at all for a while anytime I hit secondary boost. Even if I upshit and the revs drop to 2000rpm I can floor it and get no boost at all until 4500rpm. So basically it is not that I am experiencing parallel boost, I am experiencing no boost.
I am fairly certain that regulating the pressure out of the pressure chamber to the soleniod to 10psi (as described in the link I posted) will resolve my issue especially since when I lower the boost to 10 or 11 psi everything works fine. I will post results for sure.
I am fairly certain that regulating the pressure out of the pressure chamber to the soleniod to 10psi (as described in the link I posted) will resolve my issue especially since when I lower the boost to 10 or 11 psi everything works fine. I will post results for sure.
I don't think you have a problem. What you're describing sounds like normal twin turbo behaviour.
The 1st turbo works alone until 4500rpm at which point the 2nd turbo boost is added to the 1st to maintain boost levels. Once this transition has occured, you will be locked in non-sequential (both turbos on at once) mode until rpms drop below ~3000 rpm, at which point everything resets to sequential mode.
Try accelerating past 4500rpm, then letting off until you're back at 3500rpm. If you floor the car now, you're going to be spooling both turbos (which takes a good 500rpm or more) to get full boost. The only way you can get out of this condition is to drop the revs below ~3000rpm at which point the 2nd turbo will go offline and you'll be able to spool quickly again because you're only using the 1st turbo.
Mazda designed the system to be the best of both worlds. Good acceleration from low rpm by using the sequential system and the predictability and consistency of a big single after transition. You can actually learn to use the system pretty effectively by chosing when to switch from sequential to non sequential modes. Personaly, on the track, I prefer to keep both turbos going to avoid the nasty transition spike mid corner and only reset back to one turbo mode for coming out of slow speed corners.
The 1st turbo works alone until 4500rpm at which point the 2nd turbo boost is added to the 1st to maintain boost levels. Once this transition has occured, you will be locked in non-sequential (both turbos on at once) mode until rpms drop below ~3000 rpm, at which point everything resets to sequential mode.
Try accelerating past 4500rpm, then letting off until you're back at 3500rpm. If you floor the car now, you're going to be spooling both turbos (which takes a good 500rpm or more) to get full boost. The only way you can get out of this condition is to drop the revs below ~3000rpm at which point the 2nd turbo will go offline and you'll be able to spool quickly again because you're only using the 1st turbo.
Mazda designed the system to be the best of both worlds. Good acceleration from low rpm by using the sequential system and the predictability and consistency of a big single after transition. You can actually learn to use the system pretty effectively by chosing when to switch from sequential to non sequential modes. Personaly, on the track, I prefer to keep both turbos going to avoid the nasty transition spike mid corner and only reset back to one turbo mode for coming out of slow speed corners.
Last edited by NTIMD8; 09-02-07 at 09:36 PM.
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09-02-07, 11:07 PM
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Hey Jason 
.
No problem... I didnt realize you were getting zero boost till 4500 lol. Good luck figuring this out.
BTW, I think people are confusing us and our cars around here... I'm always getting strangers waving at me when I'm driving around your place lol.
. No problem... I didnt realize you were getting zero boost till 4500 lol. Good luck figuring this out.
BTW, I think people are confusing us and our cars around here... I'm always getting strangers waving at me when I'm driving around your place lol.
09-03-07, 09:21 AM
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I too get people saying they saw me somewhere when I was never in the area so I assume it is you they are seeing. I also get a couple of people stop and talk to me and mention that there is one other MB 3rd gen in town and a couple of them knew you by name.
PS, whenever a stranger waves to me thinking it is you, I give them the finger or ignore them. That way they will think your are a jerk or a snob. LOL just joking of course.
09-03-07, 12:08 PM
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Thanks for the link.
09-07-07, 09:51 PM
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UPDATE: I installed a pressure regulator on the hose that air leavs the pressure chamber from and regulated the pressure to 10psi and everything works perfect now.
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