hey all...

just finished tuning my afr's for the current boost pattern i have of 12-9.5-14...want to even out the boost and tune for the next step up as I move toward 16lbs (max until I get the 3bar map sensor).

I am currently running the pfc in conjunction with a manual boost controller.

I dont get much response using the pfc to control the boost...I rely on the manual (needle valves) to control prespool and to control max boost.

if i close the prespool all the way I get 14lbs on the first turbo...however the second turbo needs the prespool to get going so I have to open it up...when I open the prespool valve at all I get a max boost of 12-13lbs depending on how far it is open.

why am i not able to get more boost to the first turbo...from what i understand the ecu should be compensating for the loss of pressure during prespool and should be evening things out.

Im stuck...at a loss.

any input is appreciated.

jason

PS..the manual boost controller is hooked up properly and the actuators are NEW and working....the sensors are new as well at 5k miles.

any ideas???

 

surely someone has some input right??

 

I think an ideal boost control system which would allow you to 'optimally' set everything up would involve using two separate boost controllers, one for the prespool and wastegate actuators. On primary, all control would be through prespool only, with the wastegate opening only after the prespool was completely open. I think the stock system doesnt quite do this...it goes back to the question of whether the wastegate is used to control boost before 4500 rpm (which I think it does). Feel free to buy 2 avcrs and tell us how things work out

 

hahah...thanks for the info aristo...however if you would kindly send me two avcrs I would be happy to let you know what the results are.

Im going to have to go with the profec b I think...

I thought tuning for proper afr's was a pain..boost is the other half of that.

at least ive got the first half down


j

 

artguy,

I have had the same problem for a long time. I want to run 15psi on both turbos with a minimal drop in boost at changover. I can have 15psi on the pri but in order to do so I have to close the PC too much, and the 4500 RPM dip is too deep. In order to get a good spike to 14-15psi on the secondary, I have to open the valve enough so that I only get 12psi on the primary. I don't think there is anything that can be done about this, short of moving the changeover RPM. I think it is a flow issue, not enough to get 15psi on primary and also adequately spool the secondary. And yes the wg does have an effect on primary boost.

You could switch to non-seq to get rid of the spike/dip but you would still have the same flow problem. The difference would be you wouldn't have the flow to spool both turbos to high boost until the RPM's were too high (instead of a weak transition).

A good compromise might be running 12psi pri 16psi (or whatever) secondary, and lowering the switch RPM so the boost spike isn't as violent. If you could do this at 3500 RPM I would think the spike might not be such a big deal. But then the question is will the spike be temporary, would boost drop after the spike and would it take too long to rebuild the boost. Then you'd be back to the non-seq problems again.

If you do figure out a workaround, please let me know.

Wade

 

now wade my friend..that is good information.

what has to be done to lower the switch? Id be willing to try it out....wouldnt that basically be like non seq but with the primary offering low end kick that the non seq setup lacks? oh the joy!!

surely there is someone who has found a solution to the problem.

anyone else have input for us?? come on guys..please share!

 

Yeah, as Wade said you are obviously restricted by the available energy from the exhaust. Artguy, do you have a midpipe?

 

no..Im running the stock cat

That is a good point though....could be a flow problem there too. Will try a high flow cat later this week hopefully. I have to get the piping for it. I DIDNT want to do that until i was done tuning what i have...maybe thats the way to go.


I didnt think of that...thanks....

I dont have any probs though boosting after the transition....its seen as high as 16lbs...the m2ds spool reallllly quickly which would counter the idea of flow problem Id think...maybe not...

the probs are all with the primary not going past 11-13lbs and boost drop at transition...I can boost to the moon with the secondary and primary in conjunction.

j

 

I think you can lower the transition RPM with the datalogit.

I have the same problem with a midpipe so don't get your hopes up about that. However I haven't tried closing my wastegate valve a lot, since I have been using the PMS for boost control. Raising the wg too much would make it so the PMS couldn't run a lower PSI program.

You'll have to experiment, like I said I have had the same problem for awhile. I haven't really tried anything for a long time because I've had more important things to work on. I'd be interested in anything you find though, since I will eventually be working through this problem again.

Wade

 

thanks wade...I appreciate it.

I tried yesterday to lengthen the actuator to the wastegate..(the lower one). The m2 turbos are 3/4 inch longer and I still had a stock actuator on there...in effect my actuator was holding the wastegate closed even longer because it was too short...it was pulling it tightly closed if ya can picture what im trying to say.

My question is...I lengthend the actuator to the exact point where movement in the actuator would cause it to open. I was hoping for great response...but Im not sure if its worse or not.

will try it again...

will try larger hoses and valves for the manual boost contrllr...

will try a diff cat....

may try another solonoid...though mine is brand new.

will try some boost logs with the datalogit...too see exactly what is happening.

will get this i swear! if all else fails I will pick up the profec b in a couple weeks.

thanks for the input guys...ANY other ideas???

j

 

Even if you can boost over 16 psi on secondary, freeing up the exhaust would allow you to get more boost down low...there may not be enough pie to split between the two during the primary operation, so you might as well make the pie bigger!

 

I don't think this is the way you want to go. Lengthening the rod will cause your wg to open sooner, which if anything, will lower your boost. Since you are having a problem making enough boost I think lengthening the rod would make the problem worse, if anything.

Quote:

My question is...I lengthend the actuator to the exact point where movement in the actuator would cause it to open. I was hoping for great response...but Im not sure if its worse or not.

will try it again...

will try larger hoses and valves for the manual boost contrllr...

The size of the hose and solenoid can limit your boost. BUT, closing the orifice in the wastegate line before the actuator combats this. You shouldn't need to enlarge any lines/solenoids.

Quote:

will try a diff cat....

may try another solonoid...though mine is brand new.

will try some boost logs with the datalogit...too see exactly what is happening.

will get this i swear! if all else fails I will pick up the profec b in a couple weeks.

thanks for the input guys...ANY other ideas???

j

I think the best idea is to close the wg pill a lot. I haven't personally tried this because of the PMS thing (wanting to be able to get lower boost with the in-car switch).

I have no way of trying this right now or I would. I would like to fix this problem on my car as well, if possible.

Wade

 

thanks guys...will try some of these solutions this week...if you have any other input please share.

wade..Ill keep you informed.

j

 

Are you using the Home Depot needle valves to control prespool? Perhaps you have a resolution issue...

Has anyone checked what the flow is when the Home Depot valve is first cracked open? If you could get the pressure behind that actuator to fill slowly enough, you shouldn't see the boost drop. Clearly, if the actuator hasn't started to move yet, you shouldn't see an effect on boost.

I never had much success with the Home Depot valves. I used the Holley jets. Of course, I'm not trying to run 16 psi.

I found some precision valves on the internet. I calculated the flow through an oriface in the ranges of the stock pills, then found a precision valve that spanned that range.

They are stainless and high quality. I never bought them because when I used the jets, all was ok.

Just a thought...

 

Let me add that I do think what has been suggested above is correct. You don't have enough exhaust at the lower rpms to spin the first turbo enough to produce 15 psi of boost AND to prespin the second turbo to prevent a low transition.

You've just reached the mechanical limit. I guess I am a little bit surprised the M2 turbo doesn't produce more boost. It is limited by the stock manifold, though.

 

We need to start off by making sure that the wastegate is staying sufficiently closed during primary-only operation. The only danger there is over boosting, which has not been a problem yet. To do this we need to take a good look at the hoses going to and from the wastegate actuator and it's corresponding solenoid. The hose size (restriction) before the wastegate actuator sounds like it's not an issue, after all you're under boosting which would suggest that you are getting good flow to the actuator. Now, the hoses leaving the wastegate actuator going to the solenoid may need to be addressed since they are the gateway for the pressure venting via the solenoid which is responsible for keeping the wastegate closed (mostly) during primary-only boost since the boost is being controlled more so by the pre-control actuator. Basically, if the wastegate actuator is not being vented adequately during primary-only operation, your primary boost will be significantly lower than your pri + sec boost. So how the hell do we do that? I have a couple ideas, which includes hooking up a boost gauge to the wastegate bleed line to monitor the venting of the wastegate actuator to verify that it is at least trying to vent. Then finding out why it's not being vented enough. The sequential system is designed to work this way, so it's just a matter making sure it working properly for your boost levels.

The precontrol actuator would be the next thing to look at. This is more strait foward, as we only have to worry about a fixed signal going to the pre-control actuator. It's been a while since I've been sequential so I might be forgetting some stuff, but we'll figure it out.

-Ray

 

No because when you close the needle valve on the precontrol all the way the primary boost hits 15 easy. (yes I was in the car)

 

Just to clarify on my last post....If the wastegate is indeed shut during primary-only boost and the opening of the precontrol gate, at the desired amount, causes the inability to get the desired boost presure, then johnchabin may be correct in that the M2 turbo has reached it's mechanical limit. I simply dont think it has.

Futhermore...freeing up exhaust restrictions (i.e. removing clogged cat, adding a mp, etc) will help to get primary boost up, but it will also increase pri + sec boost keeping the problem basically the same, no?

 

the m2 turbo set has not reached its mechanical limit...the m2 guys built them to run 20lbs.

everything you have said ray sounds right...some of the above info sounds right too...I will see about a midpipe regardless.

thanks for the help guys...if anyone else has info..please let us know.

this thread will hopefully be helpful to others facing the same issues.

we have max boost set at 14-15lbs that is why we dont spool more than that...we are starting small and moving big...but to up the boost the precontrol has to be spot on FIRST... then its a matter of inching up the boost and tuning for proper AFR'S

 

Again, I think that the wg solenoid and post-actuator line could be a restriction causing the wg to open too much... BUT closing the pre-wg actuator pill/valve more should remove this problem, if it exists.

Wade

 

Yes, but wouldn’t that continue to raise boost after the transition as a side effect?.....he's looking to raise boost overall AFTER he gets the primary to catch up to the pri + sec level. You need adequate venting on the post wg line no matter what, or else you will never balance the two turbos out and still maintain an acceptable transition drop/spike

 

I don't think the wastegate pill is the issue. The wastegate is opening at the proper point when the precontrol valve is closed to give him 15 psi. With less boost, the wastegate actuator should fill more slowly and open later rather than sooner.

I realize the wastegate actuator is under duty control, but isn't it effectively closed, thus not having an effect on how quickly the actuator fills?

A post actuator line with more volume (longer) should have some effect, though.

 

The PFC allows vent duty cycles to be adjusted. Stock oem is about 90% open primary, around 60% open twinmode. The high primary vent allows the high stock primary boost, in spite of added exh dumping thru the PC wg.

Contrary to many declarations, the wg also opens for primary control ... think it doesn't? just plug hose TO wg actuator, and go wot in 4th at 3500 rpm and watch boost gauge. ( but stay under transition) .

If u raise boost, should raise vent values too, and keep the highest % on the primary.

AFIK, the PFC is set initially to work with stock pills, so I'd use em to get a starting point, say 13/13 psi. Then just replace wg pill with valve (precontrol has sensitive interation with primary boost control). trim valve to get same boost as with stock pill for starters.

For 15/15, also need to change the 'high' transition setting to around 3600 rpm, per this link:

https://www.rx7club.com/forum/showth...ght=transition

This keeps trans at a lower power level, before the torque peak. he's at 14/14 psi. note also the wg vent %'s on the graphs. in his case, a slightly higher secondary % vent value, and/or larger PC pill would have reduced his new boost drop at the earlier trans.

The stock set up has a basic wg setting of 8 psi, with venting controls to get about 11 on primary. May need the put washers under wg actauator bracket and raise the basic setting to 9-10 psi, to ease control at 15+ psi.

 

If I were you Artguy, I would get a closed loop boost controller with RPM adjustable boost levels, to make sure you keep that wastegate closed during primary operation. Allow the prespool actuator to be controlled by the stock solenoid (ie DO NOT t that into the boost controller, only let it control the wastegate). This way you know as much exhaust as possible is going to spool
up the secondary, and not wasted by the wastegate...then you can adust the precontrol pills to get the pattern you want.

 

great info guys...honestly.

my brains are stirring...the challenges of the sequential system show me why peeps go non seq. I aint goin that way...haha

j

all yer info helps a lot...appreciated.