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-   -   Overboosting and no transition: problems with stock twin control (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/overboosting-no-transition-problems-stock-twin-control-850444/)

alexdimen 07-07-09 06:11 PM

Overboosting and no transition: problems with stock twin control
 
Running stock twins with a hallman MBC on the wastegate line.

Here are my symptoms:

-MBC adjusted all the way out (spring loose inside) still boosts to 12 psi in low gears
-in 5th on the highway it only boosts to 10psi WOT IIRC
-turbo control actuator does not move when I do KOKO like the troubleshooting guide says
-no secondary transition
-do not get 4 psi when i WOT in neutral, it's more like 0

Here's what I just did to the car: traded out rebuilt twins for low mile stockers. The rebuild ones had a perfect 10-8-10 but were noisy. When I first put on the new ones I had a rattle and they didn't make enough boost. The rattle was the precontrol actuator rod out of adjustment and not holding the flapper closed. I fixed that and then they started to overboost.

What I've checked and has passed inspection:

-correct routing of lines to MBC
-BOV
-charge control actuator works during KOKO
-made sure the wastegate line went to the correct (USDM driver's side) actuator and correct nipple on actuator by disconnecting lines and blowing through them
-pressure and vac tanks hold

I'm running out of ideas, time, and patience and could use some help. Thanks everyone.

dgeesaman 07-07-09 07:35 PM

Are you running with the extra pc / wg actuator nipples capped?

(I would)

alexdimen 07-07-09 09:39 PM


Originally Posted by dgeesaman (Post 9341109)
Are you running with the extra pc / wg actuator nipples capped?

(I would)

Nope. They run to the PC and WG solenoids just like stock.

arghx 07-07-09 10:38 PM

Long term, either take out the MBC and control boost with a PFC and stock solenoids (no pills), or cap the nipple to the solenoids and control it only with an aftermarket boost controller of some sort.

but what you should do first as a diagnostic procedure is cap the nipple on the actuators that go to the wastegate/precontrol solenoids. Then remove the MBC's and run straight uninterrupted pressure sources to one nipple on each actuator. That should put you right at spring pressure assuming nothing else is wrong.

dgeesaman 07-08-09 05:16 AM


Originally Posted by alexdimen (Post 9341474)
Nope. They run to the PC and WG solenoids just like stock.


I found that with my manual boost controllers they did not work well unless I put a cap on the actuators. Too much air passing through the actuators unless your boost controller spring was very sensitive.

IIRC Damian eventually did the same thing but it's listed at one of the later posts in his thread.

alexdimen 07-08-09 01:27 PM

Well, I only have one MBC and it's on the WG pressure line. I think I'm going to cap off the aux nipples on the actuators, but leave the MBC there. Maybe eventually put in another MBC on the PC.

ARGHX, why are you against MBCs and say I should use a boost controller? I thought these hallman MBC's were supposed to work pretty well.

arghx 07-08-09 03:13 PM

I am not against MBC's. I said "aftermarket boost controller of some sort." in my mind that includes MBC's. they get the job done. I prefer tuning the stock solenoids through a PFC actually, but there is a cost and a learning curve that many would understandably like to avoid.

alexdimen 07-08-09 05:01 PM


Originally Posted by arghx (Post 9343375)
I am not against MBC's. I said "aftermarket boost controller of some sort." in my mind that includes MBC's. they get the job done. I prefer tuning the stock solenoids through a PFC actually, but there is a cost and a learning curve that many would understandably like to avoid.

OK, I understand. Unfortunately a PFC is not in my budget right now.

I just got done capping the extra actuator nipples and I've gotta drive to the UPS depot down I95, so we'll see what happens. So far boost looks lower on the short ride home from work.

alexdimen 07-08-09 07:12 PM

Ok, I'm officially confused. Couldn't get the boost over 7 psi regardless of MBC adjustment. No transition. Boost gradually fell off to ~3psi after 5k rpm or so.

dgeesaman 07-08-09 10:32 PM

If you only have a boost controller on the wastegate, then that's the only one I'd cap off. I hadn't directly asked whether you have a controller installed on just one or both.

I would reconnect the precontrol to it's solenoid or else you might not generate enough boost on the primary to activate the secondary.

Dave

arghx 07-08-09 11:39 PM

the whole point of this exercise was to start with an underboosting car and then set the boost to where it needs to be, rather than starting with an overboosting car and risking the motor as you tried to drop the boost down

alexdimen 07-09-09 12:08 PM


Originally Posted by dgeesaman (Post 9344485)
If you only have a boost controller on the wastegate, then that's the only one I'd cap off. I hadn't directly asked whether you have a controller installed on just one or both.

I would reconnect the precontrol to it's solenoid or else you might not generate enough boost on the primary to activate the secondary.

Dave

Ok, I'll try that this weekend.


Originally Posted by arghx (Post 9344625)
the whole point of this exercise was to start with an underboosting car and then set the boost to where it needs to be, rather than starting with an overboosting car and risking the motor as you tried to drop the boost down

well at least we've accomplished that, right? hehe. i'll post back after reconnecting the precontrol to the solenoid.

alexdimen 07-12-09 09:31 PM

reconnecting the precontrol to the solenoid fixed it. turbos are working great and the wastegate keeps it at 10psi.

alexdimen 07-18-09 05:05 PM

I lied. My boost pattern is still off. I'm getting 10-5-8 in third gear. Seems to be proper timing, just not the right pressures.

My turbo control actuator still does not move when I KOKO after building good vac and pressure in the tanks.

The turbo control solenoid under the UIM and next to the ACV (not the rats nest turbo control solenoid) does not click with KOKO. I took off the connector and it's not getting +12v between the terminals with the key on.

With the key off, both terminals are 0v. Key on they both go to 12v.

dgeesaman 07-18-09 08:22 PM

There you go - replace that solenoid. It's a very common bad actor.

I can't guarantee it will fix the 5psi transition but it will help a lot.

alexdimen 07-19-09 10:27 AM


Originally Posted by dgeesaman (Post 9366769)
There you go - replace that solenoid. It's a very common bad actor.

I can't guarantee it will fix the 5psi transition but it will help a lot.

Ok, but I'm kind of confused about the voltage at the connector. Why would both wires have 12v?

dgeesaman 07-19-09 06:23 PM

Oh, both terminals on the same connector? That's not right. I think you're onto something with that.

Does it make 12v on both sides with the solenoid connected or disconnected? Hopefully it's just a shorted solenoid.

David

alexdimen 07-19-09 09:09 PM


Originally Posted by dgeesaman (Post 9368149)
Oh, both terminals on the same connector? That's not right. I think you're onto something with that.

Does it make 12v on both sides with the solenoid connected or disconnected? Hopefully it's just a shorted solenoid.

David

that's just the connector, no solenoid. starting to feel like i'm losing it... i swear this car worked before i switched turbos. haha

Here's what I'm gonna do. I know the hot wire (black/white, just like all the other solenoids) is good and has 12v key on. The ground wire, which the ecu controls is pin 4R on the ecu harness. I'm going to make sure the two ends have continuity. Then i'll ground pin 4R with the ignition on and see if i can make the solenoid work that way.

Hopefully that will tell me if it's wiring or in the ecu. Sounds relatively sane, right?

dgeesaman 07-20-09 05:16 AM

Sounds reasonable. Good luck(?!)

alexdimen 08-10-09 10:11 PM

Well, that was def a bad solenoid, got open open circuit when i put the multimeter on it, new solenoid was about 34 ohms. It's def better, but not 100 percent. I need to do some country road pulls this week and 2x check the pattern.

I actually managed to R&R it without pulling the UIM believe it or not. Not sure i'd recommend it though....

It's def pulling better after 4500, but i'm pretty sure it still dropped to 6 psi and only maxed out at 9 psi.

Starting to see why you guys told me to throw these things away, but I'm too damn hard headed.

adam c 08-11-09 08:46 AM

Have you checked to make sure your pre spool line a pill in it? If it doesn't, that could be your problem.

alexdimen 08-12-09 06:38 PM


Originally Posted by adam c (Post 9418295)
Have you checked to make sure your pre spool line a pill in it? If it doesn't, that could be your problem.

Nearly 100% i checked that when i capped the WG to solenoid line. I can always double check it when i tear into it again.

I think i'm going to one by one ground the turbo related solenoids at the ECU harness with the key on and check for clicking, taking the more accessible ones off. Then double check the line to solenoid routing.

I'm leaning towards something precontrol related since i get good primary and my transition happens at the right time. Maybe CRV or charge control?

dgeesaman 08-13-09 05:05 AM

Wait, if you have MBCs you should not have a pill in that line.

alexdimen 08-13-09 06:42 PM


Originally Posted by dgeesaman (Post 9423506)
Wait, if you have MBCs you should not have a pill in that line.

It's just in the precontrol line, since there's no MBC on it and i just let the solenoid/ecu control precontrol. The WG line is straight hose to the MBC.

alexdimen 10-01-09 05:59 PM

I just got a chance to mess with the car this evening.

RECAP:

- i get good primary boost
- 4 psi WOT in neutral
- MBC on wastegate ONLY
- precontrol is still controlled by stock ECU
- my boost pattern is 10-5-8, so i get a large pressure drop at transition and it will not build full boost afterwards... would this indicate that the secondary is not producing any boost and the pressure is being fed back thru the secondary when the charge control actuator opens?
- i also sometimes have a hard time generating any boost pressure at all and the car feels sluggish

I switched the lines to the turbo control actuator and it caused no transition at all. I just switched it back after verifying that the lines were hooked up right to begin with:

I checked:

- pressure and vac resevoirs (good)
- put a mity vac on the turbo control and actuated it. (good)
- put vac guage on turbo control vac supply nipple under pressure tank. key on i got vac for a second then it switched it off.
- put pressure guage on turbo control pressure supply nipple under pressure tank. key on i got pressure for a second and it switched off.

each time i did key on key off i got pressure or vacuum reading for a second, then relay clicked and back to zero.

any suggestions? I'm considering going poor man's non-sequential for the time being.

arghx 10-01-09 06:21 PM

check valves good?

pomanferrari 10-01-09 11:22 PM

I went through something like this 6 years ago and wasted so much time diagnosing that I ended up buying all new solenoids, something like 7 or 8 at $50 a pop and like 10 of the check valves at like $10 each. And I made sure that the vaccuum lines were exactly as on the factory diagram. Never had issue after that.



Originally Posted by alexdimen (Post 9535126)
I just got a chance to mess with the car this evening.

RECAP:

- i get good primary boost
- 4 psi WOT in neutral
- MBC on wastegate ONLY
- precontrol is still controlled by stock ECU
- my boost pattern is 10-5-8, so i get a large pressure drop at transition and it will not build full boost afterwards... would this indicate that the secondary is not producing any boost and the pressure is being fed back thru the secondary when the charge control actuator opens?
- i also sometimes have a hard time generating any boost pressure at all and the car feels sluggish

I switched the lines to the turbo control actuator and it caused no transition at all. I just switched it back after verifying that the lines were hooked up right to begin with:

I checked:

- pressure and vac resevoirs (good)
- put a mity vac on the turbo control and actuated it. (good)
- put vac guage on turbo control vac supply nipple under pressure tank. key on i got vac for a second then it switched it off.
- put pressure guage on turbo control pressure supply nipple under pressure tank. key on i got pressure for a second and it switched off.

each time i did key on key off i got pressure or vacuum reading for a second, then relay clicked and back to zero.

any suggestions? I'm considering going poor man's non-sequential for the time being.


gracer7-rx7 10-01-09 11:32 PM

Check for a clogged cat. I posted how in the past if you want to search for it.

I'm going through my own troubleshooting for a transition issue so I feel your pain.

alexdimen 10-02-09 03:31 PM


Originally Posted by arghx (Post 9535163)
check valves good?

I haven't checked them since I put them on, but they are new viton check valves from dale clark. not very old or many miles.


Originally Posted by pomanferrari (Post 9535812)
I went through something like this 6 years ago and wasted so much time diagnosing that I ended up buying all new solenoids, something like 7 or 8 at $50 a pop and like 10 of the check valves at like $10 each. And I made sure that the vaccuum lines were exactly as on the factory diagram. Never had issue after that.

ugh... i'm trying to avoid pulling off the uim again. I know the vacuum lines are right under there and new.


Originally Posted by gracer7-rx7 (Post 9535830)
Check for a clogged cat. I posted how in the past if you want to search for it.

I'm going through my own troubleshooting for a transition issue so I feel your pain.

I have a PFS downpipe and stock main cat. I doubt it's clogged because it pulls really hard up to transition. When I said the car feels sluggish I meant every once in a while when I don't get boost. Feels like a boost leak that's not always there.

Today I swapped the connectors for the WG and precontrol solenoids, thinking they could have their lines switched and got no change...

Now, what exactly is the turbo control actuator supposed to do when you key on key off after a drive? Is it supposed to move all the way when you KOn and stay there until you KOff... just like the charge control actuator? Just move a little bit every time you key on?

alexdimen 10-02-09 04:27 PM

Is it true that the precontrol actuator largely controls boost pressure before 4500 rpm? The troubleshooting guide states this...

If so, I've been trying to adjust the system ass backwards. I figured the wastegate controlled boost pressure all the time... maybe I just need a MBC on both actuators. I think I'll try that.

DaveW 10-02-09 05:34 PM

Yes, that's true. Here are some threads with some useful related info on using dual ball/spring MBC's. This is the system I use, and it works great.

https://www.rx7club.com/showpost.php...6&postcount=10

dgeesaman 10-02-09 05:55 PM

The TCA will briefly extend during the KOKO test. You'll need a helper to perform this part of the test.

David

violentsnail 10-03-09 12:59 PM

sounds like a problem I couldn't figure out for the life of me. All hoses were connected, bought new solenoids, made sure that they were all getting the right voltage, but for whatever reason i could never hold pressure at 10lbs in the secondary. I'd be interested to know what you came up with.

TheAsset 10-07-09 09:33 AM

Could it possibly be the Charge Solenoid, maybe it's not letting things open up once the secondary is pre-spooled...The issue with mine right now, is I get no secondary turbo at all. I'm trying to pinpoint that solenoid

alexdimen 10-09-09 07:00 PM


Originally Posted by TheAsset (Post 9546840)
Could it possibly be the Charge Solenoid, maybe it's not letting things open up once the secondary is pre-spooled...The issue with mine right now, is I get no secondary turbo at all. I'm trying to pinpoint that solenoid

Well there are two. The charge relief and the charge control. Charge relief opens a BOV type thing to vent the secondary pressure back to air box pre-transition. The charge control opens as the charge relief closes to put all the secondary boost into the intake.

The valve and actuator should be easily checked with a mity vac and the manual. You could put a mity vac on a long line to the supply lines to the actuators and see if they get good vacuum from their solenoids at transition.

adam c 10-09-09 07:28 PM


Originally Posted by alexdimen (Post 9537172)
Is it true that the precontrol actuator largely controls boost pressure before 4500 rpm? The troubleshooting guide states this...

If so, I've been trying to adjust the system ass backwards. I figured the wastegate controlled boost pressure all the time... maybe I just need a MBC on both actuators. I think I'll try that.

Its my understanding that the precontrol actuator controls boost at transition only. A stock pill in the precontrol line should give you a transition boost of 8 psi regardless of higher boost settings on the wastegate control.

dgeesaman 10-10-09 07:19 AM

I've found it's as easy as precontrol adjusts below transition, and wastegate adjusts above transtion. The settings of each relative to each other controls the shape of the transition dip/spike.

Dave

DaveW 10-10-09 08:40 AM


Originally Posted by dgeesaman (Post 9553431)
I've found it's as easy as precontrol adjusts below transition, and wastegate adjusts above transtion. The settings of each relative to each other controls the shape of the transition dip/spike.

Dave

Exactly. That's why I run 2 ball-spring MBC's. One controls the PC actuator, and thus, the boost before transition, and the other controls the WG actuator, and, thus, the boost after transition. The lines from the actuators to the solenoids are blocked with solid (no holes) pills. I set the PC at 11 psi, and the WG at 10 psi to optimize the performance w/o fuel cut (stock ECU). See the chart below:

MrNizzles 10-10-09 04:33 PM

^ DaveW are you still using the stock ecu or do you have a PFC with that boost control setup?

nvm, read your post again .. <- slap me

anyway, I bet the turbos last longer at stock boost lvls ... ?

alexdimen 10-11-09 05:11 PM

I'm just waiting on another MBC. Pretty confident that will solve my problem.

Glad to have started a constructive conversation... seems like this isn't common knowledge for some reason. I misunderstood the boost control system entirely until I ran into this problem.


Originally Posted by DaveW (Post 9553472)
Exactly. That's why I run 2 ball-spring MBC's. One controls the PC actuator, and thus, the boost before transition, and the other controls the WG actuator, and, thus, the boost after transition. The lines from the actuators to the solenoids are blocked with solid (no holes) pills. I set the PC at 11 psi, and the WG at 10 psi to optimize the performance w/o fuel cut (stock ECU). See the chart below:

Why 11 psi and not leave it at stock 10?

DaveW 10-12-09 07:18 AM


Originally Posted by alexdimen (Post 9555728)
1. I'm just waiting on another MBC. Pretty confident that will solve my problem.

2. Glad to have started a constructive conversation... seems like this isn't common knowledge for some reason. I misunderstood the boost control system entirely until I ran into this problem.

3. Why 11 psi and not leave it at stock 10?

1. I'm sure it will.

2. It originally took me about a month of reading posts and articles on boost control for the FD before I REALLY understood how it works, so I can easily understand how confusing it is.

3. Actually, the "stock 10" can be more or less than that depending on weather conditions, intake and exhaust flow mods, etc. Remember that there is no feedback with the stock boost "control" system. The stock "boost-control" relies on a predetermined map, and is not very good at actually "controlling" the boost.

I set the PC at 11 because (1) I can do so w/o fear of fuel cut, (2) 11 psi provides more power than 10, and (3) with my setup (see my signature) the 11 psi on the PC setting minimized the boost dip/spike at transition.

alexdimen 02-10-10 08:32 AM

keeping thread up to date... adding another MBC worked!

NeoTuri 02-10-10 09:14 AM

Yeah, I found that after I replaced my WG/PC solenoids with MBCs, the boost patterns have become far more consistent.

DaveW 02-10-10 09:56 AM


Originally Posted by alexdimen (Post 9794975)
keeping thread up to date... adding another MBC worked!

Great. Glad to hear it!

Dave

Monkman33 02-10-10 11:28 AM

Check the Crv?


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