aReX-7

iTrader: (3)

I just installed an M2 reprogrammed ECU and PFS Intake and IC. Total mods now include DP, Cat Back, PFS Intake and IC, and Effiny Y-pipe. I installed needle valves on wastegate and precontrol lines to limit boost to 12 psi. Primary boost at WOT is 12 psi, drops to 6-7 psi at transition, and then back up to 12 psi. When I barely adjust the precontrol valve up, the primary boost falls to 10 psi and the transition comes up to around 8 psi, and so on. Seems like I can't raise transition without loosing primary boost!

[B]Prior setup (DP, CB, effiny Y-pipe, stock ecu) gave 12-10-12 pattern with stock pills. [B/]

Do others with M2 Ecu's have the same problem? Is there something else that could result in low transition?

Any help would be great!

Jeff

Trexthe3rd

First off, you do not have a problem. Second, installing a needle valve for wastegate control does nothing to limit your boost at 12 psi (what ever gave you that idea??).
Boost control 101:
When you modify enough components effecting the air to fuel mixture (ie. intake, exhust, ecu etc.) The overall air flow is increased, especially is you have full exhaust (dp, mp, catback or straight). The effect of the exhaust mods will eliminate all back pressure and allow for maximum exhaust flow. Under these conditions, the stock wasetgate (oroginally sized for 2 cats and a muffler) becomes insufficient. By not being able to allow excess exhaust to pass when the desired boost level is achieved (by the pill or valve) boost creep will occur. The only remedy is to port the wastegate or replace it with a larger unit. A manual valve will not prevent boost creep when it occures.

From your discription, you will need to close the wastgate control needle valve a bit (turning it clockwise, a 1/16-1/8 th of a turn) this will close the wastegate a little and increase the overall boost and then back off on the prespool needle valve a bit, this should get you back to the 12-10-12 pattern.

phatmonky

I don't own an FD (until the near future) so excuse me if this is blatently obvious for owners. The stock wastegate is internal right? what can you replace it with (brands?)

Thanks for the info Just trying to learn all I can now.

aReX-7

iTrader: (3)

Thank you for your response.

In reThe valve I installed replaced the stock restrictor (pill) between the wastegate soledoid and the wastegate actuator. I did the same for the precontrol. If that doesn't make sense to you, we might be wasting our time here.

I graduated from boost control 101 awhile ago, and I definately do not have boost creep. That might be a problem if I removed my cat, but still have mine. The third gen wastegate is plenty big enough for my mods.

My primary and secondary boost pressures are already at 12 psi. If I restrict air pressure to the wastegate actuator, and increase to the precontrol actuator, would be fine before and during transition, but it would run more than 12 psi after transition. Not good. I know the precontrol is very sensitive, but I have been testing with this system for a couple of days and I can't seem to make the transition better without lowering primary boost below 12 psi or raising secondary boost above 12 psi.

I am coming to the conclusion that I will need to run an electronic boost controler to solve this thing. What do you think?

Jeff

rynberg

It is internal, but I didn't know you could replace it with a larger unit without going single (changing the exhaust manifold).

Pressurized

I have the M2 ECU as well and after I installed my FMIC and Intakes my boost pattern went to 12-8-12 too.....

I only guess that it's working properly if you're getting the same results. It wasn't until I took my hi-flo out and put a mid-pipe on, that I started having problems with boost patterns...

I'm not sure what causes this, before I installed these parts I was getting 13-13-13, so I have no idea what the intercooler did to it. Maybe it's just pressure loss through the tarnsition across the intercooler?

Trexthe3rd

Electronic boost controllers will not effect the transition boost drop. I know this because I have the Blitz SBC-ID boost controller and am using a manual valve to adjust the prespool. All boost controllers (electronic or manual) controls the wastegate, nothing else. I don't remember where it was memtioned before, but someone was able to get the manual valves to minimize the transition drop. Unfortunately the typical needle valves lack the necessary dial resolution to easily adjust the boost pattern. I was able to get 12-10-12, but at higher boost the drops become more dramatic (13-11-14). If all you want to do is limit boost, then just play with the settings on the manual valves until you get what you like.

ZoomZoom

iTrader: (2)

The problem lies with the ECU. It was remapped to run with a more open exhaust and intake. Not only does it run more fuel to compensate for the added air but it also lowers the duty cycle of the solinoids that control boost pressure as not to overboost due to the limited capacity of the stock wastegate. This problem also is excentuated by getting the pressure drop associated with a bigger intercooler. So you lose much of the quick spooling primary turbo. I run a DP MP M2 intake, M2 Med intercooler and Power FC. The ECu controls boost by keeping the duty cycle much lower than the stock ECU. It rises on its own with higher duty cycles that are preset on stock ECU's just from opening up the backpressure. There are a few more variables but this explains part of your boost troubles. The intercooler does need more air volume to pressurize so you will always lose primary boost pressure down low.

rerx7

how to get the wastegate ported? Anyone?
thanks

aReX-7

iTrader: (3)

Thanks for the insight. I agree that the minimal increase in system volume would only account for a small increase in spool-up time on the first turbo. I am just not clear why I am getting such a dramatic drop at transition.

So are you saying that the Power FC helps with this problem? What kind of boost patterns do you get with your setup? Where did you get your maps?

Also, you mentioned in your post that the reprogrammed ecu uses lower duty cycles. Do you really mean that it uses higher duty cycles, since a lower wastegate duty cycle will raise boost?

Jeff

phatmonky

My point exactly. I don't see how it would be easily possible. But if he knows what he's saying it would be nice to hear about

Trexthe3rd

<QUOTE>how to get the wastegate ported? Anyone?
thanks<\QUOTE>
You'll need to remove the turbo assemble find and enlarge the wastegate opening to the point where the cover plate just cover the opening.

<QUOTE>
quote:
--------------------------------------------------------------------------------
Originally posted by rynberg


It is internal, but I didn't know you could replace it with a larger unit without going single (changing the exhaust manifold).
--------------------------------------------------------------------------------

My point exactly. I don't see how it would be easily possible. But if he knows what he's saying it would be nice to hear about <\QUOTE>

Sorry about the misleading wording of the paragraph. external wastegate controls are only viable with single or custom upgraded twins.

<QUOTE>Also, you mentioned in your post that the reprogrammed ecu uses lower duty cycles. Do you really mean that it uses higher duty cycles, since a lower wastegate duty cycle will raise boost? <\QUOTE>

95% duty = Fully closed, 5% duty =Fully open
(RX-7 Workshop Manual page F-84)
hence lower duty = more open = less boost

aReX-7

iTrader: (3)

Thank you for the clarification on that. Looks like I was the one who had it backwards. I was assuming that the solenoid default position was CLOSED, but it looks like it is OPEN by default.

I just spoke with M2 on the phone, and they say that I should see 0.7 bar (10 psi) at transition with my setup (M2 ecu, DP, CB, IC, Intake.) They suggested using pills instead of the manual valves to control the wastegate and precontrol, but I am not really convinced that the valves are causing my boost to fall to 7 psi at transition.

I think I will try to adjust the valves a few more times before I go the pill route.

Jeff

aReX-7

iTrader: (3)

Darn double posts!

aReX-7

iTrader: (3)

Has anyone ever had to adjust their precontrol actuator rod? I read on Rob Robinette's site that Pettit has had to adjust this in the past to fix precontrol problems. I am thinking about checking mine. Has anyone done this before? Any advise on how to determine proper adjustment?

Any experience/advise would be appreciated!

Jeff

ZoomZoom

iTrader: (2)

Actually a stock ECU will run 18 or 19 psi or more if it is not remapped when running a DP MP and cat back, intake etc. I was waiting for my PFC and had to drive on the Stock ECU until it arrived. I took it easy because the boost spikes were insane. Also I got 10 psi before 3k RPM on the primary turbo. And it would spike up to 19psi or higher if I let it transition to the second turbo. The reason I am pointing this out is to show that a remapped ECU "LOWERS" duty cycle so the boost will not go as high as fast. The Duty cycle on the stock ECU is higher, thats why more than 2 mods and the boost goes to the moon. Its tuned so it will run decent boost under all the backpressure of the stock exhaust, intake etc. But with increased exhaust flow and intake volume you need to lower duty cycles from stock settings. Also add fuel to compensate for the natural rise in boost pressure due to the open air flow from the Modifications. In fact your remapped ECU its not going to run as high of boost without the Mods it tuned for. SO your seeing the effect of a remapped ECU with a basically stock exhaust and intake. It will run rich and will not boost as high.