MR2 Owners Club Forum banner
1 - 20 of 28 Posts

·
Registered
1992 Toyota MR2 Turbo
Joined
·
24 Posts
Discussion Starter · #1 · (Edited)
Hey I'm still new here, I tried to look up old threads about tuning but did not find the answers I needed, if I missed something, I apologize in advance.

I have a 1992 MR2 Turbo, totally stock (except for aftermarket exhaust), I am planning to purchase a direct bolt on turbo upgrade, which from my understanding only requires bigger fuel injectors, and a ecu retune. I am told the factory manifold and downpipe will bolt on.

This is the turbo I plan to purchase. CT26 MR2 Internal Wastegate Turbocharger 91-98 Upgrade
I plan to use 550cc injectors. Also the Twos R Us manual boost controller Manual Boost Controller | Twos R Us
Now the tuning. Is it possible to flash or chip my stock ecu? At this moment I don't want to buy an aftermarket standalone unit.

Please recommend shops where I can send in my ecu to have it tuned.
Thanks everyone!
 

·
Registered
Joined
·
8,036 Posts
Sorry, can’t flash or reprogrammed stock ECU. There use to be piggy back type devices for altering VE tables but these have been superceeded by aftermarket EMS.

As the OEM ECU’s are now quite ancient and prone to failure (Google cap fails) replacing with a stand-alone is the best viable option. There are now several reasonably priced PNP units ( Link, MSPNP, etc) to choose from that offer all the advantages of higher end models without having to spend a kings ransom to tune. You can make as complex or simple to suit your individual needs.

Jimb
 

·
Premium Member
'91 MR2 Turbo, '20 BRZ
Joined
·
491 Posts
I am planning to purchase a direct bolt on turbo upgrade, which from my understanding only requires bigger fuel injectors, and a ecu retune.
I wouldn't think a CT26 in of itself requires bigger fuel injectors. So long as you keep the boost levels reasonable 14-16PSI, upgrading to the 550 injectors is not necessary. Now to push further, yeah some fuel system upgrades are recommended.

In addition to the dead on comments Ben made, you might also find a G-Force ECU (piggy-back modified from a stock ECU) that is already programmed/tuned for the 550cc injectors. Personally I'd go with LINK or similar nowadays so you can truly fine-tune.
 

·
Registered
1992 Toyota MR2 Turbo
Joined
·
24 Posts
Discussion Starter · #4 ·
I wouldn't think a CT26 in of itself requires bigger fuel injectors. So long as you keep the boost levels reasonable 14-16PSI, upgrading to the 550 injectors is not necessary. Now to push further, yeah some fuel system upgrades are recommended.

In addition to the dead on comments Ben made, you might also find a G-Force ECU (piggy-back modified from a stock ECU) that is already programmed/tuned for the 550cc injectors. Personally I'd go with LINK or similar nowadays so you can truly fine-tune.
Ok so if I put on the upgraded CT26 turbo, and keep the boost reasonable as you said (less than 16psi) would I still need a tune?
I imagine I would at least need a boost controller to get 16psi, no? and a Fuel Cut Defender?
 

·
Registered
Joined
·
8,036 Posts
We are guessing on what an upgraded ct26 turbo actually is. Ad states it has a larger compressor wheel but no mention of hot side or other requirements to drive compressor. Disclaimer states you will get same as OEM performance. Its most likely a Chinese knock-off which will perform worse than OEM due to no ceramic turbine. You may or may not need larger injectors, fuel control, better exhaust, decent IC, etc plus the boost control and FCD.

Most people start small and install mods as they reach practical limits. You have jumped into a new turbo without much explanation to your end goal. If indeed this turbo can produce 300+hp then you will need more fuel, mods as listed above or it may be laggy enough that 300hp is a pipe dream. Hard to say

jimb
 

·
Premium Member
'91 MR2 Turbo, '20 BRZ
Joined
·
491 Posts
I imagine I would at least need a boost controller to get 16psi, no? and a Fuel Cut Defender?
Depending on the stock wastegate PSI setting, and the PSI you desire to run, you may need some form of boost controller. Without such, it will simply run whatever the wastegate is set to open at. If you go beyond ECU stock levels you will want a form of FCD to increase the cut-off point, while still keeping a level of over-boost/runaway protection.

To add on top of benckj comments, and to further augment my own... It's all about what performance level you have planned for. The turbo, in off itself doesn't necessarily drive the increased fuel need...it's levels of boost you plan to run it and where in the heat map the turbo is for those levels. The stock fuel system can handle 15-16psi fairly well in my experience. So IF and ONLY if I wanted to start pushing it harder than that, would I start looking into a more heat efficient turbo, fuel upgrades (pump/injectors/custom ECU).
 
  • Like
Reactions: SW187

·
Registered
1992 Toyota MR2 Turbo
Joined
·
24 Posts
Discussion Starter · #8 · (Edited)
Depending on the stock wastegate PSI setting, and the PSI you desire to run, you may need some form of boost controller. Without such, it will simply run whatever the wastegate is set to open at. If you go beyond ECU stock levels you will want a form of FCD to increase the cut-off point, while still keeping a level of over-boost/runaway protection.

To add on top of benckj comments, and to further augment my own... It's all about what performance level you have planned for. The turbo, in off itself doesn't necessarily drive the increased fuel need...it's levels of boost you plan to run it and where in the heat map the turbo is for those levels. The stock fuel system can handle 15-16psi fairly well in my experience. So IF and ONLY if I wanted to start pushing it harder than that, would I start looking into a more heat efficient turbo, fuel upgrades (pump/injectors/custom ECU).
I would be happy with 250-275hp to the wheels for a daily driver.
The reason for upgraded turbo is I figured this would be the cheapest way to obtain that power. I won't need a new downpipe or exhaust manifold, everything bolts up. I am told I also would not need to upgrade injectors, though in the future I can go with bigger injectors and at that point I would look for a better ecu, and try to hit 300hp.

Is this boost controller any good? SCG-1 Solenoid Boost Controller Gauge

If there is better way I can obtain 250-275hp, and save money, I am open to suggestions..
As mentioned, it is a daily driver, not a track car.
 

·
Registered
1992 Toyota MR2 Turbo
Joined
·
24 Posts
Discussion Starter · #9 ·
Yes and yes.
How does the ecu know to add more fuel or how much fuel to add, after the FCD is installed? With the boost turned up (via boost controller) Would it get lean? at 15-16psi, am I within safe limits (of the factory ecu), and what power can I reasonably expect? 250hp? more?
 

·
Premium Member
'91 MR2 Turbo, '20 BRZ
Joined
·
491 Posts
I haven't used Innovate's boost controllers, so I have no opinion myself. I've only had their wideband O2 kits and those worked well.

How does the ecu know to add more fuel or how much fuel to add, after the FCD is installed? With the boost turned up (via boost controller) Would it get lean? at 15-16psi, am I within safe limits (of the factory ecu), and what power can I reasonably expect? 250hp? more?
Now you are getting into Engine Management theory. I'm not an ECU tuner, so someone else may be best to explain. Simply put, the ECU takes all forms of inputs, one of which is the intake (boost) pressure, to determine how much fuel to deliver. (AFM, Inlet Temp, Coolant Temp, RPM, Intake pressure, etc...) Most FCDs alter the boost input, by either limiting it to just under the "trip" threshold voltage, and based on the setting will rise it above such trip level when high PSI hit OR by simply lowering the output by a factor. Either way its manipulating the voltage the ECU sees.

Now IIRC, the ECU runs fuel extremely rich at high boost levels. So even though it's "seeing" lower or capped boost, the fuel is still sufficient in the 15-16PSI realm. My recommendation is even at these boost levels, you SHOULD invest in a wideband to monitor such. This will most certainly tell you if you should be investing into better fuel system (at least reprogrammed ECU, bigger injectors, boost cut raised, and maybe even Gen 3 2.5bar sensor.)

You mention a goal of 275hp to the wheels. With 15-20% transmission losses that's ~ 345HP @ crank. For each additional PSI of boost ~ 10HP adder...thus ~40HP increase @16PSI from stock. With intake, downpipe, performance exhaust, I would gather such gets you around 230-240RWHP. That's about what I'm putting down, which is plenty enough for my needs personally :) I am working on adding water/meth injection to make the intake charge even cooler (heat is the enemy!!)
 

·
Registered
1992 Toyota MR2 Turbo
Joined
·
24 Posts
Discussion Starter · #11 · (Edited)
I haven't used Innovate's boost controllers, so I have no opinion myself. I've only had their wideband O2 kits and those worked well.



Now you are getting into Engine Management theory. I'm not an ECU tuner, so someone else may be best to explain. Simply put, the ECU takes all forms of inputs, one of which is the intake (boost) pressure, to determine how much fuel to deliver. (AFM, Inlet Temp, Coolant Temp, RPM, Intake pressure, etc...) Most FCDs alter the boost input, by either limiting it to just under the "trip" threshold voltage, and based on the setting will rise it above such trip level when high PSI hit OR by simply lowering the output by a factor. Either way its manipulating the voltage the ECU sees.

Now IIRC, the ECU runs fuel extremely rich at high boost levels. So even though it's "seeing" lower or capped boost, the fuel is still sufficient in the 15-16PSI realm. My recommendation is even at these boost levels, you SHOULD invest in a wideband to monitor such. This will most certainly tell you if you should be investing into better fuel system (at least reprogrammed ECU, bigger injectors, boost cut raised, and maybe even Gen 3 2.5bar sensor.)

You mention a goal of 275hp to the wheels. With 15-20% transmission losses that's ~ 345HP @ crank. For each additional PSI of boost ~ 10HP adder...thus ~40HP increase @16PSI from stock. With intake, downpipe, performance exhaust, I would gather such gets you around 230-240RWHP. That's about what I'm putting down, which is plenty enough for my needs personally :) I am working on adding water/meth injection to make the intake charge even cooler (heat is the enemy!!)
Hey hey, was on vacation, just got back, and yesterday was the 1st day I took my car out for a proper drive, cleaned it up, and here are some photos.
Unfortunately today (2nd day) i somehow managed to get a flat tire. No punctures, but some air hissing out between the wheel and tire (not sure what happened)
The MBC and HKS FCD are already in hand, and the downpipe is on the way.. Going to slap that on, and see what difference it makes (will dyno it too)

The aftermarket boost gauge in the car indicates ~8 psi, I haven't seen more than that. Is that normal on a stock set up?

Wheel Car Tire Land vehicle Plant
Wheel Tire Sky Vehicle Car
Wheel Automotive parking light Car Tire Vehicle
Wheel Tire Car Vehicle Land vehicle
 

·
Registered
Joined
·
4,720 Posts
I’m currently running 550, upgraded ct26, and safc neo. You cannot safely remove more than ~10% of fuel with an safc or it dangerously increases ignition timing. (The first mr2 I purchased blew a head gasket as a result of removing more than 10% w/ safc. That was almost 20 years ago). my current setup has 10 a/f on full throttle. I’ve flirted w/ putting the factory 440’s back in and having my stock fuel pressure regulator modified by ats to increase the stock fuel pressure thusly increasing the stock injector flow by 9%. I SHOULD be able to get a/f to a more reasonable high 11 or low 12 while removing no more than 10% of fuel with safc.

or I could get a link or megsquirt.

as benckj has already said, the stock ecu’s are running on borrowed time.
 

·
Registered
1992 Toyota MR2 Turbo
Joined
·
24 Posts
Discussion Starter · #13 ·
I’m currently running 550, upgraded ct26, and safc neo. You cannot safely remove more than ~10% of fuel with an safc or it dangerously increases ignition timing. (The first mr2 I purchased blew a head gasket as a result of removing more than 10% w/ safc. That was almost 20 years ago). my current setup has 10 a/f on full throttle. I’ve flirted w/ putting the factory 440’s back in and having my stock fuel pressure regulator modified by ats to increase the stock fuel pressure thusly increasing the stock injector flow by 9%. I SHOULD be able to get a/f to a more reasonable high 11 or low 12 while removing no more than 10% of fuel with safc.

or I could get a link or megsquirt.

as benckj has already said, the stock ecu’s are running on borrowed time.
With that set up, do you know how much power you are making?
 

·
Premium Member
'91 MR2 Turbo, '20 BRZ
Joined
·
491 Posts
The aftermarket boost gauge in the car indicates ~8 psi, I haven't seen more than that. Is that normal on a stock set up?
Typically stock is around 7PSI until it A)Warms up and B)is in 3rd gear or higher. After that ~12PSI is normal (assuming adequate RPM). Here is the BGB spec:
Font Rectangle Number Circle Electric blue
 

·
Registered
1992 Toyota MR2 Turbo
Joined
·
24 Posts
Discussion Starter · #17 ·
Today I had the Two's R Us MBC installed. Took a few adjustments to dial in the boost, 1st try it hit 15psi + and of course the fuel cut out and engine light came on, so we adjusted again, and it was doing 11psi in 2nd and in 3rd it did a little more (didn't exactly see), and cut out again. So 3rd time adjustment, it did 9psi in 2nd, and the same in 3rd, and I decided to leave it at that level until monday when I install the HKS FCD. Weird though, on my way home, while on the highway, in 4th gear I let it rip and it cut out once again, could this have been a boost spike that caused the fuel to cut out?
Are MBC's not stable in the amount of boost they regulate?
 

·
Super Moderator
Joined
·
3,630 Posts
A lot of boost controllers, manual or electronic will not hold a stable boost level depending on many factors. These are Open Loop Boost Controllers.
Engine load, outside air temps and the settings on the controller.

A manual controller is a valve set by bleeding a set amount of air off the wastegate to allow it to increase or decrease boost. Set it one way and change how the car is driven and how cold/hot the air is and it will change the amount of boost you get. The lower gears have less load on the engine so when you are in a higher gear the boost levels can increase of which you are seeing.

Even a lot electronic units set a duty cycle(the amount of time the bleed valve is open vs closed). So bleed the same amount of air off to try achieve the boost level you set it to during testing. If you set it to say 12psi on a warm day then drove it on a cold night, you will get more boost than when you set it. Some have a boost number setting and some use duty cycle number/percentage only.

When you go into using a fancy ECU and use Closed Loop Boost Control that is when you can get the best control within reason. Other factors can mess with boost levels too but I won't go into that. It's much more stable once tuned properly as it can see what boost level it is at and make adjustments to increase or decrease to meet the target number you set.
 

·
Registered
88 Aw11
Joined
·
4 Posts
Honestly your best bet to get the most out of the larger injectors and turbo upgrade would just to get a standalone instead of using a piggyback then tune it or get it tuned, then you can dial in your AFRs, boost, fueling, ignition and with knock control to keep things in check. Megasquirt has a Toyota MR2/Celica All-trac 3SGTE 1990-1992 MSPNP Gen2 Plug and Play ECU. How are you monitoring your afr? Are you taking readings from a factory narrow band or do you have a wideband controller?
 

·
Registered
1992 Toyota MR2 Turbo
Joined
·
24 Posts
Discussion Starter · #20 ·
Honestly your best bet to get the most out of the larger injectors and turbo upgrade would just to get a standalone instead of using a piggyback then tune it or get it tuned, then you can dial in your AFRs, boost, fueling, ignition and with knock control to keep things in check. Megasquirt has a Toyota MR2/Celica All-trac 3SGTE 1990-1992 MSPNP Gen2 Plug and Play ECU. How are you monitoring your afr? Are you taking readings from a factory narrow band or do you have a wideband controller?
Thank you for the reply to the Megasquirt ECU, I will definitely look into that, until now I was thinking of Link G4X because i was told it is plug and play also..
No, I do not currently have a way to monitor AFR. I am looking into the boostcontroller/afr with wideband i mentioned above, that is probably the next thing i plan to buy now that I have the new turbo and downpipe installed. I ended up taking off the MBC, but with the new turbo and downpipe on, it manages to do way more boost than before, problem is it is over boosting and cutting out.. I have the HKS fuel cut defender but im not sure if i have it set up wrong, or if i should leave it where it is, right now it cuts out in 3rd/4th around 16psi. I was told theres a setting to eliminate boost cut altogether, but im not sure if i should do that considering that car's not tuned at all..
 
1 - 20 of 28 Posts
Top