UKtheGREAT
Member
- :
- 2003.5 MSP
Sure. I would imagine the ECU has detected a WOT condition, and has reverted to that portion of it's "script" as a default, more or less.
A cheap "standalone" solution?
- Thread starter CustomMSP
- Start date
UKtheGREAT
Member
- :
- 2003.5 MSP
Alright- just to clear this little bit up right quick. 
Our cars do not have a dedicated MAP sensor (Manifold Absolute Pressure) or a derivative of that (Barometric sensor; horrible), however they are all equipped with whats called an EGR Boost Sensor, which monitors Manifold Pressure for the EGR system. Additionally, this information is relayed to the ECU via Pins 72, 68, 56 and 46 (OE Mazda part # KL47-18-211 or variant). The wires coming out of the EGR Boost sensor are Grey / Red striped, and White / Red striped. Hope this helps!
Our cars do not have a dedicated MAP sensor (Manifold Absolute Pressure) or a derivative of that (Barometric sensor; horrible), however they are all equipped with whats called an EGR Boost Sensor, which monitors Manifold Pressure for the EGR system. Additionally, this information is relayed to the ECU via Pins 72, 68, 56 and 46 (OE Mazda part # KL47-18-211 or variant). The wires coming out of the EGR Boost sensor are Grey / Red striped, and White / Red striped. Hope this helps!Ricktalife
Member
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- 2012 Subaru WRX
In short, our ECU acts like a narrowband when it comes to fuel delivery. It reads either lean, stoich or rich. If you are crusing along it will maintain the stoich 14.X AFR, but once the ECU reads any amount of boost it will dump a set amount of fuel because it does not know how to measure exactly how much fuel needs to be added.
dacquesta1
Member
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- 2000 Mazda Protege ES
thats why im just biting the bullet and buying a haltech platinum 1000 with my tax return
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- 03.5 YLW MSP
yep once you go into open loop. Once you go into open loop it will go stupid rich for a good while even after cursing for a mile or two on the highway if it goes anywhere near 1psi. However if you don’t get it to go into open loop in the lower gears your pretty much screwed AFR wise tell you get around 4k rpms or at least that’s how my car acts. You can run 10psi at 3k rpm with 14-15afr. To bad we can't just trick the cars to go into open loop 100% of the time. It would make tuning these cars a breeze and making them more consistent.
SeR_Cyclops
Member
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- Mazdaspeed Protege
I just say leave it to mazda to f$%k it all up.
UKtheGREAT
Member
- :
- 2003.5 MSP
Anyone have experience with the AEM EMS4? Looks pretty legit, and starts at what, ~760? For a full standalone? Why don't I see us jumping all over this? Has every option imaginable, a true standalone; and its by AEM? lol I'm looking in to it. From the looks of it, their software is pretty top notch. Believe the PN is 30-1910.
hornsfan10609
Certified Mazda Tech
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- 2003.5 Mazdaspeed Protege x2
Like an O2 voltage clamp? That's exactly what the SSAFC does.
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- 03.5 YLW MSP
Not sure to be honest with you. I haven't read up on 02 voltage clamps and how they work. On the SSAFC does the 02 clamp fool the ecu into going into open loop on any sign of postive presure?
hornsfan10609
Certified Mazda Tech
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- 2003.5 Mazdaspeed Protege x2
You can set the AFC to kick on at whatever pressure you want, mine is at -1psi.
racerx43269
Member
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- 2002 mazda protege 5
For the record.. I'm trying to crack the Ecu with a tactrix cable
YELLOWMAZDAPR5
Member
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- 2002 MAZDA, PROTEGE 5 Turbo
sub.....
Looking forward to your progress.
Even if you crack it, the stock PCM doesn't have some of the proper sensors needed to manage a turbocharged car. For instance, the IAT reads nothing even close to what the manifold sees. There is no MAP. There is no wideband. While you can tune a turbocharged car without these things and relocating the MAF does help, I don't think it is ideal.
Hopefully, you can at least get the PCM to get out closed loop anytime you mash the throttle and not just above a certain rpm, but there is no way to know unless you try. I wish you the best of luck. There will certainly be a lot of happy MSP owners if you are successful.
A O2 voltage clamp is simple--taps into your signal wire on your primary O2 sensor, uses an adjustable pressure switch you tee off of any boost/vacuum source....you can dial it in to switch right before boost comes in, makes the computer think it needs full enrichment.
The voltage clamp will cause the PCM to start adding fuel with the short term fuel trims. The PCM only sees rich or lean, there is no magnitude. It adds fuel in 1% duty cycle increments to all four injectors, exactly one second between increments. After one minute at a given rpm and MAF value, the short term fuel trim will be added to the long term trim value, and the short term trim will reset to 0. If the long term trim goes to 25% and the O2 still reads lean, you will get a code for a bad O2 sensor.
Under normal driving, you don't stay at one rpm and one MAF value, you drive in a range of both, so it will take a while for the trims to be maxed out and longer still for them to converted to long term.
The real problem with a clamp though is the long term fuel trim is carried into open loop. I was never able to determine precisely how it is calculated, as in whether it is an average of the previous cells at a given rpm, or previous cells at a given MAF value, or just the last value it read from the table. I am pretty sure it is just the last value from the table, but without seeing the actual table, it's hard to say for sure.
What I do know is that with my O2 clamped only at 4psi and above, it only took about 30 minutes of driving before my long term fuel trims in open loop were 25%, and my injector duty cycle hit 100% and the accompanying brick wall. If the PCM calculates a 100% duty cycle or more from the tables, it will shut the ignition down, but is still referred to as "fuel cut" since cars used to have distributors and could not stop spark.
Since the trims add 25%, that only gives you 75% to work with, which most stock cars will hit as long as the weather is nice. You'll also be running stupid rich unless you have a biggyback to back off the MAF signal.
So in short, an O2 clamp will not work in the MSP. Anyone that has it working has maxed out their trims and is using a piggyback to reduce the MAF signal below a 75% duty cycle to avoid cutting the ignition. Bigger injectors would also help since you could run a very low MAF voltage and not worry about hitting 100% duty cycle even with more boost. All the piggybacks have their own O2 manipulation though so there isn't really a point to making your own.
Of course, there is always the option of unplugging your PCM every time you get out of the car.
Under normal driving, you don't stay at one rpm and one MAF value, you drive in a range of both, so it will take a while for the trims to be maxed out and longer still for them to converted to long term.
The real problem with a clamp though is the long term fuel trim is carried into open loop. I was never able to determine precisely how it is calculated, as in whether it is an average of the previous cells at a given rpm, or previous cells at a given MAF value, or just the last value it read from the table. I am pretty sure it is just the last value from the table, but without seeing the actual table, it's hard to say for sure.
What I do know is that with my O2 clamped only at 4psi and above, it only took about 30 minutes of driving before my long term fuel trims in open loop were 25%, and my injector duty cycle hit 100% and the accompanying brick wall. If the PCM calculates a 100% duty cycle or more from the tables, it will shut the ignition down, but is still referred to as "fuel cut" since cars used to have distributors and could not stop spark.
Since the trims add 25%, that only gives you 75% to work with, which most stock cars will hit as long as the weather is nice. You'll also be running stupid rich unless you have a biggyback to back off the MAF signal.
So in short, an O2 clamp will not work in the MSP. Anyone that has it working has maxed out their trims and is using a piggyback to reduce the MAF signal below a 75% duty cycle to avoid cutting the ignition. Bigger injectors would also help since you could run a very low MAF voltage and not worry about hitting 100% duty cycle even with more boost. All the piggybacks have their own O2 manipulation though so there isn't really a point to making your own.
Of course, there is always the option of unplugging your PCM every time you get out of the car.
A friend of mine who is a Nissan tuner has suggested to me that we use a SR20-DET computer, since they can be tuned easily, and wire a jumper harness in-between our harness and the SR20 ecm matching the pinouts with the correct functions and such....not sure what kind of crank trigger they use i guess they would have to be the 1 missing tooth design like ours...
But could this work?
But could this work?
dacquesta1
Member
- :
- 2000 Mazda Protege ES
Idk but why not just grab an mpi? They are cheap and work well. That or an ssafc
The chance that all the sensors are exactly the same is incredibly low. Cam, crank, IAT, CLT, TPS, MAF, speed, EGR, etc would all have to be the same or somehow translated. You have the same problem with all the outputs as well. Gauges, fans, alternator, a/c, and ignition could all be different.
It would be an incredible amount of work with a data logging oscilloscope, making your own circuits and harness, and then tuning with the transplanted PCM.
If you have the skills and time to to do that, you might as well just build your own megasquirt.
