ECU Identification

Hello, I own a 2003.5 MSP and I may need to get a new stock ecu for it, I was wondering if anyone knows the numbers I should be looking for to ensure I’m getting the right part. I have seen parts with code MSP0-18881, along with MSP0-18881-A, and even one with FSAE-18881-B. I’m assuming the one with MSP in the name is the correct one, but the version with the -A and without concern me. Any help with identifying the correct one for my car is appreciated.
 
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2000 Protege ES
MJJ8 and MJJ9 are the turbo specific ECUs. What makes you suspect the stock ECU is going bad? They typically have a pretty poor tune from the factory that runs the car very rich. It helps manually resetting the car by disconnecting power to the ECU but you'll eventually run into the same problem. SSAFC are the cheaper options to help the problem but again the ecu will learn over that as well.
 
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MJJ8 and MJJ9 are the turbo specific ECUs. What makes you suspect the stock ECU is going bad? They typically have a pretty poor tune from the factory that runs the car very rich. It helps manually resetting the car by disconnecting power to the ECU but you'll eventually run into the same problem. SSAFC are the cheaper options to help the problem but again the ecu will learn over that as well.
Thank you for your help, I suspect the ECU is going bad as I have just recently bought the car, and when trying to take it above 3k rpm I get fuel cut or lose all boost. Looking at the ECU, it was obviously tampered with by the previous owner. Took it to a mechanic I know and he also said it was most likely a problem with the ECU. They seem to be relatively cheap so I thought I would try to replace it.
 
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jeffmsp

Member
Contributor
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2003 MazdaSpeed Protege
Sounds like your ECU is doing exactly what it is supposed to do if you are over-boosting.

This is a very common issue and the ECU is most likely trying to stop you from blowing up the motor. There is very little headroom for increasing the boost on the stock ECU/MAF/injectors.

Step 1. IMO Stop talking to your mechanic as it sounds like he is clueless when it comes to this car. You cannot afford to have clueless people working on the car it can be blown up very easily and in these cases they will make some BS excuse that it was something else and not their problem.

Step 2. Get a boost gauge on the car asap and confirm that you are not boosting over 6-8 psi. If you are then that is almost certainly the problem. This is typically caused by a leaking, or broken or sticky wastewater actuator. Very common issue on almost all turbo cars. Has your mechanical looked to confirm that the vacuum line running to the wastegate is even attached and does not have any cracks or leaks in the line? This is the most important vacuum line on the whole turbo FSDET motor.

The stock airflow meter can only meter so much before it maxes out. At the point that it is maxed (due to too much airflow from too much boost) it is unable to tell the ECU to add more fuel (and there really isn't much head room with the stock injectors anyways) and so it behaves EXACTLY as you described. It is not designed to read much more than stock airflow and if you have an aftermarket intake on the car it can even hit fuel cut at relatively low boost levels.

This is MSP turbo tuning 101 stuff. Again, find a different mechanic and/or start reading up yourself. Do not just "keep your foot in it" or you will blow up the engine even the fuel cut can only do so much to prevent utter stupidity
 
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Sounds like your ECU is doing exactly what it is supposed to do if you are over-boosting.

This is a very common issue and the ECU is most likely trying to stop you from blowing up the motor. There is very little headroom for increasing the boost on the stock ECU/MAF/injectors.

Step 1. IMO Stop talking to your mechanic as it sounds like he is clueless when it comes to this car. You cannot afford to have clueless people working on the car it can be blown up very easily and in these cases they will make some BS excuse that it was something else and not their problem.

Step 2. Get a boost gauge on the car asap and confirm that you are not boosting over 6-8 psi. If you are then that is almost certainly the problem. This is typically caused by a leaking, or broken or sticky wastewater actuator. Very common issue on almost all turbo cars. Has your mechanical looked to confirm that the vacuum line running to the wastegate is even attached and does not have any cracks or leaks in the line? This is the most important vacuum line on the whole turbo FSDET motor.

The stock airflow meter can only meter so much before it maxes out. At the point that it is maxed (due to too much airflow from too much boost) it is unable to tell the ECU to add more fuel (and there really isn't much head room with the stock injectors anyways) and so it behaves EXACTLY as you described. It is not designed to read much more than stock airflow and if you have an aftermarket intake on the car it can even hit fuel cut at relatively low boost levels.

This is MSP turbo tuning 101 stuff. Again, find a different mechanic and/or start reading up yourself. Do not just "keep your foot in it" or you will blow up the engine even the fuel cut can only do so much to prevent utter stupidity
I've already ordered a new ECU anyway so I will replace that first and see if it does anything. If it doesn't I will return it and try this. Thanks for the info.
 
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