MAP sensor modification

Ted · March 12, 2017

Dear All,

I failed my emission test even after injector cleaning. Then i went to an ECU guy and what he did first was replacing O2 sensor. After than CO emission was 4.8 which is not acceptable. Then in order to improve the CO emission further, he modified MAP sensor by adding resistors in between map sensor and ECU. Then CO emission was 0.029%.

However when i drive a steep hill road eg. Galagedara steep, i cannot pick up the car even after i peddle the engine to very high rpms ( 4000 - 4500).

What i want to know is by modifying MAP in addition to improve CO emission and make the car fuel economy, does the acceleration capacity of the car reduce??

If so could you please let me know of a skilled genuine guy who does not these kind of modification but does as per maintenance instructions recommended by toyota?

Thanks..

Davy · March 12, 2017

What your "ECU guy" has done is fool the ECU (and you by the way) into thinking that the pressure in the manifold is less than it actually is. As a result the engine doesn't adjust fuel pressure and timing to produce the necessary power depending on the load. So yes, your car isn't able to handle load due to the "modification".

I suggest you restore it to how it was originally and find a good mechanic who can fix the issue properly. A simple diagnosis will tell you why the engine is running rich. I doubt even the O2 sensor this guy used is a working one. What's important is to address the actual issue instead of focusing on the symptoms.

Edited March 12, 2017 by Davy

Ted · March 13, 2017

On 3/12/2017 at 1:15 PM, Davy said:

What your "ECU guy" has done is fool the ECU (and you by the way) into thinking that the pressure in the manifold is less than it actually is. As a result the engine doesn't adjust fuel pressure and timing to produce the necessary power depending on the load. So yes, your car isn't able to handle load due to the "modification".

I suggest you restore it to how it was originally and find a good mechanic who can fix the issue properly. A simple diagnosis will tell you why the engine is running rich. I doubt even the O2 sensor this guy used is a working one. What's important is to address the actual issue instead of focusing on the symptoms.

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Hi Davy,

Thnx for the advise.. anyone who knows of such a good, honest and skilled mechanic????