Engine surging

There are a number of things that can cause this so we need to start with this guide on this issue.

https://www.2carpros.com/articles/engine-surges

Below is a guide on testing for a vacuum leak which is the most likely cause of this.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Once we run through these guides we will have a better idea what the possible cause is. Let us know if you have questions or what you find and we can go from there. Thanks

Can't find vacuum leak. could it be the MAP sensor causing the surge problem? and where is the MAP sensor located on the hiace 2007 , engine 2TR - FE model TRH 201 /223? I can't locate it without workshop manual.

Unfortunately, we don't have a manual on this specific engine as it is Mexico only and we don't have the detail.

If you have no external vacuum leak, I would hook a vacuum gauge to it and make sure the intake valves are not leaking either.

If you are not able to locate the MAP then it may not have one. This engine may use a mass air flow sensor and then it calculates the MAP based on throttle input and amount of air coming in.