New supra owner (with a few questions)

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You posted to a section for issues pertaining to the site, not the cars... so it wasn't showing up. I've moved this the MKIII section.

Originally Posted by manrique112

1. engine looks like it was rebuild by someone inexperience and neglected to proper place the vacuum lines. There were a couple i found laying around.

Vacuum diagrams are posted here frequently, a search will certainly locate them for you.

Originally Posted by manrique112

2. car idle is bad. sometimes is steady and then it goes up and down.

Fix the vacuum lines first and check for diagnostic codes (details are posted in the FAQ section).

Originally Posted by manrique112

3. car tends to stall specially when i'm at a light and when i make slow turns. (kind of scary)

The vacuum lines, BOV, a bad air flow meter (KVAFM aka AFM for short), TPS and ISCV (Idle Speed Control Valve) are all suspect... Again, begin with the vacuum lines and checking for diagnostic error codes.

Originally Posted by manrique112

4.The throttle body and TPS are of a non-supra engine. I was wondering if thats and issue.

What are they out of? If the values and measurements are far from stock and you're running the stock ECU with no additional tuning devices then yes, this could be PART of the issue. It wouldn't contribute to the code 31 I now see you've read from the ECU.

The VTA signal must be around .5v at 0 throttle and approx 3.48 at WOT. Lower than .48v and higher than 3.48 may cause the ECU to decide there's a problem.

The must also be an IDL switch present (it's built into the stock TPS), it if's not present one needs to be supplied or other modifications to the intake must be made.

Originally Posted by manrique112

5. Manual showed me to do a check engine scan. Codes 21,31,41 came out. TPS, MAF.

You don't have a MAF..... You have a KVAFM (Karmann Vortex Air Flow Meter); They're VERY different and the mistake can cost a pretty penny... for example MAF cleaner will usually slaughter the KVAFM (which is an optical sensor).

The errors are covered in the manual:

http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx

21 - The O2 sensor is damaged or absent... fix it.
31 - AFM signal is out of bounds, wiring is shorted, sensor is bad or the ECU is bad... Figure out which and... fix it.
41 - TPS signal.... no TPS signal (or no valid signal) to the ECU. I covered the valid range for this signal above.

I would start with the TPS; just because it should be an easy fix. Then the AFM which is the biggest priority but may take more time. I would be least concerned about the O2 signal error.

The vacuum lines need to be checked too, I'd probably verify their routing before anything else to eliminate doubt with other repairs.

Good luck!