New supra owner (with a few questions)
 

Good day Supra owners, i became a proud owner a few weeks ago. Since I do not know much about this car I will like to ask the experts for advice. Here is a link to the supra I purchased. It's a 1990 red,auto, turbo, targa top.
http://g35nyc.com/forums/showthread.php?t=36538

Here is a list of concerns.
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.
2. car idle is bad. sometimes is steady and then it goes up and down.
3. car tends to stall specially when i'm at a light and when i make slow turns. (kind of scary)
4.The throttle body and TPS are of a non-supra engine. I was wondering if thats and issue.
5. Manual showed me to do a check engine scan. Codes 21,31,41 came out. TPS, MAF.
6. Should I replace the TPS even if the throttle and tps in the car is of a non-tubo supra.

Any suggetions will be appreciated. I will like to have the car up and running before May. Thanks.

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.

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

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

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.

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.

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!

I apologized for posting in the wrong threat. I appreciate the advice, right now the car is being looked up by a mechanic who has worked on supras before. I did not want to put my hands on a car I have never worked on. On one of the questions i forgot to mention that the Throttle and TPS are part of a non-turbo supra engine. The car has the stock turbo with an HKS bov. I was wondering if that's an issue specially when it seems that whoever worked on it did not know what he was doing. Thanks again.

I've already answered all of you questions as best I can without additional info.

If the intake is from a 7M-GE then it is possible the engine is a non-turbo engine which has has one added... not something I recommend. A couple easy ways to spot a conversion are:
The timing belt cover may still say "7M-GE".
The oil return from the turbo runs to a port added to the oil pan and not to the GTE return location in the block.
The intake pipe after the throttle body is a "Y".
The VIN number contains JT2MA70 (as opposed to JT2MA71 which is a VIN for a turbo model).... this would only indicate if the engine has been swapped OR converted to a turbo.

I bought a manual and I am doing a search on what exactly was done to this car. I will post pictures of the engine. I looked at the vin # and the car does have a turbo engine, intake is NOT a Y shaped. but the throttle and tps is of a non-turbo supra.

post a picture of the engine bay bro. your car is also Canadian. just an fyi

How'd you determine it's a N/A throttle body? The 7M-GE's throttle body from the MKIII Supra doesn't fit and I'm certain the throttle body from the 7M-GE from the Cressida doesn't fit either. The TPS would be fine though as long as tabs which mate with the throttle body line up... there was a mid year change where those were rotated 90? and that's not compatible, but that's not a GE or GTE thing.

Post the part numbers off of the throttle body and off of the TPS please. BTW, the MKIII 7M-GE's TB is LONG.

Thank you gents. Here are a couple of pictures of the car. As I mention I'm not a Supra expert so want to know if the engine and parts are stock..specially the thrttle body and Tps. The car according to vin is a 1990 supra turbo.

so did you repair the vacuum lines and redo your diagnostic codes?

Looks like the stock throttle body to me.... Who told you otherwise? Post the part numbers already... sheesh.