Wiring Help with 94 1UZ into 82 Supra

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New Member
I have swapped a 1UZFE into my 82 Supra. The engine, harness and ECU are from a 94 without traction control.

I am not running any emissions on the car, all of the holes for emissions on the intake manifold have been welded up.

I fired up the engine and it took it a while to idle by itself but the ECU finally learned and idled. However, after a little bit it gave me some check engine light codes. The codes were 24, 31, 48 and 71. It also wouldn't let me rev past 4K RPM. When I drove it the same thing. It wouldn't go past 4K RPM and it would stumble at wide open throttle. I know that 48 just needs a resistor for the EGR to fix. 71 I haven't figured out how to fix yet. For 24 and 31 I Figured it was MAF so I went through the steps checking the resistance like the repair manual said to. All the wiring seemed right so I got a known good MAF and put it on. The CEL didn't have the 24 or 31 codes right away but I still couldn't rev past 4K RPM. After about 10 minutes codes 24 and 31 came back. Making me believe that something in the wiring maybe fried the MAF. Someone suggested adding a known good ground from the engine to the chassis. So I added two. When I fired it up I still can't get past 4K RPM and if I hold the throttle at 2K RPM it surges (see video below). Above 2K holding the throttle it seems to run fine. I feel like it is in limp mode but I have no clue how to fix this.

Here is where my grounds are:
- oil dipstick tube holder on the left head to the same bolt on chassis where battery ground is
- bottom right of right hand side of block to lower part of the right strut tower
- engine harness to spot on the right side head.
-the same spot on right side head to the firewall.
- back of trans to the outer part of the trans cross member.
- bell housing to the subframe.

Please let me know what I should look at next to find the problem.

Here are a couple of videos of the tach with the engine running:
Surging at 2K RPM

Above 2K RPM


Well-Known Member
Staff member
Russia, Moscow
Inspect ECU for leaky capacitors
Run diagnostics to see real time data (most importantly, MAF readings and fuel trims)
One guy in Canada makes bluetooth device and android app for scanning these rare old engines

Make sure you use exactly the same igniters that are suitable for your ecu part number (consult toyodiy.com or other catalogue)