1UZ into Mkiv Supra

[straightsix]

Nearly sorted with this project but after a test drive something doesn't seem right.

I'm running the Soarer auto box and although the car seems to change up as it should and it kicks down OK, it seems to be hitting a rev limit before getting to the top of it's speed range. I got up to about 65mph and it seemed to be bouncing off the rev limiter.

It's hard to tell exactly what engine rpm this happens as obviously the Supra's tacho is incorrect due to it sensing for a six pot (not sure if this could actually be the cause as I would have thought this was only down to instrumentation/driver information?)

Apart from the above problem, acceleration seems OK. I was wondering if the gearbox wiring needs lookingat as the Soarer plug is different to the Supra plug.

All other engine functions seem OK with no error codes showing up.

I've been scratching my head for ages - I'm not a complete beginner with electrics but this has me stumped.

Anyone have any ideas?

 

[cribbj]

You're being too modest about the electrics; if you've gotten this combo to run, you're well past being a beginner

Tell us more about your setup in general, your ECU, etc., and that'll help us diagnose some possible trouble areas.

 

[rms]

The 1990 Celsior (LS400) standard cruise control has a speed limit of around 105 KPH, which is about 65 MPH. It hits the rev limiter at that speed regardless of what gear you are in.

Somewhere on this site, or the 'net, there are details to disable the cruise limit.

If it is a Japanese import engine, computer and loom, it is more than likely the problem.

Erol

 

[straightsix]

I'm running a 1992 Soarer engine, box and ECU.

It seems almost as if the OD isn't working.

Other thought was fuel supply? Not sure if I should have removed or bypassed the Supra's fuel pump control?

 

[ugp]

I'm running a 1992 Soarer engine, box and ECU.

It seems almost as if the OD isn't working.

Other thought was fuel supply? Not sure if I should have removed or bypassed the Supra's fuel pump control?

Scott, I've tried calling but not got a response, give me a call and I'll talk you through removing the limiter.

How did you wire up the O/D switch? I hadn't got that far when I left your place.

Do you have an ABS warning light on? Does the VSS signal from the ABS sensor on the box get to the ECU?

I wired your ECU up to control the stock JZA80 FPC as it should have from the factory. Have you got an AFR gauge?

Ben

 

[straightsix]

Scott, I've tried calling but not got a response, give me a call and I'll talk you through removing the limiter.

How did you wire up the O/D switch? I hadn't got that far when I left your place.

Do you have an ABS warning light on? Does the VSS signal from the ABS sensor on the box get to the ECU?

I wired your ECU up to control the stock JZA80 FPC as it should have from the factory. Have you got an AFR gauge?

Ben

Not on that phone anymore so don't have your number.

1. Sounds like OD switch could be an issue although wired to ECU as per diagram
2. No ABS warning lamps or any other fault warning lamps illuminated.
3. No AFR gauge fitted but if FPC can be ruled out that's fine.

I'll have to get an accurate tacho to check engine speeds....

 

[ugp]

Not on that phone anymore so don't have your number.

1. Sounds like OD switch could be an issue although wired to ECU as per diagram
2. No ABS warning lamps or any other fault warning lamps illuminated.
3. No AFR gauge fitted but if FPC can be ruled out that's fine.

I'll have to get an accurate tacho to check engine speeds....

Does it go into O/d or not? Check the o/d pin in the wiring loom goes to ground when the switch is enabled.

Assuming it still revs cleanly to the limiter in lower gears? 4.2krpm on the supra tach is 6800k on the motor, should stop there. Idle should show at about 400rpm on your tach, of which equates to around 750rpm on the motor.

Give me a call, 07932580804, I'll run a few other things past you.

 

[straightsix]

After spending a lot of time tracking back through wiring (remaking several connections and tidying the whole lot up) I had solved a few problems but the 'rev limit' was still there.

As I had started with a 1996 LS400 lump which then had to be bastardised with Soarer parts and ECU (long story), the igniters were mismatched.

Stuck on a pair of Soarer igniters and it's all sorted.