1G-GTE Diagnostic System Issue...HELP!

[Toyo Truck]

Hey guys,

I am having a few weird Diagnostic issues with my 1989 GZ20 Soarer.
I really need to sort these out so I can go to a track day real soon in March.
It's been AGES since I have been to any sort of track event, so I am mad keen.
So any help you can give me would be great.

Now I got this Diagnostic problem.
I have been driving around for the last week or so, and every now and again, my
CHECK ENGINE light comes on and stays on. It usually comes on under sedate
boosting/driving. For instance...
Last night, due to the rainy goodness, I went out for a drive/slide, on private property.
I was drifting it and it and revving it out OK, and boosting hard...the light doesn't
come on at all??? I stopped the car after drifting, no engine light at all.

Then when I am carefully driving home, I got to about 5 psi, (or about 2300 RPM)
then backed off and changed to 3rd, and the light came on?? So under no boost at all
the light comes on, but it'll hit 15psi and 5500RPM no worries, and no light?
How can this be?
Also, after the light does come on, if you leave the car OFF for a while, and then start it
again, the CHECK ENGINE light does not come on? So has it self cleared these issues?
(If I start the car again within say 10 minutes though, the CHECK ENGINE light remains)

When I jumper the DIAG connector, I always get the following codes:-
Code 24 - Intake air thermo sensor signal
Code 31 - Air flow meter signal
Code 34 - Over Boost (Air to Water Intercooler)
Code 41 - Throttle position sensor
Code 42 - Vehicle speed sensor signal

NOTE:-
I recently swapped in a 2nd Hand W58 and a new Excedy HD Clutch,
my gearbox woes are resolved for now. 2nd is mad notchy, but at least it works.
The Speedo is not working now, so the Speed Sensor is not hooked up or working.
So that explains the Code 42.

Basically this is the only thing stopping me from signing up to the track day,
If you had these issues in your 1G-GTE, would you risk going to a track day?
Especially considering I can boost the car hard and no light comes on?
It is very intermittent, maybe a loose connection??

Cheers,
Bart

[swan86]

Just a long shot, but if you unplug the air flow meter on a magna while it is running it throws all these codes bar the speed sensor and boost codes. (In saying this however, i'm not sure if a turbo engine would throw the same diagnostic codes) After running for a while these codes will self clear but will be stores in the computer for diagnostic memory. Could be an idea to check the plug connection for corrosion and pin wear. Maybe the vibration while driving is causing an intermittant poor connection.

[Gttwinturbomk3]

I would get the speed sensor fixed since that is a problem, and see how it goes then. As the computer uses the speed sensor, it will be effecting the tuning which in different circumstances is making air/flow, tps etc and other codes showup as well. See if thre light still comes on after that, i would be surprised if it did.

[Luke20t]

I agree with Gttwin.
I had the exact same problem, under light engine load and a constant speed held for around 5 seconds or more, would trigger code 42. My speed sender was working, but i had a broken wire for the speed input into the E.C.U.
fix your speedo and problems will be gone.

[Toyo Truck]

Ok that is some positive news.

How do I fix the speed sensor though?? Its digital so I presume it doesn't have a
spinning cable to dictate speed to the speedo, does it just have a sensor that plugs into
the box or something? does this sensor output to the ECU and then to the dash cluster?

Cheers,
Bart

[Luke20t]

Hey guys,
NOTE:-
I recently swapped in a 2nd Hand W58 and a new Excedy HD Clutch,
my gearbox woes are resolved for now. 2nd is mad notchy, but at least it works.
The Speedo is not working now, so the Speed Sensor is not hooked up or working.
So that explains the Code 42.
Bart

Have you done a manual conversion or just replaced the gear box? If you just replaced the gear box have you swapped over the speed sender unit and plugged it back in?

From memory i think the speed signal is sent through to the dash then to the ecu.

[Toyo Truck]

What does the speed sender unit look like mate?
Got any pics of it?
I'll get under there and check...also where on the box is it located mate?

Cheers,
Bart

Cheers,
Bart

[Luke20t]

dodgy phone camera
This is on a r154
its located on the right hand side towards the rear.

[Toyo Truck]

Thanks man.

I will get under and have alook tonight.
But from memory on the W58 that came out I only saw a "screw in" connection
on the side of the box.

Will let you know how I go

Cheers for the info once again

Bart