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Need help understanding the procedure to check timing on L Series 4 plug ECU.

The factory manual- ON CAR SERVICES- 2-2 page 2 tells us to:

1. warm engine
3. connect the test mode connector, and

2. Make sure that the idle contact of throttle sensor is ON position
(refer to Chapter 2-7)

"Ignition timng can be set when the test mode connector is connected ( I unnerstand this green plug thing) and the idle switch is turned ON, regardles of engine RPM. Do not check ignition timing while the connector is disconnected and the switch OFF"

Is there really a switch as such other than TPS which is a sensor not a switch as such eh ?

Anyone that can do this and explain in slow mans terms about this ON OFF of idle switch - be greatful

Does not give us a page number of the chapter (just two digits more??)
Ts'ubaru has indicated the throotle stuff is on page 21 and 22 of the US version, thankyou heaps, but I am a bit slow.... cannot see a relevance to ON or OFF as required by instruction #2 above in here it is titled inspection and adjustment

the tps has an idle switch inside it. there is no reason why it wouldnt be on, especially if the white paint is still on the throttle body and tps screws.

showthread.php?t=3784

Then there are also different throttles on non spider too, had one that was simple TPS on the end of the throttle shaft, another had this and another black box with three? wires connected.

Should mentin I am chasing 4 legged spider manifold stuff too.

So timng is or has been just ensure it is idling and greens? connected? Diagnostic plugs same thing?

manual calls it throttle sensor, dia of throttle sensor has four wire ports it calls 1,2,3,4

Insert a feeler gauge between the stopper screw of the TB and the stopper and check for continuity between 3 and 4
Make sure 4 and 3 are conducting when the throttle is fully closed

Conducting is ON eh ?

Then we got resistance values to check....

Sheesh, sounds like a lot of stuffing around, maybe they just being overly cautious and explain the lot. Reckon most not know this or assume it is idle nice so just connect timing light and go for it?

Hi Steppy , I have the 87+L WSM here but I don't think it covers Spider TB and TPS .

Just another unique part of the Spider system its is TPS which is actually a combination of a switch to tell the computer when the throttle is closed and a reostat (rotary quadrant variable resistor) like a volume dial to tell the computer how far the throttle is open and how fast the transients are .

A continuity test is basically a circuit test to show a closed circuit when ypu probe the relivant sensor pins . The better multi meters have a buzzer that sounds when there is continuity and not if the circuit is open ie the idle contacts are apart .

That Spider sensor has an early Bosch injector type connector only a four pin one rather than a two pin one .
The 4 plug L Series sensor has the same style plug but in three pin width and also a round connector with three pins in it . The rectangular three pin one only has two pins inside because the sensor doesn't actually have full throttle switch like the 3 plug one does .
The round plug has the wires for the reostat .

Now before you ask why the Spiders sensor has 4 pins and the L one effectively five , the spiders one doubles up on the earth where the L uses two earths . I think they join in the loom .

From memory works like this for 4P L Series .
Rectangular plug - power and earth for ilde contacts .
Round plug - reostat power earth and signal wires .

4P Spider - idle power/common earth/reostat signal/reostat power .

The bride is asleep and too close to where my Spider WSM lives , will pass on the relivant colour codes in the daylight hours .

Cheers A .

Just so you understand with the throttle sensor correctly set and the diagnostic plugs connected you can check the ignition timing with a timing light and set the distributors base timing just like any other distributor . With those connectors plugged in the computer "knows" to lock the timing at a set figure so you can move the distributor so say 10 degrees on the engine corresponds with 10 degrees in the computer - synchronising things so to speak .

A very good explanation there Adrian, but i have to add that the 85-87 RX didn't have the rheostat in the TPS. It was just idle switch and a half throttle switch.

After a slumber the words "make sure the idle contact is ON" reads a little differently ~ means ensure it is ON, does not mean we must switch it ON and OFF at the end of the procedure, just ensure it is operational and has the ON condition.

Thanks Adrian, sort of remembered some of the above but not in one big picture, matching theory to practice can sometimes confuse my small mind - if I think too hard about it! I like it, your bride sleeping in your parts cave?

Gannon, (formerly known as Suparoo) It is hard to say which models got what and when with these as we know, and over the years do not know what people have changed on us after the factory.

My GLTA is 3/87 compliance plate, VIN code says it is 86 model, yet was born SEP85 ~ same as what we get today ~ AUG 2011 " Sir, we have here the 2012 model ready for you to drive away"

Sorry , I have yet to inspect the throttle body switch type, been too busy looking below at the orange stains on the block trying to determine where they originate - in doing so found an oil cap under the spiders legs LHS - explains the very new looking oil cap in service

Yess Gannon thats right , just being economic with words at that time of the morning . Actually the turbo and NA 3P TPSs are different as in where the "full power" contacts open .
Anyhow , easy to tell between 3p and 4P L Series TPSs . The 3p only has the moulded in rectangular connector where the 4P one has a short length of wire with a round plug on the side of it .
From what I can tell the Spider TPSs are the same with the single moulded in rectangular connector , and they rotate in the opposite direction to suit a Vortexs bay layout and cable arrangement .

Hokay , Spider throttle position sensor details for steppy .

This is looking at the top of the TPS and the four pin retangular connector pointing upwards .
The pins are numbered left to right 1-4 .

1) Power (Sensor) meaning reostat .
2) Sensor signal - for reostat .
3) Power (idle switch) .
4) GND meaning earth

Ah now the settings .
Spider WSM says make sure that the pins 3 and 4 are conducting when there is a 0.55mm/22 thou thickness piece between the throttle quadrant and stop screw corresponding to throttle plate angle of 1.5 degrees .
Make sure the contacts are not conducting when the thickness piece is 0.92mm/38 thou which corresponds to 2.5 degrees of throttle plate opening .

So in other words when the throttle is fully closed there shoud be continuity between pins 3 and 4 , same with a 0.55mm/22 thou feeler gauge packing out the throttle stop . No continuity with a 0.92mm/38 thou feeler gauge used as the packing piece .
For anyone with a calculator I rounded the imperial measures because 0.0382 means 38.2 thou and 2 then thousandths mean SFA , 38 plenty close enough .

Hope this helps , cheers A .

Yes, thanks Adrian, it is all becoming a lot clearer in the head, your explain and the technical notes. Almost a secret Masonic handshake !!

By todays standards any EA engine management system is crude with the 3 plug one being pre historic . The 4 plug one was a jump on the earlier one but it still used a single coil and distributor and had no idle speed motor or truly sequential injection .
The XT6 was getting closer to what 1st gen Libs had .

A .