Electronics help with TPS circuit.

[BMWTurbo]

I have all the ones marked yellow connected besides the stop switch. Plus I have TE1 connected. You need to hook TE1 up to get the error codes to come up when you bridge the contacts in the diagnostics terminal. (you were just doing it at the ECU but weren't you which would be the same thing). Maybe there is a prob with the stop switch wiring and it thinks you are hitting the brake and accelerator at the same time?

Possibly Denis.. I don't think the brake light would be comming on under accell though I'll get someoen to have a good look and tell me though, stranger things have happened.

[2JZR31]

Brake light might not be coming on but maybe the ECU thinks it is somehow???

[Mos]

I will update this to reflect the few wires that I bridged across previously that were bridged inside the cabin at the large boxy plug.
This is how my wiring stands atm, though with what is connected and what isn't connected.

A/C is A/C input. ACMG is AC relay, open collector output shorting to ground.


No idea what MI is, don't remember seeing it on any of the three half cuts...?

CCO is the exhaust temperature sensor, used in conjuction with EGW. Goes to diag and to sensor after cat.

ELS - not a bad idea to hook it up, does idle up for electrical loads.

Your SP1 waveforms look strange - the 8v referenced to ground might work, but doubt the 6v referenced to 6v will (I guess there's a possibility, just that I doubt it).

Well as mos said the way its wired shouldnt affect the shape of the pulse , seems you have wired it ok , i allways know sp1 to switch to ground thats why i wondered about how you connect it , when i have wired sp1 sensors before ( the 3 wires ) i allways kept positive to the same pin but swaped the other 2 around till i got the negative pulse.

The two waveforms Ben posted look strange - no idea how the R31 speed sensor is supposed to work.
I think it's not correct to just play around with the other two wires - there is a definite ground and a definite signal output on every toyota speed sensor I have seen. I'm not sure if there's a chance the sensor will work properly if the two connections are interchanged.
I have pulled apart an MX83 sensor (screws into the speedo drive) - it has a 3 pin IC inside (hall effect pickup I guess) and a disc with either 4 poles (NSNS) or 8 poles (NSNSNSNS) and the hall effect only picks up one polarity.
I'm yet to pull apart the large speed sensors (eg aristo) but I'd suspect they are similar.

Mos says that due to the use of pull up resistors in the ecu ( is that right mos) that it shouldnt matter if sp1 recieves a positve pulse but from my experience it seems to work 1 way around and not the other.

No no.. it does matter. Something that supplies only +ve and relies on something else externally to supply the ground probably will not work - IE if you had a reed switch with a magnet, and you connect one end of the reed switch to +ve and the other to SP1 input, it wont work (because both the pullup resistor and the reed switch are pulling to +ve). But if you connect one end of the reed switch to ground and the other to the SP1 input, then either the reed switch will supply 0V when the reed switch is activated, or the resistor will supply 12V when the reed switch is not activated.

Mos.

[Mos]

Perhaps I have the SP wired incorrectly? I used the centre pin Blue-Red as the signal out/feed into the ECU, the Red-blue as my 12v positive in (already connected throguh loom) and the Blue-lellow as my negative in (tied to a brown earth wire in the loom).

The wire colours and functions are the same as my notes, so it should be correct, except in my notes the aristo speed sensor centre pin is blue-yellow (ground through aristo cluster pcb); the outside pins are blue-red signal out and red-blue power...? (On Jason Kirk's the L-Y and L-R were both L for some reason, operationally identical to the other two (mine and Jesse's)).
If you slowly rock the car you should be able to observe the transition from 0V to 12V and vice versa on the signal pin using a multimeter.

Mos.

[sideshow]

sp1 comes from dash
so if the speedo works ok then sp1 should be fine

none of the wires from the plug on the speedo drive goto the ecu

they go to the dash spin the speedo

then theres a unit in back of speedo that then sends a signal to the ecu

i dont thik sp1 should cause any probs if tis not connected as long as sp2- and sp2+ are connected properly

[Mos]

Yeah, agreed, normally they don't, but in Ben's case the BMW speedo doesn't have provision for that, so I was saying hooking up SP1 directly should work.

Mos.

[2JZR31]

i dont thik sp1 should cause any probs if tis not connected as long as sp2- and sp2+ are connected properly

It was throwing error codes in my car and causing limp mode for some reason.

[cambelt]

It will only log sp1/2 faults if the car is moving , or has moved with the ignition on . if you reset the ecu and then checked for codes it would show all clear ,
Dave

[sideshow]

we then u have to check what sensor is on the gbox

sp1 should be 4 pulse per rev of speedo gear
toyotas have 20 or 4
just make sure its the 4 pulse sensor and not the 20
otherwise sp1 will be sending to fast a sinal to the ecu

and maybe telling the ecu the wrong speed

maybe without sp1 it throws a code

but with sp1 connected with wrong amount or pulses could be making it even worse

not sure just a guess like everyhting else in this post hehehe

[2JZR31]

There is no guessing about the speed sensors ,well not on my car anyway. Without SP1 connected I was getting a SP1 error code. Seems pretty straight forward. With it connected I am not, and any problems I did have went away. Like I have said, SP1 can be connected straight up to the ECU without signal modification. So unless they changed the pulses on different models it would be the same for any Aristo. My AVCR instructions say to set the speed sensor input to 4 pulse for all Aristos.

[BMWTurbo]

[QUOTE=Mos]A/C is A/C input. ACMG is AC relay, open collector output shorting to ground.





Thank you MOS I had no idea the ECU switched the A/C clutch on. I'll have to have a look at this as I'm not sure what the BMW is doing in this regards as it has it's own wire to turn it one, sending 12V to it.

The toyota does this due to a change over system. I might just use the BMW wiring and connect the A/C wire to the ECU and not use it's output.

I have been looking at my set-up and am wondering if the air filter directly on the 'Y' pipe might be drawing in very hot air and perhaps playing havoc with the IAT temp.

Are the other set-ups that are experiencing this potentially drawing in hot air? I haven't had the time to change my induction yet.

I was gongi to use a spare IAT outside the plenum for a try.

The reason I thought of this is the car seems to rev a little bit longer when it's cold then when it's hot.

[BMWTurbo]

Circuit almost complete that will delay the onset of a 2.7V clamped signal to the TPS ECU input by approx 2-3 seconds.

I'll need to test the time, but this was my rough guesstimate of how long after you hit the KD switch the GB drops down a gear. It could be set longer as a precuation, but I wanted it as close as possible for when you are higher in the rev range.

[Mos]

Thank you MOS I had no idea the ECU switched the A/C clutch on. I'll have to have a look at this as I'm not sure what the BMW is doing in this regards as it has it's own wire to turn it one, sending 12V to it.

The toyota does this due to a change over system. I might just use the BMW wiring and connect the A/C wire to the ECU and not use it's output.

You don't have to hook it up this way - it just pre-empts idle up and turns off at higher rpm. Feeding 12V to the A/C pin still provides sufficient and acceptable idle up.

I have been looking at my set-up and am wondering if the air filter directly on the 'Y' pipe might be drawing in very hot air and perhaps playing havoc with the IAT temp.

Isn't the IAT sensor in the plenum?
It's generally a bad idea to be drawing in engine bay air. Evidently it will have a corresponding power loss. Changing the reading will just stuff up mixtures and not actually give you more air in the intake....
I don't think it's a good idea to play with the IAT sensor to "fix" the problem of drawing in hot air... make a proper airbox and don't stuff around with the electronics

Mos.

[BMWTurbo]

MOS I was thinking about doing it as a 'test' not as a fix... If I can find something else that triggers the problem then that's part way to the solution...

I have thought right down to fluid levels in the G'box, but I've double checked mine are fine.

I upgraded my fuel pump to something suitable, no difference... I'm at loss and it's driving me nuts, the car feels slow because of this.

[sideshow]

wire up a diag plug and fit a scanner to it

then go for drive and see the live data

see what some sensors are doin at that time it plays up