High Idle / Speed Sensor bypass F7P

[James5]

Is there some magic trick to tricking the ECU into thinking it has a VSS? Maybe solder in a resistor between the VSS wires or something? I have no speed sensor in the transmission as I am using th GTT box. I believe the valver has this is there a way to bypass this or fall the ECU into believing it's working??

Before someone tells me to ground Pin 3 I will just say no that will not work :laugh: as already tried and it's not a good thing to do.

I assume I need to some how give it some kind of pulse signal:scratch:, how have peeps got around this before whom have done the f7p conversion using the phase 1 ECU?



F7p ECU pin out's

1 - EARTH
2 - EARTH
3 - VSS SPEED SENSOR INPUT
4 - BATTERY POSITIVE
5 - CHARCOAL CANISTER SOLENOID (OR EVAP PURGE VALVE IF YOU'D RATHER)
6 - FUEL PUMP RELAY (THIS IS A SWITCHED EARTH SO WITH PUMP RUNNING 0V)
7 - ECU power relay SWITCHED EARTH
8 - OIL PRESSURE SWITCH (ONLY SEEMS ACTIVE ON SOME MODELS)
9 - TPS INPUT (0.2V THROTTLE CLOSED 4.7V FULLY OPEN)
10 - COLD START INJECTOR
11 - CRANK POSITION SENSOR
12 - NOT USED
13 - INSTRUMENT PANEL (I THINK THIS IS ONE OF THE ECU LIGHTS, SOME HAVE NOTHING HERE)
14 - INTAKE AIR TEMP SENDER
15 - ENGINE COOLANT TEMP SENDER
16 - MAP AND TPS POSITIVE FEED
17 - MAP AND TPS SWITCHED EARTH
18 - MIL (ECU LIGHT) NOT ON ALL MODELS

NEXT ROW UNDER PINS 1/2

19 - ENGINE CONTROL RELAY POSITIVE FEED
20 - INJECTORS SWITCHED EARTH
21 - INJECTORS SWITCHED EARTH
22 - A/C LOAD SWITCH OR OIL PRESSURE WARNING LAMP
23 - IDLE CONTROL VALVE CONTROL SIGNAL
24 - IDLE CONTROL VALVE CONTROL SIGNAL (DUNNO WHY ITS THERE TWICE)
25 - POWER STEERING PRESSURE SWITCH (NOT APPLICABLE ON ALL MODELS)
26 - INSTRUMENT PANEL CYCLING OUTPUT (DIGI DASH?)
27 - IGNITION AMPLIFIER
28 - CRANKSHAFT SENSOR INPUT SIGNAL
29 - IGNITION SWITCH 9V WHEN CRANKING
30 - AIR CON (WHO ACTUALLY IN THE UK HAS A/C?)
31 - KNOCK SENSOR (INPUT FROM SENSOR)
32 - KNOCK SENSOR, IAT AND ECT SENSOR SWITCHED EARTHS
33 - MAP SENSOR INPUT (2V IDLE 4.8 FULL THROTTLE)
34 - AIRCON (AGAIN)
35 - LAMBDA SENSOR OR CO ADJUSTMENT



I have attached a pic of the R19 Haynes Guide for the valver engine as you can see I have marked a few things on it I take it the speed sensor itself is in the valver box??


Ok found some more out it's just a +12v pulse, once every 0.2m is there a way I can emulate this?

[James5]

Thought I better add to this.

To start with whatever you do Don't ground the ECU VSS pin number 3, this will cause smoke and fire to your loom:scared: this needs VSS signal to the ECU.


I have kind of found a simple solution to the problem if anybody else comes across it but there is a downside to it.

The simple solution is to get the engine upto temp then remove the ICV totally and block up the holes in the pipes were the ICV connected to. Then adjust the brass screw on top of the throttle body by undoing it all the way (not so it falls out) then start the car it will idle high at this point then screw it in until the revs sit around 1100-1200rpm's. Then take the car for a good drive and check were idle is sitting and adjust so it stays around the 1100 rpm's. This will illiminate the high idle after a good thrashing the downside is the idle when cold isn't so good due to the lack of the ICV but it's better than a carb'd 5 and once warm which doesn't take long it will idle fine. I found going any lower than 1100rpm's the car would sometimes want to stall after a thrashing with no ICV installed.


There are other options to get around it like fit valver box and clocks and use valver speedo, then you have to wire in the valver clocks to the GTT loom which is just more wiring.

Standalone management is another option,

Or you could use an ABS ring on the front hub and use a Hall sensor to get your VSS signal, but without the correct tools to do so and knowledge not as easy as it sounds but would be the best option really and you can then retain GTT dash and box and have perfect cold starting.

[Chunk]

Completely unrelated but thanks for posting up the ECU pin out, that's very useful.

I'm having massive issues with mine stalling and running like a dog and it's 100% lambda sensor. I'm also suffering from the high idle issue caused by a dodgy road speed sensor on the speedo cable (although not on my 5, this is on my valver)

I've had this exact issue previously (except the high idle, just bogging down when cold) and the only resolution was to change the wiring loom. I can only assume the lambda wiring was broken somewhere and the ECU was not getting a signal.

Now i've sold that car and got a new car, i've got the same problem, so this time I think i'm just going to run fresh wiring from the lambda sensor to the ECU.

Question is, there's three wires from the Lambda. Which pins on the ECU should these three wires go to?

Also, does anyone know which pins on the ECU the road speed sensor should go to? I might re-wire this also..

[James5]

Completely unrelated but thanks for posting up the ECU pin out, that's very useful.

I'm having massive issues with mine stalling and running like a dog and it's 100% lambda sensor. I'm also suffering from the high idle issue caused by a dodgy road speed sensor on the speedo cable (although not on my 5, this is on my valver)

I've had this exact issue previously (except the high idle, just bogging down when cold) and the only resolution was to change the wiring loom. I can only assume the lambda wiring was broken somewhere and the ECU was not getting a signal.

Now i've sold that car and got a new car, i've got the same problem, so this time I think i'm just going to run fresh wiring from the lambda sensor to the ECU.

Question is, there's three wires from the Lambda. Which pins on the ECU should these three wires go to?

Also, does anyone know which pins on the ECU the road speed sensor should go to? I might re-wire this also..

Have just simply uplugged the Lambda it will cause it to run richer but shouldn't bog or stall.

I think the Lambda will have ingition live feed, earth and the white wire will be signal wire which will be pin 35, to find out which pin is whick just take the cover of the connector to the ECU and they are number within on the plastic:agree:

With ref to the high idle after a bit of a thrashing that will be down to a bad earth on the VSS cable behing your clocks you need to add another earth point to the black cable Pin 3 on the ECU is the VSS speed signal input.