does disconnecting the knock sensor on either the series 2 rst or 4x4 sapphire cos have any effect on the running of the car??

 

Not sure about the Saph, but it'll run like shit on an S2

 

in what way?

 

the ignition is retarded massively, so it feels very flat as soon as you start to come on boost.

 

The knock sensor detects pinking of the engine, if i remember rightly so, and disconnecting it puts the ECU into limp home mode i.e low boost and lumpy.

Not a good idea unless you have S1 loom and ECU or a S1 ECU.

 

If you disconnect the sensor, the wires act like antennas and pick
up noise which can fool the ecu into thinking you have detontation
resulting in poor performance due to ignition retardation.

If you disconnect it, short out the two connections together
(not the screened cable part - leave this alone) and this will result in no
electrical noise being sent to the ecu and the car will run ok.

 

if thats the case with the wires picking up interferance then what about using a series 2 ecu on a series 1 which doesn't have any wires for the knock sensor?

 

Should be ok in that setup.

 

why do a lot of people say that the series 2 ecu is not compatable with a series 1 car?
also what about the 4x4 sapphire?

 

The series 2 RST car had more sensors and a different ignition offset in
the software. (2 degrees different if I remember correctly).

If you use a S2 ecu on an S1 then the sensors that are need wont
be there and you will get unpredictable results.
This also depends on the chip fitted in the ecu too.
The extra sensors are a temperature sensor an the knock sensor.

You could retro fit the extra S2 sensors (with or without knock) then use
the newer ecu on the car and the dizzi adjusted correctly.


As for cosworth ecus, should be ok to swap as long as you understand the
other issues that need sorting apart from the knock sensor.
(TPS type, Lambda sensor etc...)

 

simon,

What temp sensor's are you saying, as both s1 & s2, have cts & act sensors, although no knock sensor on s1 or early s2's.



Dave R,

 

On the S2, there is a SECOND coolant temp sensor for the ignition ecu.

 

SIMON.

What year approx as i've had 8, S2, where was it fitted, was it still in the inlet manifold or pipe in the waterways, as have only seen the one CTS,
only difference between s1 & s2 was the thread, i assume the resistance
stayed the same, without checking it,

Dave R.

 

On my G plate S2, I had two coolant sensors.

The second was located next to the original on the rubber pipe in a brass
boss behind the inlet manifold.

If you look in the Haynes manual, it is clearly marked on the ciruit
diagram.

From memory, my silver ecu was hearts and diamonds type.

 

S1 has 2 temp sensors too, one for each ECU.

You can't run an S2 ecu on an S1 without a knock sensor. It will still retard the ignition. You can compenstate to a degree with the dizzy, but it will never be right. This goes for shorting the knock sensor wires too. Sending 5v straight back to the knock sensor input will have a an effect on the ignition timing too.

 

Rick,

The knock sensor isnt fed with 5 volts . Its a piezo electric crystal that
generates its own AC voltage from vibrations. !

Shorting it will work

 

Yea, ur right. I was just going off the colour code - think it's a black and yellow feed, which is supposed to be a common feed to all sensors.

Shorting it doesn't seem to work though. I've set up a few, which have been acting up for no apparent reason. Under further investigation, the insulation had begun to come away from the sensor, and the wires shorting. Sepertating them cures the problem.

It's as if the ECU needs a waveform from a "normal" sounding engine to work correctly. Knock sensors give endless greif. If it was so easy, then tuners would just short the wires.

 

I just remove it from the engine and wrap it in bubble wrap.

 

i have a 4x4 cosworth engined sierra, about five or so years ago i noticed the knock sensor wireing had rubbed showing the inner cable. i have used the car ever since with it disconnected and havent had any problems

 

 

that doesn't always work either

 

Have you had any boost problems ?? i.e. low boost or pinking at high boost?

 

rf interference is a big issue on knock sensor erst ecu's
there are also different types of s2 knocksensor ecu's
fitting a non knock sensor early ecu cures the problem.The knock sensor stratergy can go hay wire and takes 11 degrees out of the current ignition load site .
The erst knock sensor ecu has no default stratergy for knock sensor issues so 11 degree's comes out ,this is ok on part throttle light load situations as the ignition timing can be as high as 50 degrees advanced at this point.But at 10 psi the ignition timing is typicaly 10 degrees of advance and the engine does not like 11 degrees taking out.
The knock sensor can be removed and wrapped and tied away from the engine you can also install a 47 k resistor and throw the knock sensor away .
Cosworths don't really have these issues better ecu better maps better default stratergies.

 

L1 / L6 / L8 dont have a knock sensor though, or is that what you mean by better strategy?

 

L8 DOES have a knock sensor Chip - its located on a 200 block just to the right of the coolant drain bung

 

Ah, mine is on an L1 or L6 loom by the looks of it then so doesnt, lol, cheers for the though, sounds deserved.

 

Been wanting to use that one against you for aaaaaaages

 

Well have one of these for being so sad

 

bitchwhore