Tacho Info

[Micramad]

This is going to sound quite weird but can anyone answer some questions about the k11 tacho?

Firstly, how its generated (using the spark plugs so u get 4 pulses every one revolution) etc or does the ECU just output one pulse every revolution?

Secondly,is it a square-wave?

The reason i ask is i want to make an LED tachometer but with out this information i would have to assume somethings so it prob wouldnt work.

thanks

 

[frank]

micramad

the cas is driven by the cam, so i think it,s 2 pulses/rev ( if it,s non coilpack)

 

[Micramad]

micramad

the cas is driven by the cam, so i think it,s 2 pulses/rev ( if it,s non coilpack)

thanks for the quick reply. it confused me though, what is the cas and what does the qoilpack do?

thanks again

 

[frank]

micramad

i think it,s cam angle sensor (triggered by a disc in the dizzy with 4 holes, one for each sparkplug) but there,s a 5th hole for the rev limiter which might complicate your setup :glare:
the post 2000 (?) k11,s are coilpack jobbies, with a crank sensor instead (1 signal/rev)

 

[Micramad]

micramad

i think it,s cam angle sensor (triggered by a disc in the dizzy with 4 holes, one for each sparkplug) but there,s a 5th hole for the rev limiter which might complicate your setup :glare:
the post 2000 (?) k11,s are coilpack jobbies, with a crank sensor instead (1 signal/rev)

danm it, i wish i had a post 2000 (mines a 1997), that would make life alot simpler! whats a dizzy? thanks for clearing that up. all i have to say is its a qomplicated way to do it.

ive just looked im my hayness manual (dont know why i didnt in the first place) and it says the tacho signal line comes from 'injection control unit' which is part of the engine managment system.

thanks

 

[Ed]

This is going to sound quite weird but can anyone answer some questions about the k11 tacho?

Firstly, how its generated (using the spark plugs so u get 4 pulses every one revolution) etc or does the ECU just output one pulse every revolution?

Secondly,is it a square-wave?

The reason i ask is i want to make an LED tachometer but with out this information i would have to assume somethings so it prob wouldnt work.

thanks

Tacho comes from pin 32 on the ECU. Weather the car has one or not. Its square wave, usually pull to ground but I have not looked on the K11 to be sure. You never need to interface with the distributor, but people seem to do it anyway.

 

[Micramad]

Tacho comes from pin 32 on the ECU. Weather the car has one or not. Its square wave, usually pull to ground but I have not looked on the K11 to be sure. You never need to interface with the distributor, but people seem to do it anyway.

ok ive learnt never to trust heyness manual. mine says tacho is pin 2 and 'speed sensor' is pin 32. i thought the speed sensor was for the mph?

thanks for the square wave info, can u tell me about its frequency in relation to rpm? eg frequency/2 = rpm?

i can easily test to see if its pulled to ground or not but thanks for mentioning it, i didnt think about that. ill try and test it tomorrow if i can locate the ecu...

thanks for the help

 

[Ed]

Your correct I read the diagram wrong. Its next to the ign signal. Freq is 2/rpm same as ignition, and almost every 4cyl.

Ed

 

[Micramad]

Your correct I read the diagram wrong. Its next to the ign signal. Freq is 2/rpm same as ignition, and almost every 4cyl.

Ed

thanks for your help. i can crack on with designing now. two more questions though. where is the ecu? and seeing as it was brought up, what is the speed sensor for?

 

[Ed]

ECU uses speed sensor for a various monitoring states, fail safe modes etc. ECU is bolted to the floor behind the centre console.

Ed