crankshaft position sensor (cps)

[kitcrazy]

me asking more questions again i'm afraid...

I have a problem starting my 1.8 and i have narrowed it down to an issue with the coil pack and the cps. i have 2 coil packs, one from the original engine and one for the replacement engine and its interesting to note that the original cp has 3 pins where as the replacement has 4. the replacement is a Japanese engine and the orgingal a brit. Now apparently the 4th pin sends a signal to the rev counter and if you have a 3 pin the signal is taken from the cps and if you don't have this signal coming back to the ecu then the engine will cut out within half a second of starting, which is exactly what mine is doing.

problem is it does this whether i try the 3 or 4 pin and seeing as i have the original wiring loom and ecu you would think the 3 pin would work, but oh no...
So now i need to locate the cps and i can't find it anywhere, does anyone have an idea where it is on the block and also does anyone really know what is going on with the different types of rev sensing that mazda see fit to install in seemingly indentical cars.
I should say that the block i am using is the jap replacement so i'm not even sure if there is a way to send a signal from the cps with this one as it came with a 4 pin cp.

Did you follow that??

Made a whole lot of trouble for myself i think!!!!

Anyone know anything about this subject i would love to hear thanks
KC

[frazbomb]

Hi There,
I assume that you reffering to a MK1 MX5 engine? If yes then you'll never find the crank postion sensor, because they don't have one.

The MK1 1.8 engines use a cam angle sensor (cas) as the ignition trigger and the symptoms you describe point squarely at it being the fault, I would recommend you replace it with a good used item, or new if your feeling flush.

PS, on a side note there is no differance between MK1 1.8 jap engines and MK1 1.8 UK engines, the 4 pin coil was used '94~95.5 and the 3 pin coil from '95.5~98

[kitcrazy]

It is indeed a mk1 and thanks for that advice as i was about to go mad trying to find the elusive cps on my engine. Will try the one off my old engine and pray that works.

cheers

[fasteddie]

Frazbomb is smack on, cam position sensor is on rear of engine to right of coil pack looking from front of engine, this is a known weakness of these engines so try to obtain one off low milage unit if possible. hope this sorts out your problem. Ted