Technical Cam position sensor...

[Smiler121]

After reading up I now know that most cars use marks on the pulley itself, but I have been told that the Sei Mpi doesn't do this?

I have just taken the cam sensor off, looked down the hole & turned the engine over (put it in gear & rocked it) it DEFINATELY reads a "lump" on a disc which looked about 5mm wide. Is this a seperate disc fixed next to the pulley, or is it part of the pulley & therefore means that the pulley HAS to be specific to the engine with a cam sensor I couldn't see without really taking things apart further?

Shame that when I had my cam cover off a few weeks ago I diddn't really understand what I was looking at (was more fussed with getting it put back together as quickly as possible!!!

 

[randomizered]

on the mpi sei, its part of the pulley, its moulded to the "rear" of the pulley and is a single piece unit. You can swap the pulley to another cam and retain it though

It may be of interest, the superfire (16v), it reads the actuall cam itself. There is a missing notch in the inlet cam. about 2/3's down from the pulley end.

For the sei mpi, when i looked it was a more complicated sync pattern than just one lump, but that doesn't matter to you i doubt, just the ecu.

Kristian

 

[Smiler121]

Well, I only saw the 1 "lump" but only rocked it far enough to be sure there were any there!!!

If it is definately part of the pulley then the guy I'd been speaking to was wrong, I think He was just assuming I had a Spi. I knew I could retain the Mpi one on my P75 cam, but was doing some reading up in advance of using my head on a 1242 bottom end & had been enquiring about sourcing a vernier pulley which I think I'd need if I go for a high compression ratio gasket?

I'm treating this all as more of a learning experience than a desperate desire for more power, never know though - if I do get a 16v donor I may go down the route of custom ECU in the long run

Quoting for a P75 engine swap I was only quoted £20 per year more on my insurance - Adrian Flux are just SO much better to talk to than everyone else I've tried so far!!!

Kristian you might know this without my getting at them to see their code - Is the flow rate for the Sei Mpi injectors 155 cc/min? I could have sworn I read that somewhere & that the P75 uses ones rated to 175cc/min?

Using online calculators if that 155cc/min figure is correct it suggests they'll supply a max 94.48HP @ 80% - if so my thinking of using all the 1108 externals on the 1108 head doesn't sound so bad, & shop4parts do show them as being used on a few different later 1.2 cars.

Oh, my HR suspension kit arrived today - 40mm springs with new shocks so I'll be fitting them, my rear discs & polybushes @ the same time

 

[Smiler121]

Have tried ringing around - seems like nobody does a vernier pulley for the fiat 1108 mpi, you can get one suitable for the spi but not one for mpi that has the cam sensor "lobes".

Is it correct that you don't actually need an adjustable pulley if you can change the timing settings in the ECU instead?

 

[randomizered]

Cam timing vs ignition timing is a different kettle of fish and you cant substitute one for the other. But i don't think you'll have major issues not using a venier pulley. What are your plans?

You can also run the mpi ecu without the cam sensor linked up properly. I plugged the sei mpi cam sensor to the 1242 16v sensor, which is a totally different pattern, and triggered an ecu error....but it still seemed to run fine

Kristian

 

[Smiler121]

Ahh, just been doing a bit more reading & thinking - the idea of vernier adjustability is about timing the cam position & therefore valves relative to the position of the pistons & therefore actually not an ECU controlled thing, but lobes would be read to inform the ECU for ignition timing.

:bang:

Wasn't getting that before!!!

I had been looking for one 'cos I'd seen them mentioned as being helpful to accurately adjust for changes in relative head height after skimming & use of different compression pistons, but had not actually fully understood their role until now.

In all honesty, I don't so much have a real plan, as a general idea - looking to replace my 1108 mpi for 1242, had considered 1368 but don't think that I could re-use my existing head. I'd like to go for the simplest route of re-using my existing 8v head & externals, then maybe consider going for a custom ECU further down the line.

Was quoted only £20 per year extra for putting a P75 lump in

 

[fingers99]

Ahh, just been doing a bit more reading & thinking - the idea of vernier adjustability is about timing the cam position & therefore valves relative to the position of the pistons & therefore actually not an ECU controlled thing, but lobes would be read to inform the ECU for ignition timing.

I think injector timing. I think the MPI is at least semi-sequential. Maybe it reverts back to batch if the sensor is missing.

But it may be possible to introduce adjustability simply by removing the tang in the pulley. Remember, the tang is just for location, it doesn't actually hold the pulley in place. It's becoming common for engines not to have the tang (I don't think the 16v FIRE engines have it).