Mi16 Question

[smokey 0]

Hiya guys

 

Just trying to sort out a discussion my flatmate and i are having.

 

Even though the Mi16 have an ECU and a coil pack. There is still a Dissy isn't there?

 

One came with my engine and we were trying to figure out where it went.

 

I think it goes on the front right cam (if your facing the engine)

[Anthony 1,003]

The is a distributor cap and arm, but no distributor per-se on 1.9 Mi16's.

 

2.0 Mi16's use individual coils, one per cylinder.

[C_W 3 1 Cars]

The 1.9 Mi16 has a normal coil that is bolted to the side of the inlet manifold.

[smokey 0]

The is a distributor cap and arm, but no distributor per-se on 1.9 Mi16's.

 

2.0 Mi16's use individual coils, one per cylinder.

 

 

Ok

 

Thanks for that. Just got all the bits out of the box and i have the small plastic bit which bolts to the end of the Cam and the Dissy Cap.

 

One thing which confuses me is i have 5 ends on my cap. Where does the extra 5th one go?

 

My Mi16 is a D6C 1.9L

Edited March 5, 2008 by smokey

[smokey 0]

After reading C_W's post

 

Does a HT lead go from the coil to the 5th point on the Dissy then the other 4 point go to the spark plugs?

[nick 3]

Your not building this engine alone are you.....?

 

Cam cover to the top, sump to the bottom......!!

 

[smokey 0]

Your not building this engine alone are you.....?

 

Cam cover to the top, sump to the bottom......!!

 

 

Lol no i'm building it with my flatmate.

 

He's built a fair few engines, just not mi16's.

 

He said to me that if an engine has an ECU it normally has a coil pack and no dissy.

 

But i was saying to him that my mi16 does have a dissy.

 

So going back to what i just said above am i right?

 

Lead from coil pack to dissy. HT leads from dissy to sparks?

 

(This is my 1st engine build though hence the silly questions)

[Miles 331 1 Cars]

Just think of it as your old 8v engine is the best way, Ton's of car's back in the 80's ran a Dizzy and basic ECU with AFM, odd as the 8v 405 SRI used a coil pack on later car's and they run allot better, slightly going off topic but gives you I hope a basic idea.

[Normski 1]

Lol no i'm building it with my flatmate.

 

He's built a fair few engines, just not mi16's.

 

He said to me that if an engine has an ECU it normally has a coil pack and no dissy.

 

But i was saying to him that my mi16 does have a dissy.

 

So going back to what i just said above am i right?

 

Lead from coil pack to dissy. HT leads from dissy to sparks?

 

(This is my 1st engine build though hence the silly questions)

 

Your both kind of right. The 1.9 Mi does have a distributor but all it does is give the spark to the correct plug lead, it's doesn't have anything to do with altering the ignition timing. The Ecu controls that. It's kind of in between the mechanical distributor and the modern wasted spark coil pack systems.

 

The distributor cap is connected the way you say.

[DrSarty 90 1 Cars]

There are 3 components on the Mi all triggered by the ECU reading what the TDC sensor says, which sits on top the clutch housing.

 

There's the ignition amplifier (on the inner wing with a heat sink) which IIRC, on a signal from the ECU triggers the coil which is bolted on top of the manifold to fire a high current pulse down HT lead number 5 to the centre of the dizzy (on the clutch end of the head - the arm being rotated by the inlet cam) to distribute the HT current to the relevant spark plug.

 

The S16 as someone mentioned has a second sensor like the TDC sensor mounted on the inlet cam, which tells the ECU to fire directly individual coils over their own spark plug. This system as a result has no dizzy, as all of the distribution is done at low tension level.

 

It's brill!

[smokey 0]

There's the ignition amplifier (on the inner wing with a heat sink)

 

Does my 1.6 engine have one of these or do i need a Mi16 one?

[DrSarty 90 1 Cars]

Yep all the same. Pug part 5945 48 'Module', by Bosch.

 

Might be worth replacing (though perhaps not from Pug direct if mega bucks) as they can fail when old.

[Henry 1.9GTi 36]

do the earlier Mi engines have a distributor? Ive seen a fair few pics of Mis with distributors I'm sure.

 

I know the ones with DIS (distributorless ignition system) use a pre programmed ECU which has the ignition timing pre-loaded into it for given loads. The knock sensor tells the ECU when the engine is pinging so the ECU retards the ignition timing then it slowly raises it incrementally untill it reaches the pre programmed advance again, assuming no more knock is sensed whilst doing this. Unfortuantly means not much tuning to be had with standard motronic as you cant use an agressive ignition timing map, or change it!

 

Rotor and cap still present along with one small coil. But as said all the timing is controlled by the ECU. I assume by varying the dwell time of the coil.

 

Hows the car coming along anyway Greg?

[GLPoomobile 958]

do the earlier Mi engines have a distributor? Ive seen a fair few pics of Mis with distributors I'm sure.

 

Probably ones that have retained the 8v jetronic system, so they use an adaptor to stick the 8v distributor on the end.

[smokey 0]

Very slowly mate.

 

Had a few problems with certain parts of the engine having surface rust on due where the engine was left.

Sadly did not see these when i bought it and have had to spend extra £££ getting it sorted.

 

Just got some 2nd hand liners from jonnie on here. As soon as i have those honed and new rings, the whole engine will be ready to be rebuilt and ready to go

 

Rest of the car is sanded down. Waiting for my flatmate to do some welding to it before i get the old filler out

 

How about you? Back at uni now?

[Super Josh 4]

do the earlier Mi engines have a distributor? Ive seen a fair few pics of Mis with distributors I'm sure.

 

Yep, all the 1.9 Mis have a dizzy, although it is only used to distribute the HT to the each spark plug. The timing is still controlled by the ECU.

 

 

Probably ones that have retained the 8v jetronic system, so they use an adaptor to stick the 8v distributor on the end.

 

Steve, you should go and look under your bonnet. You'll find a dizzy with your Mi loom

 

 

Josh

[GLPoomobile 958]

Steve, you should go and look under your bonnet. You'll find a dizzy with your Mi loom

Josh

 

Whatever

 

Josh, I know it is a distributor in the literal sense. But I, and I assume many others don't often think of it as a distributor in the same way that an 8v has a distributor. The 8v has a big chunk of metal with a vacuum advance stuck on the end of the cam, and we commonly call that the distributor, whereas the plastic cap is just referred to as the dizzy cap. I suppose in truth the whole unit including the rotor arm is the distributor. An Mi doesn't have this big metal thing we identify as a distributor, it just has the cap.

 

Hence why I assumed that Henry had seen pictures of Mis with 8v distributors stuck on the end, and was getting this confused and thinking it was the standard set up on early models.

 

 

One thing I don't understand about the Mi dizzy, is how the ignition timing actually works. With a mechanical dizzy you can adjust it's orientation to change the timing, and it has a weight thingymebob (that's the technical jargon for it ) inside and a vacuum advance that can change things. But on the Mi the cap (ok, ok, the distributor) is fixed in place and cannot move. It's driven by the cam, so the rotor arm inside will turn at the same speed as the cam. So everythig is pretty much 'fixed'. So how does ignition timing changes take place?

[jackherer 543]

But on the Mi the cap (ok, ok, the distributor) is fixed in place and cannot move. It's driven by the cam, so the rotor arm inside will turn at the same speed as the cam. So everythig is pretty much 'fixed'. So how does ignition timing changes take place?

 

The ECU fires the coil at exactly the right moment while the arm passes the correct post in the cap for several degrees and even if there was a bit of a gap the spark would jump it and still go to the right post. This means that the cap could be rotated quite a long way and the timing would still be spot on, right up until the point where the spark starts to go to the wrong cylinder. With an 8V distributor the trigger is in the distributor so as the advance mechanism moves so does the trigger point, whereas on an Mi16 the trigger is fixed on the crank.

 

8v distributors with clip on caps illustrate this perfectly, the caps are pretty loose and can be moved quite easily over a few degrees but this doesn't affect the timing as the cap just distributes the spark. To adjust the timing you have to move the advance mechanism on the cam.

[Normski 1]

^^ Yes, just to add, the metal contact on the rotor is quite long (~16mm) so each ignition event will have a window in which it can take place. With it being driven by the cam, it's going half the crank speed, so the rotors degree of movement needs to be multiplied by 2 to give the crank degree.

 

I happen to have a rotor in front of me and a bit of trig gives the window to be ~ 73 degrees of crank rotation.

 

How much does it actually alter the ignition by?