New engine. won't start.

[nalimugmug]

Have you tried squirting damp start into the intake?

Just a thought

Bob

[CRC]

You've got me intrigued now

Looked around the net and found a couple of different Honda part numbers for reluctor rings - one a photo and one a drawing, but they look remarkably similar to me.

A notice that there's also a TDC position plate on the end of the camshaft which I assume must be read by a sensor?

You've got my total respect for taking this on in this weather ...

[sparky Paul]

Looked around the net and found a couple of different Honda part numbers for reluctor rings - one a photo and one a drawing, but they look remarkably similar to me.

All interesting stuff, I couldn't find anything that pointed to them being different, or the same for that matter... I guess we'll find out when he delves into it.

There is a camshaft sensor, but the fault codes relate to the crank position sensor.

[Si Crewe]

This is very deep and way over my head, but I just wanted to suggest something straightforward, do you have the HT leads in the right order??

Good luck

Related to another comment, I AM getting advice and help (and borrowing tools) from a friend who's a superb car mechanic.

He kept insisting that we should pull apart the ignition wiring and try swapping the connectors around to try and get it to start - like I said, it DOES sound a bit like when, in the past, you pulled all the HT leads off a Rover V8 and then put them back in the wrong order.

Thing is, these days, the wiring loom is all so neat that there's no chance of getting it wrong.
There's just a neat little conduit that runs along the front and back of the engine and provides 8 connectors which clip straigh on to each of the 8 coil packs.

To me, there's no way the ignition can be "messed up" unless the ECU has properly lost it's marbles and is sending pulses of leccy to the coil packs at the wrong time.

As it turns out (if I'm right about the reluctor ring), I guess the ECU is sending out spurious pulses of leccy but only because the reluctor ring is telling to to do so at the wrong time.


Also, on a lighter note, when I was checking the plugs in the replacement engine I found it had 4 shiny new Champion plugs in the front and 4 crusty old NGK plugs in the back.
I guess somebody either didn't realise the Jazz has 8 spark plugs, or changing the rear ones was too much like hard work. 

I've actually been lucky, at this, insofar as I haven't encountered any seized bolts and things like the plugs all came out painlessly.

[CRC]

I would say that you're definitely onto something if the reluctor ring on your new engine has twice the number of teeth as your old one does ..... which makes me wonder what engine you actually have as the "twelve tooth" ring seems to fit every Mk1 Jazz engine I can think of according to the component suppliers websites ....

If you think about how the ECU probably works, it will almost certainly use the camshaft TDC sensor to determine the instant the engine gets to TDC and as there only seem to be 12 teeth on the CKP ring, then it probably uses the CKP sensor pulses to determine how fast the engine is rotating, in other words the RPM.

On a petrol engine, the instant of delivering the spark is critical ( compared to a diesel engine where the instant of delivering the fuel is critical) and the spark ignition point will vary hugely depending on rpm, load, temperature, throttle position etc.  The brilliant fuel economy of the Jazz engine is very much a function of getting the right amount of correctly vapourised fuel ignited at the correct time to allow complete burn and maximum energy utilisation.

As the CKP ring has only 12 teeth, it can't really be used as an accurate enough position sensor to determine the number of degrees before TDC that the spark needs to happen ( I'm used to shaft encoders on industrial machines that often deliver 360 pulses per rotation, but going much slower in general).

Given that there are only 12 teeth on the ring, the best resolution that can be achieved by using it as a position sensor is a very coarse 30 degrees, which can't be good enough to determine the spark point, so I assume that the TDC sensor supplies the TDC postion and the CPK sensor pulses allow the ECU to calculate the  RPM and then the ECU uses that information to calculate the "TIME after the last TDC" to introduce the spark.

Obviously if your ring has 24 teeth, then it would probably immediately send out an error as the ECU would be seeing twice the number of pulses from TDC to TDC and would twig that something was up as the data was "impossible".

I would imagine that it might possibly still try and spark, but, as you rightly say, the spark would be completely wrong as the ECU would think that the engine was rotating at twice the RPM that it was actually doing?

Having said all that, I have no idea of the function of the "double tooth" on the CKP ring, unless it's used as an indicator to say that the ring has done a complete rotation. On shaft encoders that I've worked with, there is normally a "channel B" that pulses to indicate TDC and allows the controller to reset the "channel A" pulse counter and start counting from zero again.

I'm pretty sure you're right, but would love to know what that engine is ..... a rare 1.5 perhaps?

 

[sparky Paul]

Related to another comment, I AM getting advice and help (and borrowing tools) from a friend who's a superb car mechanic.

He kept insisting that we should pull apart the ignition wiring and try swapping the connectors around to try and get it to start - like I said, it DOES sound a bit like when, in the past, you pulled all the HT leads off a Rover V8 and then put them back in the wrong order.

Thing is, these days, the wiring loom is all so neat that there's no chance of getting it wrong.

Agree, most of the modern injector and coil looms will only fit one way. The few times something will cross to another component, it usually looks wrong.

I think you are on the right track. I know it doesn't always give you the answer, but if the ECU is telling you there's something wrong with the signal from a particular sensor, that's where I start.

While you are in there changing the reluctor ring over, I would check the gap between the ring and the sensor - it needs to be quite narrow, and I have had occasions when a refitted sensor hasn't quite fully seated, due to scale on the outer casting for example.

Handy to have someone to bounce stuff off, sometimes just another pair of eyes on something can be a big help. Likewise, I have a good friend who spent most of his life in the trade and has seen just about everything mechanically, and knows all the tricks. I'm not bad with the diagnostics and electrical side, so we help each other out.

[Westy36]

I take my hat off to you fella. More work than I would even begin to attempt. Its been interesting following the progress of your project and I wish you all the luck with getting it sorted. 

[olduser1]

Tricky when you have an untested engine that's been changed around. If it were mine I would remove it refit to original spec and see if it started.
Good luck.

[sparky Paul]

Having said all that, I have no idea of the function of the "double tooth" on the CKP ring, unless it's used as an indicator to say that the ring has done a complete rotation.

The extra nib will be the TDC index point for the ECU.

I don't think the 30° nibs relate to any specific action, they are simply there so that the ECU can determine where the crank is in the cycle, in conjunction with the cam sensor. Injector and spark timing are dynamic and timed from within the ECU, determined from a number of engine factors. The crankshaft sensor pulses are also compared with the ECU's internal timing map to detect misfires.

[sparky Paul]

Tricky when you have an untested engine that's been changed around. If it were mine I would remove it refit to original spec and see if it started.

Agree, and a sensible idea, but not always possible when you don't have the ECU etc. to go with it. If you end up having to buy a used engine, they usually come bare.

Of course, the best option is to take a known good engine out of a donor yourself, but that's not always possible either.

[Si Crewe]

Well, there's more bits on the floor!

The reluctor ring out of my old engine has 12 teeth on it.

The ring in the replacement engine has... 34 teeth on it.
Also, it doesn't have a double-tooth on it to mark TDC. Instead, it has a gap where there are no teeth at all.
On top of that, strangely, the gap (which, presumably, is the timing mark for the sensor) is in a different place than on my old ring.

I HAVE set my old engine to TDC (and eyeballed the position of the pistons for confirmation) and looked at the position of the timing mark on the ring and confirmed that it's in the same place when fitted to the new engine.

Thankfully, Honda didn't decide to cut the keyway in the crankshaft in a different position in the replacement engine.
Also, I guess I'm lucky that my mangled conrod didn't wreck the reluctor ring in my old engine.

Anyway, fed and watered now so it's back outside to throw it all back together again.

I've been taking pictures so I'll post some up later on.

[sparky Paul]

Well, that would explain the problems!

I HAVE set my old engine to TDC (and eyeballed the position of the pistons for confirmation) and looked at the position of the timing mark on the ring and confirmed that it's in the same place when fitted to the new engine.

Thankfully, Honda didn't decide to cut the keyway in the crankshaft in a different position in the replacement engine.
Also, I guess I'm lucky that my mangled conrod didn't wreck the reluctor ring in my old engine.

Fortunately, the ring is tucked out of the way, and it's certainly a relief that the crank is the same. Things are certainly starting to look promising!

I'll give you 10/10 for perseverance! 

Look forward to the pics, they are always appreciated 

[Si Crewe]

It's alive! 

Still a lot to do but it's running well.

It's a bit of a faff getting pictures off my phone so I'll post more later but, in the mean time, here's the pic' of the cause of the problem.



My old engine had the left-hand ring in it.
The new engine had the right-hand ring.
Sump off, engine mount off, front cover off, water-pump pulley off, front pulley off, swap rings over and reassemble.

[CRC]

Top man!!

Really pleased that it all came together for you ..... perseverance and refusal to be beaten pays off in the end.

Well done.

[sparky Paul]

Well done, my friend! 

There's nothing like the feeling when it fires up... lots of buttoning up to do now!

My old engine had the left-hand ring in it.
The new engine had the right-hand ring.

There's a lesson for anyone doing an engine swap on one of these things, or indeed an ECU!