Espace 3 v6 non starter after engine change

[roy4matra]

There is a marker in the flywheel that the sensor picks up to determine tdc but as you say this is a 4 stroke engine which means that the crank rotates @ a different speed to the camshaft. Also the marker does not appear to be tdc on cly no. 1. With so many modern engines ther are no timing markings other than to time the camshafts & this is done when all the pistons are equidistant from the cylinder head as to allow the valves to open when positioning the camshafts. To determine tdc on no.1 i have viewed the camshaft lobe through the oil filler in the cam cover.   The document you reference to is for the older engine, mine only has the one sensor, interestingly the newer vvc engine reverted to two!
If it does not remember where the crank is when stopped, then how come it fires before it does one revolution before it sees the tdc marker?  Flywheel has not been touched nor camshafts, just complete engine out of one to another. I can see the gap in the flywheel, it is in the same position as other engine, I scoped the senor & it sees the gap. Swapped out sensor, swapped out coil pack, checked wiring, no faults in ecu. Swapped ecu even. Will check ecu to coil pulses next.

As Graham says Brian and I've said before, the ECU has no memory about where the flywheel was or stops, it simply starts again from scratch each time you attempt to start the engine.  This is why the start is quicker when you have a cam sensor too.

Now if it is firing the mixture even before it has 'seen' the TDC sensor mark, that suggests a fault.  Bear in mind though that if cranking speed is 240 rpm which is quite likely, then the flywheel will rotate 4 times in a second, so it will only take a max. of 0.25 of a second to start firing, and since the timing mark may be closer it could start firing even quicker.

Since you have a scope, you really need to scope the feeds to the coils and the firing pulses if you can.  Injectors are not so critical since they don't need to be timed and very often are not. Some engines actually open multiple injectors at one time, because as they are injecting into the intake manifold, some may be injecting in at just the right time to be drawn in to a particular cylinder whilst others may be spraying in whilst the valves are closed but it will 'hang around' and get drawn in when they open which will only be fractions of a second later.  You can work out the timing of opening and closing if you wish but at even 1000 rpm you are talking in milliseconds.

If it really is firing before the TDC has picked up and 'knows' the position/timing, then that might indicate you have a coil or coils firing randomly, maybe because of a short.

However, you have to go back to the fact that it worked before you swapped it over, and immediately after it won't start.  So logic says it has something to do with the swap.  Something that has been done, or not done, or some fault that has been introduced, such as a wire cut and shorted by the engine as it was lifted in or out...  It is rare and probably very high odds that something unrelated has happened at the very same time.

Regarding the backfire of the Easystart in the inlet, be careful (in both senses!) not only of injury but in misinterpretation.  By holding the butterfly open and using Easystart you alter the mixture ratio and because of valve overlap it is always likely that some ignition flame will come back in the intake.

P.S. Isn't this the engine with three coil packs at the 'front' on one bank of the V6 with H.T. leads to the rear bank?  If it is, then you could at least get a connection in to the H.T. feeds to the rear plugs.

Roy

[BrianM]

This has me dumfounded! I dont really know what to do with it. It would be a shame to scrap it after all the work I have put in. I could do with it on the road next weekend but think i'm going to have to hire a mpv again for the family weekend away. Fecking thing. Yes it injects fuel & the plugs get wet. As I spin it over you can see the timing change on clip but then it is too late as the plugs are wet. I put an adjustable resistor on the temp sender so it thinks its hot & not inject as much but it just backfires when cranked. Maybe the injection loom is shorted & its firing fuel all the time.

[Anders Dinsen]

I understand your frustration, Brian. This car deserves to run.

I read your post,, and I've been thinking a bit. I thought about wires, but you say you have the CLIP on, which reports everything ok. I thought about cam sensors, which 6-cylinder engines with wasted spark like this one incidentially do not need (unlike a 4 cylinder engine with wasted spark, and the later V6 used in the Avantime, which has a coil per cylinder and therefore need to know exactly which coil to fire).

I thought about ignition and the connection to the autobox. The gearbox retards ignition when it's shifting. Could there be a problem here? It's retarding so much that the engine can't start?

And then it occurred to me, that you may have a problem with the fitting of the flywheel (which is not really a flywheel on the autobox). I think I have a picture of it somewhere... yes here it is:



The TDC opening is on the left, barely visible in the picture (the flywheel was taken off my old engine when it was replaced with a new from a Laguna with manual box, after the cam belt came off 5 years ago).

Anyway, there's spark and fuel, but the spark must be coming at the wrong time. Have I missed something? I don't think so.

My suggestion is to get the gearbox off, and recheck the fitting of the flywheel on the engine. Something must be wrong...

Good luck!

I'll be picking up the Espace today. Really looking forward to going home to Denmark in it now :-)

Cheers,
Anders

[roy4matra]

This has me dumfounded! I dont really know what to do with it. It would be a shame to scrap it after all the work I have put in. I could do with it on the road next weekend but think i'm going to have to hire a mpv again for the family weekend away. Fecking thing. Yes it injects fuel & the plugs get wet. As I spin it over you can see the timing change on clip but then it is too late as the plugs are wet.

I'm not sure I understand you here Brian.  You say it injects fuel and the plugs get wet.  So whilst that tells us there is fuel getting in, it also says it is not being fired.  If it was the plugs would not be wet.  Wet plugs indicate fuel but no ignition of that fuel.  So as I've said before it appears the timing is out and/or you are not getting a good spark.

However, you also say you can see the timing change on Clip as you spin it over.  This I don't understand.  It is quite a few years now since I actually used a Clip, but I don't remember this.  Can you explain a little more please.

I put an adjustable resistor on the temp sender so it thinks its hot & not inject as much but it just backfires when cranked. Maybe the injection loom is shorted & its firing fuel all the time.

As you crank what does it show for the length of the injection pulses?  This should be in milli-seconds.

However, I don't think this is a fuelling issue Brian, it is a timing issue.  Since these modern engines don't have a key anymore to lock the gear to the crank, maybe the gear has slipped on the crank and the cam timing has slipped?  You really need to start from basics and check it all carefully.

Roy

[BrianM]

Hi Anders, glad to hear your getting yours back & heding home. I never removed the flywheel & I have checked that the reluctor is in the same place on this engine as my old one. I had brought the original ecu to this car also at one point just to see if there was a difference. There wasn't! crank, backfire, plugs then get wet & I have to remove them again to dry them. The gbox theory is now in the mix!

So Roy, it appears as if it stops sparking after the backfire. With the resistor on the temp sender it appears to be injecting less as i'm giving it a high temp reading. From memory clip displays the three coil pack advance figures. as i crank these change significantly, i cant remember the figures though. It is not easy to determine timing on an engine with no timing marks that can be seen. Neither the cambelt nor the reluctor were touched during the exchange. I need to check injector & ignition pulses, this is my next step.
to be continued.......

[roy4matra]

So Roy, it appears as if it stops sparking after the backfire. With the resistor on the temp sender it appears to be injecting less as i'm giving it a high temp reading. From memory clip displays the three coil pack advance figures. as i crank these change significantly, i cant remember the figures though. It is not easy to determine timing on an engine with no timing marks that can be seen. Neither the cambelt nor the reluctor were touched during the exchange. I need to check injector & ignition pulses, this is my next step.
to be continued.......

I remember you said earlier on Brian, you had not disturbed the flywheel and therefore the timing pick up so that can be discounted; so if the computer is 'seeing' that it should be able to calculate the correct timing - unless something else is wrong.  Since yours does not have a cam sensor, I was suggesting maybe the cam timing has slipped - not that you have done anything to it, but unknown to you it has moved.  That could account for a timing issue.

However, it is interesting that you say you think the firing stops after the initial backfire.  That needs to be investigated further.  Obviously if it does not continue to fire then that sounds like the root problem.  I think you said you have a scope, so that should be easy to check - you could even disconnect the injectors to stop them fuelling, and simply crank the engine for a period and watch the firing pulses - if they are stopping that should be easy to see.  Why might be harder to figure!  Could the knock sensor be involved here?  It should trigger a retard of the firing via the computer if it detects a knock but the backfire could be causing more of a problem.  Or if it can't detect the knock sensor, maybe it is shutting down because it won't know when there is a need to retard the firing.

These computers have failsafe modes where they shut down if they can't detect a signal they need, to save the engine from any possible damage.  Other times they have a 'limp home' mode where they allow a restricted running, but it may be yours is going into shut down?

Regarding not being able to see the timing, why not do a static timing set up and mark either the flywheel or crank pulley, wherever you can get a timing light signal on and see it, then connect a timing light and crank the engine and see if it really is firing and at the right time?

Roy

[BrianM]

Hi all, looking at this again. From what I can tell, this is firing on coil 1, when cranking, at 40 degrees. I thought it would be a lot more but I guess this is why I get a pop back through the inlet. I need to check that the other coils are respective & that there is not a short somewhere that makes them all fire at the same time.
Why would this be the case though? After all I never had the flywheel off. One bolt hole is 45 degrees which doesnt help me. I would have thought it would start at 5 - 10 degrees. Report again tomorrow

[BrianM]

Oh dear    crank is out 80 degrees to the camshafts. The ac compressor is siezed, maybe this held the pully from turning? All very strange.
 Turning by hand I can feel what I think is piston against valve. Off to buy another car for the holiday, again!

[WessexElectricNutter]

Oh dear    crank is out 80 degrees to the camshafts. The ac compressor is siezed, maybe this held the pully from turning? All very strange.
 Turning by hand I can feel what I think is piston against valve. Off to buy another car for the holiday, again!

Odd, but if the compressor had seize, surely the belt should be slipping to begin with and that shouldn't affect the crankshaft? I thought compressors are engaged by a electrical "clutch", unless something is feeding the electrics permanently.

[BrianM]

Yes all very strange, but there is no keyway on the crank to the sprocket to my knowledge. Just the tightness of the center bolt. I had pressure cleaned the engine before I fitted it so maybe this added to the siezure. The center of the pump will rotate but the pully is locked solid.

[roy4matra]

Oh dear    crank is out 80 degrees to the camshafts. The ac compressor is siezed, maybe this held the pully from turning? All very strange.
 Turning by hand I can feel what I think is piston against valve. Off to buy another car for the holiday, again!

Ah so I was correct in saying that the timing had somehow slipped.  Thanks for posting the answer Brian.  It is always good to know the answer to any puzzle like this as it adds to ones knowledge and experience.  Sorry it had to be something like this though.  Hope you find it has not done any damage when you get to repair it (assuming you will).  I did a repair on a Focus recently where the belt had snapped but only when the engine was being started, so although they are supposed to have valves hit pistons and bend them, if a belt has broken, as this had only been turning on the starter it turned out none were damaged and it just needed retiming and a new belt.  Finger crossed yours may be the same.

Roy

[BrianM]

Yes you were right   I'm going to use an old belt on it if it has stripped teeth just to see if it will run. Then i'll fix it up. (with a new belt at least) I still have the old engine so I have plenty of parts. It will go back into its original car & may be sell it, it a 'Initiale' so a nice model & has to be worth something!
I have a low mileage Laguna engine (already had the cambelt changed) & box that I want to fit in this one I'm keeping. Its the vvc fly by wire. So I need a scraped laguna for the throttle, wiring, ecu etc, or an Avantine of course.