VVC Running rich on Cylinder 1 (solved)

[pahu_CH]

Hi Blatchat

This is my first post on Blatchat… some info about me, my name is Patrick, living in Switzerland, Seven owner since 3 years.
Last year i started to rebuild a VVC Engine (160PS from a MG) to fit in the 7.So far no problem (with a little help from my friends and some mails with DVA*smile*).
Fitting the new Engine in the Car also no problem.

The following modifications have been made:
- Lighter Flywheel from TTV Racing
- New clutch (also delivered by TTV)
- EU Head Cover
- Timing of the Camshafts
- New Lambda-Sensor

When i started the Engine first time idle was at about 1200RPM.
When checking the Plugs, first Plug was wet and black the other 3 Plugs in a light brown (ok according to mi colleague). I changed the following:
- Changed Injectors Cyl 1 - 2
- Ignition Leads
- Ignition Coils (delivered by Elise-Parts)

After Changing of the Ignition components, there was no change in the behavior.
I took a ride and found the Engine lacking power, lots of rough running and missfires.
I bought a PSCAN-Interface and found out, that the VVC mechanism is stuck in the fully increased position (290°). I then fixed this by taking of the Cam-Carrier and honing the bearing surfaces oft he crosshaft. Afterwards VVC is working properly, angle is 223-225° at idle, idle is around 860RPM.
Compression  measured, 15 bar on all cylinders the same reading.
But Cyl 1 still running rich (Plug wet and black).

I cheked the live-data again with the PSCAN and found out that the Oxygen-sensor shows a very low reading and state „inactive“. I changed the Lambda-Sensor with the old one, now the readings are correct.
Afterwards i took another ride. The Engine is running ok (but not really good). After the ride (of approx 15min) i took out the plugs. Plug of Cyl 1 is still black (but not wet), the others are gray-brown.

Big question is there anybody out there with the answers, whats wrong….

Greetings

Patrick

edited: added changing of injectors, measuring of compression.

[Jonathan Kay]

While we're waiting for the experts... welcome, Patrick.

Jonathan

[SM25T]

Welcome to BlatChat. Hope you get it sorted OK .... and maybe we meet you at the St Moritz meeting the beginning of July.

[revilla]

Hi Patrick,

I also rebuilt a VVC 160 from an MG for my car and had a few teething troubles.

First of all - the sticking VVC - I know it appears to be OK now but just make sure that the camshaft position sensor is wired the correct way around, the K Series wiring diagram I hed from Caterham showed it wired incorrectly (the two pins swapped over) when compared to the Rover/RAVE diagrams and the result is that if the VVC duration is say too high, the ECU reads the sensor signal as "too low" and tries to increase it, so it ends up jamming hard against one end or the other, in my case apparently at random. If that is your problem, rather than being OK now it might just be locking the VVCs at minimum duration rather than maximum which would leave it idling fine but short on top end power. You would probably get a DTC logged in this case (from memory 1520 or 1521). You would also probably find the ECU limited the RPM to 5000 or 5500 - will it rev beyond these limits?

If No. 1 really is running excessively rich compared to the other cylinders, the only things I can think of might be:

1) Injector problem (but you say you have tried swapping with no improvement).

2) Injector drive problem from the ECU; I've recently seen an ECU with burned out lambda sensor drive so it's possible the output driver circuitry in the ECU for injector No. 1 might be damaged. You could try swapping ECU (and 5AS as a set) if you could get hold of one. I've got one you could borrow to try if you wanted but being in Switzerland the postage will be a bit steep.

3) Some kind of airflow obstruction into No. 1 but this seems unlikely; might be worth looking at the manifold gasket just to make sure it's not damaged / obstructing airflow.

4) There is a water channel from the head that passes through the inlet manifold gasket adjacent to cylinder number 1 to the "jiggle valve" that bleeds airlocks from the head back to the expansion bottle. If there is a problem with the sealing of the inlet manifold gasket, it could be drawing a little coolant into number 1 cylinder from leakage across the gasket. Are you losing any coolant? No idea what this would do for the combustion in number 1 cylinder but probably wouldn't be a positive effect. I did find that the manifold was slightly warped on mine so the gasket leaked first time I fitted it - it was obvious in my case because the engine made a noise like a loud whistle at idle. Careful adjustment of the tightening sequence of the manifold bolts was enough to pull it in flat once I had worked out in what way it was off-flat.

5) (Really just a wild guess) Does it sound OK? No excessive tappet-like noise? Just wondering if you have for example one hydraulic lifter that isn't pumping up and the consequent breathing problems cause it to appear to be running rich. In this case, compression wouldn't be affected.

Not sure if any of this is relevant to your problem but they are the first things that come to mind.

Andrew

PS: Welcome!

[revilla]

One other thought; assuming your exhaust manifold has the lambda sensor after the point where the primaries merge, it will see a kind of average of all the cylinders. If the lambda sensor is cycling normally but one cylinder is grossly rich, this would suggest that the ECU has trimmed to compensate which would leave the other cylinders running lean. Does the colour of the other plugs suggest they are running lean or normally? Is there any possibility that the blackness of No. 1 is not due to rich running but due to oil burning which could suggest a valve stem oil seal problem?

[pahu_CH]

Hi Andrew

A VVC EU2 Engine was already fitted in the 7. i took a EU3 Engine, rebiult it, took all the sensors and the head-cover of the old engine and fitted these to the new one. Si i don't thin, that the fault is a general wiring fault...

1) and 3) i already checked.

2) i will try to get a complete ECU to test this out

4) There is no leakage of coolant, there is also no white smoke from the exhaust

5) there is a tapping noise.I can' t lokate it, where on the Engine. The old engine made approx. the same noises, so i was thinking that this could be normal with the VVC engines. When i took of the Cam Carrier i tryed the lifters if they are hard. all the Lifters felt like pumped up...

6) the Piston in Cyl 1 looks wet (not as much now as before, when Plug was also wet). I swapped the Piston with a little piece of cloth and tryed to find out if its Petrol or Engine oil. i'm not shure which it is,but i think it's Petrol. All the gaskets on the Engine habe been changed while rebuilding. I will post a picture of the plugs tomorrow, so maybee you can see if its running lean on the other cylinders...

Thank you for the good inputs...

[SM25T]

The injectors each make a lot of noise ...... clicking like a sewing machine.

[revilla]

Regarding number 5 yes the VVC system does seem to be a bit noisy anyway, there is a certain amount of tapping from both my engines - I also put that down to being just the normal noise of the VVC mechanisms as both engines sound the same.

[revilla]

Do I understand correctly that you have re-used an EU2 cam cover to allow you to use the original EU2 ignition components, loom and ECU on what is otherwise an EU3 engine (with bigger throttle body, stronger pistons etc.)?

Two thoughts:

1) Are you aware that when they moved from EU2 to EU3, Rover in their wisdom reversed the blue / brown colour coding of the VVC solenoids? So if you have used an EU2 loom on this engine you will need to ensure you connect the wires as they would be on an EU2 engine and not as they would be on an EU3 engine.

Discussion here but images below:

http://www.acleach.me.uk/mg/VVC1.jpg

http://www.acleach.me.uk/mg/VVC2.jpg

2) The EU2 and EU3 engines used different injectors. The EU3 injectors were actually smaller and then run at a higher duty cycle to get a finer spray pattern and lower emissions. I know it seems odd that they reduced the size of the injectors whilst increasing the power. Which injectors have you used? If you are still using the EU2 ECU it will be mapped for the larger EU2 injectors, so you should use the older EU2 injectors. If you have used EU3 injectors it will naturally run very lean due to the reduced flow rate (unless you have fiddled with the fuel pressure too). If the ECU tries to trim for this, just wondering if it could end up outside the normal operational envelope of the injectors where the behaviour may be unpredictable?

[pahu_CH]

Do I understand correctly that you have re-used an EU2 cam cover to allow you to use the original EU2 ignition components, loom and ECU on what is otherwise an EU3 engine (with bigger throttle body, stronger pistons etc.)?
 

Exactly, but i used the original TB, Injectors, Inlet Plenum.... From the EU2 Engine. So basicly it's just the Block and head from the EU 3 Engine, all the electrical components and anciliarys are from the EU2 Engine...

[revilla]

In which case, if it was all working OK before, I'd be looking primarily at the things you changed, and the only thing that comes to mind would be the valve stem oil seal idea I mentioned earlier and it being oil rather than petrol - other than that I'm afraid I'm running out of ideas!

I'm struggling to think what else on a block or head would give the symptoms, especially if compressions all look OK. You don't mention anything about the head having been ported so I guess it's a standard head - I was just wondering about mismatched airflow between the cylinders if it had been badly ported, but on a standard head you should be able to forget that kind of thing.

You're sure the VVC mechanisms were synchronised correctly after you had the synchroniser shaft out? I would expect any timing error on one of the VVC units to affect two cylinders not one, but just a thought.

Post up the pictures of the plugs when you can and hopefully I or somebody else will have some more ideas.

[Bio]

Are you sure that the wet and black plug and piston top is not oil.....Damaged stem seals or oil control rings could cause this.

Does the engine use oil

[revilla]

You say the piston in cylinder No. 1 looks wet. If you warm the engine up the leave the plug out for a while, does it still look wet? I would have thought petrol would evaporate away quickly, if it stays wet I'd say it must be oil.
 

[pahu_CH]

Here pictures of the plugs:

The right one is cyl 1.... The left one was on Cyl1 before, after approx 15min running the black surface changed to almost white...

[revilla]

The plug on the left is cleaner and whiter than mine run. Mine are more of a tan brown colour. If 15 minutes of running is enought to turn the plug from the black colour on the right back to the white colour on the left, I would guess it is indeed running rich on cylinder 1 and lean on cylinders 2, 3 and 4, suggesting that the ECU has trimmed everything back to compensate for the one rich cylinder based on what it is reading from the lambda sensor.

What kind of exhaust system do you have? Standard 4-into-1 with single pipe exit through sideskin? Just wondering if you have anything different and there is any possiblity of any kind of obstruction to engine breathing on the exhaust side affecting just the one cylinder.

If you plug your diagnostic scanner in again, can you post up a complete list of any DTC fault codes logged?

Well if there is no reason to suspect airflow differences between the cylinders it must be fuel flow which is controlled as far as I can see entirely by fuel pressure (common rail so should be the same for all cylinders), injector size and proper functioning (but you've tried swapping injectors with no effect) and the signal from the ECU to drive the injector.

If I were you I would swap the injectors around once more just to be absolutely sure, then think about trying a replacement ECU just to see what happens. I can't see how a wiring fault could cause the injector be OVERdriven, if the injector is opening too long or flowing too much whilst open I can only think it must be a fault of the injector or the ECU drivers.

I have to admit - none of what I'm suggesting really sounds very convincing even to me but I can't think what else to suggest. Anyone else got any bright ideas here?

[pahu_CH]

Hi Andrew

I will be away the whole next week (working to get the money to try every possible solution*loser*)...

Next weekend i will try your suggestions above...

Exhaust is standard as described by you.

I'll try on...

 

patrick

[revilla]

By the way, sorry I keep forgetting that your EU3 engine has an EU2 ECU ... not sure what that provides in terms of diagnostic code capabilities.

I've just had a good trawl through the Internet looking for references to one cylinder giving the impression of running richer than the others particularly on K Series, and the suggestions always seem to come down to a stuck injector or poor compression on the one cylinder. So basically nothing that we haven't already thought of

Will look forward to an update next weekend.

[Jonathan Kay]

In the 70s we'd have borrowed a Colortune plug to find out what was happening... could that help?

Jonathan

[SM25T]

Clearing out a box in the garage today , I threw out a colourtune kit !!

[revilla]

Well I never - not heard of those before! With an EU3 head with its coil-on-plug packs you might struggle but as this engine has been retrofitted with the EU2 ignition arrangement it would probably fit OK. I guess it might show whether it was indeed the case that one cylinder was richer than the others, but there's precious little one can do in terms of "twiddling the mixture screw" on an EU2 ECU and it still seems strange that one cylinder would be running so differently to all the others.

@Ian - Exactly how far did you throw it? (i.e. could it be retrieved?)

[SM25T]

Not sure if it went to local tip or in our wheelie bin. Want me to look ?

[revilla]

If you wouldn't mind ...

[revilla]

Just one more thing to check. I'm assuming that both of the pictures you posted show the same two plugs, and that you haven't posted pictures of plugs 3 and 4? Can you double-check that plugs 3 and 4 really are running as clean and white as plug 2?

My thinking is this; injector faults normally manifest themselves the other war around - it's a lot more common to find one cylinder running lean and the others running rich where the ECU has compensated for the lean one.

As the water enters the head and block from the water pump at the front, number 1 may run a little cooler than the others.

I'm just exploring the possibility that it is actually a problem of number 2 running lean and all the others then running slightly rich, with it appearing more obvious on plug 1 than plugs 3 and 4 due to the cooler running.

Maybe another long shot but we seem to have exhausted all the obvious things!

[pahu_CH]

Hi Andrew

The Plugs on Cyl 2-4 look all the same (almost white coated).

I bought an ECU on Ebay today (complete with AS5 and FOB)... I hope the Parcel arrives until Friday*driving*....

[revilla]

OK let us know how you get on ... fingers crossed :)