Problem starting - 2.2dCi

[Martin Tyas]

If the car hadn't been OK for a couple of weeks after I got it back from the 72,000 mile / 120.000 km service then I would have thought that the starting problem was something to do with what they had done during the service.

Instead of it firing up immediately once the heater plug OK light has come on I now have to crank the engine over 6 or 7 turns before it comes to life and it can be even longer when the engine is already hot.

I've had a couple of doses of injector cleaning fuel additive through it and also changed all 4 heater plugs but it's still no better.

Anyone any other ideas?

I have wondered if it may be the heater plug relay that is malfunctioning but half the wiring loom seems to go into that and without a wiring diagram I wouldn't be sure which terminals are which and I haven't found anything in Lennart's "Vault" specifically relating to the this relay either in the G9T engine bulletin or in the German "electrik" PDF. But then I may have missed due to my lack of German language skills!!

thanks in advance for any input

Martin

[Anders Dinsen]

Hi Martin

There's probably nothing wrong with your German language skills, as the wiring diagrams aren't included in the "Electrics" manuals. I'm sitting here with the diagram for your car... and I'm think whether it would be of any use to you?

There's a lot of electronics in there and it could be lots of things that are wrong. The engine management computer seems to have more than 70 wires going in and out of it, and there's also several additional heaters too. I think the best would be to run a diagnostic scan on the engine computer, hoping that it "knows" what's wrong already.

I can make a scan of the diagram if you absolutely need it, and then you could work your way through each and every wire to check it. But as we don't have any means of checking the sensors, the chance of succes in identifying the problem is probably quite small.

I'm afraid that wasn't much help...

- Anders

[Lennart Sorth]

and I assume it is not related to the current UK contaminated fuel-scare ?
Initially I thought it was only petrol, but a number of diesel owners have had breakdowns as well ??

On petrol cars, the oxygen sensor goes awol - not sure what the diesel problem does to the engine, but certainly a lot of people have reported breakdowns. Mainly using fuel from Tesco and Morrisons, but now Shell have been mentioned as well.

But if a sensor is damaged, there should be some fault reporting in the car. hmm.

/Lennart

[Anders Dinsen]

and I assume it is not related to the current UK contaminated fuel-scare ?

WHAT is that about? It will take some effort to kill a car by putting something in the fuel, for example the "old trick" putting sugar in the tank (has been reported to kill german cars during the occupation in WWII) can not kill a car. Sand could probably, if you put in a lot, but sugar is just dissolved in the petrol and burnt in the cylinder.

So without knowing, I'd say that it's probably more of a rumour than a fact... but then again, I'm in Denmark. So please share some info. After all, fuel supply is a global business

- Anders

[TheJoker]

This one is very much real:
http://news.bbc.co.uk/1/hi/uk/6410511.stm

A colleague of mine has got his car in the shop

[Anders Dinsen]

Thanks for the link, silicone would be one interesting possibility and the SiO₂ being produced in the cumbustion is just rock so the expression of "a stone dead engine" gets a whole new meaning!

If the SiO₂ sticks to the oxygen sensor, then it can also stick to the valves or inside the cylinder. Hmm, this could turn out serious.

Silicone cant dissolve in almost anything, so I would think it simply stays on the bottom or the top of the tank. That could explain why tests have not shown anything.

[Martin Tyas]

Apologies for the delay in replying after you guys have spent the time in trying to help but I have been away on business and hadn't had the time to make it back to the forum.

It has since emerged that the problem with fuel was indeed due to contamination with silicone.
However, I do not suspect the fuel to be an issue as firstly the problems have occured with fuel supplied in the south of England and I live in the north. Secondly, the engine runs just fine once it has started.

The only problem is with starting which is why I immediately suspected that one of more of the heater plugs had given up. When having changed all 4 of them didn't resolve the problem I wondered if the heater plug relay was malfunctioning and that's when I started looking for info or a wiring diagram to the relay so that I could work out which terminals to run a multi-meter across and at least eliminate or otherwise the relay as being the cause of the problem.... preferably before having to take it to a Renault dealer. But I guess that's what I'll have to do and hope that the car's computer tells their magic box exactly what's wrong.... otherwise, based on previous experiences and those of others, they will simply change one component after another until they hit on the right one.... and at ever increasing cost to me!

Martin

[Martin Tyas]

I've been putting up with the poor starting for a couple of weeks now as it doesn't start too badly from cold and eventually comes to life when hot but now I really am going to have to get to the bottom of the problem because it now won't start at all.

Just my luck as well.... it had started OK from cold, ran perfectly throughout the 20 minute journey and got all the way home without any problem but as it's broken down at home it really is my problem because I'm not covered on the breakdown or tow away cover if the car is within a quarter of a mile of home. Think I'll tow it up the road and then call out the AA!!

When trying to start it the heater plug symbol comes on, then goes out and is replaced by OK as normal and no other dashboard warnings come on except the oil pressure warning.
I had been beginning to wonder if it could be the TDC sensor but thinking back now the starting problems seem to coincide with me having bought a new power inverter to get a 240 volt supply for my laptop from the 12 volt power supply at the rear of the console between the two front seats..... just hope that it hasn't screwed up the car's electronic box of tricks. 

[Martin Tyas]

UPDATE

It wouldn't start again this morning but just before I hooked up the tow rope to drag it down to the Renault dealer this lunchtime I thought I'd try it again..... and it fired up!!

I took it down to the dealership anyway and they phoned later to advise that it needs a TDC sensor as well as a Cam sensor.... parts are ordered, pick it back up tomorrow and get relieved of another £250.

Martin

[Anders Dinsen]

I took it down to the dealership anyway and they phoned later to advise that it needs a TDC sensor as well as a Cam sensor.... parts are ordered, pick it back up tomorrow and get relieved of another £250.

Hi Martin, the TDC sensor sounds very likely, they are very often the cause of problems. The cam sensor, I don't know... I would expect this to be a hall effect active sensor which doens't "go bad", but works until they stop. Unlike like the TDC pickup which is "just" the old style coil over a permanent magnet, and where it seems that the ones Renault uses are *not* very reliable.

- Anders

[Martin Tyas]

Hi Anders
I'd seen on the forum that one or two others have had problems with the TDC sensor so I half expected that one but really not sure that the Renault diagnostics system is so good that it can detect two faults at the same time!!.... and as you say it's likely that any Cam sensor (if they even have one fitted) is a simple Hall effect sensor which either work or they don't.
I am sure that you noted my cynicism.... but I can't help being suspicious about the supposed cam sensor especially knowing that this same dealer tried to charge a colleague for a diesel filter that they didn't change.

But we'll see tomorrow.... I may just surprise them and ask for the faulty parts and they can't use the excuse that they have to go back to Renault as the car is no longer in warranty!!

Martin

[Anders Dinsen]

It is *possible* that both have failed, but I think it's more likely that it's the computer that is confused. The thing is that if one of them is failing, the computer can't know which one it really is. It would have needed a third sensor to know for sure.  Of course it has certain criteria that must be met before it claims a sensor to be faulty, and I would expect that "weak signals" or something similar would be one criteria on the TDC sensor, but as there's no such thing as a "weak signal" from the other sensor, chances are that the computer is just playing the game safely, if you know what I mean.

Besides, Renault makes more money that way....

I guess I'd require them to change the TDC sensor and reset the error list in the ECU. Then if the problem persists, replace the other one.

Getting the old parts is always a good idea.

- Anders

[Martin Tyas]

I did a bit more browsing Anders and found reference to a camshaft sensor within the G9T engine-specific service notes (3444A.pdf) in Lennart's vault.
It is indeed a hall effect sensor made by Electrifil.... but that is the only information about it that I have found so far.
Now that we know for sure that it is a Hall effect sensor then despite what the computer may be telling them it may well be worthwhile, as you suggest, getting the TDC sensor changed first and see if it cures the problem before changing the camshaft sensor.
I'll update you tomorrow.... thanks for your input Anders.

Martin

[Anders Dinsen]

I'll update you tomorrow.... thanks for your input Anders.

You're very welcome. I'll be looking forward to reading the next chapter here...

[Martin Tyas]

Hi Anders.... just to let you know that the Renault dealership phoned back to advise that changing only the TDC sensor cured the problem and cleared the fault code in the ECU.

But having collected the car later I'm still not so sure that it actually starts as well as it used when cold but it is certainly better than it has been when hot. However, I did also got more of an insight into what the diagnostic was telling them. It seems that it showed an incoherance between the TDC and Camshaft sensors.... or in other words the position of rotation of the camshaft didn't match with where the ECU expected it to be in comparison to the position of the flywheel. So that's why they'd said that they would need to change both sensors but the reality was, as suspected, that it was only the TDC sensor that was at fault.
So, thanks for your input Anders.... it was good to have someone to bounce off this problem.

Martin