Megane 1.5 DCi Struggles to cold start.

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Megane 1.5 DCi Struggles to cold start.

Postby Liam-R » Mon Oct 29, 2012 5:22 pm

Hi all,

Hoping one of you boffins on here can help me with a few problems Im having with the megane II 1.5 DCi which I bought 2 months ago for the missus as im pulling my hair out day by day!


Ok basically, got the car from manchester, test drove it around message on dash said "card battery low' or something like, and dealer said was just the key card battery. Ok no worries, car drove spot on except for that light and "service" in yellow. Was told service light means it needed a service, pretty straight forward no problem.

Anyway, picked the car up few days later as it needed an MOT and taxing. Started fine, driving down the road... BEEEEEEEEEP "Check injection" on the dash. Pulled into a fuel station, filled up and carried on driving as no loss of power or anything unusual other than the message displayed on the dashboard.

Got home, searched internet for "check injection" etc and found many people saying it was the glow plugs. Ordered new ones from net etc. Done a voltage check and found out that one glowplug was totally dead other 3 were fine. Tried to remove the broken plug to find out the nut had seperated from the glow plug shaft so just span around. Tried a few things to get it out but nothing, eventually glow plug snapped in the head. So its now sitting with a broken plug.

Next morning, got in, tried starting and struggled to start. Took 8 attempts to start with a HUGE white clouds coming from the exhaust. Drives fine when started until I get on the motorway and put foot down which is when I get a "beeeeep" injection fault and red stop message which disappears after 5 seconds.

This is now the normal routine from day to day except it takes around 20 starts now its cold and has drained my battery twice.

Ive had the car 2 months and already im beginning to think I should have taken friends advice and stay away from renaults.

Ive searched high and low for answers which it could be but im on a tight budget (which is why I got this car as I thought it might help with money) and replacing injectors is a costly business and is NOT an option atm... especially when ive been reading that it didnt fix the problem for a lot of people.

This is what Ive done so far.....

Took the whole fuse box section out of the engine bay, checked all fuses... everything seems fine.
Purchased a used GLOW PLUG RELAY from ebay, as my old one was unplugged for some reason and was feeding a constant 12v to the plugs when I plugged it in.
The new relay is now showing constant 6v to the plugs which I think may be at fault too. With the newest relay plugged in, I get "STOP & Injection Fault" and car will not even attempt to start with immobiliser light stuck on. Turns over when the relay is unplugged and immobiliser light goes out but gives "SERVICE & Check Injection instead.
Ive checked the plug that goes into the glow plug relay, constant voltage at pin 3, 12v at pin 7 or 8 (cant remember off top of my head) with ignition on, pretty sure both pins 7&8 should have 12v not just one?
Ive purchased a new genuine fuel filter as there is air in the fuel lines (which will be fitted wednesday) have been hand priming since purchasing the car but still no joy.
There seems to be a different injector in number 1 cylinder, Has a purple band, other 3 have green bands?
Ive cleaned the EGR Valve, and the TDC sensor, No help at all....
Ive noticed the ECU has been opened for some reason and sealed with silicone.... Could this be the actual problem?

I hope a renault guru can help me out here!
Sorry for the long essay but trying to give you guys as much info as possible.
In the RAF and need this car to get home on weekends to see the other half (im quite mechanically skilled just have no idea about renault electronics)

Please please help, Thanks Liam.
Liam-R
 
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Re: Megane 1.5 DCi Struggles to cold start.

Postby neilm » Mon Oct 29, 2012 9:32 pm

not an electronic guru so apologies - but stop injection......appears on mine under sudden acceleration - then goes after a few seconds without power loss or any other symptom - worried me for the first 20,000 miles (point being no driving impact)- however i can see air in the clear supply pipe near the hand bulb - so my conclusion is drawn into the fuel pipe whilst under suction - due to leaky primer pump fittings, and under heavy acceleration gets drawn into (down) into the fuel system - temporary `injection fault` light.
only a small part but maybe it will help explain one possible fault.
good luck
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Re: Megane 1.5 DCi Struggles to cold start.

Postby Liam-R » Tue Oct 30, 2012 7:31 am

Cheers for the reply Neil.

Yeah that's' one job I'm hoping will be cured with a genuine new Renault fuel filter which I'm fitting tomorrow. When I turn the car off, the clear pipe from the primer bulb to the fuel filter empties within 15/20 seconds.
I have a feeling its the fuel filter or the "Non return valve" but I have no idea where this valve is located on the fuel line?
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Re: Megane 1.5 DCi Struggles to cold start.

Postby AlexB » Tue Oct 30, 2012 2:36 pm

Edited and shortened later: apparently, the OBD diagnosis was done, although not mentioned, and additional fault with the fuel filter existed, and the faulty glow plug relay was disconnected since the car was bought without any attempts to hide this problem... So, we have two independent faults and one of them is made worse by breaking off the plug, which, as I understand, did not fall into the cylinder.

This makes my earlier response meaningless, as I wrote it without knowing all details.

Hi Liam,

... It looks like the garage damaged your car... In any case, start with assessing the situation with the broken glow plug... Read the OBD codes as soon as possible in order to understand what is going on.

Don't blame Renault for the broken plug. The same plugs are used in many other cars. You didn't didn't attempt to remove the plug on a hot engine, did you?.. It is remarkable that the car still drives, and even more remarkable that you take it on a motorway.
Last edited by AlexB on Sun Nov 04, 2012 10:28 am, edited 1 time in total.
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Re: Megane 1.5 DCi Struggles to cold start.

Postby biggydoug » Tue Oct 30, 2012 6:27 pm

hi when i 1st got my megane i had the same problem check injetion when puttilng my foot down. the gargage did every think they could from changing injetors new pipes and any other thing they could do. in the end it turned out to be the fuel filter. thr problem was they had put a universal one on and my megane wassent happy at all about it so when they change it to oem one the problem went away and my car was grate after that. but it did happen a couple times after BUT my wife put petrol in it so that dident help
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Re: Megane 1.5 DCi Struggles to cold start.

Postby Liam-R » Tue Oct 30, 2012 7:53 pm

Thanks for your replies.

Alex I think you have read the situation totally wrong buddy...

Whats wrong with driving a car, whether it be on the motorway or around town, that works perfectly once it has started? The problem is getting the thing started.

Ive plugged a reader into the car, not a renault CLIP and it displayed "no faults"

Please dont get into the illusion that I have no idea how cars work, Im a mechanical engineer in the RAF and rebuilt many engines in my time, I just have no idea how the electronics are all over the place in this Renault, the STOP and injection fault will be due to the air in the fuel line being injected rather than fuel. I already know this is the cause and the OEM filter will fix the fuel line problem.

Anyway, I tried to remove the plug when it was cold, I do already know the head will need to come off, drilled, tapped etc etc, but when renault use the "Injection" error for a numerous amount of things then its not as easy to diagnose.

Ive done a lot of electrical current tests between the circuits on the heater plug system. On some forums I find that the glow relay should display 0v output when the key is out, others say <3v. The fact is, the car will NOT start with a glow plug relay plugged in when its cold. Once it has started, I plug the relay in turn off engine and restart, then engine fires up. This indicates there is a problem with the Glow plug system. The ecu has been opened so that rang alarm bells straight away.

A few people have said take it to renault to wipe the ECU of the codes and start again.

Im just looking for ideas instead of stabbing in the dark.


Didnt mean this to be any way offensive or nasty Alex, but thanks for your ideas, much appreciated.
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Re: Megane 1.5 DCi Struggles to cold start.

Postby AlexB » Wed Oct 31, 2012 5:04 pm

Edited later: Parts of the text have been removed as it became clear at a later stage that the glow-plugs were not hot-wired, which eliminates the hypothesis of the malicious intent. I need to revisit this problem and to look at the electrical diagrams...

Liam,

Yes upon reading my reply again, it looks like I am wrong. The glow plugs were hot-wired... Careful with the plug, the last thing you want is its parts falling into the cylinder.

Regarding the injectors, the only way to check if they are coded correctly is to use Clip.

Regarding removal of glow plugs - it is done on the hot engine, which is the opposite of what you attempted to do. It is down to expansion coefficients of steel and aluminium.

Operation of the preheating system is described well in the factory manual in the sticky thread. You may want to have a look. It provides different voltages to the glow plugs under different temperatures. There is a timer as well.
Last edited by AlexB on Sun Nov 04, 2012 10:33 am, edited 1 time in total.
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Re: Megane 1.5 DCi Struggles to cold start.

Postby Liam-R » Wed Oct 31, 2012 11:22 pm

Hi Alex, the glow plugs were not hot wired, I just connected a new one where the broken one would be, using the black cap ontop and earthing it to the battery negative so it tricks the car into thinking its actually all connected.

Changed the fuel filter tonight... NO AIR BUBBLES ANYMORE!! WAHOOOOOOOO...

Now, done some more checks... The glow plug leads on the car show a constant 6.5v when the relay is plugged in, and 0v when its disconnected. I have a feeling that both the relays are knackered or the ECU has been messed with. I would ideally like to borrow a working relay and hopefully that would be the problem.

If its the ECU, then im just going to wire up my own relay with a push button so I can control the glow plugs myself from under the dash as I really cant afford a new ECU :(


Thanks for your help once again Alex :)
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Re: Megane 1.5 DCi Struggles to cold start.

Postby AlexB » Thu Nov 01, 2012 12:08 pm

OK, I see... It is a good sign.

You've mentioned the voltage 6.5V. Is it when the lead from the relay is disconnected from the plug? Is the ignition on or off during the measurement?
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Re: Megane 1.5 DCi Struggles to cold start.

Postby Liam-R » Thu Nov 01, 2012 4:22 pm

No, its when the ignition is off, the relay is connected as normal. When I disconnect the relay, the voltage goes to ZERO at the plugs.

The voltage was being taken from the black plug that goes on-top of the glow plug.

Ive been reading a few places that this voltage should be ZERO.

When I try to start the car, it doesnt even crank or turn the starter motor. When the relay is plugged in once the car has already been started, then the car will start but with the "Injection Fault & STOP" message on the dash.
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Re: Megane 1.5 DCi Struggles to cold start.

Postby AlexB » Sun Nov 04, 2012 10:58 am

With the ignition off there should be zero voltage there. However, if the ECU is not in the sleep mode, it is possible that it is testing the glow plug circuits by applying a very small current. I am not sure about it, but possible. This small current will cause next to zero voltage across a glow plug due to its low resistance. However, when the plug is disconnected, its resistance is infinity, which may cause the testing circuit to produce a measurable voltage. The voltage which you observed on a disconnected plug (please confirm if it was disconnected!) looks very much like a testing circuit in operation. This conclusion may be not true if the measurement was done under load, i.e. the glow plug was connected.

This is something to check. I know, that 1.5dci use a lot of electrics different from my car (1.9dci). Therefore, it would be quite useful if someone with 1.5dci could pull the plug wire off and measure the voltage on it without load when ignition is off, but the car is powered up...

In any case, check the ground/power wires everywhere. The glow plugs take a lot of current, which may cause a glitch on ground/power, upsetting various other electronics. It is a long shot...

I'll look into the wiring diagrams later tonight. Liam, you may want to download the wiring diagrams yourself as well. The names of the files are in the sticky thread, search Google for them.

"Injection fault"+"Stop" can be due to the relay circuit doing something nasty. Is it possible to read the OBD codes exactly when the fault is being indicated? BTW, are you sure your OBD scanner is good? What model is it and what protocol does it use? Megane can respond to several protocols, but only the slow one (ISO something on the K-line) is for the general purpose equipment.
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Re: Megane 1.5 DCi Struggles to cold start.

Postby Liam-R » Tue Nov 13, 2012 8:39 pm

Hi alex,

What your saying seems correct.

Tomorrow im rigging up my own pre-heating system with a 100amp relay and moment switch in the dash to determine if it is indeed the relay, ecu or some kind of sensor that is causing the cold start problems.

The air in the fuel line has now gone! YIPPEEEE!

I had to use a can of easy start the other morning as a last resort as it was -2 and would never have started, squirted it in, first attempt and it started perfectly!

I was using a ebay jobbie obd2 scanner, which works perfect on my dad renault clio 1.2 but not on the megane. :/

I really need to take it to a renault specialist who will be able to plug it on the clip machine and reset the ecu!
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Re: Megane 1.5 DCi Struggles to cold start.

Postby AlexB » Thu Nov 15, 2012 8:50 am

It is, probably, a wise decision. On the other hand, I just looked in the wiring diagrams - everything there is not more complicated than a flash light... Basically, the preheating unit is connected directly to the ECU with 2 wires, ECU contacts GR F2 and D3 for K9K engines. One more wire goes into the fuse box. The connection to the ECU is capable to communicate the partial voltage information and provide the feedback, so expect a complex protocol on it (CAN bus probably). In any case, these connections must be checked, power and ground circuits as well, the next is replacing the unit and then the ECU... I hope it is not the ECU fried - check with an oscilloscope whether the CAN bus is alive or not.

The garage, of course, will not be investigating anything. They will just replace the preheat unit, then the ECU, then the wiring harness, if the latter does not help.

The glow plug control module is not a relay, it is much more complex. There is some very high-tech power electronics in it plus an embedded computer. These things are very sensitive to the quality of power/ground circuits.
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