Independent Renault Forums banner

1 - 20 of 74 Posts

·
Premium Member
Joined
·
172 Posts
Discussion Starter · #1 · (Edited)
There seems to be a recurring non-start problem with the 1.5 dCi; there have been numerous threads regarding this recently. Rather than type the same thing in response to each new poster, I thought it'd be good to make a check list of basic, initial tests to narrow down the problem. The thread can be linked to in future when a new non-start thread pops up.

This list is not exhaustive and is not necessarily designed to find the fault. It is designed to furnish you with a better picture of the health of various components of your engine that can affect starting. This thread is a starting point only: further research may be required by you after running these tests to determine the exact nature of the fault.

To anyone with a reasonable level of mechanical knowledge, this information will be teaching granny to suck eggs so it is not designed for you. I'm well aware that you know all of this information (and more) already. This is to help people who may not know about these things to check.

Much of the data has come from my (2001-2005 Clio) Haynes. If you haven't got a Haynes, buy one: it's cheap and will help you.

One last thing: the below is only to be used and acted upon if you have more than 2 brain cells. Please check to see if you're an idiot or not before trying any of these tests. If you find that you are an idiot, please do not procede any further. If you break your own car, it is your fault. You are an adult: make an informed, reasoned, balanced decision to continue. If you get a kick out of fixing things that are broken and enjoy saving money, please continue.




So, your dCi didn't (or struggled to) start this morning and you've just posted a thread about it on the forum.

Did it turn over fast or slowly?

Put a multimeter across the battery terminals with the engine off. What is the voltage? It should be ~12.6v (Haynes, 2010) or more.

Now put the multimeter across the terminals with the engine idling. What is the voltage? It should be between ~13.5v and ~14.8v (Haynes, 2010). If it is, congratulations; your alternator and auxilary belt are working well.

If your voltage is low at rest, your battery *may* be at fault, you may have a parasitic drain or your charging system may have a fault (which should show up in the idle test).


Are there any DTCs?

Diagnostic Trouble Codes. Ideally use CAN Clip or DDT2000 to read the Renault-specific codes. Alternatively, use a cheap eBay ELM327 wireless/bluetooth adapter and a free app (Torque for Android or something similar for Apple) to interrogate the car's ECUs.
If there are DTCs stored, what are they? Google the code to find out more.
The code could be a red herring! Delete all of them and run/start the engine again. Now reconnect the code reader and check for DTCs again. Are there any there or are they all gone? Any new ones now are likely to be genuine codes, not red herrings. Investigate these.

If a code points to a particular sensor, the resistance readings of that sensor can commonly be found in Haynes or online. Before condemning the sensor, test it with your multimeter!

Clean the TDC sensor.

Top Dead Centre.
This is recommended commonly on the forum for any non-start issue, including petrols. As the sensor collects ferrous particles over time, the signal to the ECU can become weak/erratic. A quick clean may solve your problem.
The sensor is located in the top of the bell housing.

Clean the EGR and intake pipe.

Another commonly recommended course of action is to clean the EGR and the inlet pipe, at the back of the engine. They can clog up and cause running issues. An ill-functioning EGR will likely (but not always) throw a DTC.

Are your glow plugs working properly?

Your engine prefers working glow plugs in order to start. The injection pressures in a DI diesel are usually enough to start the engine without glow plug assistance in all but the coldest climes, but having the plugs working properly certainly helps.
Using your multimeter, measure the resistance between the upper wiring contact and the glow plug body. You can do this in situ to save breaking out the socket set and potentially snapping a plug off in the head. Each plug should have a resistance of 0.6 ohms (Haynes, 2010).

*Check the inherent resistance in your multimeter leads before this test, then remove this number from the indicated glow plug resistance to get their true resistance!*

This is a good video of how to test your glow plugs:
https://www.youtube.com/watch?v=4Po_1pNHE1Y
Yes, it's for a D5 engine but the principle is the same.

Have you got a voltage supply to your glow plugs?

Put the multimeter back to VDC and check that the glow plug supply wire is receiving voltage when the ignition is switched on. It should maintain a voltage for several seconds after the glow plug light has extinguised, too.

Carry out a leak off test.

If your injectors leak back too much fuel they will rob the rail of pressure and the car will struggle to start (if at all). This is a known mode of failure for DI diesel engines, especially ones using a common rail.
You will need 4 lengths of tubing to attach to the return line output of each injector and 4 bottles for each to drip their fuel into. This equipment can be bought for very little cost. I've used tubing from a DIY store and drinks bottles with holes cut in the caps before to run this test and it has worked perfectly.
The return lines are under no pressure so you won't cut a limb off with high pressure spray, don't worry.

Start the engine (use Easy Start if you have to) and allow it to idle for a few minutes, max. The permissible fuel leak back differs between manufacturers but if one (or more) of your bottles looks like this, you have a failed injector:
https://www.youtube.com/watch?v=Gaqx9ATOg3A
The other three injectors in that video are leaking back agreeable amounts and are fine.

Enjoy that video? I thought so. Here's another:
https://www.youtube.com/watch?v=F9pTdgxk20Y
After idling for ~1 minute, that guy has very little fuel in each cup. Did you notice how quickly and easily the engine started at the beginning? That was not a coincidence.

You are looking for consistancy here, not necessarily outright volumes. Searching Google and Youtube for 'Leak off test' should furnish you with all the information and examples you need to carry out this quick, easy, cheap and illuminating test.

If one or more of your injectors fail this test, they require refurbishment (specialist) or replacement. You can buy new or take a punt on a used one from a known-good engine. New or used, it'll likely require coding to your ECU. This can be done in CAN Clip or DDT2000, I believe. A suitably equipped garage or the main dealer can, of course, also do this.



That's the quick, basic list done.
Other faults can and will stop your car from starting, the above are just some common examples for the 1.5 dCi.

I've written all of this in relation to my 2003 Clio dCi 65 engine. I'm sure many are the same/similar but care should be taken with considerably different units (much newer, higher power output etc.) to ensure correct procedure and data.

If there are any Renault-specific glaring errors with any of the above or if you would like to add some more points for owners to check, chime in by all means.

:)
 

·
Premium Member
Joined
·
824 Posts
Nice thread.

Suggestion though, maybe you could alter each title with either a DIESEL or PETROL header. Just saves people looking for things on their car that don't exist.
 

·
Premium Member
Joined
·
172 Posts
Discussion Starter · #4 ·
The thread is designed for the 1.5 dCi only, I don't have any experience of the petrols!
 

·
Super fantastic Mod Technical Supremo Nice Guy
Joined
·
37,906 Posts
Very well written sir ,,would be nice to see how many people read this and cure their problem...then thank you for this post .
 

·
Super fantastic Mod Technical Supremo Nice Guy
Joined
·
37,906 Posts
because it will allow people with no experience on cars to check these (simple things to us)first before asking questions,,
 
  • Like
Reactions: 170421

·
Registered
Joined
·
1 Posts
Hi, does any one have a location of the TDC sensor on the 1.5DCI, our car is turning over with the odd fire. I am hoping the TDC sensor is at fault otherwise I'm thinking the Fuel pump could be the issue. Although the only code present is Glowplug relay, I know this wont help but it should start in this mild winter.
Ive looked in the obvious location which is middle of Engine/Gearbox.... please help so I can get to work in the new year :-(
 

·
Premium Member
Joined
·
172 Posts
Discussion Starter · #13 ·
I haven't found cause to look at mine just yet but understand it to be located in the top of the bell housing. Remember that it takes its signal from the flywheel so you'll find it around the periphery. You may need to move the hoses and wiring in the area to find it.
 

·
Registered
Joined
·
4 Posts
Carry out a leak off test.

If your injectors leak back too much fuel they will rob the rail of pressure and the car will struggle to start (if at all). This is a known mode of failure for DI diesel engines, especially ones using a common rail.
You will need 4 lengths of tubing to attach to the return line output of each injector and 4 bottles for each to drip their fuel into. This equipment can be bought for very little cost. I've used tubing from a DIY store and drinks bottles with holes cut in the caps before to run this test and it has worked perfectly.
Quick query on this, trying to do it on a 1.5dci 110ps 2008 Laguna engine as there is some random faults (ill put up a separate thread if this doesn't give answers). The issue is that the return line nearest the pump has a double outlet and the pipes are the hard plastic ones on it so don't pop off easily. Is it ok to man handles these off or are they under high pressure too?
 

·
Super Moderator Technical Supremo Platinum Member
Joined
·
22,112 Posts
Returns aren't under high pressure.
But will spurt fuel out on cranking
 

·
Registered
Joined
·
1 Posts
Hi experts!
1.2 clio 2009 done 48k miles
Realised vehicle was using oil
Then did diagnostics and did coil packs and plugs..then did a couple of tanks of fuel..only getting average of 36 mpg .compression test good . Did exhaust splatter test..fuel being emitted ..any ideas?
Thanks in advance
 

·
Super fantastic Mod Technical Supremo Nice Guy
Joined
·
37,906 Posts
Did exhaust splatter test..fuel being emitted .:surprise:
Can you explain,
 
1 - 20 of 74 Posts
Top