Laguna mk2 : warm (petrol) engine starting problems - Renault Forums :: Independent Renault forum

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post #1 of 21 (permalink) Old 7th January 2017 Thread Starter
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Laguna mk2 : warm (petrol) engine starting problems

Hi,

I'm having problems with my Laguna 1.6 16v 112hp - has 125k miles.
It never starts right away/good when car is warm - when I turn off the engine and let it cool for 30 min - few hours. I also smell gas in the cabin after it has finally started. Sometimes it seems like it has started - then it just dies out.
It's always ok when it's still hot...so if I just restart it or start it again after 5 minutes. It's generally also ok when it's totally cold - happened only once it didn't start up cold otherwise, it's always no-problem.

Car also has lpg installed. When it's running (petrol or lpg) there's never a problem - runs ok.
What I noticed is that the engine isn't as calm as it used to be. When I stop the car the rpm is is slowly dropping from 1000rpm to cca 700. This always used to be just below 1000 - and car it then not so "shaky".

I've changed/repaired lots of stuff in trying to fix this issue - all with no luck! My repairs:
- Changed thermostat with coolant temperature sensor (was leaking)
- Changed crankshaft sensor with wiring
- Changed camshaft sensor (http://www.renaultpartsdirect.co.uk/...61091_zoom.jpg)
- Changed air intake sensor (http://i.ebayimg.com/images/g/fMsAAO...6Dx/s-l300.jpg)
- Cleaned the fuel injectors
- Changed spark plugs
- Changed the battery
- Changed ignition coils

Some say I need to do a compression test (which I did 2 months ago and was ok), cause LPG might have done damage to the engine. But then it generally wouldn't run ok, not just having problems with warm start.. or?

I'm really running out of options here. I've thrown too much money into this car and yet this problem persists. I'm sick of always thinking if it's even gonna start when I'm approaching the car after 1h of stopping it.

If someone has any idea please help.
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post #2 of 21 (permalink) Old 7th January 2017
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Re: Laguna mk2 : warm (petrol) engine starting problems

My gut feeling is coolant temp sensor, except you have swapped it.
Was it a genuine Renault part or a generic aftermarket?
Reason for the feeling is that what you describe is typical of auto choke problems on carburettor motors.
Engine cold enough to need choke but too warm for the choke to operate.
Modern equivalent is often CTS.

What state were the plugs in?
Any sign of overfueling or burning?

Is problem confined to one fuel ?
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Re: Laguna mk2 : warm (petrol) engine starting problems

Hi,

Thanks for your reply.
The thermostat isn't genuine Renault, but aftermarket.
Problem is on both fuels. Plugs seemed ok.

I'll try to get ahold of another sensor and test.
I was thinking if maybe some there's an issue with some relays/fuses or wires. Is there a way to test the sensor, maybe on a tester?
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Re: Laguna mk2 : warm (petrol) engine starting problems

Oh a question...I know how I'd replace this sensor, but I'm not sure regarding the coolant..when I remove the sensor it will probably start flowing out of the thermostat?
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post #5 of 21 (permalink) Old 7th January 2017
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Re: Laguna mk2 : warm (petrol) engine starting problems

Put a sheet of polythene (plastic bag) under pressure cap and tighten.
Will hold a vacuum so will only get a dribble.
Work fast
Remove placcie when finished.

Bear in mind this is only a gut feeling of mine, no guarantees but is where I would start.

Give the wiring and connections a good coating of looking at as well.
Normally issues there would manifest more on cold starts but any corrosion, nasty looking green gunge, worn cables or insulation...can all affect to an extent.

AFAIK, no foolproof way of testing a CTS..... yes you can check resistance at specific temperatures but you are relying on a variable resistance over a temperature range and if slightly off at a critical point, bu55erred !
But to all intents, a perfectly good sensor that tests out fine.
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engine , laguna , mk2 , petrol , problems , starting , warm

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