Cold Start Engine Problem - Can You Help (WM?)

Hi all,

Hope you can help. A mate of mine has a Y Reg Renault Clio 1.4 16v, it has had an on going problem since it was new and all the muppets at Renault seem to be able to do is plug their machine into the ECU. If it says there's a fault, fine, if not, well there isn't one, they have remapped the ECU twice now and the problem hasn't disappeared (which it wont do because IMHO it has f**k all to do with it). This kind of thing has pissed him off big time TBH, so we need an angle to tell them the next time it goes in for a service.

Basically what happens is regardless of ambient temperature the engine will hesitate from cold, like a manual choke car when the choke isn't pulled out far enough. The trouble is it only happens when cold, as soon as the car has driven for around a mile the problem goes away. It is just a minor niggle, and one he can live with, but really he shouldn't have to, it's not 1985, and it doesn't have a manual choke :banghead:

So chaps I need a few pointers (or ideally one unified one!!) as to what could cause this problem. Hope you can help us out here as he kind of looks to me to try and solve his car problems (as I'm “into†cars)

Cheers, Rick

 

Hi Rick
Im no expert, but to me it sounds like it could be an automatic choke problem. Hopefully someone can give a more educated response.

 

the car will have efi and therefore no choke. sounds to me like a sensor problem - modern engines have about 10 sensors all over the engine and exhaust system to tell the ecu what's going on. if one of these is broken or has an intermittent fault then you may get the symptos you describe. get him to leave it with the garage overnight so they can duplicate it on the test rig. he should have a good case for a free courtesy car by now as they've not managed to find the fault before and presumably they've charged for all the faffing they've done.
cheers


julian

 

Rick (it's been a while mate so you'l have to exscue any lapses), First check CTS (Coolant temp sensor from Memory about 6.5-8K Ohms (not exact figs ok), when stone cold depending on coolant temp), before firing it up, also check the 2 pin 'amp' connection on the CTS, check for Fir, green gunk/loose wires, crap on the spring pins inside the plug (pull the rubber boot back and check, but be careful, the wires can go hard over time).
Also check TPS/TS throttle position sensor/throotle switch I can't remeber which one it has, it may have a Stepper motor or Idle control valve, again check for crap/fir/loose wires (this one may have between 3 to 6 wires on the plugs, also clean the terminals, on both sensors and plug sockets , with switch cleaner or similar
Next check either, air flow meter/hot wire sensor (air box area or in take trunking), or MAP sensor, manifold absolue pressure (vacuam transduicer), all these sensors should be 5v Ignition on,, check all earths to battery, (pin out), the rest are return wires, to ecu or instructions coming back to indivdual components.
Could also be a fuel pressure problem, as in the pressure relief valve in the pump is u/s, causing the fuel to leak back to the tank, and not 'be in the system' straight away so to speak.
maybe a leaky injector (is it single point or multipoint?)
Thats all I can think for the moment I will need to consault my books (which aint here sorry) Tone

 

Thanks for that chaps,

Sorry for the delay in responding, I wasn't being ignorant but my house purchase has just gone through and I've only just managed to get back on t'internet.

That was some serious info there Tone!! I will leave that report in the car when it's dropped off, hopefully it will give them some pointers on how to fix a fault properly

I will probably go with that idea and suggest it's left with them overnight. Either way everyone (including me) is pointing towards a sensor fault rather than a software ECU fault, their probably trying to bodge the fault rather than fix it at the source - that would mean doing some actual work with a spanner and horrible oily stuff.

Thanks again,
Rick

PS : Happy belated birthday WM, it was mine on the 19th, not far off!!