How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Matt Your Own Question
Matt
Matt, Mechanical Engineer
Category: Renault
Satisfied Customers: 22142
Experience:  BEng hons Mech engineering, in auto industry 22 years
12772297
Type Your Renault Question Here...
Matt is online now

Renault scenic 2003 1.6 problem is intermittent either

Customer Question

renault scenic 2003 1.6 problem is intermittent either difficult to keep revs going when starting .can start and tick over between 5-7.v thou revs but can cut out and need to touch accelorator to keep going or will start and engine revs up in nuetral to 20 thou revs. also when driving in all gears feels as if engine racing .also stopping at lights/junctions handbrake on in nuetral engine will either race up to 20 thou or drop right off and cut out/only kept going by pressure on accelerator. car has done 135 thou miles
Submitted: 3 months ago.
Category: Renault
Expert:  Nicola-mod replied 3 months ago.
Hello,
I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.
I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.
Thank you!
Nicola
Customer: replied 3 months ago.
please continue
Expert:  Matt replied 3 months ago.

Hello

can you tell me if this is the petrol or diesel engine?

also how many miles are roughly on it and when it was last serviced?

Customer: replied 3 months ago.
mileage is 135,300 petrol 1.6
Expert:  Matt replied 3 months ago.

Hello

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

air / vacuum leaks can be very temperature dependent as things in the engine bay will expand as they warm up so you can have leak that come and go with different temperatures

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Might also be worth cleaning out the throttle body as these get clogged up with carbon and some brake cleaner washed through helps free things off.

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

It’s also worth cleaning the MAF sensor wires, as they can get coated with dirt over time which then offsets the reading

Use some contact cleaner or brake cleaner to spray onto the wires to remove the dirt – on no account touch the wires with anything as they are very fragile

Expert:  Matt replied 2 months ago.

Hi
do you still need help?
Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you