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Robert
Robert, UK Car Mechanic
Category: UK Car
Satisfied Customers: 4424
Experience:  Fully qualified / self employed garage technician in the UK
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2004 Renault Megane. Bought used about 6 months ago. Ran ok;

Customer Question

2004 Renault Megane. Bought used about 6 months ago. Ran ok; but rough. Issue was motor mounts which were replaced. While I was at it, had the timing belt replaced, as it was time to do so. Soon after, at low speeds and often while changing hears the "check fuel injection" light would pop on, car looses power, and behaves as if its misfiring. However, if I stop the car, turn off the engine, wait a minute, and start it back up it seems perfect. Occurrence is irregular and unpredictable. Its almost like the restart resets....something. Of course, it will not happen when the mechanic looks at it. Ideas?
JA: How many miles are on the timing belt? Have you ever had to change it before?
Customer: Its new. Less than 1000 miles.
JA: What is the model of your '04 Renault?
Customer: Megane
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: No. I take it to a mechanic...who I think is pretty good.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 1 month ago.
Category: UK Car
Expert:  Robert replied 1 month ago.

Hi..there..

Ideally you want to be scanning the car for codes as first step..preferably with the "check" warning on as this will mean codes will be set in ecu memory..although they may want to check in pending and or history codes incase anything is logged there..if they have a good enough scanner of course.... If the car seems to run ok upto and till it plays up id asume the engine would be timed up correctly as far as the timing belt goes so that could be ruled out...things id say would be checked on is the engine wiring harness and plugs are secure if work recently was done on the car. check for intake leaks, check missfire counters on live data too see which cylinder maybe be playing up and if one cylinder is causing the problem investigate ignition system..lambda sensor performance needs to be checked..could be a bad lambda sensor..I do hope hope this helps