Unusual engine problem

[knoby]

2007 1.6 megane estate. 57000 miles. When driving the engine will sometimes cut out, no warning light or ignition light come up. Lifting fully off the throttle pedal & re applying it cures the problem every time. The same also happens when in cruise control, hitting the resume button cures the problem.When it happens, there is no feel of engine breaking & its so subtle any passengers in the car do not feel it, just assume i have eased up on the throttle.
I have had the car on diagnostics & amazingly for a Megane there weren't any codes at all. I have removed the throttle body & it was exceptionally clean. I also happened to have another throttle body which i fitted, but it did not cure the problem. The engine starts perfectly from cold, but can take a little encouragement to start when hot. I have checked all the pipework & electrical connections & found no obvious problems.
I suspect the throttle butterfly is closing, but can not find a reason for it to do so. Maybe software related or inlet manifold pressure related.
Anyone have any suggestions?

Thanks.

[VroomVroomClonk]

Hi,

Yes, I know this sounds completely mad but please stick with me just for a few minutes when I say that it sounds like a problem with your brake-pedal switch!

I had the same problem and it took me many, many months to work out what was causing it, but see here for how I finally managed to fix it.

If you doubt me, then please see here and here for other equally baffled owners who have had success doing the same thing

[knoby]

No, I dont think thats crazy at all. It is probabl ygoing to be something weird thats causing the problem & changing the brake switch is an cheap & easy thing to try. I will report back as to the outcome.
Thank you.

[VroomVroomClonk]

I wouldn't even bother changing it at first. Just try pulling the adjustable plunger out by a few clicks and see if that fixes it. (remember that the switch is in the passenger side on a right-hand drive car)
Both myself and Triumph2.5man did dismantle and clean the contacts in our switches, but neither of us found any noticeable problems with dirty or damaged contacts.
I believe the problem is just that the switch plunger needs adjusting to compensate for age and / or wear somewhere in the system.

Good luck, and please report back.

[knoby]

Ok, I pulled the plunger out 2 clicks & refitted the switch. The problem seems to have got worse, especially when using cruise control. Today I have put the plunger back to old setting & will drive it some more. I am actually hoping the problem will return to how it was before. If so, this would indicate we are on the right track. Will report back once I have established the effect.