Strange Misfiring

[top_driver]

car seems to run perfect until i press the brakes then it misfires on pressing then goes back to normal, anyone any ideas

[bhg481]

A bit more information could be useful. Petrol/diesel? Car age/mileage? Most cars cut the fuel supply when the engine is on the overrun, so there is no fuel to ignite anyway. Do you mean the car backfires and does it only happen when you actually press the brake pedal?

[top_driver]

its a petrol and 110 miles. i mean my car would be idling and i press the brake pedal and it would suddenly misfire release it and it slowly stops misifirng

[derekpara]

With only 110 miles on the clock I know what I would do !

But to clarify, do you mean a backfire ( popping from the exhuast ) or a misfire ( firing on only two or three cylinders) ?

D

[bhg481]

It could be the gasket on the inlet manifold or maybe a leak in the pipe connecting the inlet manifold to the brake servo. When you press the brake pedal the vacuum in the inlet manifold, which sucks the petrol into the engine, is used to operate the brake servo and a leak in this system can cause uneven running. Check the condition of the pipe connecting the servo to the manifold and also check the connections at both ends are tight. If that looks OK it could be the gasket between the cylinder head and the inlet manifold leaking.

[TWR]

Check the Flexi pipe the Mass Flow Sensor Tops.

[top_driver]

all the pipes are fine it only started after new brakes and sensors were fitted
and it cylinder misfires

[TWR]

I can not see new Brakes / Sensors having anything to do with the Misfire Tops, have you checked the Coil Pack? the do have a tendency to crack.

[top_driver]

everything is fine. i replaced the only faulty coil. also the brakes are not as affective well as my completely worn pads

[TWR]

When you removed the Coil Pack did you check the Plug Connector? the wires brake just above the Plug.

[top_driver]

plus a fault like that and it would be misfiring almost always

[top_driver]

its misfiring cylinders 4.5. 6

[bhg481]

New pads do need to bed-in before they reach best performance. Having said that, if there is a leak in the servo/manifold system that could explain both problems.

[Baldric]

///its a petrol and 110 miles.///

///it only started after new brakes and sensors were fitted///

@ 110 mls?

[top_driver]

i almost forgot to mention when it started the brake fluid
pushed its way out of the lid

[top_driver]

hahaha surely you would know that was 110k miles haha

[Baldric]

I do now ha ha!

[bhg481]

Mistake by whoever fitted the new brakes then Topdriver - you need to remove brake fluid when you fit new pads. I think I'd go back to whoever fitted the pads and have a moan.

[top_driver]

i will have to moan at myself.. the breaks were fitted properly i went over it in my head. but i forgot to leave fluid cap off when doing back breaks, and i was quite tired and didn't have anyone to bleed brakes with me, maybe there is a pressure build up causing leak from the servo which would be similar to pulling out the vacuum hose from intake

[TWR]

Naughty Naughty Boy, give yourself a slap then go for a pint. lol

[top_driver]

ha i think i might. i had to do it in minus not sure what temperature but i was split all over from the cold