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Mark
Mark, Auto Service Technician
Category: Ford
Satisfied Customers: 1504
Experience:  Qualified City & Guilds
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I have a 03 mk1 mod Focus 1.8 tdci which has started backfiring

Customer Question

I have a 03 mk1 mod Focus 1.8 tdci which has started 'backfiring' for want of a better term. At low revs and high torque it blows back out thru exhaust pipe high revs low torque has been ok but prob is getting worse.
I believe it's leaking back thru exhaust valve.
Exhaust pipe is on its way out so could this be causing prob with valve or is it just valve seating shot.
It could be beyond economical repair or is it worth giving a replacement exhaust a try ?
Submitted: 4 years ago.
Category: Ford
Expert:  Mark replied 4 years ago.

Mark :

Hello. My name is Mark and I will be assisting you today.

Mark :

I don't think replacing the exhaust is the answer.

Mark :

If the exhaust was blocked then it would be worse at high revs as there is more gas to remove.

Mark :

If it is under powered at high revs and also back firing at low revs then that could be a blockage.

Mark :

Your question isn't very clear about what is happening at high revs.

Mark :

Is high revs ok with no problem or is high rev ok but problem starting to occur at higher revs also?

JACUSTOMER-k0ijeoym- : Hi revs are ok cruising on m-way etc decelerating rapidly will cause a fast popping sound thru exhaust Problem is at it's worse when cold or when moving slowly in 2nd or 3rd gear again this cases fast popping/backfiring
Mark :

That sounds like you have a burnt valve or two.

Mark :

First thing to check is cylinder compressions and then a cylinder leakage test.