High rpm misfire?

[Patrick Bateman]

At 14 secs, 22 secs and 31 secs.

Never had a misfire at high rpm before so assuming this is the case. Only ever happens in 2nd gear (although didn't go flat out in first right enough so might need to try that tomorrow) from around 5500rpm or thereabouts. When there's no load on the engine there's no sign of it.

Only noticed this last week. Tonight it was only in the last 10/15 mins of my journey that it seemed to do it (35 min journey), when the car must be fully up to temperature.

In the past year it's had the following done-

Spark plugs
Ignitions leads
Injectors

Timing belt was done in 2015 at a specialist. Get super unleaded from the same esso every time I fill up. Does this all point to a dodgy coil pack? Not sure what else is left given what's been done of late.

 

[flebay]

At 14 secs, 22 secs and 31 secs.

Sounds like the exhaust manifold if hitting the anti roll bar.
Also sounds like the exhaust is whistling/ blowing from the cat to mid section (most likely)

 

[Patrick Bateman]

That would be an odd one at a specific rpm range and linear acceleration would it not? I can feel the hesitation, it's not just a sound.

I've had the exhaust manifold hitting before when on and off the accelerator and it makes a definitive knock.

 

[imprezaworks]

Worth checking the exhaust on a ramp

 

[STEVE.M]

In the past year it's had the following done-

Spark plugs
Ignitions leads
Injectors

.

All proper stuff, not cheap substitues?

 

[Patrick Bateman]

Yeah all Renault OEM stuff.

 

[Patrick Bateman]

Tried shell v-power in it to rule anything fuel related out and there's no difference. I have a simple OBD code reader, is there a chance that could show anything stored without the EML being triggered?

 

[STEVE.M]

Tonight it was only in the last 10/15 mins of my journey that it seemed to do it (35 min journey), when the car must be fully up to temperature.

Does this all point to a dodgy coil pack? Not sure what else is left given what's been done of late.

Electrical windings tend to fail/ break down with higher temperatures, which would be consistent with the misfire occurring in the latter half of your journey. but

not the earlier part.

Replacing the coil pack £42, Bosch lambda sensors £37 each, & crank sensor with the uprated blue one , as they are all 15 years old would be sufficient grounds

for justification for me.

Did you check the compression of each cylinder when you changed the spark plugs?

My other thought is that the cat is collapsing.

 

[Patrick Bateman]

Compression never checked.

Almost totally forgot to mention this. A while ago now the car would occasionally hesitate to start from cold just slightly but on the odd occasion it wouldn't actually start. An immediate second attempt was always instantaneous though without a hint of any problem. This was along with a hesitant feeling for the first 30 secs or so of a journey.

When the ignition leads were done both these totally disappeared although in recent weeks these have returned. I wonder if this could well be linked with what I've got here.

The best way I could describe the hesitant feeling changing would be when I'm heading along the road on a steady throttle then the engine suddenly wants to pull a bit more without me having pressed the accelerator any more.

Once the car is warm there are no starting issues.

 

[Patrick Bateman]

Sounds like the exhaust manifold if hitting the anti roll bar.
Also sounds like the exhaust is whistling/ blowing from the cat to mid section (most likely)

Worth checking the exhaust on a ramp

Apparently this is the case!

How much potential adjustment is there in the position of the dogbone mount?

The gearbox was refitted fairly recently and it's likely since then that this has been happening. The dogbone was only replaced this year after the powerflexed one that was on the car had a little play in it so I can only assume there's some movement in it all before tightening it up as it didn't do it before.