Help with acceleration.

[Devon_Fourie]

Hi all, I hope someone can shed some light on a issue I am having.

When I accelerate through my gears and go past 5k rpm it starts making a very fine spluttering noise and struggles to rev more. If I am stationary and rev the car then it goes all the way up and seems fine.

It has 53k on the clock with a full service history. Sparks, oil and oil filters were all replaced in jan 2018. Regular oil top ups have been fine and I actually topped it up about a week ago.

I am concerned as I know these are delicate engine so if anyone can shed some light then that would be amazing.

Oh and no warning lights are on.

Thanks
Devon.

[SeeJay]

A failing cat would be my guess..the collapsing innards are 'strangling' the engine,with the effect you describe.

If you aren't able to drop the cat yourself,to inspect it,have an exhaust place do it asap.

[warpc0il]

How old are the ignition coils and ht leads?

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[Devon_Fourie]

I don’t know how old they are but it is a 08 plate and they have been replaced 2 or 3 times by the previous owner. He said they were not cheap ones either.

[warpc0il]

Some people would define £20 each as "not cheap".....

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[Devon_Fourie]

A failing cat would be my guess..the collapsing innards are 'strangling' the engine,with the effect you describe.

If you aren't able to drop the cat yourself,to inspect it,have an exhaust place do it asap.

My brother in law has a garage so I will ask him to put it on his car lift and inspect them.

[Devon_Fourie]

Some people would define £20 each as "not cheap".....

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The guy I purchased the car from is a work colleague and he has done some changes to car, eg new springs, filters, brake discs, brake pads etc and has gone for quality so I am sure they will be decent ones, he also dealt with a rotary garage in Market Harborough to do all his work so hopefully he advised on the right stuff.

[phoenix11]

Mine used to splutter when using low octane supermarket fuel, plus large numberplate relocated to bottom of front spoiler, which blocks airflow when car is moving quite fast.

[goodeggbob]

how many miles has the car done? as you say the coils have been changed 2 or 3 times ,that would suggest it has had at least three sets since new. i think you should investigate the coils a bit more.

[Devon_Fourie]

It has done 53k miles with a full service history from a rotary garage. I have a suspicion that it might be the cat as I seem to remember trying a obd checker on it before and seen on past warnings something about the cat. Does that have a sensor that could trigger a warning?

[98of400]

Take a look at my recent thread. Not dissimilar to you and it was solved by using 97/99 RON fuel.

[Devon_Fourie]

Hi guys, just a little update that I have noticed when reversing or walking around the back of the car that the exhaust fumes smell quite bad, it’s not a clean typical smell of a car. This leads me more to the cat system being full of crap and needs replacing.

The car starts, idles and runs absolutely fine apart from when riding for a while then going over 5k then it starts struggling.

Thanks
Devon

[warpc0il]

That could just be a sign of incomplete combustion.

Not enough sparks or too much fuel


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[98of400]

Possible dim question but does the car have a cat fitted? A decat would smell and it can also cause cat related OBD error codes.

[leetrx8]

I had this issue with my 1st RX8 just 8000 miles into a rebuild. I was also advised it was the CAT, fuel or coils. Gutted the Cat, nope. Changed the coils, nope. Tried different fuels, nope.
Took it back to Hurley's who rebuilt it, they had the car about a week, they swapped the spark plugs because the others "were knackered" (after 8k, doubt that) and still the same. They told me to take it to Ben, I drove all the way up there and Ben did look at it but again, nope, still the same as before. Wouldn't rev above about 6k. Started fine and everything else. Never fixed it in the end, scrapped the car.
After watching Car throttle and seeing the issue they had with the fuel pump, perhaps it was this but I'll never know. I was pretty pi**ed about it for a while. Didn't stop me getting another 2 after that though

[Devon_Fourie]

It still has the full stock exhaust system on it, I am sure the engine light came on once before which it does sometimes due to a k&n filter that was fitted prior to me owning the car but the light went out again, i purchased a obd reader and it had a error code previously about the cat system, i will try replace that first then move on.

It doesn’t always struggle over 5k but it will go past it but there is a slight hassle with it.

Thanks
Devon.

[Dazza44]

The k&N filter wouldnt cause it to throw a cel

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[warpc0il]

Unless it had been totally soaked in oil...
viewtopic.php?f=25&t=36391

[Dazza44]

Thats a good point dave, as i recently had a similiar issue were car would splutter at around 6k which was down to an oil burp my maf was contaminated and air filter and intake had oil over/inside it.

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[ninjarrr]

Sorry to ressurrect an old thread. Dazza - did you find what was causing your issue?

[Lemon]

did you clean out the resonator on the intake?

[ninjarrr]

Yep