Hi guys, Ive joined the forum to try and find some answers

I bought a cooper s R53 a few months back, Its had this horrible flat spot since i bought it, ive read about others having flat spots on motorways ect ect, but cant find anything on what mine is;
Its like a stutter/flat spot from tickover, so booting it, then on every gear change. if i rev is slowly its fine, also when coming off accelerator it has a burst of power, sorry im really not very good at explaining stuff
So cold of hot if i rev the engine you can feel a noticable stutter.

I dont have much money so i replaced the following with used parts from ebay
coil/leads
throttle body
BPV
MAP
new belt
new plugs
new kavs 17% pulley (was doing this before i changed pulley)
Ive checked and double checked the IC rubber joiners

This problem has been here since i bought the car before mods

I get no more than 25 mpg if i drive like miss daisy not far off from what ive read

No codes are shown, i dont have the money for garage bills or paying for data logging ect, just wondering if anyone had any solid ideas as everything ive tried hasnt worked

also have a crunchy 3rd gear unless i move into 3rd slowley, (6 speed), it seems fine when cold, could an oil change fix this ?

 

Does it still have the stock engine management software on it?

 

Going to move you to the Stock Problems/Issues area.

What year?
Mileage?
What RPM does the stutter/flat spot occur?
The rubber around the BPV/TB is not soft?

 

Hi Thanks for replying, As far as im aware its stock and unmapped, but this problem has been here since i put the pulley mod on

 

the car is a 2004
110k miles
from tickover and every gear change
soft ? yes but not stretchy
to add i live in the UK
when driving it almost feels like its choking, then when letting off the accelorator it almost feels like it breaths easier and a slight burst of power
Ive put a standard air filter on and made no difference

 

You put cooler plugs in correct?

 

Hi, Yes cooler plugs

 

What rev range is the flat spot at?

25 MPG is about average for most folks.

Unfortunately you open yourself up to a handful of extra variables when you install used parts that you're not 100% certain work properly.

But. Assuming everything else checks out, you could have an issue with either the precat or the cat, I've had cars that run fine when driven like a granny but once you lay into it or build boost it would fall on its face and it came down to the precat either melted or broke free and spun in the header and was creating immense backpressure.

 

Hi its not the cat as ive de cat it, rev range is from tickover and every gear change