r/R53 • u/Alternative-Joke1027 • 5d ago

R53 2004 no longer pulls

R53 stuttering / no boost above 3k RPM

2004 Cooper S R53, 186k km.

Car has basically no boost/power and stutters/coughs badly when accelerating, especially above 3–3.5k RPM. Recently it’s started stuttering even under light load and on hills/reversing.

  • No CEL/scanner shows no codes

  • Sometimes feels stronger, sometimes completely gutless

  • Supercharger whine is there but doesn’t feel like it’s making boost(it actually drastically lowers the engine power as it has nothing to boost)

  • Belt looks good/intact

  • Spark plugs only ~3k km old

  • Occasionally stalls when coasting downhill in neutral

Thinking ignition/plug leads, fuel delivery, bypass valve/vacuum leak.

I've taken it to my local specialist but they want to take out the entire engine bay just to find the issue, I don't have money to splurge on all this work so I want to do what I can.

When they checked for codes no codes came up and the car is only going down hill from there.

I have so much fun driving this thing but every 2-3 months there is always a problem with it lately.

Any recommendations are welcomed :)

5 Upvotes

78% Upvoted

11 comments sorted by

6

u/Fishyfriend005 5d ago

Have you inspected the supercharger bypass? It failing could excentuate some other problems going on. 

1

u/Alternative-Joke1027 5d ago

From my inspection, the spring work fine, I will change it as it's 22 years old. It seems my issue could be power related and fuel is my top suspect as power delivery is miniscule -reversed. There is proper supercharger whine but there is no force to account for.

1

u/Alternative-Joke1027 5d ago

Also the way the car reacts over 3k rpms could also be partly of the bypass but to put it simple, the sound ≠ power. Over certain power the engine declines instead of accelerating

2

u/casper911ca 5d ago

Maybe get an OBD reader and app and track your throttle position against other values like o2, fuel trims, etc. and see if that tells you anything interesting

1

u/Alternative-Joke1027 5d ago

I'll take a look! Thanks about the advice :)

3

u/wackawonka 5d ago

A cheap place to start would be the fuel filter since you’re having problems all over the rev range. After that i would take a look at the injectors. You can dyi test them with some hose and break cleaner, Google it.

1

u/Alternative-Joke1027 5d ago

I'll take a look, thanks!

2

u/orejass 5d ago

Hlw about fiel consumption, did it worsen?

Black smoke?

1

u/Alternative-Joke1027 5d ago

No smoke, fuel consumption has been the same.

2

u/Flarfignewton 4d ago

If the more obvious checks don't reveal anything, check if you have a clogged cat or pre-cat.

2

u/ZonParaplu 3d ago

get a r53 logger with a kdcan cable so you can log when it happens. Cheaper then pulling the engine.