Hello everyone,
I was wondering if anyone could help me with advice on my 2005 Mini Cooper s that has engine ping under load. My car has 150k miles, I recently installed a 15% reduction pulley as well as a magnaflow cat back. The engine ping has started about 3k miles ago, and the car is lacking power obviously. I checked the fuel pressure which charged up to 51 psi, 42 at idle and under WOT it goes to 54 psi. I seafoamed my engine, checked the plugs as well as the vacuum. Has anyone had these issues before and solved it? Any input would be appreciated, thanks!

 

Did you put colder spark plugs in when you changed the pulley?

 

If you're using the highest octane gas you can find, the chances are that the knock sensor has gone bad.
Check the wiring first as changing the sensor is a bit of a performance, it's all labor, the sensor is around $50.

https://www.pelicanparts.com/techart...eplacement.htm

 

Oo

when I did the pulley I bought the wrong plugs, the NGK 6 series iridium plugs. I just recently installed the correct NGK 7 series iridium plugs that are a step colder.

 

Would the knock sensor be bad even if my check engine light is not illuminated?

 

I don't think a bad sensor triggers the CEL, but it should generate an OBD code P0325. Do you have that code? or any others?
Do you routinely use the highest octane gas you can find? This is important on a MINI.
The spark plugs don't really have any effect as long as the gap is correct - since your plugs are new you should be OK.
I'd check the wiring & plug & socket for corrosion first as not much dis-assembly is needed.

 

I checked on my code reader, and there are no codes. I only use 91 oct as I am in California for it’s the highest oct available except for 100 oct racing fuel. The wires are new, but the coil pack is original. Curious to see if maybe there is some corrosion in the coil pack. Wires look fine

 

91 octane gas is fine.
Cleaning the coil pack plugs, especially #3, is a good idea, but would cause a misfire rather than pinging.

It's the knock sensor wiring plug, under the intercooler, that needs to be checked for corrosion.
The sensor is a microphone; is it possible there's something loose & causing a tapping noise?

Other than that, there are a couple of YT videos that might help before you tear the entire front end apart!

 

thanks for your input. I checked the plugs which look good. I did a compression test, which resulted in all cylinders having different readings which is a concern. Don’t know if that would have anything to do with it.

 

Just to clarify, have you cleaned the knock sensor electrical plug?
The compression test may or may not tell you much. You should see something like 160lbs psi, give or take 10-15. If they are all low, the chances are the test wasn't done correctly - a common error. (There's another thread on here somewhere).
Send the readings you have, but I don't think they have much to do with pinging.

 

I have not cleaned the knock sensor electrical plug. I checked the end in front of the intercooler which seemed fine.

 

Yes, that's the one. I suppose you could disconnect it & see if it makes any difference - better or worse.
But at this point, it seems the sensor has failed.
Do you have a local, independent MINI specialist who could give you his opinion?

 

I disconnected the knock sensor plug, and pinging went away. Started the car up again, pinging got real loud and threw a code. Plugged the sensor in again. There is a BMW specialist near me, but not willing to cooperate

 

Well, that's confusing! It seems the knock sensor is doing something, but I'm not sure what.
You seem to be back to where you were.
So more questions:
What was the code?
Has the code now gone away? - or can you clear it & it stays away?

In your first post you said you'd checked the vacuum - do you mean you checked for vacuum leaks? They are tricky to find.

It's a pity about your BMW guy, but I think any other experienced mechanic would give you some ideas without it necessarily costing megabucks.

 

I used to have vacuum leaks, but I fixed them. The codes I have now are p0326 p2303 p2300. 2 of those codes occurred when I unplugged both the TMap sensor and the knock sensor and the coil pack. There is no engine light on. I erased the codes and now they haven’t come back. I will try a different mechanic. I pulled my plugs out, and cylinders 3 and 4 have lean looking spark plugs, the rest seem fine, wondering if it’s the fuel system.Thanks for your help

 

You're on the right track, Massimo.
It looks to me like a vacuum leak affecting 3&4 cylinders. MINIs like to run rich.
Injector seals?

 

That’s a very good point, but would it throw a vacuum leak code? I will spray soapy water on the seals to see if the engine idle changes