Recently I’ve been suffering some detonation

It appears to be occurring mainly in cylinder #4 and to a much lesser degree cylinder #1. It seems to occur at any RPM – even under light throttle at take off. Its throttle sensitive – once it starts the more one applies throttle the worse it becomes, though backing off will stop it. It is sporadic – it doesn’t happen every time I accelerate, but does occur every time I drive. It is definitely more likely to occur under hard acceleration.

The reasons I believe it's detonation are several:
a) sound
b) loss in power
c) metallic particles found on spark plug insulator(s)

Examination of spark plugs with 5k Miles:
Electrodes in good condition & gaps are spot on - no erosion. All plug insulators are coated in a rust-brown colored haze. I understand this is supposed to be caused by fuel additives. Plugs from cylinders #1 and #4 also have very tiny metal particles on the insulators. #4 has a bunch, while #1 has hardly any. Both plugs appear darker than those in cylinders #2 and #3.

cylinder 3

cylinder 4 - det

The metal particles I am speaking of are very tiny, and can only be seen by serious magnification. I used my digital camera’s macro function. Sorry for the poor quality image, but file size is limited to 6k in the gallery.

FYI
My 2003 MCS is modified: EVOtech software, 15% pulley, cat-back exhaust, cold air intake, throttle body, coil pack, Denso IK22 plugs. I've run nothing but Sunoco 94 Octane fuel since new. The car has run better than new with all mods installed for over 5 months – this through the hottest part of the year where detonation would seem more likely to occur (than now as temperatures drop).

My thoughts at this point:
Clogged injector(s) or fuel filter, fuel pump or defective MAP sensor.

Any further ideas of what might be causing this?

 

First thing I would do is get the ECU flashed back to stock, replace plugs, check the ignition connections and put in a bottle of injection cleaner.

As the Mini ECU has a dual method to control detonation based upon intake temp and a knock sensor an intake and exhaust temp log might be in order as would be a check of wiring to the knock sensor. Does anyone know where it is?

Is it throwing any codes?

 

I just put in half gallon of toluene and man does the car run better....

 

No Codes (yet). New plugs were in this afternoon. All obvious connections checked already. Injector cleaner and octane booster in car yesterday - 2 hour journey with some slow & some hwy - no discernable difference.

This isn't the first time this has happened. ...On the previous occasion I wasn't certain it was detonation, now I am.

The last time this happened was in Dec/Jan. Dealer had car no less than 5 times & returned the car to bone-stock (excepting the pulley - claimed it didn't matter). All of that didn't make one bit of difference to detonation. They finally "fixed" the problem. ...But they couldn't (or wouldn't) tell me what they'd done. After that experience & outcome I'm less inclined to leave things to the dealer alone to sort out.

FWIW
Car was malfunctioning with OE software back then with same problem - so the EVOtech isn't the culprit. Also, if the software was the issue then I should be seeing det in all cylinders, not just 1 (maybe 2) of 4.


What software are you suggesting I use to log? To my knowledge most can't sample enough parameters simultaneously or frequently enough to capture the quality of information needed to diagnose this sort of issue.

 

http://www.obd-2.com

It ain't pretty but it works great and logs 1 to all ODBII parameters for as long as you have room on your disk drive.

Your dealer might want to think about starting to swap parts like sensors, ECU's, and the like. Or do that Voodoo that heedoo so well B4.

Any funny sounds or smells out of the exhaust that might indicate an obstruction or melted cat?

 

It's a bit odd that you are having detonation in holes 1 and 4 only. The first thing that comes to my mind is that 1 and 4 are 360 degrees from each other, and on the same coil. It could be some sort of strange timing issue, especially considering that the knock sensor retard does not seem to help those two cylinders. Problems with fuel pressure, bad gas, engine overheating and such would affect all 4 cylinders equally for the most part.

Do you encounter the knock when the engine is cool too?

 

No, no smell - but I did think my Magnaflow was sounding different. But I figured this is more a symptom than the problem. If the cat were the issue I'd expect to see my temp gauge higher than normal, the radiator fan running overtime and the plugs looking a bit more cooked. ...So I'm thinking no. ...But its something to consider.:smile:


Interesting thoughts...

Not sure, I'll have to try it tomorrow.

Earlier today I swapped out the plugs for a lightly used set of IK20's, but I guess I'll pop the IK22's back in for the sake of consistency.

 

Couldn't sleep so I just went out for a VERY short drive. The Answer to your question Gbear is a resounding YES. I was able to induce it with quick on/off throttle actuation. I didn't even get 1/4 mile down the street! Its 45 degrees F outside (according to OBC) ACK!

 

not sure, but here's a swing....

1. Winterized gas gets around starting october...you might have it (?)
2. Colder air will mean denser oxygen...possibly A/F too lean?

I would try... 100 octane gas if you have access to it. If not,
toulene.... 2 gallons into your Sunco 94. see if that helps. :smile:
but as mentioned above, I would atleast try a stock ECU before
anything.

 

Have you tried going back to the stock coil?

 

Things I would try first is a return to your stock coil and plugs and a quick run to see if it is changed. In some rare cases a coil that requires too much primary current will cause the ECU to shut the coil current off prematurely or repeatedly as it's internal circuitry tries to preotect itself from an overcurrent condition. This has the same effect as firing the plug early and sometimes often in the combustion cycle, creating a very advanced spark.

I would have this all checked out soon because the MINI engine, as strong as it is, has pistons that can be damaged by knocking. The ring pack sits very high on the piston with the upper ring land half the size of conventional pistons. This can be cracked or the rings siezed easier than on old-skool pistons.

 

No I haven't swapped the coil yet, but will today. ...I know why we're going this direction, but FWIW last time swapping the coil didn't make one bit of difference.

I have a set of OE plugs that I can put in along with the OE coil, and have a scheduled service apt. on Thursday.

The thing that bothers me about all of this is that all should work fine for months at a time, then go bad suddenly & for no particular reason.

Thanks one & all for the continued suggestions.:smile:

 

UPDATE

Swapped out the coil & reset the computer (adaptive logic). Seems like the det is now gone While I'm very pleased I'm not 100% sure I've licked this problem. I guess time and a bit more driving will tell though. I'll keep you posted.

mc

 

Det came back on evening drive. ...Back to the drawing board.

Thinking I'm going to put the performance coil back and just swap plugs at this point.

 

1:19PM

Have since swapped in (and back out) performance coil. Det seemed worse than ever. OE coil and OE plugs now installed. Still det. + new (& never previously experienced by me) the infamous 'stumble' ...And it is BRUTAL

This is begining to freak me out. Hope visit to dealer tomorrow helps.

 

Yikes! This sounds mostly to me like a defective ECU. Something is just not right regarding the spark delivery, and it's not throwing any codes or the check engine light. Hopefully the dealer can help out AND not get in your face about "the mods being the problem" which we know isnt the case here.

Good luck!

 

Well, the dealer was cool about the mods (again) but is no closer to understanding what's wrong. Now I'm uncomforatable driving anywhere. Am going to bring the car in (hopefully next week) for a battery of tests. Most likely means I'll be driving a Cooper CVT - Nothing against you CVT folks, but when you're used to driving a 6-speed 200+ HP MCS the CVT only shows me what I'm missing.

 

Weird things are going on in my MINI.

I spent the weekend mucking about with coils, wires and plugs. I changed my Magnecor for the OE wires, and the car suddenly idled more smoothly. I then swapped plugs back to Denso IK22's & still smooth.

Could it have been so simple...? NO

Decided to drive car in this state of tune. Car was good. Acceleration seemed normal as did idle. Then when I thought I was certain I'd 'fixed' everything... blam, I go into limp mode. No warning whatsoever. I'd gone from driving cautiously back to normal, and then on to spirited when this occurred.

Even more interesting and unusual is that there were no error codes in the computer!!!! WTF??? Furthermore after one or two restarts the EML turned itself off. When I'd previously experienced a limp-mode educing fault it took 5 or 6 trips to reset its self. This is the fastest I've heard of.

I examined the Magnecor wires today, they looked fine. Just for giggles I put them back on. The car seems good.

Oh man but this is frustrating & preplexing.

 

You know its probably the ECU. Get the dealer to loan you one and get that swap out of the way. If its not the ECU you can swap parts till you find the problem. IMHO!

 

I know this is an old thread... I've had an issue like this and it was corroded wires.

Consider replacing harness.