I have a 2007 MCS 80K. I have been working on a sputter for months now. Here is the progression:

1. At highway speeds a downshift from 6 to 5 and accelerating will cause a sputter.
2. Driving in the mountains under load with curves can cause a sputter with shift changes keeping the engine at around 3000rpm which is about the top of my torque curve will cause a sputter as well
3. Punching it to get on the highway will cause a sputter.

The sputter can range from a bumpy loss of power to a hard bump.
I always am aware and let off the gas whenever it happens. I never push through.

The car has a KO4 turbo, high flow cat, 3" exhaust, tune through JM turbocoopers, wagner intercooler...

Current remedies tried:

1. Had the car on the dyno twice this month. 1st attempt showed a/f was lean. I replaced the Air Mass Meter and the fueling went back to normal. It still sputters.
2. I changed the spark plugs. Before: Brisk. Now: NGK 1 step cooler than stock. Sputter continues...

Recent suggestions:

1. Change the fuel filter -I'm learning what that takes to replace now.
2. Change the tune -I've looked into it with the power cable, dyno time, and remotely tuning the car with the guys who did it last time.

What else am I missing here?



Thanks, Dan

 

EDIT:

You need to switch back to the stock tune and see if it happens.

Also look at HPFP pressures using DashCommand or Torque Apps.

 

I had a similar issue and it was a bad coil pack. In fact I've found it's more likely to be a coil pack if you misfire on the mid to high end of the power band and more likely a spark plug if you have a rough idle and misfire on the low end of the power band.

 

Thank you. Did you discover the problem via odb2 scan or trial and error? I am on my second set of coils. And about to invest in a new fuel filter

 

When was the last time you did a de-carb on the intake valves?

 

Hi: about 12,000 miles ago. Im pushing 80k now.
DR

 

If you have a CEL you can see in the code which cylinder is misfiring and try replacing just that coil pack. I also found you can tell a bad coil pack by getting a multimeter and putting leads between each combination of terminals and measuring resistance. They should all read no connection or zero resistance. When I got a bad one the resistance was about 7 ohms between the left and center terminals.

 

Thank you. I'll try it. I don't have a meter but I can get one. DR

 

Thank you. I'll try it. I don't have a meter but I can get one. I assume the center contact is the ground. DR

 

Thanks. I have a scantool. Can't change the tune. Too much brain damage.

 

[QUOTE=thebombardier;4173267]If you have a CEL you can see in the code which cylinder is misfiring and try replacing just that coil pack. I also found you can tell a bad coil pack by getting a multimeter and putting leads between each combination of terminals and measuring resistance. They should all read no connection or zero resistance. When I got a bad one the resistance was about 7 ohms between the left and center terminals.

Do you know which is the negative tab on the coil? And what the ohm range is for a good coil on the primary and secondary circuits? I did a little research and it was mentioned that sometimes a bad coil can be rusty on the outer metal sleeve. Because of the sound of the stutter and the regularity of it, I am pretty certain it is a coil. Just not sure which one. #4 is rusty on the metal sleeve.

Also which brand of coil is a better choice. My OEM is Delphi.

Thanks, DR

 

Have you tried to change the plug gap clearance 0.8(NGK) to 0.6/065mm? It helps sometimes when you run under heavy load/boost..

 

[QUOTE=danraabe;4173674]It shouldn't matter which is the negative since your measuring resistance. But you may be able to tell by measuring continuity between the terminals and chassis (ground).

 

Curious. Where did you get these numbers. Ngk comes gapped at .036 and Brisk @ .028

 

It looks like we are using to different units, millimeters and inches.

For higher boost applications it is common to regap the plugs to 0.6 millimeters or .024 inches.

 

Understood. The plugs I removed were 3 steps colder than stock. I replaced those with an iridium ngk at one step colder than stock gapped from ngk at .036". I've ordered from Brisk one step colder silver plugs that they are gapping for me @ .028". I had a shop owner drive the car yesterday and they deduced the Mini is having an ignition issue most likely on one cylinder and it's not on a consistent basis. I looked into diagnosing the separate coils but haven't found a 1,2,3 procedure that I understand. I have s multi meter and odb2 adapter and software. Now considering just replacing all 4 coils. Also learned that misfires don't always make codes and that the situation can clog up the O2 sensors. Too bad all this troubleshooting isn't in my Bentley manual.

 

They sometimes are stored codes that dont throw a CEL all the time. And some scanner dont show anything. More general. I found bad battery codes, old faults not cleared by dealership...etc Like a history lesson on your MINI.

You may need this to find all the codes, then go through them :


Professional BMW/MINI Scan Tool

https://www.ecstuning.com/Search/SiteSearch/ES2975699/

 

Easy to try,just decrease the gap of those Ngk iridiums to .024 or ,028 inches.I running one step colder NGK than JCW plugs are , gapped that 0,65mm. I have almoust same mods that You have,ported JMTC S42 hp with big IC,custom made tune ,JCW intake etc.I had replace all coils(4) once, it helps for mine ignition problems, it gives sometimes "missfire-code"...

 

I changed two coils #4 and #3 to see if the misfire when away and it didn't. I'll try two more in a week or so. I also found a thread under "
Rough Idle, Black Plugs, Misfires, Backfiring, Sputtering

This discussion while almost 3 years old addressed the same issue but faded away rather quickly.


Here is some more information for the Sherlock Holmes in this group. After speaking with Arric at JMTC, here are a few things I've noticed. When I take off the intake at the turbo there is always wet oil inside the pipe. The car drives okay as long as I don't push it. But after changing the plugs and swapping two of the coils it seemed to backfire blowing black smoke out of the A*S end. It still misfires in a regular pattern when it does it. Arric suggested I try a catless down pipe, check for oil in the intercooler, etc. He suspects that I may have a burned valve. I'll check for error codes in the next couple of days and report back here. I'll also pull the plugs and see if they are fouled. If the cat is clogged a downpipe might buy me some time until I can pull the engine and fix everything, especially the valves, etc...

 

Thanks for the update, let us know what you find.

 

Taking the car to have it diagnosed. Scan tool didn't work. It doesn't recognize the car much less show the codes. My expectations were too high.
It's time to get closer to the truth. It seems that Mini has a service bulletin for this very problem. I say we storm the castle.
I'll solve this and share the results.

 

Good Luck! Looking forward to the results!!

 

" Taking the car to have it diagnosed. Scan tool didn't work. "

Which scan tool did you use ?

 

I couldn't find the exact source of the misfiring and have been eliminating the problem one step at a time. I had the ignition checked out and there were no misfire codes. This is what I've done in the last few days, as the car started to idle very rough:

1. Removed the magnaflow cat and replaced it with a straight downpipe
2. Replaced the NGK plugs with Brisk Silver QR12LS gapped at .028"
3. Replaced upper O2 Sensor

The NGK plugs appeared fouled
#1 very fouled and sooty
#2 dry and not fouled
#3 a little fouled w/oily threads
#4 same as above


Result: Idle is smooth, I didn't drive it hard to see if it misfired. i'm hearing a little extra clicking noise under the hood and wondering if it is detonating. And haven't seen the usual cloud of black smoke from the tail pipe.



I'm wondering if this is typical N14 high mileage problems.



Bottom line. The car runs okay, but not sure if I fixed the problem or not.

 

danraabe - Did you have the carbon blasting done ?