Hi guys,

I'm looking for some insight on your part, I searched and found topics about this but resolutions never seem to converge towards a common solution so I need your help!

at WOT between 2500-3500rpm I experience slight stuttering that I did not have before I had some work done on the car. This is especially noticeable on 4/5/6 gear but does not occur systematically, it does it 70% of the time and it seems mostly when I let the revs drop and reaccelerate in this rev range.
The problem appeared with the latest modifications to the car, the mechanic told me that it might be a timing problem from the ECU (maybe) too aggressive. No error code whatsoever.

I just had this done to the car:
- service n°2
- JCW CAI
- 380cc injectors
- GP intercooler
- Schrick cam
- JCW plugs
- ECU remap

What I already checked:
- ECU reset done
- no engine error
- no coilpack corrosion at all
- original oem ignition wires but looks brand new, no corrosion
- changed fuel and currently testing vpower 100, no change

 

Just a thought, but you may want to reset the computer. The easiest way is to pull the battery cable off for a minute or two and the reconnect it. You can also go through a reset sequence using the ECU reset steps. You will need to do a "search" in the forum section for your year of car and it will walk you through it. I have reset mine several times and I'm surprised each time I do it.

 

Hi, thanks for the input.
i forgot to mention that I already did this (added to the list), no luck unfortunately.

 

with that many mods it might be time for a custom tune....
you have LOTS of changes the car is trying to compensate for....
a tune will likely fix it....lets face it..with the mods and ONLY JCW380 injectors you are likely running LEAN...the the computer might be picking up a slight knock/ping, and be pulling the timing..
the jcw380's are only good for about 210 hp or so...with a CAM you can make more...and a tune+bigger injectors are needed for max power, safely...or a tune to keep it safe imo.

 

PS Do you have a pulley?

 

Yes I do have a 15%
I will have a talk with the mechanic about the injectors, we already talked about the tune change and we will likely dial down some parameters to be on the safe side.
I will later contact a garage where they do custom tunes on rolling roads to get the best out of the car.
What do you people think?

 

what injector size do you recommend for a 240hp mod? I didn't really think about that issue because I didn't think I would max out the jcw injectors.
can you direct me to specific models?

 

You prolly wanna check your coil pack and/or wires. My car did this exact same thing, and i never figured out what it was until my coil pack went out and it ran like complete dog **** (firing on 1-2 cylinders FTL)

Once i replaced both the coil pack and wires, it ran like a champ...
BTW all of this happened over the course of about 10 days from start of stutter to finish of the problem

 

BTW my coil pack also showed no signs of corrosion, but once it went out, it did throw a cylinder 1+2 misfire

 

"ECU Remap" you listed, from where and how was it loaded, on a dyno ?

Are you experiencing misfire/pinging usually attributed to poor spark/low octane fuel or more like a pause or stutter in power ?

Are you runing a boost gauge to see what is going on there ?

If your still running the original stock BPV it could be a worn out spring too weak for the mods you have now or the "ECU tune" just loaded has just too aggressive throttle signal between the accelerator pedal and the throttle body.

 

I believe this thread should converge w/ this:
https://www.northamericanmotoring.co...53-help-3.html

 

Good point on the rpms of the lag matching closing of the bpv.....

 

Unfortunately, not all are BPV related. Tried zip tying it & same symptom prevails. New plugs & wires improved it a bit but symptom still persists.

 

Some versions of ecu software did/do have issues with the sudden changes when the bpv closes...mini went through many versions to find a cure...so cars had a yoyo, so a pause in power...issue bacame apparent in about 2005...about the same time e-10fuel became common, and the bpv was made stiffer from the factory.
some versions worked on some cars, but not others...was an interisted time...cars that rarly went to dealers still have the issues....
the op in saying a pause inpower or along those lines, it sounds like a timing pull.....
good test, get some higher octane fuel...run it for a bit..see if it continues.
The car does use various coping stratgies for high intake temps/low octane...but mostly timing reduction and richer mixture....and once you run a cam, the duration of the valves being open for the intake imo NEEDS a custom tune to take advange of this...more air getting sucked in, more time to inject fuel...the computer is amazing on the mini in its ability to compensate and run well with mods...but there are limits!!

 

OP here I think was describing a pause or hesitation at RPM/boost changes before accellerating, not NVH or flywheel issues. So not sure what your perspective is on the correlation of these two threads and posting the link.

 

I have not read here where the OP has tested this possibility yet..... What and who are you referring to here ?

 

My issue can be described as very brief pauses in power delivery.
The ecu had a remote tune loaded, the BPV is stock and I don't know if the boost has been tested, will also put this on the to do list.

 

Just sharing that many have pointed to the BPV on this, but not all might be caused by it. Trying to seek inputs w/ the process of elimination to help solve this age-old issue plaguing many. On the other thread linked, I agree that the NVH & clutch issues are unrelated, but the hesitation at low rpm seems to be a common denominator.

 

if the clutch/flywheel had a problem, wouldn't I feel it before the modifications?
the clutch worked great before modding and it feels just the same after, I don't think it's the culprit.
What is the typical feeling you get when the BPV yo-yo's? In my case it really doesn't feel like speed variations, I get brief interruptions in the acceleration but I don't get a "slow down-acceleration" effect.

 

Loss of power can also be caused by a bad seal at the inlet of the supercharger. When I fixed that leak in my car it helped this same symptom out a lot. Is the car really hot most of the time when this happens? The GP intercooler is larger and some say it never fully recovers during city driving, depending on ambient temps. Excess heat in the engine bay greatly contributes to the loss of power you are feeling, as mine NEVER did this when it is 40 degrees and below. But these guys are right, every mini is different and with a cam a box tune won't cut it... Which is what's holding me back from doing a cam...

If I were you, I would stop trying to diagnose this, get a proper tune on a dyno and then if it is still doing it check for that leak at the inlet of the SC. Just my $.02

PS. Don't worry about your clutch. If it was gonna slip while already engaged and in gear you would experience massive power loss at every where > 4k rpm

 

The issue occurs at any engine temperature.
I will have the seals checked for leaks.
it's too bad the mechanic can't dyno tune to make the best out of this, I think I found another place where they are quite experienced doing custom tunes. if the issue is not mechanical, I will just ask for a less aggressive box tune for the time being and go to a well equipped specialist later.

 

Problem solved! the problem was caused by a weasel attack! they chewed on my ignition wires and the bad isulation was arcing with the motor.
Now everything is extra smooth and the car is just a joy to drive.

Thank you all for your support!

 

Glad you had it sorted!

 

How did ya miss that when checking the coilpack terminals for corrosion and seeing wires as brand new condition....lol. ?

 

the damage was on one wire near the block, the animal managed to cut a fine slit in the insulation that was quite difficult to see, the shorting didn't even occur at normal acceleration, you had to go WOT to get the spark to escape the wire.