I've only run dry air filters on this MINI. The stumble goes away if I go back to the stock tune, but comes back if I go back to the 1a or 1b manic tune. I just figure that the tune is a little more aggressive in those conditions and I'm wondering if better coils would help.

Its not a big deal, but when I come home from work there is one interchange that I can put power down and not cause attention, and that is where the stumble is. If I downshift to 2nd instead of 3rd (4500 instead of 2700) the stumble isnt there. Its just an odd combination of throttle position, RPM, and load that I happen to use.

Mike

 

Did you replace the spark plugs when the tune was installed?

 

Yep, went to the 1422 plugs as recommended by Manic, 1 range colder than stock.

Its an odd thing, this is really the only issue that I have with the tune. Full throttle it is smooth and strong, the idle is good. Sport mode the stumble is reduced (but I hate the pop and burble in sport mode), likely due to the increased throttle response map.

Mike

 

 

How much cc meth you inject?

 

Most people run anywhere between 350-500cc/min

 

Mine struggles while running at 500cc. I wondered it would be OK around 500-750cc if i use IP coils.

 

What do you mean struggles? Like it bogs down when it starts to inject?

 

Yes, and kinda misfiring/bogging.

 

Are you tuned for meth? If you're not you need to lower the jet size so you're around 350-400cc. People that aren't tuned for it meth run around 350-450cc

 

Yes. My AFR and STFT is not going rich at that moment.

 

When does it start injecting the meth then ramp in to 100%? Where is it set for those two points?

 

Almost immediately full pressure after 10 psi turbo boost. But bogging not always starts immediately.

 

How much boost are you running/holding?

 

25-27 psi.

 

I would try and change the start injection to like 5-7psi then all of it at like 12-14psi. Might be too much at once or the car doesn't have enough ignition timing in it to help with it not bogging down. I have mine setup where its all of it after 5ish psi and run 12 degrees of timing after like 5k rpm.

Are you built motor and big turbo? Like a garret?

 

Forged engine. 51mm hybird OEM turbo. 13.5 degrees of timing at redline.

 

Hmmm. Are you running straight 100% meth or a mix? Like 80/20 meth to water. What kit are you using? Have you tested the flow rate of the jet in the car so you know its actually 500cc?
Also have you looked into multi port meth injection? Everyone on here with a built motor runs it. This dude runs it for track days but its similar to oldbrokenwinds setup as well. Helps spread the fuel to each cylinder evenly rather than just running one jet and cylinders 2 and 3 getting more than 1 and 4. https://www.northamericanmotoring.co...ction-wmi.html

 

Pure meth. AEM V2. Didnt test the flow, but dont think that more than 500cc. I know the multi port injection thing but why would cylinder 2 and 3 get more meth than 1 and 4. Our intake manifold looks pretty equal runners and mid enterance.

 

Its a straight shot to those two cylinders. The air charge is also heavier with the meth added so it will take the path of least resistance. One of the tuners on here was talking about it.

What plugs are you running? The ngk 1422? Also who are you tuned by? When running pure meth this tuner ran into an issue where there was pre-ignition occurring. https://www.northamericanmotoring.co...ml#post4336901

 

I am injecting right after cooler. Thats why i think there is a lot of room to vaporize meth before reaching runners inequally. Yes, i am using NGK 1422, but considering switch to Brisk Silver Racings...

I would try to add %5 acetone and %5 water maybe then

 

Ya lower the better on the charge pipe for mounting the jet. Keep in mind you mix meth by weight and not volume. https://www.northamericanmotoring.co...ml#post4336592