Near the end of the day yesterday at Sebring, my MCS's motor abruptly cut power around 5500 rpm every so often (I only noticed on the front straight). I also noticed this loss of power on the way home, still at 5500, but less sudden. After sitting overnight though, the car feels fine. What could have caused this?

 

Was it during shifting at all? Mine did this as I was shifting, and it was a stuck bypass valve. Only other thing I can think of is an electrical problem?

mb

 

How much gas was in it?

 

mbcoops - it occurred at full throttle in third gear, ~5500 rpm. I don't quite understand how it could cut power during shifting, though - you would be letting off the throttle anyways, no? An electric problem may very well have been the reason.

Motor On - a little more than 1/4 tank. I only noticed on the front straight, driving in a straight line, so I don't think it was fuel starvation.

 

I've heard of bad plugs causing sudden power loss in cars but I have no idea if that would apply here - couldn't hurt to check though...

 

Sorry, I wasn't clear. When I said during shifting, I should have said after shifting and while engaging the next gear and expecting there to be power on throttle input. It probably can't be a stuck BPV because at WOT, it too is WO, so it can't get stuck.

mb

 

umm, (not in an insulting way) was it the DSC?

 

Sounds like a loose battery conection, or possible grounding out on the battery.

 

What other mods besides these?:

HAI, 17x7 Enkei RPF-1, 215/45 Kumho MXs, etc.

I guess you didn't get an SES light... The code(s) for which certainly help...

 

eVal - thank you for the suggestion, I'll try to check that out.

mbcoops - thanks for the clarification.

ashboomstick - ASC was disabled.

onasled - I'll check that out right now.

TonyB - the only other mods in addition to those are small cosmetic ones. No warning lights came on at the track, and there are none on right now.

 

Are you running a boost gauge? Is there such a thing as fuel cut on these cars?

 

i had this; and although i can't as yet say it's gone i did lose half of my coil(screamin' deamon ) just the other day. is it related? time will tell. but if you lose your coil please post . would be interested to here.

 

At WOT, it's closed. At light throttle, it's open. Otherwise you'd get boost when you don't need it, and no boost when you do.

FWIW.

Matt

 

sounds like spark blowout to me...
you have 15% and IK22s in there?

 

Bah, the problem's still there. It's definitely cutting around 5500 rpm. I checked the battery connections, and they didn't look loose. Next step is plugs.

 

I've gone through a fair share of troubleshooting where I've had codes to help though. I just found that my coil wires were the culprit as I had spliced into them for various gadgets over the past few years...

Check the torque on the plugs before you take them out, plug wires, clean-up the contacts on them and the coil. Those are some of the simple things to do first. Too bad it's not throwing an SES light! Best of luck.

 

Stock pulley and plugs.

 

Many folks have had plugs back-out on them, sometimes causing some serious issues. I'd first check them for proper torque (21 ft-lbs). Please report back...

 

When I installed my mods I noticed several times a pwoer loss during shifting from 1st gear going in to 2nd, the car would just seem like it would die for a good second and then throttle back up. I told my mechanic about it and he didn't mention anything serious. I need to be clear on this power loss at or near gear shifting as well.

 

I checked the plugs' torque, removed them, and retorqued. Didn't help. I then removed the intercooler and cleaned it out (first time in 8000 mi of ownership). Also did not help. What should I do next?

 

Clogged or dirty fuel line or somewhere in the fuel system, may be?

 

Possible. I was thinking of putting some injector cleaner in, but decided against it in the end. The car only has 8k mi, and gets 93 oct. fuel from the same Shell station 90% of the time. But running some through won't hurt, right?

 

Given the minimal mileage, and rather tame mods, if you are close to a dealership, I'd consider bringing it in.

 

Where in FL are you located? I have the autoengenuity and can do some datalogging with it.

 

I think the BPV issue in Mini's is that it gets stuck open.

The car tries to close it and goes 'omfg! it's stuck open! nerf the engine!', and then you get a severe power loss. Once the valve closes, you get your power back.

I can't say that's the problem you're having... Only how the BPV symptoms are created.