On track today and all of a sudden in 4th gear the car completely lost power. Didn't cut off, just lost power around 5k rpm. Some time it did it sometimes not. I would down shift to 3rd or up shift to 5th pending spot on track.

Then started happening in 5th gear too occasionally as well. No codes from my simple code reader as of yet.

Any ideas? Plugs? MAF? Fuel pump? Alternator?

 

This would be a good question for our new technical advisor section

 

Just taking a stab at it, possible fuel cut off? My previous car (WRX Sti) I use to track would cut off (fall flat on it’s face) on the banking with low fuel (less 1/4 tank). Could it be a possible rupture in one of the fuel pick up hoses? Were you running on a full tank-ish when this was happing? I guess if it was going in limp mode it would throw a code? Using Durametric?

 

Plugs or alternator would not cause complete power loss. A momentary power loss then regain is most likely electrical. This could also be fuel related, caused by electrical interruption of power to fuel devices, pump, injectors, etc. Your car will start and run without the alternator with a highly charged battery.

For a total loss of power it's most likely not something related to only one cylinder, plug, coil, one injector, etc. A misfire would give a code alerting you to which cylinder/bank. Could you have been really low on fuel and cornering hard to pick up air only with your fuel pump?

 

Nope 3/4 full tank.

Power went away then came back if I waited on that gear.

 

Boost leak?

 

Nick to your point I have a cup clutch and flywheel. The flywheel has very little substance to it and as such always reads a misfire. Been like that since I got it.

 

I'd recommend checking your wiring to relays, fuel pump, etc. I once spent 13 hours to diagnosis and fix an electrical issue that kept a vehicle from running. It turned out to be a $15 relay that would intermittently fail. I had replaced it once, but hadn't fixed another issue that was part of the problem. I put the original relay back. A mistake!

Most relays have bimetallic strips and points inside. They age and can become less sensitive, oxidized, etc. You may replace critical ones with new as it's difficult to test for intermittent failure.

 

Did you have any codes at the time? Use Durametric or Piwis?

 

This was not on a P car, but yes I had codes. Codes were related to CPS, coils, injectors. I corrected problems or verified issue free performance and eliminated codes. Got vehicle to start once and run perfect. Then it would not run at all, same thing, no codes. Went like this for hours, in circles.

 

Yup that's a common problem in the STI. I tracked my '13 half the time and my Porsche the other half and the STI always needed at least a half a tank or it would lose pick up on long sweepers.

But that's not a problem in these cars. It's most likely fuel cut due to the ECU sensing a misfire/lean condition, though it may not in fact exist. I've had the same thing happen in my Turbo occasionally but haven't been able to track down the source. It only happens when the car is hot so I'm betting it's a MAF issue. It doesn't throw any codes either and it usually goes away as fast as it comes. It happened when my car was stock too so it has nothing to do with all of my mods, nor does it happen any more frequently with all of the mods. If it ever happens more than once in a blue moon I'll start with replacing the MAF since that's the most logical failure point that would be triggered when the car is hot.

 

check your turbos... compressor wheel and Wgs...

 

I had my power cutting out suddenly for a while. Sometimes it was a hiccup, some times under full boost it felt like a cylinder shut down. For me it was because my ignition coils cracked and my cylinder was shutting down. This was as a result of a small coolant leak dumping onto the ignition coils. New coils and plugs and I'm pulling hard again.

 

If you haven't solved the problem before you're on track again, plug in your Durametric and secure your computer somewhere onboard and log about a dozen actual values during part of a session. You can get the parameters set up and run some warm up laps, then pull into hot pit area and press F6. Run just a couple of laps, hoping to record the problem/s and then come in and shut it down (F6 again). Don't stay out long with the computer running. It will log an immense amount of data in just one lap. I can help you with the data you would need to gather but I suspect you already know the values needed.

 

Though it hasn't been tested yet I think I know what the problem is based on some info from my mechanic. So Saturday, I had a brake fire on the track. FIRE! Master cylinder failed and the rear brakes baked and caught on fire. The car progressively slowed over the course of a lap and then just stopped and shut off just after I got off the track to pit lane. The rear brakes completely locked up. heat welded themselves to the rear rotors until broken loose by the tow truck.

After all day figuring out the issue was the master cylinder, had to piece meal some brakes together from some spares a friend had. But they were all C2 brakes. Master cylinder and front brakes on my rear. The front calipers of the C2 fit but have much bigger calipers and possibly thinner rotors because my rear pads were scrubbing with the C2 fronts bolted on.

We think similar to what happened with the fire, when the car senses rear brakes scrubbing it cuts power temporarily and intermittently. There is no other explanation for why the two events happened simultaneously. Once my rear calipers are rebuild will bolt on and try again. Think it will fix the issue.