My Renesis powered sports racer loves to start on one rotor, but only when cold. I've checked compression, that's all fine. New and old plugs, same thing. Hot or cold plugs, same. Once the engine is warmed up, both rotors come alive and she runs great.

My MircoTech ECU doesn't allow for very high fidelity tuning, so I've never been able to get rid of the one rotor start. Is there anything I might be missing that would cause this?

 

How do you know its only one rotor? Is there any other symptoms other than low power?

Just curious why are you using a microtech? Is it turbo or in another vehicle?

 

At some point in the last few months I noticed the car was running really rich on cold start up. I never had this before and figured that maybe the rotors were starting to lose a little compression and she would run a little rough. I went into the cranking and idle fuel maps and pulled a little fuel out trying to fix the richness. I didn't take out too much fuel and the car died from fuel starvation. I figured that there was no way the car was running that rich if taking out a little fuel would stall it.

Once coolant and oil temps are above 100-120F, a little blip of the throttle will clean it right up and it runs nice and clean. No other symptoms really, I'm just not sure why it would be doing this all of a sudden.

The car is a Diasio D962R. The builders chose to use a MicroTech ECU, so that's what I'm stuck with at the moment. D I A S I O | Car Company

 

Cold start problems that clear up quickly once the engine and fluids warm up is often a sign of a coolant seal failure. Leaking coolant into the housing is fouling the ignition for that rotor.

All the unburnt fuel might be what is indicating that you are running rich.

 

Is there any way to verify a leaking coolant seal short of opening up the engine?

 

Yes, a cooling system pressure test, a hydrocarbon test of the cooling fluid.

 

Yeah, get the pressure test just to see if it fails. Majority of mechanic shops can do it for around 20-40 dollars.

 

Thanks for the replies. I will look into a coolant system pressure test.