I have an AEM EMS in my car and the car sometimes misfires. I think it is because of how cold it is here in NY. Will someone else who has an AEM EMS in there car please chime in and let me know if it happens to them and my theory is correct.

 

It should not misfire just due to cold weather, is this during startup or normal driving? When does the misfire happen?

 

I let the car warm up everyday until oil pressure is about 35 psi, and i can feel it misfiring under normal acceleration or when i floor it after the turbo spools at about 6300+

 

Ok, Are you logging Stat synced to see if it is turning on and off, this will identify if it is a crank/cas sensor issue or not. Also are you on fresh plugs, it always helps to rid the easy stuff first.

 

changed the plugs numerous time never fixes it, never logged anything but im sure when my tuner ivey tunes it her logs and changes it and it almost never does it on the dyno.

 

The only way you will find it is buy logging it on the street when it happens be sure this is done so you can find the problem. I would start at the sensors and test my way forward to the plugs and you should find it. Sometimes cold weather will cause electronics to act funny if they are on the fritz. Good Luck

Also be sure you don't have one of the early AEM boxes that had ignition driver problems, you can find this info on aempower.com

 

thanks so much you have helped a lot. now heres the money question to see if you can diagnose it in one shot. When it was a little warmer out it would do it mostly at night when it was colder obviously as opposed to during the day when it would barely ever do it because it was warmer out(my belief). that is when I first thought it had to do with being cold. It was diagnosed as an intermitant ignition problem. the smaller I gap the plugs the less it will happen. they are at 22 thousands now. If I put some higher octane fuel in it will barely do it even if it is very cold out. I think thats pretty much all the info on it that I have if you can help me more I would be beyond thrilled. If not don't worry I will take all your other advice and be very thankful
by the way I got a RMA number from AEM because I was going to send the box back to get looked at tomorrow morning so if you can help me that would be amazing because it would either save me the trouble of sending it or actually convince me that it needs to be sent and that i'm not just wasting money on a problem that will never be fixed

 

send it back.

Sean

 

Agreed.

 

I agree with Sean. Call and explain to them the problem. Then send it back for repair. I've ran into similar issue with ONE EVO IX box

 

I live in germany and i know its much colder here in the winter and i dont have that problem.

 

i never had that problem with my AEM, but i did have to replace the plugs every 6 months or so, but thats probably the tune.

 

Hope I don't have problems on those long winter days

 

i still have hard starts on cold days, mostly below 30deg. i just give it some gas after the pump primes while turning the key and it fires up pretty good. not as good as stock but i can live with it.

 

what size turbo are you running?? it sounds like you are spike boosting..i had this problem when it got cold out so i went in a and lowered my boost cycles and havnt had the problem agian...big turbos are real finicky about cold weather..