cold cranking amps and battery voltage question . hot start issues
 

past few days ive been messing with my fc . i got a apexi power fc for it running 1600s and 750 primarys . the motor has low compression due to me driivng it untuned for a long time . its a full s4 t2 rebuilt stock port ra super seals 2mm . car used to run and drive everyday on stock injecters and ecu . now with power fc and new injectors it starts up only when car is jumped . power fc reads battery voltage around13.6 when its on and running . but when its off reads around 12.3 crank crank crank no start down to 12v then lower and battery almost dies out completly . its about 10 degress outside too . like i said it starts up only when car is jumped around 13v . i have a honda half size batt cause my ic piping takes up too much space to fit a regular size batt . i tired everything on the power fc and it ONLY starts when its jumped . wont start with 12.3v . do i need a regular size batt now?

Check the starter. I had a bad one that would Crank slow and Draw too much amps. just a thought

It could be the starter as he stated but if not

You're using a small battery with low cold cranking amps that's your problem.

The engine needs to spin as fast as possible inorder to start and to do that you need a powerful battery, especially in the cold.

The extra power the jump start provides is spinning the engine that much faster make it start. I'd get a bigger battery and relocate it one of the rear storage bins or wherever you think is a good place.

Rotary >Pistons

When your car ran on the factory ecu would it start at 12v? You should certainly get a battery thats the proper size for the job. I haven't played with a FPC but does it have a place to set the injector dead times?

Your engine has low compression because of RA seals, not because you ran it untuned for a while.

Try installing a motorcycle/trickle charger in your car, leave the plug hanging down an inch or so under the car tied in place, and plug in an extension cord overnight. The battery will be at full power the next day and it might start better. Your battery may just be getting weak, usually after about 3-4 years, or after any discharge event, a batter will begin to lose some cranking amps and performance especially in the cold.

You can also experiment with the cranking MS fuel settings in the PFC settings menu and that can change how the car starts up. Start by selecting the temperature range of the ambient air when you're having the starting issues. Alter the corresponding setting significantly in one direction and then see what the car does. IF it seems worse then go the other way with it and see what it does. Continue to experiment and fine tune it until you find where the car "likes" to be.

like RR is advising you on- consider the cold weather- is this car kept in a heated garage or outside?
perhaps you need to tweak the cold start

How do the ra seals cause low compression?

Iirc its because they don't break-in as easily due to the harder material.

Rotary >Pistons

Dino oil, 20w50, right?
 

Are you running a thicker oil than is called for in your winter temps? You are in Frickin' Rhode Island fer gosh sakes! It's 10 degrees! Are you running 20w50, most likely? Dino oil?

Of course it cranks slow. Throw in the small cranking capacity of the small battery and you are starting slow.



Try running a 10w30 Dino oil in winter. Your engine will crank faster .

Try a 5w20 oil in winter. Your engine will crank much faster.

You have little likelihood that you will ever get the oil warm enough in this weather to need the thicker viscosity of the 20w50.

yes i run 20-50 i just changed the oil before i got the pfc and my freind thats tunning it hes on here "smg44" has tried everything on the pfc lowing the fuel retarting the spark etc .today its about 20 degrees outside i changed my starter and im gonna try a bigg batt from a lexus and see if it does anything . but its weird how it started up everytime time with stock injecters and ecu with the batt i have now . and i know i have low compression cause i drove it untuned for soo long beating on it . sort of my fault .

but like i said it starts up when its jumped with his audi . it just catches starts runs fine

I'm telling you, the 5w20 or 5w30 will make a big difference.:icon_tup:

In my experience and that of some other builders who've torn down engines built with them, they are harder on the chrome surface and tend to cause accelerated and uneven wear, and of course wear and grooving on the chrome can reduce compression just like worn apex seals can....so although nothing is "broken" those engines do not make much compression.

Don't use a 5 weight oil in the rotary. The rx8s EAT bearings because of mazda's recommendation of 5-20/5-30 oil. Run 10-30 in very cold weather, 10-40 or 20-50 all other times.

Is this a problem everyone has? I see other seals like als that are harder material than stock, do they cause similar problems.

There's no way to prevent this uneven wear? I read lots of stories about people running high boost on these seals with no problems.

Rotary >Pistons

Get an Optima red top and be done with it. My Optima reads 1200 CCA! That's 3 times more that what you need in warmer months. Alternator voltage reads a steady 13.6 V. Reads about 12.8 V after it's sat over night.

fixed it . tried a 800cca amp batt and changed starter strarts up first crank . tried it after warmed up started right up. so buying aq new batt

So it was the starter and battery? Or u can't say for sure. Maybe I should get mine tested if I can't get mine started on a good battery

Rotary >Pistons

I worked part time at an auto parts store for about three years for a little extra money and shits and giggles. It was ALWAYS the battery in a rough or no start scenario. Amazing how people expected their 9 year old AC Delco battery to last literally forever.

Most batteries last 3 years at the most, in my old rx7 I was replacing it like once a year

Rotary >Pistons

well i got system . walbro all my electronics still work . fd alternator now . and it was the batt and the starter lol

That sucks, my car was cranking slow but I was jump starting it on a dead battery.

I'll be getting a new battery soon, I hope its just that and not the starter.

Rotary >Pistons

LETS CLEAR SOMETHING UP.
The Ra SUPER SEALS can cause issues on certain applications. They are known for eating housings as they are not designed for a passenger car but for a airplane that is rebuilt every so many hours of operation and are designed not to break so no matter what your motor will not just die when in the air.
RA (rotary aviation also known as real world solutions ) make another set of seals called the classics that are more designed for a all purpose use and is very friendly to housings.
To simply state RA seals eat housings is a uneducated statement.
It would be like saying atkins seals are junk on a high hp motor. But they have a purpose for different rotary engine applications.

You might look into running Ngk egv plugs. If your still running stock plugs then put some ngk b7egv and b9egv plugs. You will see a difference.

I bet that I have taken apart more RA sealed-engines than you have, and I've tossed or refused to reuse all the rotor housings from those engines due to rough condition, chatter and grooving. In light of this information, I would not call what I wrote an "uneducated statement".

i know my compression is low . beating it so bad with no fuel . ill admist tho these seals are the best hands down . take such a beating . there gasket set is pretty good also ive overheated my motor plenty of time and it still runs cool . i have almost 10k on this daily driven .. cant wait to see wat my housings look like lol