2005 RX8 Misfiring
 

Hey guys i just finished swaping my 4 port engine and now its misfiring. First of all after i did the swap i had hard time starting the car but i figured out that the gas was old because the car was siting for about half a year so i put in some octane boster and it fired. At first it was smoking really bad but then it cleared up but the car was runing like crap. Check engine was flashing due to multiple misfires and rotor 1 misfire and when i try reving it goes up nice and smooth until 5k rpm and then it like chokes like its slow to 6k rpm but then when it gets pass it its good. Because my engine was used with 60k miles i changed the spark plugs, wires and coils it made it a liltle better but still the same problem, lack of power and flashing CEL. Then i took out the ess and clean it and i took out ess from my original blown motor and cleaner it too. I meseared resistance in both of them and one was 1ohm and the other was 1.11ohm so i put the one with 1.11ohm. It did not help at all and after driving the car for couple of minutes and reving it i shut it off. Two minutes later i tried starting it to pull it into the garage but it wouldnt start it had the same problem as i tired starting the car for the first time after the engine swap. I thought the gas was bad so i hooked up a hose to the fuel pump and a battery jumper and drained most of the fuel. I left a little less then 1/4 gas in the gas tank and filled 4 gallons of premium from BP and still nothing. It has the same problem. Then i decided to hook up smoke machine and the machine said it had a leak somewhere but i cant find it. At this point im frustrated and exhausted. Also that red light goes off thats by the oil pressure gause what does it mean? I was reading that it could be carbon build up and sea foam is good to get rid of it but i was wondering whats the best spot to hook it up.

Also when i was draining the gas tank i noticed that the fuel pump is kind of slow but could that really cause this problem?

too much too read.

you need new spark plugs, wires and coils.

lol thats why you should read the post, i put brand new ngk plugs, wires, and oem coils

bump, im getting the dealer to check the compression tomorrow

so did you found out what happen?
mine got error for missfire on cilinder 1

Mine too :(

-Compression test is always best.
-seafoam is added to the sevice ports on the intake manifold, there is a DIY on here
-Make sure your wires are going to and from the right coils/sparkplugs
-20 brake stomp
-make sure you omp sensor is in the correct posistion. There is also a thread on here on how to set it
-test the valves on your intake manifold, also a thread on here how to do that.

Hope that sets you in the right direction.

my rx8 has the same problem. what was the solution

i bought a used engine from a junk yard, it was from a crashed rx8 and the lower intake manifold was cracked so i swapped out my original intake manifold but i didnt check it thoroughly and one of the valves was stuck due to carbon build up but i ended up replacing my engine with a factory rebuild staight up from mazda

Mine was a faulty ESS/Crankshaft Sensor and a faulty MAF. They were both causing it to misfire and have trouble idling

Were you getting CELs for those components (ESS & MAF)? If not, how did you determine they were bad?

Idk if you noticed, but that's a nearly 4 year old post.

I did notice.

I think he was trying to point out that asking a question directed at a user that has been off the forum for over 2 years in an old thread is kinda useless 😊