ok. im told its a new remanufactured mazda engine with about 2K on it. its been sitting for 21/2 yrs. same fluids. it will idle a little rough when warm, but when cold it wont at all. it'll bounce real bad even if you hold it to a certien rpm like 600-700 rpm bounce. no accelerated warm up. but nothings been removed. any ideas. it didnt smoke at all when i started it. what do you think? afm? throffle plates?tps?ecu? any ideas?

 

Do a compression check. Run a OZ of oil in the chamber to seal evrything up. Run it until warm do another compression check.

See what that does. After that I would look at the fuel injectors and the pressur sensor.

Is this turbo or NA?

 

Check the coolant temp sensor.

 

That would just make it run rich.

 

mine has a mazda reman with about 3k on it and it sat for 2 1/2 years too. lol, my fuel pump was kinda "iffy" it worked but not too great and spark plugs were old. got a new fuel pump (there expensive but you get a lifetime warranty wich i used to get my buddy a fuel pump for free for his 7) and put new plugs and wires. still ran like doodoo for about a day... after blowing all the old **** out of the chambers and exhuast (by the way my cats were nasty so i got exhuast too) and it runs like a bat out of hell too

 

I've worked on numerous cars with bad ECT's and their symptoms went from no-starts, to hard starts. If it is running rich enough, it won't start, or run.