I have a 96 miata and it has a pretty bad hesitation below 4000 rpm but above 4000 its great. Any ideas what it might be?

 

Completely stock?

 

the motor is completely stock

 

Plugs, plug wires, maybe a coil going bad? Not sure what the symptoms of a failing CAS are but if it runs fine above 4000 rpm I would guess it's more related to spark than fuel.

 

Check your base timing with a timing light to see if it is retarded. It will act just like this if it has moved a little and made it at 6 or 8* static.

 

ok is there anyother way to tell about timing?

 

only reason i ask is i dont have a timing lite to check

 

i will change plugs and wires. how easy is it to change a coil

 

Call your local auto parts stores and ask if they have a timing light you can borrow, then limp your car over there and check it. Mine drove about like that when my timing belt skipped a tooth and was running retarded timing, so that could definitely be the problem. It doesn't cost anything to check & adjust so I'd do that before buying any parts.

 

cool will do that. would that make my check engine light come on?

 

No it wouldn't typically give a check engine light.

 

ok will have them check the check engine light to

 

I've experienced this when a timing belt was installed one tooth off. How long since you've changed your timing belt?

 

So you have a CEL on too? If you have a 96 then you're OBD II and should own a code reader (and a timing gun). They are inexpensive tools and quite handy. But yeah, the auto parts store can probably pull codes for you too.

If you can't get it to time properly no matter how much you rotate the CAS, then your timing belt isn't on correctly. I guess it might throw a CEL for a misfire or something seemingly related to the O2 sensor if the timing was fux0red, but maybe not. I have a 94 so I dunno how your newfangled diagnostic systems behave.

 

lol cool will check it out thanks!