ok so the trottle cable is loose so its not artificially set high but it wants to idle around 3k the motor seems like its trying to fix its self as in it will drop to 2500 and bounce back up sometimes. im thinking its a major vac leak. but ive never seen one stay running that high, usually if theres a vac leak that large it'll just bog down from lack of fuel.
any thoughts?
thanks

 

Sounds like a TPS or T-wax issue.

 

it might be the BAC being stuck.

 

Sitto, this could be it. Also, set the TPS and idle per the FSM. see if that will drop it. When i first got my car it would idle at 1500 no matter what i did.

Ended up being the thermo wax being stuck but that only makes it idle at 1500, not 3000.

Check the cruise control cable, make sure it is not to tight as well.

 

ok the lowest idle i could get was 2k if i adjust the timing to lower it it dies.
i have replaced the following with known good components;
tps
afm
ecu

i have pulled the upper manifold and replaced the gaskets
i pulled off the tb and its plates close fully

the car pops at when it tries to idle and the inside of the strait piped exhaust glows bright red.

so im thinking its running rich, and where its getting enough air to run at 3k is still a mystery.

tany thoughts

 

I had this same exact problem when i got my car. After weeks of trying to figure it out it ended up being that the TB set screws were set to far open and kept the TB open a little all the time. And my thermowax was bad and would not disengage the cam.

Fixed both of those and it has idled fine ever since.

 

ok guys update
i swapped the following now;
ecu, tps, afm, cas, tb, all manifolds, fuel rails, stripped emissions, new vac lines, swapped fuel injectors. and it still does it?
im totally lost. any suggestions are awesome

the motors a recent mazda reman, runs fine over 3k btw

thanks

 

Air is getting past the TB some how.

Either through a vacume leak or through the TB plates not closing all the way (like mine).

First spray down ALL of the vacume lines with brake cleaner to see if they are leaking. If not then pull the TB off and make sure the TB is closing ALL the way.