fast idle

[a.tapos]

Hello,ive just finished my second fd rebuild for water seals tips etc,all went as well as possibly could untill i started putting coolant in it,as it all found its way to the passanger side footwell,as you can well imagine i was chuffed:mad: to find id have to do a matrix on it,as it happens its not a bad job at all if you dont mind taking dashes out its a mornings work,so now weve got coolant and its alive,problem is its idling at about 2.5 to 3k rpm,my initial reaction is air leak as i can feel the idle control trying to pull the revs down i have replaced all 4 miles of vac hose and both inlet gaskets with mazda ones,my quesion is when i block the inlet pipe shouldnt the engine die as with a piston engine as i use this at work to find leaks and always seems to work,if i do this on the mazda the idle wont even drop a touch which suggests air leak,eventually the engine cuts out im guessing when the cpu gets annoyed,has anybody had this before or am i missing something,thanks,andy,p.s.ill give you free advice on your ford.:Thumbsup!

[leon]

Rats nest job WHAT A JOB! *twitch* but its somthing worth doing! When you say that you are blocking the inlet pipe, do you mean litraly blocking of the air getting into the engine via the throttle body? i would expect the engine to die from lack of air!

Just an idea: The gaskets that you changed were the Upper intake manifold and the throttle body ones? Did you change the lower gasket, as you may have a leak down there, or even a cracked manifold letting a shed load of unmetered air into the engine (the gasket that goes from the Lower manifold to the block)

[kev-yorks]

As you suspect you\'ve a vac leak somewhere. Yes the hand over the inlet does work like a piston motor.
Kevin

[a.tapos]

yes i mean i literally put my hand over the throttle body inlet pipe without it dying,well at least i know its the same theory as a piston engine,i havn`t replaced throttle body gasket as i didnt split it i have replaced upper and lower fannymould gaskets with gen mazda metal items during rebuild,i cant imagine they would be able to leak,im thinking it may be a blanking plug or summit,i may block it up then use some brake cleaner to look for a leak,thanks for your input,

[kev-yorks]

Probably something silly as you say. Sounds more like a pipe you forgot etc rather than a gasket. I normally spray easystart to find the source of the leak myself.
Kevin