DBOGGSRX7

While investigating my 1k rpm rattle, I was revving the engine up and letting it go back down so i could make it go past 1k to hear the noise and see where it was coming from. After a couple of times of doing this however, the engine stay at 1500 rpm and wont go any lower. I can't find any vacuum leaks, The primary and secondary butterflies are shut. I just don't get what the hell is going on with this thing. Anyone have any ideas?

DBOGGSRX7

I just checked out a couple of things first. it idles fine when cold, but after you gun it a couple of times it stays above 1500. Float level is fine. linkages are fine. all butterflies are closed. still cannot find vacuum leak... Need help. Has anyone ever heard of this?

180sx-x

idle too high when warm?

1badFB

iTrader: (1)

Just a thought, but the gas pedal isnt just sticking a bit is it?, when this happens, try pulling on the gas pedal with your foot or something and see if that helps. Ive heard of this happening a few times so maybe its your problem.

Rx7carl

Or try manually closing the throttle at the linkage and let us know if it helps.

tempusfugitive

i don't have the rattle, but mine does thesame thing, usally if i've been driving for a bit, if i come to a stop and rev the gas, ocasionaly the idle will sit around 1500, then after a 30 seconds or longer it will go back to 750/800

DBOGGSRX7

linkages are not binding and the dashpot retracts all the way.... just put in a K&N filter???? that shouldn't have affected anything.

Rx7carl

No, shouldnt affect anything unless you possibly knocked off a vacuum hose when working on it.

DBOGGSRX7

What purpose and sequence of operation does the decel valve have. I have only a rough idea.

DBOGGSRX7

?bump?

DBOGGSRX7

bump jr.

DBOGGSRX7

That Was Close.. Almost Made To The Bottom....
Bumperoony

Rx7carl

Not sure what component your speaking of. Maybe you mean the dashpot?

DBOGGSRX7

There is a valve assebly on the side of the carb. it has a vacuum hose hooked to it and has a hose that goes up to the air filter assebly and a hose the goes down to the intake manifold.

Rx7carl

Thats an anti afterburn valve. Its part of the emissions system. But the vacuum source is a possible point of a leak.

DBOGGSRX7

Do i need it? or can i yank it off without affecting drivability too much?

Rx7carl

Depends. Do you need to keep emissions on the car?

DBOGGSRX7

no. not really concerned about the enviroment here in va beach... more concerned with tourists.

Rx7carl

Then do the emissions removal tutorial and ditch it all. Probably solve your vacuum leak as well, if thats what the problem is.