copterdoctor

hi all!
i recently put a new engine in my 1991 rx-7 and evrything seems okay except that after it warms up, the idle surges 2-300 rpm. i have checked all the hoses and lines and dont know what else could be causing this. it revs fine and will hold the revs but just surges back and forth on the idle. any help or advice would be much appreciated.

alwayssideways

adjust your tps. i had the same problem .. if you look on here there are severla write ups on how to do it .. just do a tps adjustment search and you should be set

copterdoctor

great! thank you sir. oh, forgive me but what is tps???
i am seriously new. had the car so long and never needed to know a thing about it til i blew an apex seal. then i replaced the engine myself without any probs but need to learn some stuff now. thanks again.

Project84

TPS= Throttle position sensor. Tells the engine computer how far you are pressing the go pedal.

Also, you may want to check for vacuum leaks. If the engine is drawing in unmetered air, it will throw off the idle.

alwayssideways

the tps is a Throttle Postion Sensor . its mounted on the side of the Throttle body . adjust that and i think youll be ok

copterdoctor

thanks guys! i appreciate the help. i meant to mention that the little bit of gas that is in it has been there for the year and a half that it has been sitting and wondered if that may affect the idle too. it rev's fine, just idles like crap. when i step on the gas, at that moment and for just a half a second, it makes a knocking sound but the revs are smooth. the knock sound almost mechanical but everything is in neutral. any ideas? the bad gas maybe?

Project84

wouldn't hurt to get new gas. I don't know the history of the engine but you said you installed a new engine. Is it new to you or brand spankin' new? Check the timing to make sure its set right.

DEZERTE

after your car is fully warmed up, screw the idle screw on top of the TB all the way down, to see what happens.. Doing this for me removes the surging

copterdoctor

engine is a reman. tried the idle screw with no change
is the timing changed/adjusted by turning the crank angle sensor?

WAYNE88N/A

Don't start messing with the timing just yet, fix your idle first. There are millions of threads on adjusting the TPS, and if you have either the Haynes or FSM, you can use the steps contained in each also...

The idle screw won't do squat until you jumper the initial set connector on the left side of the engine bay (green one)...

alwayssideways

hey wayne ,, are you talking about the terminal near the leading coil or the washer resoviour??

Project84

that be the one he's talking about. And to check the timing, you need a timing light. If you are trying to start the engine, you should have already checked the timing.

Kenteth

my car surges when it idles... intermittently though. Project84 and I did the timing a few onths ago, and i did the tps. I'm still convinced its the TB, but its driveable at least.

copterdoctor

okay, wont mess with timing. the engine does run and seem to run okay, just that annoying idle.