My fc won't hold its idle!!!!
 

Im having such a bad week cuz my baby isnt holding its idle. this happened after i changed the alternator to an FD one for that 100 amps after i blew my old one. I also got a red top optima and TODAY i got the alt and my battery checked and both were good. So i bought new terminal connectors for the batt and all i got was a stronger start but still my idle wont hold!!! I can hold the idle by gassing it but i want to fix this problem.

PLEASE ANYONE i need just some suggestions on what could it be and how to trouble shoot it. and my fp is working, i dunno if it could be my crank angle sensor \, my injectors, my ecu =(, or just maybe i stupid ground but i dont know how to check these things. =\

fc's are prone to vacuum leaks cuz there are sooo many vacuum lines and they are hard molded rubber, they tend to get old and brittle from such high underhood temps. Thats the first thing i would check before going into management issues.

to check this, have someone, or a 2x4 hold the car at a constant rpm, spray carb cleaner or starting fluid, ether will work around the engine and listen for a RPM surge. :)
i noticed this was your first post so i figgured id go ahead and explain the process. make sure you spray under the upper intake manifold, for that is where most of the vac lines reside.

Get your hands on the downloadable/digital workshop manual and go through the troubleshooting section for idle issues. Make sure the manual is for your car, either 1986-1988 or 1989 - 1991.

I believe these guys host it:

http://bdc.genxracing.com/FC_Manual
http://tristateautosports.com/fsm/1989_1991/?D=D
http://www.teamfc3s.org/main/factory...1989_1991/?M=D
http://www.mirror.wreckedyouth.com/man/86-88/

Ok it could be a leak but its soo hard to tell bc the rpm barely moves but now i noticed my stock oil pressure guage isnt working.

I have always been wary of spraying some nice, flammable liquid around willy nilly under the hood of a running RX-7. Knowing how fast that exhaust manifold gets (heats shields? heat shields? i don't need no steenking heat shields) hot, I have never tried.

Has anyone had any success using this trick? Has anyone found a vacuum leak by this method? Anyone want to stand up and swear by this method. Beuhler...Beuhler...anyone?

Just my two cents worth.

Brian

I know that it doesn't ignight when you spray it on an engine. I've sprayed it on plenty.. it evaporates so fast that its' dry nearly instantly if it does hit direct flame. It does help by causing the RPMs to raise up when there's a vacuum leak, due to your car sucking down some easily combusted stuff. It does work.

To me, it sounds like its time to go through and replace all of your vacuum lines reguardless, actually. Normally there's no one small vacuum line that can cause your car to completely stall while idling. Dig up the Haynes or the Factory Service Manuals listed above, take off your upper intake manifold (UIM), and replace all of that crusty old hose. (I'm assuming its mostly/all original hoses).

Now the sucker is idleing VERY low (SOMETIMES) if i dont touch the gas. This is after i sprayed starter fluid around the upper and lower intake manifolds. and i think it can be a vaccum leak but i dont know where and now im worried about my oil pump b/c my stock oil pressure guage isnt showing pressure. I wanna drive it to a shop but if i can fix it myself and not put my baby in danger that would be awesome. I do have a S4 turbo II in my garage from my 1st baby, and i was wondering if i can use that oil pump and or Vaccum lines on my S5 TII if it does turn out to be anything wrong.

I have that same problem. I can start my car many times but when the rpm's go below 3,000 I pretty much have no control of it. but from 3000 up I can tap on the gas and keep it running. I've sprayed some starting fluid up in the throttle body, any other answers to this question???

Switch the tps

bump.. my baby is roaring once again..

so what was up with it? my car didnt hold its idle for the first time in awhile now. it was running perfectly great. then, my throttle cable was getting stuck on some thing (it was old and krusty) so i installed a new throttle cable, and it wont hold idle at all. i thought maybe it was the bac valve, but i put a new clip on there, and it still isnt working. i am thinking i either got the wires backward on the bac, or its just not fixed. which is probably the latter. in either case, what was wrong with your idle? maybe its the same or similar to mine.

Ryan Shannon.

It was a long story with what happened w/ my 7, but after a Fd alternator, more grounds, NEW VACUUM hoses, and a recalibration of my SAFC she was back and better than ever.

I think I found my problem as well. my oil was just about empty so I filled it back up and found that it was leaking from the hose that goes to the oil cooler in front of the radiator. I'm planning on putting that engine in a different car so I guess I'll replace that hose when the engine is out and easier to get to

i had the same proplem i bought my car from an auction and the guy biddin aginst me had taken the spark plug wires off one of the trailing and one of the leading plugs

check the tps, and check for vac leaks as suggested by vicious525E. spraying taht stuff underhood is perfectly safe, just dont walk behind the car and sniff... :p:

Just wondering. How do you check your tps and where can you purchase one.? If one day ur S5 turbo tps goes out.. lol

you can check the tps using an ohmmeter(did i spell that right?) they can be purchased at the dealership, mazdatrix, or a junkyard(test it there before you buy it). sometimes they are on ebay, or pm trainwreck517, he has them alot.