First off let me say that i am sorry about posting another question on idling issues. i have sat hear reading for over an hour and i think that i am more confused not than when i started. I just bought an 86 rx-7 and when i first bought it and got it running it ran fine. then i replaced the brakes and it all went down hill. when i first start the car in the morning it fires up and idles just fine but i cant get more than two or three blocks before the rpms start jumping all over the place. i can let it sit for a minute or two and it will end up dying then it doesnt want to start again. any help on the subject would be great thanks guys

 

What Rpm does it jump from? (xxxx-xxxx)

Any Mods to the car?

 

it has a k&n fipk kit and a cat back exhaust other than that the car is stock as far as i know. when i first start it it jumps to the 3 grand mark which i now know from reading that it is supposed to do then it settles down to around 750 or 800. ill start driving it around and within ten minutes its starts idling eraticly. when i put the clutch in it will drop from what ever rpm that i was at down to 100 then shoot back up to 1100 and drop back down to 100 and eventually it will end up shutting down luckily every time it dies its right about the time i pull into the driveway. also my horn only works from time to time i pulled the cpu and messed with it a little bit does anyone know how to test the board and repair it or am i better off going to a salvage yard thanks

 

i have the same proublem with my 86 n/a to if you find anything out let me know i got a header and a mufflers but other than that i hurd its a vacuum leak but idk

 

Adjust the TPS.

 

make sure you're cat is in good nic. i heard that this can be another source for dodgy idling if your cat is F***ed tho not to sure how true that is

 

i checked my cat and it is ok its not rusted or anything
how does one go about checking the tps sorry again this is my first rx and i dont know much about them
thanks again for the help

 

To adjust your TPS, read this: page 4A-50, aka page 51.
http://www.teamfc3s.org/main/factory...SYSTEMS_NA.pdf

This is for a Turbo, but it might help you figure out what may be the problem.
http://www.teamfc3s.org/info/articles/idle.html

If you know a little about cars and how to use an ohm meter, you should have no problem checking the TPS.


Good luck and welcome to the RX7club,
Jeff

P.S.
This is an online directory of sections of the workshop manual for 86-88 RX7.
http://www.teamfc3s.org/main/factory...ual/1986_1988/

 

thanks for the help i will try adjusting the tps tomorrow since i dont have to work

 

im having the same problem with my 87 gxl. mines jumps from 200-800, then occasionally it will drop to almost 0 and i will hear a blowing sound. its also died on me a couple of times.... tps has been adjusted to its proper setting...

 

found my problem. changed out the bac valve. idles and accelerates like a dream! even have a/c at idle... at the end of the damn summer.... smh

 

http://mazdarx7.iougs.com/idlecontrol.shtml

I found this site by googling bac valve, very intresting site for you guys that own 86-88 NA RX7s.

 

I have an 87 GXL that surges from 1500-1200 only during warm up. It idles at 1000...that sounds high to me. Also the previous owner replaced the exhaust and took out the CAT...could this have somethig to do with the surging...he pluged the vac line that went to the cat after the sensor....Can i plug the vac line befor the sensor so i don't have the thing just hanging in mid air? Also it runs really rich if I adjust the tps would that help??

 

Surges are generally caused by a combination of vacuum leaks and a misadjusted TPS.

1000 RPM when hot is a bit high. Make sure there aren't any vacuum leaks before making any adjustments.

 

Thanks for the info all the vac lines were just replaced and from what I see there are no leaks, all the lines are connected where they are supposed to be, unless of course I am missing something...duh....anyway from what I have read the idle should be around 750-800 is that correct? What about the vac line going to the sensor b4 the cat (that was removed)that has been capped off...not a leak but a vac line to a sensor that goes no where???

 

Your symptoms suggest proper running in open loop mode, and poor running in closed loop mode. This might be the result of a failing or disconnected oxygen sensor, wiring to the ECU, or a failure in the ECU itself. Best guess is the sensor itself.

If the ECU is controlling mixture properly in the closed loop mode, you should see 8 or so flashes in the green lamp test in each 10 seconds at a steady engine speed (not idle).

Green lamp: a green (or any other color you like) LED, with a 510 ohm current limiting resistor in series, connected between the center two pins on the test connector. Top pin is +12v, bottom is a pull-down (ground) to activate the lamp.

If you get proper behavior of the lamp, the ECU is actively controlling mixture, and the problem is something else. But I am betting...

 

The O2 sensor is ignored at idle and mixture is set by the pot on the passenger shock tower.

I'm still leaning towards vacuum leaks, a bad/misadjusted TPS or a bad BAC.

 

Thanks again for all the info I checkd the vac lines again and they are fine. I am going to move on to the TPS & BAC this Friday, I did some engine clean up this weekend & changed the oil....the oil filter was not on tight...hence my small oil leak...thats gone now as is the noxious exhaust fumes :-)

 

If it runs fine for the first couple of blocks and then starts having problems, that would suggest that open loop mode works and closed is in difficulty.

Any codes?

Is the emissions system going into closed loop?

If you pull the connector off of the O2 sensor, and stop and start the car again, does the stalling problem go away?

 

It runs fine for the first few blocks because there is a vacuum leak and the ECU is enriching fuel at cold start. When it starts to warm up and lean out, the symptoms occur.

 

I'll state it again, since there seem to be some non-believers.

• The vast majority of the time, an erratic idle is caused by a vacuum leak or a bad/mis-adjusted TPS. I've seen both cases many times.
• The 02 sensor is only used during cruising. It is not used at idle.