FC3S_Bat

hi everyone, my FC which I bought about 3 months ago came with aftermarket headers and no o2 sensor plug, car drives just fine but it tends to hesitate a bit during idle (randomly bounces from 1000 to 1200) its been driven like this since I bought it and I haven't ran into any issues so far, im trying to avoid something critical in the future so therefor I wanted opinions from someone whos dealt with this before or that is running a similar set up, is this ok? is it bad?
its a 1990 vert n/a.

satch

iTrader: (1)

The sensor is used while cruising and not idling so it's likely not your issue. The Green/Red wire of the TPS should read 1 volt w/key to on after the car has been driven 20 minutes or so. Check the voltage and adjust as needed.

FC3S_Bat

Do you think it will be ok without the sensor? And thanks ill check the tps. How do i adjust the voltage?

RotaryEvolution

iTrader: (30)

i ran my car without an active O2 sensor for years without any ill results.

might help a little with MPG on those really long road trips, otherwise you won't likely miss it.

satch

iTrader: (1)

There's a one inch long screw encased in a spring at the front of the throttle linkage near the TPS (not the long skinny screws in a spring).

Aaron Cake

iTrader: (1)

Don't just start twiddling the TPS screw. Look up the adjustment procedure in the Haynes or FSM.

The Factory Service Manuals for all years of RX-7 (and many other rotary cars) can be downloaded for free here: Foxed.ca - Mazda RX-7 Manuals . They contain all common service information and more, and are an essential tool for any sort of service work that needs to be performed on these cars.

Additionally, the Haynes service manual for the 1986 thru 1991 RX-7 (both turbo and NA) can be found at most local auto parts stores or purchased from any good bookstore (ISBN number 1 56392 007 7). It is only about $25 and is a great quick reference for things like this. Not only does it contain most of the information in the FSM condensed into an easy to read format, but it includes full wiring diagrams as well.

These manuals will answer 99% of service related questions for the car and if you intend to do your own repair work, you will need at least one of them. Preferably both, since the FSM is a free download. The Haynes is a good quick reference covering 99% of questions, while the FSMs show complete and detailed procedures.

FC3S_Bat

Tps has been disconnected. Got no readings when i tested for resistance. Its a bit rough when cold, once it warms up the idle is the steadiest its ever been. Surprisingly smooth. I noticed that theres three lines (which you can see on picture above) that are just open....? From when the o2 sensor was cancelled (red spot) it reaks of gasoline. More that it usually should. I checked all other fuel lines and dampener and see no signs of leaks anywhere. Is there any caps or ways to wisely block those open lines?
also the carbon canister drain is open as well, and the oil is starting to smell like gas. time for an oil change?

satch

iTrader: (1)

Are you sure you tested the resistance properly? The open lines are possibly emission hoses and they should be capped. The carbon canister's job is to remove the smell of gasoline.

FC3S_Bat

Not sure i did. Do i unplug it? Before testing? I cant get thru the waterseal while its plugged. Also. I found the o2 sensor further down the headers. Its still plugged in but the wire is cut off. Replacing it soon to see if it helps any.

satch

iTrader: (1)

If you are performing the ohm test it requires the sensor to be unplugged. You use the wires that are part of the sensor and not the harness itself.