i am having some really weird gas milage problems. I just started driving my TII to school and I am getting really bad gas milage. like a noticable drop after jsut 1/2 hour of driving. but the really weird thing is that when i stop to go somewhere and coem back in, it looks like there is less gas than when i got out. WTF? i thought i migh have a fuel leak somewhere but i dunno where to look.

I also have another problem. no matter what temperature the engien is at, it takes at least three seconds to start up. soemtimes i have to play with the fuel pump switch to get it going.

mayeb i need new injectors, i dunno but any help on what is wrong or how to get better gas milage would be great because I really can't afford this.

 

Have you checked the spark plugs and wires? When my '87 TII was running pig rich (not tuned ECU), it would foul my spark plugs easily and be a pain to start. Plus mileage sucked. With new plugs, the engine started in half the time and slightly better mileage and idle. And check your battery too while you're at it and a full tune up.

 

Check your water thermo switch at the ECU also, after checking the more obvious things...

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/troubleshooting-your-car-ecu-340578/

 

is there any way to keep my car from running "pig rich"?

 

You can buy an SAFC and lean it out, but that's expensive.

Change your plugs and O2 sensor, that should help.

 

yea, fix what's wrong!!
also, find your actual gas mileage and see where you're at. our cars are old; some sensors are out of spec, some sensors have been broken, some may have an open circuit (broken wire), some may have a high resistance, and some sensors may just be dead.
the thermosensor, as mentioned in another thread (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/cold-startup-problems-359037/) i just posted in, apparently affects startup, though i don't know its affect on gas mileage.

 

i want to change my O2 sensor but i cant get it out. the no wrench that large will fit in the engien bay so that i can turn it and i dont have a socket that will clear he sensor.

 

O2 sensor, i wouldnt think, shouldnt affect your gas mileage too much on certain short trips. it doesnt function until it reaches a certain operating temp and sometimes closed loop isnt an issue (again, short drives). i'm not sure how important it is for fuel ratios. its an older 1 wire sensor, but it may be more important than i give it credit for. in fact i shouldnt try to sound like i know its functions too well.

what you could do is volt test it. it has certain volt ranges to check for. if its old, though, might as well replace it. they make a certain socket, an O2 socket, specifically for O2 sensors. i was looking for mine recently to replace my O2 sensor. its lost.

still i really dont think the O2 sensor is your main problem. i would suggest testing your water thermosensor. its the only suggestion i have for startup problems.

 

WOW. i finally replaced my sprk plugs and its a BIG difference. my car has smooth idle, no more "rrrrrrrrrrrdup-dup-dup". smoother accceleration, and i can clearly head what my engein is doing. my car makes a totally different sound from the interior. it still takes a couple of cranks to start up soemtimes though.

 

How did your old spark plugs look? Mines were all filthy with carbon deposits.