EnBom_Rx-7

I am getting anywhere from 8 to 10 miles per gallon in my 1987 Rx-7 GXL.

My car idles high, at around 1,600 RPM. I just bought this car a couple months ago for 1,000 out the door. It had some trouble starting at first. I would pull one of the sensors from the ECU, turn it for 10 seconds on the gas, put it back in and then start the car up. After driving it over the past couple months, starting has been no problem. My new problem is gas.

I have got my car to the maximum 16gallons and driven the car. I got 160 miles exactly, and my car started to stall if the pedal was hit hard [I discovered while transferring from a local road to a busy street] so I know my car was empty [it stopped after I put some gas in it]. I have never ran it near dry before, didn't mean to even this time, and I have done this fuel test 4 times now. I get 8-10mpg. So after I get the new gas, I go to the next town over, 24 mile drive there and back for some contact lenses, and I have wasted half of the gas that I just purchased, gas meter wise [we all know how reliable that is ]

My old 86 got shitty gas mileage, but more, much more sufficient then this hog. I have done some searching, and I have heard the following;

1. O2 Sensor, no idea what or where this is.
2. Full tuneup, but my father insists that this was done already.
3. Thermostat, could possibly get the old one from my car, but I don't know if it is any good either, tbqh.
4. Dirty Filters, but my K&N filter was cleaned, and the smaller guy right next to it, forget the name, was just purchased.

Thanks in advance fellas, will really appreciate any help I can get.

Andrizzanizz

iTrader: (1)

to reach the o2 sensor you have to get under the car and it by the precat in the exhuast. you probably have to remove the precat to get to it.

and if you dont think he has done a full tune up check all the fluids again it wouldnt hurt.

get an oem thermostat they work the best.

and i dont think its the filter because the stock filters are worse.


but yeh that answers your 4 questions.

and im not sure about your gas mileage problem.

first fix the idle and then check to see if there is a leak some where in either the tank or the lines.

EnBom_Rx-7

Idle has been attempted to be fixed, don't know what I am doing wrong. My father also tried.

The questions were stating what I have stumbled apon, I was curious as to which might be the cause of said gas problem.

As for the leaks, I don't know how to go about searching the tank, and dont know what or where "the lines" are.

Sadly, the only fluids I know about that go into the car, are gasoline, oil, antifreeze and or water, and transmission fluid. [washer fluid too, but the is disregarded]

coblepots

Here are my thoughts:

You could be running extremely rich which could be due to fuel injectors sticking open or the bad O2 sensor. Do you smell any fuel coming out the tail pipe? Is there a large accumulation of soot on the inside of the tail pipe?

As for leaks. Take a look under the car at the gas tank. You should be able to locate both the return and out gas lines. They should be about as thick as a pencil. Trace them as far as you can before they disappear. Check to see if they appear wet. If at anytime you smell gas there's your leak. (don't do this right after filling up as you might smell the residual gasoline). Also, if your car has sat in a garage for awhile, check to see if there is a gas smell in the closed space. This would indicate a leak as well.

The high idle could be due to a faulty O2 sensor as the car is not able to determine if it is running stoich or not and is having difficulty stabilizing itself. The ECU uses the O2 sensor as part of a feedback loop to determine the amount of fuel needed. Try Andrizzanizz's advice for getting at it.

Good luck!

Andrizzanizz

iTrader: (1)

well the tank isnt that hard to find, you can see it when you are looking in from the rear of the car. just follow the lines leading to it.

and did you check the oil?

EnBom_Rx-7

I am going to sound about as mechanically disinclined as I possibly could right now, but unless there is more then checking the dipstick, yes I have checked it.

Andrizzanizz

iTrader: (1)

haha alright man.
well for adjusting the idle, how did you go about doing it?

there is a screw ontop of the tb and then there is one on the tps.
also sometimes the line for the cruise control gets caught and you need to fix that.

Craiger

iTrader: (1)

A lot of your poor gas miliage will be due to your high idle. My idle is at about 1400 right now and I get shitty mileage too. If you have tried normal idle adjustment procedure and can't get it down you probably need to adjust the throttle stop as someone has adjusted it out making it idle high. After you adjust this you will need to re-adjust the tps as well.

Get your idle sorted out and then see if you still have mileage issues.

P.S. What the other people wrote to check are strong possibilities too.

EnBom_Rx-7

Throttle body cleaner through the air hole was my dads attempt. He got it to go down temporarily.

I just messed with the screw, but the screw completely shut it off.

[is there more to checking the oil then the dipstick? because oil changes never made sense to me. what do they do if you pay for an oil change?]

Andrizzanizz

iTrader: (1)

do you have a multimeter? because if you do go to icemarks page and see how to adjust an idle. if you dont then just mess around with the screws till you get it right.

also dont fully thread the screw in bc it would shut off the car as you said, try to leave it "in the middle" and not full out. also mess with teh screw on teh tps.

and on the oil change.
you dont have to pay for an oil change.

it seriously takes 5-10 minutes depending on how fast your oil drains.
first you pull out the bolt on the oil pan, and have a catch can or something under it.
then you remove the oil filter to let the air push it out.

once you are done draining the oil you put the plug back in.

add a little bit of the amount needed and put some oil around a *NEW* filter, and put the filter in.
turn the engine over but dont start it.

then add the rest of the oil.

and theres an oil change.

also you need an oil change because cleaner oil helps lube up your engine more and also keeps everything working fine. oil changes are essential in keeping a car working good.

EnBom_Rx-7

Cool, will do that this weekend. Thanks a lot for the help.

How much do new filters run? 10 bucks?

When I drain the oil, can I re-use it or do I just discard it?

edit: also I do have a multi-meter so I will check it out, any keywords to search for?

Craiger

iTrader: (1)

Steps to checking oil:

1) put on a nice dress and matching shoes (borrow from mom/girlfriend/sister/any other parrent or sibling that may own such items)

2) Go talk to whoever is near by and ask them if you look sexy or if this dress makes your butt looks big

3) remove dress and put on whatever you so desire (if this happens to be the dress than just leave it on)

4) go to car and pull dipstick

5) wipe off and put dipstick back in original place.

6) pull dipstick and note oil position on indicator at bottom.

This is how you check the oil.




P.S. This is ment to be humorous and it not ment to be offensive in any way. Use at own risk. I am not responsible for anyone who gets in trouble for stealing someone's dress and shoes.

EnBom_Rx-7

Was never much for dull, unripe humor.

Craiger

iTrader: (1)

Sorry, my idea of a bad joke.

On a serious note yes there is nothing more to checking the oil then checking the level on the dipstick. If the oil is of an unknown age then you should change it, which is easy as stated above.

Oil is cheap, no sense in re-useing old oil. I don't think i've ever paid more than $5 for a filter, sometimes here you can get a free filter with a jug of oil.

EnBom_Rx-7

I know how to check the dipstick, silly. I was wondering how to change it, or if there was indeed more to a complete oil check. Andrizzanizz made it clear that there is.

Andrizzanizz

iTrader: (1)

well the point of an oil change is to change the old dirty oil and put fresh new oil in there. there is no point in doing an oil change and putting the old oil in there. same thing as using the same filter.

and just look for icemarks post on adjusting the tps. or just type in adjust tps in the search thread bar.

Taiwanese

From personal experience, the level of the idle shouldn't make too much of a difference unless you're hitting a lot of stop-and-go traffic. My RX-7 idles at near 2500-3000 and I'm getting 23-24 mpg highway.

Go48

iTrader: (7)

First thing to do is to get a copy of the factory workshop manual. It is free for the download via one of the links in the 2nd gen FAQ. Setting the idle on these cars is not as simple as on older carbureted engines, so read and follow the instructions in the manual.

NJGreenBudd

iTrader: (1)

Ok, first I would go download the FSM or buy a Haynes manual, here is a link to the manual online:

Service Manual for 86-88

I woulds spend some time reading over the maintenance section and perform a full tune up your self, doesn't matter what your dad says. Make sure you know how to do an oil change before you attempt any other work on the vehicle.

Also, is this your engine bay-


If so, you AFM is installed incorrectly. It must be oriented in the correct manner, as in side to side instead of up and down, or it will not work right and your car will suffer.

Thats some horrible gas mileage, does your exhaust reek or gasoline? What mods have been done to this car??


Edit: Yeah I'm sure a stand alone is the answer here.

helghast7

iTrader: (6)

throttle screw you should shut it them turn it about 2 full rotations and let the computer adjust,

check all sensors, especially your tps.....tps voltage should be at 1 volt on idle, and when reved up should smoothly go the about 4 volts then drop of back to 1 volt when idleing again.

i have a question of you, when you turn the car on in the morning, what does it do? does it rev up to 3k then drop off to 1500 or does it rev up then drop to 1500 and keeps rolling?

you idle should now be back at 750

if not then you need to search all the vaccum hoses to see if you have an air leak. a leak will richen up the mixture aswell.

marshall13B

iTrader: (5)

What kind of fuel are you using? If I use cheapo 87 octain i get poor mileage, if I use 92 chevron (with techron) I get great mileage. Almost like a normal car!

helghast7

iTrader: (6)

^ thats actually not quite true....an n/a was designed to use regular 87....therefore if hes using regular the car would not suffer... i have even tested this.

i usually get 87 but a couple weeks ago the price of gas went down so i switched to 91 because of the higher octane, it made my car run richer and i had worse gas mileage, you could even smell the difference.....manufactures dont tell you what gas to use for the car because they think its funny.

Roen

iTrader: (2)

I run 87 and get 24 mpg.....it's not the fuel.

NJGreenBudd

iTrader: (1)

Yeah, like they said, 87 is the stuff to use unless it's turbo, and even then only if your running higher than stock boost would you raise the octane level to prevent detonation.

Also, as far as I knew, an air leak, either in the TID or a vaccum line will cause your mixture to lean out, more air ( non metered) with the same fuel equals leaner mixture. Am I mistaken here??


Still waiting to here the mods done, some more info would be helpful. How many miles on the motor? How does the car run? Post a video of the startup if you can.

EnBom_Rx-7

I have the Haynes Manual, I use it quite frequently. Me and my father read it over for the idle, but it didn't work to MY knowledge.

Agreed, I am a little disinclined, but I catch on fast to 99% of the **** I do. I will give it a reading and see what I can get out of it. Hopefully all of you will be here to help with any questions I can't seem to find the answer to.

Yes, that is my engine bay.

AFM? I bought this car from a lot, the lot repossesses cars or receive cars that have been repossessed, so therefore I have no idea on all the mods done. I know of K&N Air Filter, Some muffler--probably not a good one, and that is all I could say for sure. I have installed the stock fan from my old car, replacing the electric of the new one.

On my way to school, a fellow senior of mine was driving behind me. He said, "Your ******* exhaust bro, made me cough... that **** is nasty" I could smell a little bit, but not to the extent he had I assume.

Standalone?

With the screws, my engine just dies if I play with them.

I would get myself into a mess of trouble checking something I am unsure about. Anything you can tell me about the sensors would definitely help. I am assuming you're talking about the ECU panel.

When I turn the car on, I have to turn the car over, and hit the gas until the engine fires up, and then I let off the gas. I will try tomorrow without hitting the gas. I think it goes to about 3k, then drops to about 1k, maybe lower and as it warms up goes to 1.7k.

I will definitely search the vacuum hoses to search for an air leak.

Car runs nice, except for the mileage. Maybe it was just me, but I felt as if my car was vibrating when I shifted to 5th gear at around 3k coming out of 4th. My 5th was near 1.8k when I initiated 5th though, so that might have just been too early of a shift.

QUESTION: What is the OPM and what are the advantages to a pre-mix?