Hey, just bought one of these 1983 12A RX-7's, and naturally its got some problems I can't seem to figure out. It passes smog good and dandy, but there's some... well... I think they're timing issues:

I did a tune up (replaced the rotor, cap, plugs, a few hoses, changed the oil, air filter looked okay so i left it alone), but it's always had a rough idle. I changed the idle speed on the Nikki so it passed smog nicely (smog guy said his sensors say it's working better than it really is), but it sputters really bad when idling at 800 RPM or lower. Also, when I floor it at idle, it WILL die unless its super warm. I can baby it up to about 2000 RPM, then if I floor it it will die for half a second then juice itself up like it should all the way to 8000 RPM.

Also, it's really rough when decellerating. The car bucks at low RPM when shifting, and the odd thing is the choke seems to help with this. I don't think it's the secondary's not goin, cuz i can feel a nice VTEC-like burst of power when I floor it and it hits 3500 RPM. Funny thing is, it actually responds better when the pedal is slightly above the floor than all the way down. 100% flooring it actually makes it sound terrible and the performance is seriously bad.

Also interestingly, it idles faster when I'm cruising at 40 MPH or faster. The air filter looks good and all the hoses are dandy (I checked all the ones I can see). And it down back-fire consistantly: like when acellerating to 5000 RPM then letting off the gas, it will back-fire all the way down to the rough idle.

So... any ideas? Should I just take it into the shop?
It runs good on the road (and gets about 20 MPG with medium spirited driving), I just gotta milk the gas and stick so it doesn't act like it has asthma.

 

What kind of plugs did you use? Only use NGK's, br8eq's leading and trailing. You can use NipponDenso plugs, but you need a thin walled socket to put them in/take them out, so just stick with the NGK's. AutoLite, etc. suck.

change your air filter. it may look good, but it's a good idea to change it. Change your fuel filter. buy yourself two cans of SeaFoam. Run one through a piece of vacuum line that you put on the brake booster vacuum nipple that is on the intake manifold. You're going to have to have a buddy keep the RPM's up so the engine doesn't die. Then wait until you get to 1/8 of a tank and pour the other can of SeaFoam into your tank. Run the **** out of the car 'til you bury the gas needle and fill it up with some good 87 octane. this should help clean up the engine.

Now for the timing. When facing the back of the car, turn the front pulley counterclockwise with a ratchet and socket until you see your timing marks. The first one is your leading, your second is your trailing. Steal some of your girlfriend/wife/mom's nailpolish (I like red on my timing mark) and get a toothpick. Clean up your pulley and paint your leading mark with the toothpick. Hook up your timing light to your battery and the spark plug lead going to L1 (bottom plug, front housing). I'm not sure what the stock timing is, as my car has serious timing issues right now. good luck

 

I used cheapo Autolites cuz I wasn't sure if the problem I have is gonna wear out the plugs faster or not and didn't wanna buy good stuff that'll crap out until i fix it.

 

did u check ur idle mixture? i believe idle runs on vacuum and also when u shift between gears and let off the gas. i think i read this somewhere recently

 

Uh... no. How does one check that? :-S

 

Check this hose. The issue is gonna be on the bottom right by the exhaust. I bet it's cracked. Take it off, and inspect it. you may not be able to feel the split yet.

 

to check the idle misture there is a screw that you will see right in front of you when u stand on the drivers side. its near the idle speed screw except to the left and more easily accessible. there is a thread in the faq section on how to tune ur mixture.

 

Nope, that hose is perfectly fine (except a little oily). I just noticed however that the big vacuum hose seen in the pic big has a large crack in it at the base. What does that hook up to?



EDIT: By the way: Thanks for your help guys.

 

Oh, also, I can't find the Idle Speed screw. I found the Thread that deals with Idle adjustment, and I found the Idle Mixture screw, but where exactly is the Speed screw? Under the linkage where? I got lost in the woods of hoses down there. :S

 

Hey, you're in reno. I'm in vegas

 

lol with the same year car, just nicer. Sup homie?

 

all right mate just reading your prob sounds like possible primary jets blocked.Have you had the carb apart

 

Haha, theres actually a few people in reno and vegas. Make sure to use the search button and check out the faq page(if you haven't already), they're very useful. Welcome to the forum. Oh ya, post pics of your 7 when you can.

 

I haven't had the carb apart, but my bud swears he saw gas spitting out of all 4 barrels when i was flooring it. Maybe he was dreaming.