Ok, after owning four 1st gens (all of them stock 12A carburated with no mods and no emission crap removed) I've seen just about everything but this is a first:

During city driving, once the engine reaches operating temps and the choke **** retracts, and once letting off the gas to stop at a traffic light, the revs drop slightly below idle (down to about 500 rpm) and then stabilize at 750 - 800 rpm.

The engine does not quit in these instances, but that situation changes if I'm hauling down from highway speed, ie: 3500 rpm for several minutes after reaching operating temps. A typical scenario is starting off cold, driving out of town for 20 minutes at highway speed (during which time the choke opens normally) and then taking the car out of gear and slowing for the off-ramp with foot removed from the gas pedal. As soon as I do this the revs drop straight through the floor with no stops in between and the engine quits. I then put the car in gear and release the clutch to re-light the engine, and it will only idle on its own if I very gradually let off on the gas. Outside air temp doesn't seem to be a factor.

Has anybody experienced this before? How did you rectify it? BTW, this car is a 1985 GSL 12A, bone stock.

Thanks,

Brett.

 

Have you tried playing with idle mixture screw?

 

Mine does the same thing, 1985 Mazda RX-7 GS. I have messed with the air/fuel mixture, how do I know where to set it? Sorry for halfway threadjacking...

 

i have an 85 gs and when i go down the road which is 50mph it drops to 25 after you get over the bridge and when i let of the gas to slow it will studer and then from 25mph i go a few blocks then slow to turn onto a street and the car cuts off every 3/5 times i turn that corner..i thought it was just my car but..... and (i dont knwo if this has anything to do with this ) when ever i go over a bridge or connector or (anything with an incline) my car starts to lurch..(same effect as if poping the clutch at to low of an rpm)???????any help with that no temp factors envovled no matter what any incline it happens

 

I have an 84GSL with a similiar issue. Mine only does it right after the car gets warmed up enough for the choke to retract back in, then if I am cruising and take it out of gear that the rpms drop like rocks and the car dies. After a little more drive time and everything truely reaches operating temp., the car runs like a champ.

 

Not usually recommended and besides, if it were a problem with the mixture or idle speed setting it would do this at ALL times. But it only rears its ugly head shortly after the engine reaches operating temps and even then only when dropping to idle from highway speeds. Doesn't make much sense.

 

Does it do it after a while of running at normal temp? You know, like when everything is warmed up completely.

 

May I ask why you drop out of gear on those occasions? My Baby is retired for the winter,and does not give me those problems during the no salt seasons. Bob

 

Sounds like you have a vacuum leak. The issue you are mentioning (slowing down), makes it seem like you have a leak in your brake vacuum.

 

Float levels ok?

 

I have an 84 GS with the 12A. It has recently started with the same problem - after it reaches running temp, it just stops. And it doesn't restart until after it has completly cooled. Its my third rx-7 (1st gen.) and have seen all the quirks (i hope) but this one has me. I don't usually take my 7's to mechanics. Can someone tell me what is going on and what i can try to fix it.

 

Ive got the same issue with my 82 12a, emmisions are removed, RB header. Also as of late... if I shut it down and run into somewhere for 5 - 10 minutes, she won't wanna start. I have to pull the fuel pump fuse, then start it, and once it runs decent, I can put the fuse back in, and all is good....... This has just started since the cold weather....

 

Have same type problem with my 84 GSL, I brought it to my local Mazda dealer and to get the compression checked (just to be sure ), what I found out was my carbeurator was flooding.

This was causing my car not to start on cold/damp mornings. I believe that the carb flooding is causing my problem with the stalling, so it may be yours as well....

I plan on rebuilding my carb this winter... I hope it solves it, I've just about had it with this problem!

sorry for minor threadsteal

 

The choke is releasing too early....in lieu of actually tuning up or replacing the coils on the carb that control when the magnet is supposed to release, I just let it idle for about 7 minutes in cold weather with the choke on while I get it ready for going to work. I also have to drop my boy off at the daycare. After I'm finished loading it up and "washing" any ice off the windows, I push the choke in, keeping the engine going with the gas pedal and then stopping the engine. I'll go inside to feed him, come out in about 10 minutes and start it again, set the choke and go on my way....I never have that problem when I follow that cold weather routine, but I always have that problem when I don't follow the routine...

 

My 7 will shut off when it was 80 degrees outside as well as now when its about 40 degrees outside. It does run longer when its cooler outside.

 

Once the car has been at operating temps for say, about 30 minutes everything returns to normal, ie: the engine no longer quits when dropping to idle.

 

This happens when I depresss the clutch and let off the gas, whether I'm still in gear or not. Once I disengage the transmission from the engine without having my foot on the gas the revs immediately drop to zero. If operating normally, the revs would drop more gradually and level off at normal idle rpm of 750 to 800 rpm.

I do drop out of gear in these instances because I intend to put it into 3rd to negotiate the curve at the end of the off-ramp.

 

Except that the engine quits even before I apply the brakes.

 

Float levels appear normal, and the problem does eventually go away.

 

Yeah, I thought of that already. But the temp guage shows full operating temp when the choke opens, and it still doesn't explain the rapid rpm drop to zero coming off highway speeds but not doing this in city driving. Strange. I'm wondering if the igniters are on the fritz, but I've never had those fail so I'm not familiar with the symptoms. Igniter temperature related maybe? Your guess is as good as mine.

 

Mine does that too when its cold out. It doesnt die, but it will drop way low like yours does. It takes it a few seconds to regain the smooth idle. But once it is warmed up all the way it will run just fine all the time. I honestly thought it was just tempramental (sp) like that.

 

Happens to me too. the same way just after the choke going in... dies.... but if i drive her a little more she is fine... i have just been dealing with it since winter has started... so oh well. i have a rebuilt carb goin in soon anyway so ill let you know if that changes anything.

 

Try turning the mixture scew anti-clockwise 1/4 or 1/2 a turn. The fact that it's stalling just after the choke goes in and before it's been at full operating temp for a while indicates the idle mixture might be a bit lean.

 

That's certainly worth a try. The puzzling thing, as mentioned, is why the problem doesn't happen in city driving at slow speeds and low average rpm. It's - 20C outside right now, but I'll try that tomorrow when it's a little warmer. Thanks REVHED.

 

Ok, just finished turning the idle mixture screw counter-clockwise 1/2 turn to allow a richer mix, but I'll have to wait until tomorrow morning to see if it has the desired effect. I'll post the results when I have them.