So this is my first rotary, and first 4 barrel and definitely my first Nikki. So my best guess is that I have a sticking float, but I don't know if it could be something else. If I come to a complete stop it accelerates fine (well kinda slow but it's going to get a tune up too) I'd say 0-60mph in approximately 11 seconds. However if I come to a yield and slow down or go around a sharp turn and attempt to get back up to speed, it will take about a minute. Once it gets above 4.5k rpm it starts to act normal again.

I tried slowing down by taking my foot mostly off the gas, taking my foot off the gas completely but not touching the brakes, and slowing with brakes. It happens in all scenarios.

I have the carb rebuild kit, I just want to get another option or three before I go tearing into it for no reason. This car has yet to have any modifications done to it. I searched the forums for a bit, but didn't see anything.

 

Is this a manual or automatic? The engine doesn't really wake up until about 3500 rpm, I'd say "play with it" and keep the rpms up higher next time you drive it. It'll never accelerate hard from 2000 rpm.

 

​​​​It's an automatic unfortunately. However, if it was better at higher rpms, then it would accelerate better from a yield than an idle, right? Yet it's the opposite. I could slow down to 20mph and floor it and it will literally take a minute to get to 50mph. Or if I completely stop it takes 9 seconds.

 

Is this a new problem, or a new car? If your trans isnt downshifting as crisp as it should, it will hang in that higher cruising gear. So it might be in drive (3rd) as your trying to pull away from that corner. Ive never had an RX7 Auto but most 80's autos have a cable or vacuum line from the carb to the trans to tell it to downshift when you jab the pedal. Yours could be out of adjustment. It sounds like slowing for a corner in a 5sp and trying to accelerate away without downshifting.

 

It's a new car. I bought it off my uncle who's had it for a long time. He said it started this year. When I quickly push in the gas pedal though, it does down shift promptly, but does not accelerate any quicker and upshifts again after a few seconds.

 

I looked up "RX7 automatic kick-down" and found some info. On the first-gen cars there is a switch on the gas pedal assembly. When the pedal is pushed mostly down (3/4 of the way?) It will downshift to the next lowest gear. I think you just need to give it more gas.
Now there may be something else going on in the tranny, but I'd look and see if that switch can be adjusted to contact sooner.
As I said though I haven't had an auto in an RX7 so hopefully one of our resident RX7 mechanics will chime in. But these engines, in stock form, in first gen cars, really don't make much power. So with a slush-box auto you're gonna need to give it more pedal to keep the rpms up closer to where the motor is happy (3000rpm +).

 

​​​​​I'm not expecting it to go 0-60 in 3 seconds. But there shouldn't be a 90 second difference between FOT from idle at a stop and FOT from 3k rpm. I checked and when the pedal is fully depressed, the carb does fully open. So I really don't think that's it man.

 

Hopefully someone well versed in rotory Automatics will chime in. The motor might need attention, or more likely the tranny. The tranny not downshifting to an acceptable rpm range to pull away from a corner, points me to either tranny or kick-down issues.
Nowadays all cars come with autos and they all drive pretty nice. But in the 80's an auto tranny on a small-engined car just sucked. An '87 Ford Escort w/auto is an absolute turd compared to an '86 w/ 5sp. An '81 Chevette with auto is a slug compared to same car with stick. An '84 Audi Quattro auto is a lazy lump but with a 5sp it is fun. I had all these cars when they were still young.
Your car is 35 or so years old. Regardless of mileage, its an old car. Everything you described makes me think its not shifting properly. Once everything gets sorted out it will be a nice little cruising car. Hopefully the Rotary Gurus wake up soon and join in. GSL-SEforme is a Mazda mechanic with extensive knowledge and experience on our cars. When he hops on this thread he'll help you figure it out. But regarding a healthy RX7 with 5sp vs Auto......

5sp Tranny -


Auto-

 

Well it's getting a tranny swap either way. I prefer my cars with sticks, especially the older ones. I just may have prematurely ruled out the transmission as the culprit since it would downshift when commanded.

Either way I appreciate you taking the time and for your help.

 

It may be something in the engine, having a lack of power at those shift-speeds. Everyone on this forum is trying to get their cars running like new again, so you're not alone. Im surprised nobody else has gotten on this thread yet. Hopefully they're out driving their RX's! Im working 7/12's and not much to do today except look at the forums.

 

Yeah I hear you, I've been working a ton myself. Well hopefully one of the ever elusive automatic guru's will show face and give some input. If not I'll probably try moving this to the 1st gen thread.

 

That's a good idea; it'll get more views there.

 

I've done the auto-to-manual swap in my 1985 GSL. If you search this forum you'll find where folks have done this using a piece of metal to span the 5" to make up the difference in the auto and manual tran body mounts. I did mine that way at first and I would not suggest that method. What I did was to remove the trans body mounts from a junker manual body and tig weld them to my auto frame.

I can also attest that the auto is a dog in the acceleration and takes away the fun of owning an RX-7.

 

Why would you not recommend not using an extension plate for the mounting?

 

The plate flexes too much. Not so much because if the thinness but more like a teeter-totter action because of the amount of span.

Here is what I did. Drilled out the trans supports from a parts car I have. I then installed the trans and cross brace and attached the drilled out supports and jacked the trans into the correct place. I then TIG welded what I could get to. Removed the trans and welded the rest. Seam sealed and painted. I powder coated the cross braces and installed both for the extra bracing.

The auto trans bracket also helps support the exhaust. The manual and auto have different mounting points because of the autp trans. I also learned this last weekend the cold air pipe that runs to the second "cat" is longer on the auto. Mine had a split I had to fix. Thought I could use a spare I had from a manual rx-7 but no.

 

What year and model is your car? There are differences in auto trans in different years,so need to know what we're working with.

 

85 gs

 

Ok,several things could cause your stated symptoms and I would check in this order:
1) does overdrive button work,can you feel trans shift/rpm on tach up/down when switched?
2) Trans issue-internal. When is last time trans was serviced?
Check for proper fluid level idling warm,in park.
Low fluid level can cause these symptoms.Level should be between marks on dipstick.If it is-don’t add additional fluid-more is not better and leads to foamed fluid which causes other problems.
3) carb issue,delayed secondary response.

1st thing to check-od operation/switch,does it work?

2nd thing to check-4/3 kick down switch. Also 3-2 and 2-1downshifts partly controlled by this switch which controls downshift solenoid inside transmission. Check for proper adjustment-AFTER you are sure floor mat(s) aren’t preventing full travel of gas pedal.

3rd thing to check-vacuum modulator.
This is mounted externally on outside rear of transmission case and is round and brass in color when new,will appear brown now. It will have a steel vacuum line with a short section of rubber vacuum hose connected to it.

The vacuum modulator receives a vacuum signal from the engine. It has a diaphragm/spring/pushrod and when vacuum in intake manifold drops from throttle opening/request for power...the spring overcomes vacuum and pushrod pushes into downshift rod in valvebody inside trans causing it to shift to a lower gear to meet power request.

You will need car jacked up(jack stands) to access it. Remove hose and look to see if hose is dry. Diaphragm in modulator can develop a pinhole and vacuum in vacuum line can pull transmission fluid out and it is burned in engine.
The modulator can also seize in position and not downshift on command.
If transmission has not been serviced in at least 3 years/36k miles,suggest fluid/filter/pan gasket/vacuum modulator replacement and see if this addresses symptoms.
If not,consider it maintenance and likely overdue.

If symptoms remain,look at engine parameters...
when is last time plugs/wires/cap/rotor/air and fuel filter were serviced?
Has ignition timing been checked,does distributor centrifugal and vacuum advance work correctly?
All these components control how the engine runs and ultimately the amount of vacuum in intake manifold and the transmission shifts in response to intake manifold vacuum.

Do these checks in order and post results here.
I will post kick down switch adjustment specs here and monitor this thread for your responses

 

I have literally no idea about autos, and have only had my RX-7 for a few months. But maybe worth checking the acceleration pump on the carb? As i understand it it's main job is to add an extra shot of fuel when rolling and throttle is applied, which sounds like your problem.

https://www.rx7club.com/attachments/...d-dscn1445.jpg

 

Well if that were the problem I believe it would have issues accelerating all of the time. I'm currently working through the list in the last comment, but so far everything checks out. I appreciate your input though.