2nd Generation Specific 1986-1992 Discussion

1987 RX-7 N/A running really rough

Old 10-24-2013, 12:35 PM
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Unhappy 1987 RX-7 N/A running really rough

I just bought this car about 6 months ago and it was running really good for a while i changed the plugs,wires,oil/filter, and added after market cone air filter just the filter and adapter for the maf not the whole kit. it has the infamous 3800 stall problem and at this moment it feels like a rotor is not firing i did a compression check and got the same on all 4 spark plug holes ( dont know the technical name) the reading was just over 120Psi. i recently changed the fuel filter as well and it made an amazing difference for about 2 weeks and now the car runs worse i need help . if it was only running on one rotor would the motor shake very badly because it does and is very slow when trying to drive it. And finally how in the world do i fix my tach my temp gauge and my volt meter or should i just replace them i already have an aftermarket temp gauge just haven't
figured out where to hook it up at under the hood.
any info will be greatly appreciated.
thanks
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Old 11-19-2013, 05:08 PM
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Originally Posted by mazdaMatt1990 View Post
I just bought this car about 6 months ago and it was running really good for a while i changed the plugs,wires,oil/filter, and added after market cone air filter just the filter and adapter for the maf not the whole kit. it has the infamous 3800 stall problem and at this moment it feels like a rotor is not firing i did a compression check and got the same on all 4 spark plug holes ( dont know the technical name) the reading was just over 120Psi. i recently changed the fuel filter as well and it made an amazing difference for about 2 weeks and now the car runs worse i need help . if it was only running on one rotor would the motor shake very badly because it does and is very slow when trying to drive it. And finally how in the world do i fix my tach my temp gauge and my volt meter or should i just replace them i already have an aftermarket temp gauge just haven't
figured out where to hook it up at under the hood.
any info will be greatly appreciated.
thanks
Did this ever get resolved? Having similar issues only iv got 60 on one and 70-75 on the other
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Old 11-19-2013, 11:24 PM
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Default Re: 1987 RX-7 N/A running really rough

The problem was resolved my primary injectors were badly clogged so the rotors were not getting enough fuel. as for your compression ratings try a wet compression test put a small amount of atf (automatic Transmission Fluid) in each rotor then do your comp test again if the numbers jump quite a ways up then you probably have bad apex seals or something else internally wrong. compression on these motors varies per year per car made that year even as far as i know they are supposed to be between 90 to 120 + psi of compression. hope this helps.
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Old 11-19-2013, 11:27 PM
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Default Re: 1987 RX-7 N/A running really rough

As for 3800 stall definitely throttle position sensor in my case. that varies as well. the compression on all three slots in the rotors themselves should be within about 5 to 6 psi of each other.
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Old 11-19-2013, 11:38 PM
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Default Re: 1987 RX-7 N/A running really rough

Ahh injectors! Exactly what I was thinking, I'm not to concerned about compression because it did run prior to having issues and I plan on just doing more exterior and interior work before under the hood just to drive it this summer as my toy and have it rebuilt next winter (hopefully I can get the summer out of it that is.) I'm new to the rotary engine as well as car engines really, raced quads and dirtbikes my whole life but small engines are a totally different story then the car engine and especially the rotary. Would u be able to point me in the right direction on how to go about getting at the injectors? Haven't even gotten that far yet (only got the car on Saturday)
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Old 11-20-2013, 12:55 PM
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Thumbs up Re: 1987 RX-7 N/A running really rough

Yea the primary injectors are under the intake manifold it has to be removed completely to get to it. Step by Step......step
1.Remove all vacuum lines from manifold.
2. remove any sensors that may be attached i dont remember how many.
3. remove the throttle cable from the rear of the manifold really easy just open the throttle cable has a quick release esentially just pulls off.
4. remove the bolts that hold it on should only be 4 main bolts 2 pasenger side and 2 driver side alond with 2 on a mounting close to the rear driver side of the manifold, manifold and throttle body will come off in one big piece the primary fuel rail will then be vary easy to see and to get to for removal.
5.remove the injectors by using a small pocket knife or flat head screw driver to release the locking metal pins, looks like a little metal C that wraps around the plug in to clip the injectors wire in to place like every other sensor on the car has,,,, or should have.
6. clean or replace injectors whichever you feel neccesary i'll give you a website where the injectors can be bought for roughly 50 dollars a piece rather then the 200 a piece you would pay at oreaillys or autozone. if you have the money i would buy 4 of them and replace the primary and the secondary injectors at the same time secondaries are easy to see from the passenger side of the car.

installation is the reverse of removal be sure to A. make a gasket with grey rtv or some kind of gasket maker or buy a new intake manifold gasket because an intake manifold leak can cause running issues. hope this helps. will private message you the name of the website for the injectors.
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