86OrangeRx-7

I just bought a 86` Rx-7 GXL with 88,000 miles on it.. her outside save for the paint job is great. The engine and Trans well thats another story. She has no get up and go on her, the Electrical system was fooled around with by a moron. I've got speaker wires hanging out the dash for non-existant speakers. Anyways...

The engine is running slow.. I rev her up in neutral, floored she only puts up 5.5k on the tach, Never any more. Shes running 20w-50 in her *god knows why.. * its a great way to hide some engine noise.

Trans seems alright cept shifting into 5th she grinds a bit when the clutch is still on the floor...

I don't know whats making her slow.. probably the compression on the engine is way off and she probably will need a rebuild..

I threw some fuel injector cleaner in the tank hoping that might be the problem a clogged injector, but no luck

And just last night the alternator went on her along with the battery...

Any recommendations on

1. Alternator and Battery (planning on running some Kicker Stereo equipment so might need more power)
2. What might be making her slow as heck
3. Anyone know a good Mechanic for Mazda's In New Jersey ?

Stepdaddy

someting is seriously wrong if you floor it and it only hits 5.5k, 20w 50 is the right type of oil, rotory engines need heavy oil, if you put normal car oil it would eat it like water, you may be right about the rebuild thoug

86OrangeRx-7

I've been throwing through my mind what it could be.. I remember reading something that the engine brings in a second set of injectors at a certain RPM I don't know... in order to keep a constant powerband for the engine..

You think it might possibly be a fuel delivery problem or just plain fuct engine ?

The Ace

It could be a number of things.... first of all, do the standard general tune-up: filters, plugs, belts, wires, oil, fluids all around, flush the radiator and the fuel tank, check timing, TPS, AFM, check ECU for error codes etc etc etc....

Oil is correct, but if the engine wont rev above 5,5K, then probably your injectors need cleaning, or something is seriously wrong with your electrical system (said so yourself). Find a good electrician who knows his way around cars, and let him have a go at it.....

Thats off the top of my head. Standard stuff, which could do wonders After all that is taken care of, then we'll talk particulars....

Icemark

20W50 is the Mazda preferred oil weight for use in all temps above 0F.

Only If you are seeing temps below 0F then you would want 10W30.

vaughnc

86OrangeRx-7,

Hey welcome to the forum.

The Ace is probably right, just get the 60K services & fuel injector cleaning done.

If your exhaust is clogged that might be it as well.

-- vaughnc

copandengr

First off make sure the tach is accurate. Check it against an optical tach known to be good. You did not make clear if your engine will only reach 5.5K when under load or simply by mashing the pedal when in neutral. The former might be any number of things, including but not limited to bad compression. The latter is almost certainly a problem with the ECU, either it is faulty or it is getting faulty signals from one of the many sensors on the engine.

Before you spend money looking for trouble elsewhere have the compression checked, along with the trouble code search. The weak point on these engines is the loss of compression due to carbon build-up on the seals.

As simple as it sounds check all the ground wires to make sure they are good. The Rex is notorious for poor grounding. Search this forum for this particular problem and related cures.


I would check the timing to make sure it is advancing as it should. A clogged exhaust might be a possibility but consider this; revving an engine with no load to a given RPM does not put out near the volume of exhaust gasses (or exhaust gas pressure) as the same RPM when the engine is under load. For this reason a limit to RPM only when revving with no load would be more likely to be caused by electrical or fuel related problems. Again, a fuel problem would almost have to be an electronic limit since no load fuel requirements are considerably less than when running under load. It almost seems you have some sort of "governor" operating at an undesired speed. There is a fuel cut on turbo models that may be causing your problem. On Na models I am not sure if there is an active rev limiter or not. My NA 86 has a buzzer that comes on at redline, but I have never tried to keep on going beyond that to see what would happen.

Do the normal things to your car first. These are new filters (air and fuel), new spark plugs, new plug wires, and check the timing. These things need to be done anyway, so you are not wasting money or time by doing them. Check the TPS and adjust if needed.


As for any other cause, all I can say is that I have been a mechanic for well over thirty years, and there is a formal vo-tech education there back in 1971. I thought I was a sharp cookie until I bought the Rex three years ago.This car made me feel like a six year old kid. Nothing I knew about engines made sense on a rotary engine. I underwent an expensive learning process and would have saved much time and money had I known about this forum then. Someone here has the answer, or can point you to someone who does know.

The important thing to remember with a rotary is its difference when compared to a recip. Unless your mechanic is a rotary guy he will not be able to help you.

The tranny trouble is common on the Rex and is more than likely caused by worn synchros. Draining the lubricant out of the tranny and replacing it with a synthetic lube such as Redline will help greatly. If you do this go ahead and change the oil in the differential while you are at it. Install Redline there as well, but make sure it is the right type if you have a limited slip diff. Also check your shifter bushings to see if they are shot. Check the bushings by wiggling the shifter up and down and side to side. It should not have any slop. If it does then they are most likely gone. This is an easy repair and will cost about 30 bucks for the parts. Mazdatrix has a piece on this on their web site FAQ, as well as an article on the use of synthetic gear lube.

The alternator may be replaced with a later year model that puts out 100 amps. Installing a better battery such as an Optima will help as well with sound equipment requirements.

Icemark

Actually poor grounding is common on most early to late '80s Japanese cars, not just the RX-7