1993-1995 Mazda RX-7
Buyer's Guide


The following is a primer I have compiled for those who are contemplating the purchase of a 3rd generation Rx-7. I have tried to make this document as accurate as possible. However, it may contain errors and it certainly does contain opinions. So, use this information at your own risk.

The third generation Mazda RX-7 was sold new in the United States from 1993 to 1995. Various equipment packages were available (R1/R2, base, touring, PEP, PEG), but all models had the 1.3L Sequential Twin Turbo, Twin Rotor Engine. According to Mazda, a little less than 10,000 '93 models and 4000 '94 models were sold in the U.S. I don't have numbers for the 1995 models, but I believe that figure to be in the low hundreds. Mazda stopped importing RX-7s into the US in 1996, but continued to sell the car overseas through the 1999 year model. 

Many people join the (RX-7 Mailing List) as prospective buyers and ask for advice on purchasing a used 3rd generation RX-7. One of their major concerns seems to be the car's reliability record. One of the goals of this guide is to address these concerns and allow buyers to make an informed purchase. 

The RX-7 has always been a high performance sports car as each new generation was introduced... with performance often exceeding competition that was priced far in excess (or for that matter, a multiple) of its purchase price. This is most true with the 3rd generation RX-7:

 

Curb Weight (lbs)

2789    (base model with 5 speed)
2857    (base model with automatic)
2800    (R1)
2862    (Touring with 5 speed)
2923    (Touring with automatic)

50/50 Weight Distribution

Engine Two Rotor
Twin Sequential Turbocharged (intercooled)
1307cc/80ci/1.3L
255 bhp @ 6500 rpm
217 lb-ft @ 5000 rpm
Electronic Fuel Injection
Drivetrain
Gear 5 speed man. 4 speed auto
1st 3.483 3.027
2nd 2.015 1.619
3rd 1.391 1.000
4th 1.000 0.694
5th 0.719
Rev 3.288 2.272
Final 4.100 3.909
Steering Power Rack & Pinion
35.4' Turning Radius
Brakes Power Assist, ABS standard
11.6", 4 piston ventilated front 
11.6", ventilated rear
Tires/Wheels 225/50VR-16 Tires
16x8 alloy wheels
Performance
(5 speed)
0-60 mph       5.0 s
1/4 mile 13.9 s
60-0 mph 110 feet
skidpad 0.97 g
Slalom 68 mph
City/Hwy 17/25 mpg

                  

Equipment Packages

I am a bit fuzzy in this area, as I cannot find any solid information as to what was included in each package. If anyone reading this has definite info on the packages, please let me know.

 

BASE 5-Speed Transmission, AM/FM Stereo Tape, Air Bag Restraint, Air Conditioning, Alarm System, Aluminum/Alloy Wheels, Anti-Lock Brakes, Cruise Control, Leather Steering Wheel, Limited Slip Diff, Power Antenna, Power Brakes, Power Door Locks, Power Mirrors, Power Steering, Power Windows, Rear Window Defroster, Remote Trunk Release, Tachometer, Velour/Cloth Seats
R1 ('93 Only) Stiffer suspension, front & rear spoilers, dual oil coolers, special cloth seats, strut tower brace
R2 ('94+) Same as the R1, but the suspension was softened somewhat
TOURING Leather seats, Bose audio system (w/CD), sunroof, cruise control
PEP/PEG Popular Equipment Package or Popular Equipment Group, depending on the year model.
I'm not sure what was included here. Probably sunroof, cruise control, maybe spoilers, leather seats...
Miscellaneous Apparently, one could order any additional option on a car (if one were willing to wait).
I say this because I have seen options that weren't part of a given package... such as R1/R2s with sunroofs (they weren't suppose to have them). Also, spoilers were often installed by the dealership.

 

Here we go...

The 3rd generation  RX-7 is a great car, but (as with anything else) it does have some problems. These problems by themselves are not serious in nature, but if not addressed can lead to catastrophic mechanical failures that may damage the reputation of the marque as well as put a sizeable dent in your wallet. You must remember that this is a high performance vehicle and it requires maintenance commensurate with its capabilities. 

The following is a list of known problems. I will address each item in order of importance, with the most critical items last.

Interior Trim

The least critical of these areas are interior trim. The black console, door and dash panels were, on the 93 cars at least, coated with material that would not hold up. Many of these early cars have already had these panels replaced under warranty. If not, this is fairly easy and cheap to fix by replacing the panel. Some people have had luck re-painting the panels with special paint for plastics.

Paint

Some early cars also had exterior paint problems, where the color coat did not adhere properly to the primer. This usually resulted in excessive chipping on the nose of the car. Bear in mind that some chipping will always occur because the cars sit low to the ground and pick up rocks thrown by other vehicles. I have also seen several cars that had faded side mirrors and/or rear bumper covers (this seems to be related to where the car was usually parked... indoors or out). By now most of those cars have been touched up or completely repainted, so don't disqualify a repainted car as a candidate for purchase. The '94s and '95s are not known to have the paint problems.

Instrumentation

Another area of concern is instrumentation. The oil pressure sending units in all 3rd generation  cars are of poor quality. They typically read low or zero at idle and will work sporadically when driving. Some people have had luck either replacing the oil pressure sending unit with a new one or carefully cleaning the terminals on the original sending unit. Another option is to replace the gauge and sender with a good aftermarket mechanical or electrical gauge and sender. Note that the oil pumps on rotary engines are known to be very robust (I have never heard of a failure).

The water temperature gauge is also too heavily center weighted, so that even an overheat condition will show only as slightly high. This should be replaced with an aftermarket gauge. It is important to ask if the car has ever been overheated. If the stock temp gauge has ever reached the 'hot' area, then engine life has almost certainly been shortened. Usually, an overheated engine will have warped aluminum rotor housings which will eventually cause the engine to fail. This is also why it is very important to stop immediately if you ever see the stock temp gauge move above the center (horizontal) position.

The car did not com from the factory with a boost gauge, which should be added and is indispensable for the diagnosis of engine or turbo control problems.

Recalls

There were 3 recalls on these cars: brakes (vacuum hose modification), new (high temp) fuel lines, and cooling system (pressure cap and fan control module). Most cars have had the cooling system recall done (the recall was issued early on). However, I have seen quite a few cars that had not had the two remaining recalls done. Mazda dealerships are supposed to place a sticker on the driver's side door jamb when they perform a recall... but the cars are often missing the sticker for various reasons (fell off, never applied, etc.). '94 and '95 models may not be subject to all of the recalls. The best thing to do is to call Mazda Customer Relations (1-800-222-5500) with the VIN number and ask which recalls the car requires and if they have been performed. You can also find out what, if any, warranty work has been done on the car. If any recall has not been performed, a Mazda dealership should perform them free of charge.

Service Bulletins

These items were not recalls, but were either issued as TSBs (Technical Service Bulletins) or are just commonly known glitches. A TSB is a bulletin issued to dealerships in order to help them with servicing a car (most vehicles have many issued). TSBs aren't critical items (like recalls). However, this means that if your car is out of warranty (a few cars still have extended warranty active), you will probably have to pay to have them taken care of. Some of the web sites listed below have more complete listings of the TSBs.

3000 rpm hesitation

Under light throttle (about 1-2 psi of boost), there may be a slight hesitation as the engine passes the 3000 rpm mark. This problem usually diminishes as the engine warms up. Some people have cured the problem by adding additional ground wires between the engine and the body (it doesn't seem to work for everyone). Various causes of the hesitation have been argued, but no one has found an absolute fix for it. 

5th Gear Synchronizer

The original 5th gear synchronizer is known to be weak and may break, especially if the driver often misses the upshift to 3rd and hits 5th instead. If the synchronizer is bad, you will hear/feel a grinding noise when shifting into 5th gear. The updated synchronizer and shift gate currently cost about $50 and can be quickly installed once the transmission is removed. However, removal and reinstall of the transmission will generate a decent labor bill. In any case, using a quality synthetic (such as RedLine or Neo) in the transmission seems to help prevent the problem and promote smoother shifting.

Vacuum Lines

Because of the complexity of the sequential twin turbo control system and the turbo system itself, the area under the hood is quite crowded, and under-hood air temperatures are very high. This causes the hoses used for vacuum and pressure operated engine controls to harden and crack. There are a few key pressure lines that can blow off and cause one or both turbos to stop working temporarily. This is easily corrected by replacing the bad line.

The map sensor line and the pressure tank lines often pop off. The map sensor line can come loose at the sensor or at the throttle body. Symptoms are: no power, won't idle, and puffs black smoke. If one of the pressure tank lines comes off, you will have low boost or other weirdness with your turbo system. Those two lines are easy to re-attach. There are a few more that require removal of the extension manifold to correct.

 

Vacuum Hoses

 

Many people have replaced all of the vacuum hoses with tie wrapped or glued hoses that can withstand much higher temperatures, such as silocone, viton, or neoprene. This is a job that involves a good bit of labor (approx 6 hours), but the materials only cost about $35. I would recommend leaving them alone if you don't have a problem.

Some of the web sites listed below have more information on replacing the vacuum lines.

Cooling System

Coolant hoses, especially to the turbos, should be checked regularly and replaced if they show any deterioration.

The stock air separation tank should be replaced with an aftermarket aluminum unit. The stock tanks are plastic and have a tendency to split at the seam. Some people have eliminated the AST completely (see web pages below for more info). If the stock AST is not replaced, it should be checked frequently for leaks. 

As part of the cooling system recall, Mazda lowered the cooling system pressure to 13psi (or 0.9 bar) by replacing the cap on the AST. It is recommended that a pressure cap rated at 13psi (or 0.9 bar) be used. The pressure rating should be printed on the top of the cap.

Proper (not too tight) belt tension is essential for water pump longevity.

Exhaust System

The exhaust system on the 3rd generation car consists of 2 catalytic converters, a front unit, called the pre-cat, and the main converter under the floor pan. The front converter has a reputation for disintegrating and subsequently clogging the exhaust system, which results in skyrocketing exhaust temperatures, backpressure,  and probable engine failure. A large number of 3rd generation cars have had engine replacements as a result. The current year (Japan only) cars no longer have the pre-cat, just a straight downpipe. 

Unfortunately, it is hard to determine the pre-cat's condition without removing the main-cat and actually looking into the pre-cat. A clogged pre-cat will often cause boost pressures to be low and slow to build up, but blockage is usually extreme when this happens.

If legal in your area, it is highly recommended that the pre-cat be replaced with a downpipe, which is readily available from the aftermarket. A downpipe will also significantly lower underhood temperatures, extending the life of all underhood components.

If you cannot use a downpipe, it is advisable to check the pre-cat and replace it with a new one if there is any question about the original's condition.

The pre-cat has a high failure rate between 50-60 thousand miles. I believe that the pre-cat is one of the big reasons that 3rd gen engines have a reputation for being short-lived.

Dealerships

The Mazda dealer service department may be the greatest threat to these 3rd generation cars. DO NOT go to a dealer for service unless you get a recommendation FROM ANOTHER RX-7 owner first. Some dealers do a great job. However, many dealers do not appear to be properly trained to service these cars and do more damage than repairs. There are enough good dealers and independent shops that specialize in this particular vehicle that service should not be a major problem.

Modifications

These cars, when fitted with just a few bolt on modifications, are capable of tremendous horsepower gains, but these modifications must not be lightly undertaken. Proper fuel enrichment to accommodate intake and exhaust flow improvements MUST be provided. If you are purchasing a modified car, make sure fuel enrichment has been taken into account. 

Improper modification is another reason the 3rd gen. has a bad reputation for engine longevity. Initially, people were opening up the exhaust, raising the boost, and popping an engine at low mileage. The rotary engine will not tolerate detonation (pre-ignition) that is caused by an overly lean fuel mixture. If the fuel mixture is not adjusted (via an ECU "chip" or replacement) along with exhaust and intake modifications, then engine problems may occur.

A downpipe alone does not require any fuel enrichment. A downpipe, free flow muffler, and free flow intake combo will probably require more fuel to be safe. If the main cat has been removed, fuel enrichment is absolutely required.

Conclusion

Remember, for a combined total of under $600 in reliability upgrades (if you do most of the work yourself), you can have a bulletproof rotary rocket capable of embarrassing some very exotic machinery. There is no need to be afraid of the car. It just requires proper preparation, that although is not required for your basic Honda, will put a huge smile on your face when you put it through its paces. As you surf the web, take a look at the enthusiasm you see in the (many) RX-7 websites you'll see. Racers, engineers and other technically oriented types are HIGHLY represented among the ranks of owners. People love the car for a reason, and these people wouldn't be so dedicated to the model if it wasn't so special.

You can browse the web pages listed below for more detailed information on many of the subjects mentioned in this guide.


Test Drive Info

Cooling System

It is best if you can see the car when the engine is cold (hasn't been started for 12 hours or so). Open the cap on the thermostat housing and take a look at the coolant. It should look clean and should show no signs of oil. Take a look at the dipstick in the coolant overflow bottle. You may see some brown crud that magically accumulates in the overflow bottle, but you should not see anything that looks like oil. Pull the engine oil dipstick and look for any signs of water. There was some trouble with engines losing internal coolant seals (usually caused by overheating), which requires a rebuild to correct. You are just looking for any sign of oil getting into the coolant or vise versa. 

Also take a look at the air separation tank (if it is the stock plastic unit). They have a tendency to leak at the seams and eventually burst. If it is leaking, it can be replaced with an aftermarket aluminum unit for about $140 or eliminated completely for about $30.

Aluminum AST 
Thermo. Housing Cap
Coolant Overflow Bottle

Oil Dipstick

Boost Gauge Hook-up

You should not look at a 3rd gen. without taking a vacuum/boost gauge with you. You can purchase a cheap vacuum/pressure gauge at most automotive parts stores. Devoted vacuum/boost gauges can be had for anywhere from $30 to $200. Autometer makes a decent gauge for about $30 that you may be able to find at some performance shops. In addition to the gauge, you will need about twelve feet of vacuum line. You can attach the line at the unused nipple on the passenger's side of the upper intake manifold. Just remove the rubber cap and stick the line on. Be sure to keep the rubber cap, as you will need to replace it when you remove the line. Snake the line between the hood and windshield and in the passenger's window. Hook the gauge to the line. 

El-Cheapo Gauge

Autometer Gauge

Boost Gauge Hookup
(Click Image for detail)

 

Engine & Turbos

Start the engine. You may see a faint puff of smoke from the exhaust. This is probably condensation in the exhaust or some other anomaly and SHOULD NOT last more than a few seconds. The idle will hop up to 3000 or 1500 rpm, depending on whether you started the car in gear or in neutral. As the engine warms up, the idle will drop to its normal range.

Remember to use common sense when test driving the car. If you don't have an area where you can perform a given test safely and legally, then don't do it.

Take the car for a drive and be easy on it until the engine is warm. The temperature gauge should reach a horizontal position (3 and 9 o'clock) and should not go above that position. Once the car is warmed up, you can do a boost test. The best way is to have a passenger call out the boost readings as you accelerate at WOT (wide open throttle) in 3rd gear (find a road where you can do this safely). At or before 3,000 rpm you should see around 10 psi (pounds per square inch, lb/in^2) of boost. At 4500 rpm you should see a quick drop to about 8 psi and an almost instantaneous recovery to 10 psi. It should continue to make 10 psi of boost until close to redline where it may drop a couple of psi. This is what is referred to as a 10-8-10 boost pattern. Note: At redline in 3rd gear you will be doing about 110 mph! So, unless you are doing this on a track, you will probably want to stop at 70-75 mph (depending on the speed limit).

Accelerate to redline and shift a few times (watch your speed please!). Keep an eye on the rearview for any smoke. The car should NOT smoke. White smoke usually means that the engine is getting water/antifreeze into the combustion chamber (predicting engine death). A puff of black/brown smoke usually means the car isn't burning all of the fuel going in. This rich condition is probably nothing to be worried and may mean that the car just needs is a tune-up. Blue smoke is burning oil, which is a bad sign. If you see large amounts of any color smoke, you should probably pass that car by. 

When driving the car with moderate to high throttle usage, you should feel an increase in power near 4500 rpm (as the secondary turbo comes on-line) and the car should pull smoothly to redline. Cars with ancient spark plug wires or worn out spark plugs may miss at high rpm... this is, of course, pretty easy to fix.

After driving the car, pull over somewhere and let the car idle. The idle should be somewhere around 800 rpm. The idle may drop a little if you have really been driving hard, but should stabilize quickly at about 800. Make sure all the accessories are off (A/C, headlights, running lights, fans, etc.) and take a look at your vacuum/boost gauge. You want to see at least 16 inches of vacuum (inHg), and 18-19 is great. Be aware that this test means nothing if the engine is cold or any accessories are on. Less than 16 inHg means that there is a problem somewhere (low compression or a vacuum leak somewhere).

Make sure the car idles well with the A/C and headlights on... then step on the brake. It is normal for the idle to drop with accessories on and use of the brake. However, it should not struggle to run or die.

You shouldn't see any oil dripping on the ground where the car is parked.

The oil pans sometimes leak a small amount of oil. This isn't too bad to have fixed. You don't want to see any large amount of oil around the turbos on the passenger's side of the engine. You can't see much of the turbos from above, so you may want to take the car somewhere where you can have it put on a rack to see the underside. The picture below was taken from under the car. You can see some slight signs of oil, which is typical. You don't want to see large amounts of oil dripping off of things. The primary turbo is a foot or so in front of the secondary turbo, which makes it hard to see (or take a picture of).

 

Turbo Area Oil Leaks

Transmission

While driving, shift into 5th gear several times and make sure it works smoothly. You should really try to drive the car in the city (stoplight traffic) and on the interstate.

Cosmetic

Check for excessive paint chipping on the nose of the car. Take a look at the rear bumper cover and make sure the paint looks good.

Check the paint under twilight conditions, or at a gas station that has fluorescent lights, as this will make it easier to see mismatched paint (from repairs), swirls, and other paint defects. Bright sun / bright lights at the used car dealer will hide defects. Dark at night will as well.

Examine the interior plastic panels for peeling. I wouldn't consider it a reason for non-purchase (they are easily replaced), but it is a potential bargaining point.

Service History

See if the owner can provide any sort of service history. You want to know that the oil was changed at least every 3000 miles. Since oil is used to cool the turbos, the oil breaks down more quickly and more frequent oil changes are a must.

Ask if the car has ever been in an accident. Frame damage is forever. The hoods are aluminum, and the bumper covers are plastic, but other than that a refrigerator magnet should be used to check for Bondo.

Ask if the car has ever been overheated. If the temperature gauge went up to the H (hot) position, then there is a good chance the engine was damaged. In that case, pay particular attention to the coolant system checklist and watch for any white smoke.

Find out if the applicable recalls have been performed. Call Mazda Customer Relations (1-800-222-5500) with the VIN number and find out which recalls were performed on the car. You can also ask about any warranty work done on the car. The VIN number is on a metal tag on the driver's side of the dash, near the windshield. It will start with FD and be 17 characters long.

Compression Test

Assuming you are pleased with the car so far, you might want to take it to a recommended mechanic and have him take a look over it. He should look for typical things such as oil/coolant leaks, make sure the water pump is in good shape (check for a worn bearing), etc.

You should also have a compression test done. Since the rotary engine requires specific test equipment, a Mazda dealer (gasp!?) will need to do this. A compression test is an excellent indicator of the engine's condition. The 1993 shop manual calls for  690 kPa {7.0 kgf/cm2, 100 psi} minimum @ 250 RPM with the maximum difference between chambers of 150 kPa {1.5 kgf/cm2, 21 psi} @ 250 RPM. These numbers will vary somewhat based on altitude, battery and starter condition, and whether the test is performed to the letter of the instructions.

 

Checklist

Cooling System

Engine & Turbos

Transmission

Cosmetic

Service History

 

Miscellaneous

For those do-it-yourselfers, you can do your own compression check by modifying a compression gauge and following a set procedure. Search the web pages below for details.

Check the price on the:

The Competition Yellow Mica color cars seem to be worth a lot more (only about 200 were sold in the U.S.). The rest of the cars should be priced at about what the sites above show. Silver may be worth a bit more due to the rarity of these as well as the yellow ones. Low mileage will also be worth more.

Run a title check on the car. It costs less than $20 and will give you a decent history on where the car has been and if anything funny has happened to it. You will need the VIN number that is located on the driver's side of the dash, near the windshield, on a small metal plate. A few good places to check are:

Vehicle History Report (1-800-633-7834)
Carfax
EZ Title Search

Stay away from any car with a Rebuild Title. This usually means the car was stolen, totaled, and then resurrected. Probably all sorts of problems.


Good Web Sites to Check Out

Steve Cirian's
Various How-To's and other good information.

Rob Robinette's
Various How-To's and other good information.

Derek Vanditmars'
Sequential Twin Turbo Troubleshooting Guide

Felix's web site
Home of the Rotary Engine FAQ

Dave's RX-7 Site
Various How-To's and other good information.


Post Purchase Maintenance & Modification

After buying a car you may want to:

And while you own the car:

Some good reliability modifications include:


Credits

This document is very strongly based on an earlier buyer's guide from Steve Cirian's web site. 
Some of that content was contributed by Tom Jelly.


Big Thanks go to the denizens of the Rx-7 Mailing List and its maintainer (thanks Reto!).
Most of the info in this guide was gleaned from its members.

I am Dave Disney