i had my 1989 non turbo in the shop about half dozen times from feb to july last year and spent 1300 before i gave up. if any one can help me id sure appreciate it. my car loses speed on grades and with the pedal to the floor it will not speed up. it drives like a volkswagen (an old one). i have had the throttle sensor replaced, the injectors cleaned, the plugs replaced, the leading igniters ($800) replaced the fuel pressure checked....i quit on the shop when it became apparent they were easter egging. mechanic friends of mine say it sounds like the car is running lean....the mechanic insisted that the electronic telemetry indicates that this is not so...there seems to be some improvement in performance when it is extremely hot outside....i forgot to mention that i put a new convertor on the car and within a month it was all melted inside......i am not a mechanic in any sense of the word. if you have any ideas i can take to the shop i would sure appreciate hearing from you. the motor is a factory rebuild with 109000 well maintained freeway miles on it. the motor is 4 yrs old.....of course many of the sensors and mechanical parts came off the original engine. when the engine starts to bog down there is a corresponding loss of rpms

 

what gear are you in when this happens? Not to be critical, but how long have you been driving stick(I assume it's a manual). when I first learned I would forget to downshift from 5th when going up large hills sometimes, that'll really cause the car to bog. try downshifting next time, especially if you aren't going too fast.

If i'm way off here, don't mind me, I'm not tring to be disrespectful by implying that you aren't used to 5 speed yet!

 

to add to what airbrush said, the rotarys arent big on low end torque, you'll find you self downshifting for more stuff than the pistion guys have to, but who get a rotary for low end torque any ways, its that high end pull we all live for

109k for a rotary is a lot, even if factory rebuilt, but you did say its a N/A so 109k isn't all that bad. However you may want to do a compression check.

 

If the cats are melting wouldn't that mean that it is running really rich? Correct me if I am wrong someone but with more unburnt fuel making it in to the exhaust then that would raise the exhaust temps and melt the cats much faster right? And with a performance gain when it is excessively hot out might also point to terribly advanced timing (which draws more fuel in to the chambers over an extended period of time) and with the hot temperatures it would burn quicker and thus put you back closer to the timing that you need to run efficiently and give you more power.

So someone give me their advice but my noobie diagnosis would be timing is too advanced and needs to be retarded. And if that doesn't clear the problem up then look towards a whole slew of ways to lean your air fuel ratio out ranging from a dirty air filter to numerous other more complicated situations. I hope this helps but wait for someone with more experience to post after me to verify that I am on the right track or totally noob wrong =).

 

Not all cats were meant for our cars. Unless the manufacturer says it's ok for rotaries, chances are it won't hold up.

http://home.rmci.net/panther/bonez.htm

Scroll down to 'Take #1.'

As for the bogging down itself, I dunno. But I wouldn't suggest messing around with your timing and a/f ratios yet. If the car won't run properly with the engine tuned to stock settings then something else definitely needs attention.

Have you recently gone after basic stuff? Don't just check the air filter - inspect the entire duct. It may have sucked up roadkill and is partially blocked. The engine can't make power if it can't breathe.

Might be some useful info in this thread:

https://www.rx7club.com/forum/showth...&highlight=bog

Also, get a compression check:

https://www.rx7club.com/forum/showth...light=no+power

Hope it's nothing serious.

 

ive been driving stick for over 40 yrs...this performance was a drastic change from previous performance that was intermittant at first but then became chronic...suggesting the breakdown of some part or system having to do with fuel delivery or mixture. this car ought to cruise at 80 mph without breathing hard and have plenty of pedal left...same with ill. hills

 

Mine does.

 

An engine that is running LEAN will run hot, so if the melted cat was made for a rotary, chances are your car is running lean. I had a similar problem with my 86 GXL. The exhaust manifold would get red hot at idle. It turned out that I had a short in the wiring to the AFM. Because of this, the Mazda computer would read everything as normal when it wasn't. Check the wiring to the Air Flow Meter, and then test the actual Meter.


I kind of doubt that this is your problem, but how old is the clutch?
If the clutch is going, it will slip under acceleration and especially on hills. When you are driving, get up to about 40-50, put it in 5th, and floor it. If the revs climb but the speed doesn't, you need a clutch.

Good Luck!

 

Go to the dealer (one with a good recommendation) and get a compression check done with their little compression checker tool ($90 +/-). I know it sounds like a pretty basic thing to do, but make certain. Low compression does not always mean a rough running motor.

 

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I would also suggest having the clutch checked out. I had a very similar problem when i got my RX, and when i had it checked out, they said i needed a new clutch, so i changed out to a racing clutch and havent had a problem since. As far as the cats are concerned, if theres no emissions laws in your area, then just take them off all together cuz they restrict flow. I noticed a whole world of difference in performance when i switched to a straight pipe, well actually it has a small muffler, but otherwise straight pipe.

 

the cat was bought from the shop ...the compression was checked when the plugs were changed out..the clutch has been checked...fuel is there, spark is there, the computer says everything is fine......ive put over 160000 mi on this car and insofar as i had a new engine and clutch put in i know how it should perform at optimum.....captn wankel and nick 86 are on the right track,but i need specifics to take to a mechanic....if this were a 59 chevy six-banger id put a new vac advance on it...........something mechanical (read non-electronic) is worn out (some of these parts are 13 yrs old and have a quarter million miles on them).....but specifically what parts and/or systems translate the commands for adjustment of the fuel air mixture at different speeds, loads, and atmospheric conditions into the mechanical actions of operating ports and valves to accomplish the adjustments..........get my drift? i will check out the short circuit idea.......keep feeding me guys......i love my car......its been better to me than either of my wives and still looks pretty good for an old gal......its breaking my heart to see her ail.....i want her to dance again

 

check the operation of the 6 ports, mine would slow down at 80 mph on the freeway with the pedal to the floor, nothing would happen at all haha, then i fixed the 6 ports and the car now pulls pretty well for an NA at the bottom end

 

Was the fuel filter changed recently?

 

a long shot but ...

check the fuel pressure regulator

the fuel pressure should follow the intake manifold pressure (differential is constant)

hugues -