I have an '88 Turbo II. If rev the car to around 5000rpm's without letting the car warm up fully (10min. or 700rpm idle) it will start to shake violently, and not really go anywhere. But recently its been doing it even when fully warmed up. I guess its OK in first gear because I get past the rough spot (like i said around 5k) and after that through 6k its super smooth before getting rough again at 7k. This really sucks though at freeway speeds because it stays in this rough area for a while, even at full throttle. I tried to 'push through it' (to the smooth 6k) about a week ago when racing an Integra but in the process blew my 'main fuse' and damaged my belts and alternator. All my emergency lights incl. 'shift up' light came on (like when you kill it) but it stayed running. This is getting to be a nuisance so I figured I'd ask my fellow rotary owners before going to the mechanic. Anyone have any ideas or suggestions, I don't want to go up to 5k before I get this problem diagnosed.

Oh yeah, I still smoked the GSR.

THANK YOU!

 

your pulleys / belts / fan / water pump etc. one of them is probably screwed up and not straight.

and you shouldn't even be trying to hit 5000rpm when the car is not fully warmed up.

 

Yeah, I figured that out pretty quick. It's just that on my 87 n/a (which I didn't treat with much respect) it had smooth power all the way through, with little to no warm up. thanks for the response. anyone else got an idea?

 

^

 

First never get on the gas too much until it is fully warmed up. If all your idiot lights came on you probably broke the belt on your alternator. Perhaps they arent torqued to spec.

 

Yeah, I did break the belt... nice. Do you mean that the belt tensioner wasn't adjusted properly or that the alternator, or one of the other components may not be torqued right?

 

Yes. Did you notice your belts squeaking prior to when it broke?

 

Yeah they were really loud and squeaky. So the consensus is that this is shaking is due to a problem with the belts, pulleys or some 'outer mechanical' thing? Not like a fuel, air, timing etc.? I don't really know much about these cars and any kind of elaboration or insight would be greatly appreciated. thanks

 

Also, I replaced all the belts, which didn't fix the problem.

 

There is a chance you will continue to change the belts if the pulleys are misalligned. Go to www.iluvmyrx7.com and take a look at the FSM (factory service manual) and check to see if the pulleys are alligned correctly.

 

so misallignment could be causing the shaking? I don't know anything about my car so this could be ignorant; remember, it only shakes violently when right around 5k, Its smooth sailing at all points around that rpm. I'd think that if the pulleys were misalligned the shaking would be sporadic and spread unevenly throughout the (powerband?). But, I'll check on their allignment or at least tell my mechanic to do so. thanks, any more ideas?

 

do you mean the car is running rough/shaking? DONT Fuking rev till your engine is warmed up. everything is still cold you are going to blow your motor. for god sake sell your Rx-7 and hang yourself.

Well. dont go that far. Check the alignment just to be sure but i think you may be detonating.

-Markus

 

what do you mean by "detonating"? Oh, thanks for the advice... does anyone else have some helpful imput?

 

detonating:

When your air/fuel mixture is ignited, there are "pressure waves" that travel way faster than the flame front. The flame front travels generally slower compared to the pressure waves, going 50-60 centimeters per second, while the shockwaves travel 300 meters per second, much faster. That gives the shockwaves time to bounce around the chamber, and when they hit eachother too much, they can creat harsh pressure points and ignite the air/fuel mixture violently, cause extreme stress to the engine. Pressure waves hit eachother the most near the tip of the rotor I would guess.

I remember this from a honda tuning book I read a long time ago

 

So is there any way to remedy this harsh detonation, or whatever you call it?

To reiterate, it happens @ 5k and 7k, nowhere else, and it seems to be getting steadily worse (used to go away if warm), although I've refrained from revving that high the last few days. anyone else have suggestions?

 

^

 

^

 

It's actually so bad now that the fan hits the plastic guard around it, now from 4500-5k rpm's. Im not sure if the fan is the problem itself, or just a symptom of something else... help?

 

If your fan blades are hitting the shroud your pullies must be misalligned.

 

Or the engine is trying to jump out and run away from the abusive owner.

 

... Whatever, the problem was diagnosed and fixed. It was a messed up water pump like someone suggested. The powerband is now smooth, although not as much as my n/a...
Dude, when I post on this forum you have to understand I am kind of a "newbie" otherwise I wouldn't be asking questions. I really appreciate the helpful insight I received, but some of the replies were just unnecessary. All of us were at one time fresh owners of an rx7, or "newbies", and to express comments in ways that imply we never experienced ignorance is just plain... Ignorant.

Thank you Scott 89t2, ilike2eatricers, and Gotenks.