hello, got a hold of a 90 vert. It will start, but it idles very rough, and has a top speed of 10-15 mph... if you try to give it more gas then that, it just makes noise through the intake (kinda howling) and when it does that creates NO power at all. If you pull the air cleaner and reach down in the air box and cover the air intake right in front of the AFM with your hand, it will rev up, but other than that you cant get it to go over 2500 rpm. You can drive the car for a block or so at a time before it dies, then you need to let it sit for a while before it will restart. The car had a bad radiator in it and the guy SAID he didnt overheat it, but my suspicion is that he overheated it and warped a rotor housing. Thinking its loosing compression after it gets hot. Does this sound like a good diagnosis? or should I be looking into something else. The car is at a friends house now, and needs to be towed here. if i'm wrong about the diagnosis and can fix it there and drive it home, that would be great.

 

why not do a compression test? That'll answer your question real quick.

 

the car is sitting at a friends and I wont be able to get to it till tomorrow, I'll do the compression test tomorrow, just looking for ideas on other things to check while I'm there

 

1. Compression test
2. Tow (its going to happen regardless from the sound of things
3. A severly blocked cat will also act as you ahve describe, however, I doubt thats the case.

 

sounds like a blown rotor. I see a rebuild in the future if you want to get it running..

 

or a TII swap

 

would a blocked cat make the engne run worse the hotter it got?

 

sounds like a massive leak in the intake piping past the AFM.

 

what would be a good way to test for this? carb cleaner sprayed on the piping?

 

just found out something about the previous owner of my car from someone who knew him... said that he doesnt think the guy overheated it because the guy supposedly babied the car and would have shut it off at the first sign of trouble. I dont know. I also don't know what this would do, but I was told that the guy drove it like he was an old lady, always drove it gently and low rpm. I was like WHAT THE @#$#@# did he have a rotary for then??!?!?!?! Would lots of low rpm driving clog a cat? or would it more than likely be excessive carbon in the engine due to the low rpm useage? Would the carbon cause the compression to drop more as the engine heats up?

 

The way I understand it, yes for the cats, yes for excessive carbon buildup, but no on the compression to drop as engine heats up.

What about just free revving the car, does it stop going up in RPM at any point (you know, besides redline)

 

timing

 

I assume by free revving you mean giving it gas without trying to get the car to move? if so, it won't rev up, if you feather the gas you can get about 2500 to 3000 grand out of it, if you try to give it more, you just get a lot of noise from the air cleaner like a howl, but the rpm drops, dont remember if I mentioned earlier, but if I pull the air filter and reach down inside the air box and cover the inlet to the afm, then I can work the throttle and get it to rev up. thats until it gets hot then it wont run at all

 

A good method to check for air intake leaks past the AFM is to get a butane/propane torch, and just turn the gas on, and vent the gas around your intake manifold/suspected areas of leakage. If the RPM's raise when you put it in a suspected area, chances are there is a leak.

-Justin

 

right now your best friend is a compression tester... get back to us the results.

 

uuuuum NO.

 

obviously, you havent been around enough to know what would happen if the timing is completely off.... but its ok, you will learn....

why isnt it worth a shot to check? just hook up the timing light and thats a 5 seconds check.

 

Heh, don't wanna get in the middle of it, but Gadget=Newbie=HA

 

lol, he probably knows more than me, but i am going to be an ***... if he is going to be an *** too!

 

I'll bet the 5/6s' are gummed shut. My seven was grandma'd, and I have an awfull hesitation. As far as the cats causing that problem, my brother's van's cats honeycomb wadded into one solid mass that would expand with heat. The thing wouldn't go over 10mph, and stalled once it was warmed up. The nice thing is that you can brake it up with a long screwdriver.

I agree with splin on the timing though. When I got my seven running after I bought it, it ran like crap. The primary coils were lined up with the secondary mark.

Listen to Karak as well. I forgot to hook the big hose on the intake that goes to the bac, and the car wouldn't even start.

Too many people here instantly go for the blown engine answer, but it's the seeming little things that really cause the problems.

 

even so, but why not do a compression check? it cant hurt, and if theres something wrong, no need to troubleshoot any longer. Him doing a comp. check is the best thing he can do.

 

you guys are so great, THANK YOU SO MUCH for all the advice...
I too was eager to jump on the blown rotor band wagon myself. I should have learned from my FB, can't tell you how many times I thought it was a blown rotor and turned out to be something else...
anyway, compression test would have been the first thing if I had a compression tester.... but I did do the 'ghetto' test, and it sounded "normal" at least it sounded like my fb did when I cranked it with a plug out. I could also tell from the plugs that I wasn't gettting any coolant into the combustion chambers, good sign.
I checked, and reset the timing, didnt help. I pulled the bolts connecting the exhaust to the thermal reactor, didnt want to drop everything so I just pryed it back about an inch, hit the key, fired right up, idled smoothly, hit the pedal and it revved wide open !!!!!!!!!
I was SOO jazzed :] And another thing that excited me was how clean it was up underneath the car, the ONLY rust I could find under there was surface rust on the flanges where the mufflers connected to the Y pipes, the mufflers themselves and they Y pipes were clean and solid. I still havent got it home, I need to get a radiator first, its got a small leak in it, no sense risking it. So, I got an RX7 with less than 90K with a PERFECT top, a VERY VERY nice body, almost perfect interior, clarion cd/cassette, and a running engine that needs exhaust work and a radiator and shifter bushings, a shifter boot, and one center cap, for 200 dollars :] I couldn't be happier
the exhaust is interesting though, someones got it welded up, from the flange on the thermal reactor to the flanges for the muffler is one piece, one ENORMOUS Y pipe, so much for changing just that cat, lol. Anyone in the KC area got a factory cat for sale cheap? or a radiator or shifter bushings, or a center cap lol

 

Glad to hear it! Good luck on the great find.

Myexlex, I didn't mean to forget the comp check, that's one thing to always check on an unknown RX-7. I was just trying to point out the other possibilities. I need to work on my clarity. :-)

 

Mazdatrix for shifter bushings/boots etc.

http://www.mazdatrix.com