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91 RX-7 Update

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Old 10-05-04, 10:30 AM
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91 RX-7 Update

Well I did the ol ATF trick (had ATF fluid laying around from when my V8SHO turned into an ATF fountain and I was going to limp it home). Got her to start up and rev to 3G, while it blew a whole lot of smoke out and killed all my mosquitos. yay!

After I let off the throttle it died, tried it again, died again. It just refuses to idle. After all this I pulled the spark plugs again. I get a good sound on the back rotor, but something comparable to a sound clip I've heard for a bad rotor on the front .

I'm going to try and get it started again to see if it really is dead on the front rotor (even though I heard that 90% of the time the rear one dies).

If it's dead, I'm pulling the whole thing out, swapping to a manual, selling the automatic, and putting in another motor.

I've also heard that I can only swap in a series 5 motor....is this correct?
Old 10-05-04, 10:47 AM
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ATF trick is generally not recommended unless your motor is one step away from rebuilding and the use of ATF is the last ditch effort before rebuilding. On a motor with less than good seals the ATF will waste the engine.

Why did you do the ATF treatment??? were you already having issues???

And yes a 89-91 non-turbo motor would be the easiest to install.
Old 10-05-04, 10:49 AM
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Originally Posted by Icemark
ATF trick is generally not recommended unless your motor is one step away from rebuilding and the use of ATF is the last ditch effort before rebuilding. On a motor with less than good seals the ATF will waste the engine.

Why did you do the ATF treatment??? were you already having issues???

And yes a 89-91 non-turbo motor would be the easiest to install.
This car was purchased with a motor that had been sitting for 2 years that was diagnosed with a bad motor to begin with.
Old 10-05-04, 11:11 AM
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does it just die right away? mine did this when i disconnected the intake :-p

make sure everything is connected properly.
Old 10-05-04, 12:40 PM
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Originally Posted by apreludem
does it just die right away? mine did this when i disconnected the intake :-p

make sure everything is connected properly.

If I let off the throttle it will go straight down and die.
Old 10-05-04, 12:47 PM
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Could be a pretty serious vacuum leak.
Old 10-05-04, 02:02 PM
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Took some vids of the front and rear rotor.

http://www.ozzmannt.com/images/browse/rx7/rearrotor.wmv
http://www.ozzmannt.com/images/brows...frontrotor.wmv

Something doesn't sound right on one of them, but comparing to the sound clip I have of a bad rotor, they don't sound exactly like that.

Also, had the car started yesterday and was reving just fine, let it die down and even today I can't get it started again. It even started immediatly after it's first start.
Old 10-05-04, 02:30 PM
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Yup - It sounds like low compression on one rotor.
Time to get some compression numbers to confirm it.

Maybe on more desperation ATF overnight soaking?

But before you you do that, It's possible that a leaking injector is flooding just the front rotor...
Old 10-05-04, 02:32 PM
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Originally Posted by SureShot
Yup - It sounds like low compression on one rotor.
Time to get some compression numbers to confirm it.

Maybe on more desperation ATF overnight soaking?

But before you you do that, It's possible that a leaking injector is flooding just the front rotor...

Which rotor? Or can you tell by the video?
Old 10-05-04, 02:35 PM
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Originally Posted by ozzmannt
I've also heard that I can only swap in a series 5 motor....is this correct?
No it isn't. you CAN have a S4 block in with all of the s5 components and it will be able to run.
--side note of all the work you must do to do this--allthough if you can obtain a S5 block and manual tranny go for that just because it's simpler and the S5 block makes more power. I did this because a lack of funding.--
Ok if you want to S5 OMP you must change the front irons on the block because the older OMP fittings don't correspond with the S5 fittings.
The waterpump should also be an S5. If you keep the S4 iron on it you must grind down the front iron where it hits the waterpump and doesn't let it even come close to sealing without grinding. about an inch of metal.
Grind down on the rear iron the part that hits the S5 intake manifold. this is the easiest of the grinding, you must take off roughly half an inch of metal and it doesn't interfere with any tranny mounting points as well.
Originally Posted by Icemark
And yes a 89-91 non-turbo motor would be the easiest to install.
so true, so true
That's a quick overview of what you need to do to an S4 block if you want to put it in an S5 car.

Hope this helps man.
Matt
Old 10-05-04, 02:38 PM
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I would compression test it first. Then move to the desperation overnight soak of ATF. Also, the S5 would be the easiest engine to put in your 91. However, the S4 is adaptable.
Old 10-05-04, 02:39 PM
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Originally Posted by marlaman
No it isn't. you CAN have a S4 block in with all of the s5 components and it will be able to run.
--side note of all the work you must do to do this--allthough if you can obtain a S5 block and manual tranny go for that just because it's simpler and the S5 block makes more power. I did this because a lack of funding.--
Ok if you want to S5 OMP you must change the front irons on the block because the older OMP fittings don't correspond with the S5 fittings.
The waterpump should also be an S5. If you keep the S4 iron on it you must grind down the front iron where it hits the waterpump and doesn't let it even come close to sealing without grinding. about an inch of metal.
Grind down on the rear iron the part that hits the S5 intake manifold. this is the easiest of the grinding, you must take off roughly half an inch of metal and it doesn't interfere with any tranny mounting points as well.

so true, so true
That's a quick overview of what you need to do to an S4 block if you want to put it in an S5 car.

Hope this helps man.
Matt
Gezz, definatly sticking to S5 motors in this. By the time you modify everything I could have probally rebuilt the damn thing.
Old 10-05-04, 02:44 PM
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Originally Posted by ozzmannt
Which rotor? Or can you tell by the video?
The S5 quickie getto compression test:
1) Pull the trailing (top) plugs.
2) Have someone crank the engine while holding the throttle wide open.
3) Feel the compression pulses at the plug holes.

All 3 faces on both rotors should be all equal.
If you get any excess fuel on your finger, it was flooded.
Old 10-05-04, 02:55 PM
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Originally Posted by SureShot
The S5 quickie getto compression test:
1) Pull the trailing (top) plugs.
2) Have someone crank the engine while holding the throttle wide open.
3) Feel the compression pulses at the plug holes.

All 3 faces on both rotors should be all equal.
If you get any excess fuel on your finger, it was flooded.

We did that on the rear rotor and it was all equal pressures. 3 times over. Didn't do this on the front one. I'll try that one later on.
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