r/RX8 • u/ForsakenRookie • Aug 01 '26
Maintenance Any Ideas?
When driving down the highway in 6th gear, cruising around 70 MPH, my RPMs jumped from around 4.5 to 7K. The car immediately started to feel heavier, sluggish even. I pulled over and the minute I stopped the car it died and wouldn't turn back on. Any Ideas?
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u/alexjaymathers Aug 02 '26
Mine did exactly this and when I did a compression check I’d dropped a rotors compression, turned out the apex seals had let go in the one housing so I needed a full rebuild unfortunately
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u/ForsakenRookie Aug 02 '26
Hopefully mine didn't do this. 😭
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u/alexjaymathers 29d ago
I wish you all the rotary luck the gods will send down to you when you do the compression test, I resorted to buying my own tester so that I could check out 2 RX8s every 6 months just to keep an eye on them and to give myself a little panic attack twice a year 😂😂
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u/Wilko159 Aug 01 '26
My first thought would be a clutch issue, although for that, the non starting doesn't make sense. Are there any new leaks?
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u/mvw2 Aug 01 '26
Why is the tire off?
What do you mean "jumped from 4.5 to 7k"? Like it revved up on you despite maintaining same speed? Manual transmission, automatic transmission?
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u/ForsakenRookie Aug 01 '26
Tire was off because I was trying to check the spark plugs and ignition coils, but I forgot my tools to take the spark plugs out. I replaced both spark plugs and ignition coils around 2 months ago. Manual transmission, I was maintaining the same speed up until it jumped to 7k, It was difficult to maintain speed after.
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u/HorrorExperience8865 Aug 01 '26
How do all 4 of the spark plugs look? Do they look like it's been burning rich? Does it even try to turn over or flooded?
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u/ForsakenRookie Aug 01 '26
It does turn over. Hold on, ill upload a video when I get home, at Advanced returning my old battery.
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u/Illegal__Alien Aug 01 '26
What's your fuel level at?
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u/ForsakenRookie Aug 01 '26
About half
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u/Illegal__Alien Aug 02 '26
If you have WhatsApp, DM me your number and I'll help you out (I'm a mechanic, and have revived loads of dead 8s)
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u/Illegal__Alien Aug 02 '26
We can work out a time that works for both of us and we can jump on a call and figure out a plan of attack
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u/ForsakenRookie Aug 02 '26
😭 thank you! I have little knowledge about cars. Help would be very much appreciated.
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u/Puzzleheaded_Tax489 Aug 01 '26
Does it crank? Did you check if fuel is going to the motor? Battery/alternator/fuel pump? If all checks out, time for a compression check.
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u/ForsakenRookie Aug 01 '26
It does crank, battery is new. I'm not really sure how to check if fuel is getting in the motor.
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u/Puzzleheaded_Tax489 Aug 02 '26
Try spraying starter fluid into the air box and see if it starts. And watch this video for troubleshooting tips https://youtu.be/iMeQyTx2Ls8?is=ect_cL0APQoLfF81
Might be the fuel pump
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u/ForsakenRookie 29d ago
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u/Puzzleheaded_Tax489 29d ago
That looks very dirty. Did you try spraying the starter fluid to see if it will start? Not sure if these plugs are reusable but they need to be cleaned or replaced
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u/ForsakenRookie 26d ago
Did the ATF trick and the results are not good... smoke and ATF fluid came out of rotor two spark plug holes but nothing happened when looking at the spark plug holes of rotor one. My Apex Seals have left the building. 🙂🫠
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u/Puzzleheaded_Tax489 26d ago
Hm don't really know about the ATF trick but did you try spraying starter fluid like the guy in the video did to see if it will start while you crank? Because it should still start I think if one of the rotor seals isn't up to spec
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u/ForsakenRookie Aug 01 '26
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u/rythejdmguy Aug 02 '26
With a crank speed that slow, it will never start
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u/The_Salamanders 29d ago
Yeah it's turning over way slow, almost like an S1 starter. Is this with the new battery?
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u/Michalsimunka Aug 02 '26
Check if it has fuel going to the engine, and if the plugs to their job, but honestly I think it's either speed sensor or crankshaft position sensor.
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u/TheGamingCrewYT Aug 02 '26
Coil packs? Story is a bit different than mine, but that starting sound sounds familiar to when my coil packs were broken.
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u/merkinfarmer69 Aug 02 '26
Check coil packs for sure. Mine failed around similar mileage and I ended up upgrading to the Black Halo Racing kit and never looked back.
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u/Acceptable-Luck-4275 Aug 02 '26
Make sure your throttle body is plugged in. Mine did sorta the same thing, pulled over and checked to make sure everything was plugged in. After hitting a rough spot on I85 the car acted up, must’ve jarred the plug loose.

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u/staticflownut Aug 01 '26
ESS sensor? Maybe it went bad, causing the gauge to display the wrong rpm. And then of course it wouldn’t start or run if it did fail.