Power loss and shut down at higher rpm
11-30-2014, 11:09 PM
#1
Power loss and shut down at higher rpm
Alright, I've got an RX-8 with a ~40k mile reman in it that has fairly low compression. I had it tested at a dealer a few months ago, and they gave me low 6's on both rotors, at 195 rpm (horrible starter). So this isn't too bad, and up until today it was perfectly driveable, smooth rpm, no problems getting to 9.5k rpm, decent power levels, etc.
Today, I was driving back from Houston to Austin, got stuck in traffic for around an hour, so I ended up sitting between 1-2k rpm for about an hour. After this, the car twice shut down when hitting higher rpm. So it would go up smoothly until 6-7k, then major power loss for a few seconds (gas pedal does almost nothing) and rpm drops, followed by complete shut down of the engine (battery light comes on). The engine will not start again immediately. Both times I managed to get it to start later without any issues, once after 30 minutes of letting it sit, the next time after 5 minutes. The second shut down was after another 1.5 hours of driving, but I kept the rpm around 4k that whole time, as I was just cruising.
So the real question is, could this problem merely be low compression? Or is there something else going on here? If it's only low compression, why was the car fine until today? Also there is still excellent power levels at lower-mid rpm, as I had no issues cruising between 4-5k. And why would the car actually shut down but have no more trouble starting?
Ignition system was replaced by Mazda dealer with stock components in March I believe. I don't have a catalytic converter. My check engine light is unfortunately covered up by the previous owner and I have not been able to get into the dash to fix it. In any case it's probably on due to the cat. So I don't have any ideas on the codes.
Thanks guys, I really appreciate any guidance here before I ask a mechanic to diagnose, and they will almost certainly only recommend an engine replacement.
Today, I was driving back from Houston to Austin, got stuck in traffic for around an hour, so I ended up sitting between 1-2k rpm for about an hour. After this, the car twice shut down when hitting higher rpm. So it would go up smoothly until 6-7k, then major power loss for a few seconds (gas pedal does almost nothing) and rpm drops, followed by complete shut down of the engine (battery light comes on). The engine will not start again immediately. Both times I managed to get it to start later without any issues, once after 30 minutes of letting it sit, the next time after 5 minutes. The second shut down was after another 1.5 hours of driving, but I kept the rpm around 4k that whole time, as I was just cruising.
So the real question is, could this problem merely be low compression? Or is there something else going on here? If it's only low compression, why was the car fine until today? Also there is still excellent power levels at lower-mid rpm, as I had no issues cruising between 4-5k. And why would the car actually shut down but have no more trouble starting?
Ignition system was replaced by Mazda dealer with stock components in March I believe. I don't have a catalytic converter. My check engine light is unfortunately covered up by the previous owner and I have not been able to get into the dash to fix it. In any case it's probably on due to the cat. So I don't have any ideas on the codes.
Thanks guys, I really appreciate any guidance here before I ask a mechanic to diagnose, and they will almost certainly only recommend an engine replacement.
11-30-2014, 11:11 PM
#2
SARX Legend
iTrader: (46)
It's just low compression, with time it gets worse. You can nurse it but when the engine gets heat soaked the symptoms worsen. The engine needs to be rebuilt, there is no point in throwing money at other parts.
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