Why are my 1997 C5 rpms keep jumping?
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Joined: May 2011
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Why are my 1997 C5 rpms keep jumping?
So here's the problem I have a 1997 corvette and the rpms have been acting pretty funny here's what happens so I'm on the freeway and I'm maintaining a speed of say 60mph and not pressing or letting off the gas the rpms decide to jump from 2000 to around 2500 for only about a couple of seconds before going back down to 2000 again it almost seems like it's trying to shift but the trans is fine so therefore I don't know what it is. I looked up similar problems online and people have been saying to replace the mass airflow sensor and or the throttle position sensor. Just as a side note my oil gauge is reading very high in fact as far as the dial can read (dial reads from 40-90psi dial stays at 90) now I don't know if this is also part of the problem I'm just throwing it in there to help it out, however I wouldn't be surprised if the oil sensor needs to be replaced so that's probably not causing it since I've read up that corvette oil sensors go out a lot. Anyway please let me know if you know what's the problem thanks
Melting Slicks
Joined: Sep 2011
Posts: 2,258
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From: Appleton WI
As asked in the previous post. What type of transmission? (auto or manual)
When the RPMs spike, does the car accelerate or maintain speed?
If the car is maintaining speed with the RPM jump, my initial thought is you have a clutch that is slipping.
When the RPMs spike, does the car accelerate or maintain speed?
If the car is maintaining speed with the RPM jump, my initial thought is you have a clutch that is slipping.
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Sorry I forgot to mention that it an Automatic & when it does the sudden jump the trans feels like it's about to shift over so therefore it kinda looses acceleration until you give it some more gas or you wait for it to go back you can also here the rpms raise and then drop to normal again
Melting Slicks
Joined: Jun 2012
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From: Oceanside California
It is most likely your torque converter unlocking and locking back up. This can be a tuning issue as well as a bad converter. But its not likely that its a bad converter. Surprisingly misfires can cause the converter to unlock. If you have bad plugs or wires or a loose connection it may be read as a missfire and unlock the converter. I suppose the same could be said for the fuel injectors etc.
Drifting
Joined: Sep 2009
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From: cinnaminson n.j.
St. Jude Donor '14
Next time it happens, very lightly apply the brakes. The ECM will see the brake switch input and unlock the converter. If the hunting stops, it's the converter. Pull and post your codes.
At this point you will need to get a scanner on it and check tcc duty cycle. Full lock up will read 99%. With no brake applied if the tcc duty is fluctuating, the PCM is commanding it. You might have a bad tcc brake switch.
At this point you will need to get a scanner on it and check tcc duty cycle. Full lock up will read 99%. With no brake applied if the tcc duty is fluctuating, the PCM is commanding it. You might have a bad tcc brake switch.
