This is my first post and Ive tried searching the entire internet but cant find a solution to my problem. My GF has a 1996 Civic LX Auto with 230k. Just recently it started having a problem of after shes been driving in stop and go traffic for about 30-45 minutes the RPMs will slowly creep up and then drop back down and then they'll get stuck between 3-4k rpm. When this happens the car will start to overheat , Im guessing this happens just because of the sustained high rpm, the cooling fan is working properly. Once the rpms get stuck she has to turn it off and let it sit for a couple of hours before it runs normal again. This problem only seems to happen if its hot outside and in stop and go, never on the highway. Ive removed and cleaned the throttle body and idle valve and it didnt seem to help. Everything I've read says it could be a vacuum leak, but ive never heard an intermittent hot vacuum leak. Any input and help would be very welcome as I am stuck.

 

100 views and nobody knows? There has to be someone.

 

3-4k is pretty high rpms even for a vacuum leak. Have you tried adjusting the throttle cable slack? Is the coolant level fine? When it overheats are both radiator hoses warm or just the top?

 

Im going to replace the throttle cable tomorrow when the parts get here so we'll see if that changes anything. When its overheating both hoses get hot. I think the radiator isnt working as well as it should but it doesnt over heat unless the rpms are jacked up.

 

Please read the forum rules sticky. Thread titles must summarize the tech issue.

 

Sorry I tried to edit it but I don't think I can

 

dont go blindly ordering parts, its easy to tell if a throttle cable is bad..and I hope you have reason to believe so.

you never mentioned if the fans coming on?

 

Sorry, yes the fan is coming on and seems to be functioning as it should. The reason for the throttle cable is when the rpms start going up they would be steady at about 1500 and when I pulled on the pedal they drop back down to 600 or so. Will cooling system issues cause idle problems on these cars?

 

Yes but it won't make it rev high. In the FAQ there is a throttle cable adjustment DIY. Also when it overheats are both radiator hoses warm? You could have a bad thermostat and the high rpms are just increasing the likely hood of it over heating.

 

Ok. Thanks. When I look at it tonight I'll be sure to check it out. Any thoughts as to what else could be causing my rpm problem beside the throttle cable.? I just want to make sure I'm covering all my bases.

 

Yes both upper and lower hoses get warm