I drive a 2000 Monte LS 3.4L. Always on top of oil changes and regular maintenance. Recently while in a rush I put alittle extra strain on my engine driving at high speeds (90+) for roughly 15-20 minutes. This is uncommon for my car. Shortly after, approx. next day. i noticed my check engine light on, slight whining sound that increases in pitch while accelerating, and my RPMs are consistlently 300-500 higher than normal under all driving conditions except while idle. Autozone says the comp is throwing an evac code and to check gas cap. i dont buy it. possible vaccuum leak? feul pump? Any help/advice would be appreciated. Thanks,
-Rob

 

How hot is your engine getting during this?

 

Check your alternator for the whining issue.

 

sensor for o2? maybe it was sucking in alot of o2 and that threw it for a whirl

 

the temp goes slightly above half sometimes, i notice as long as i have the a/c on or the car is in motion the temp stays at normal level. i had replaced the thermostat and done a radiator clean/flush a few months ago, early summer due to an over heating issue. I know keeping the air on is not really a fix for this but i cant afford to/have the time to get it properly taken care of just yet.

 

I highly doubt that you driving it at 90 MPH for 15-20 min has anything to do with your problems. Your car should be able to handle that no problem. I've driven mine at 90-107 for 7hours straight in 100 degree heat with no problems.

As for your temp going up, have you ever had the lower intake manifold gasket, or head gasket changed on your Monte? These gaskets commonly fail and leak coolant. Have you noticed your coolant level dropping? If so, this could be your problem right there.

As for the whining noise. Look at your alternator, or your power steering pump.

 

Mamonte, I didnt think it should have anything to do with it either, i just realized the problem after that. As for the coolant levels, it stays consistant, I have however had problems in the past with the coolant, it would develop a thick red clay around the rediator cap, and elsewhere im sure, and the coolant itself would thicken with red gunk, becomming almost like tomoato sauce or ketchup. mechanics found nothing wrong as the gunk would apparently recede back into the engine once the temp lowered. clueless as to whats causing that but thats why i now do a coolant clean/flush myself once a year.

Others had mentioned the alternator for the noise also, ill be sure to check. would the alternator contribute to higher RPMs also?

 

Alternator should nt do anything to your RPM's

The coolant thing is a common problem with Dex-Cool. The best thing you can do is change it often.

The fact that you are throwing a code, and your RPM's a little higher makes me think its a sensor of some sort. Maybe a crank sensor?

 

No, no, no, when a crank sensor goes bad, the car dies out of nowhere. The raised idle could be numerous things. Plugs, wires, vac leak, gasket leak, effed up IAC, MAF, the list goes on and on.