Replaced Intake Gasket, Now experincing High Revs

[ilovemytracker]

Many, if not all Chevy owners of the 3.1L V6 are now aware of the infamous intake gasket coolant leak. Thanks to the thread explaining how to replace these gaskets as it helped me through the entire job.

However, when I went to start my 2003 Malibu 3.1L V6 last night for the second time (the first time I messed up the push rods! Thankfully, none were bent!) it struggled for a moment to turn over. When it did, the engine began to run very fast in idle (about 2400 RPM). When I put it in gear, the RPM dropped to about 1200 which (if I remember right) is where it runs when the engine is cold. I guess the best way to describe it is having your foot on the gas and pushing it down slightly. I haven't moved the car in fear that something is going to blow up.

I am going to be looking at sensors and vacuum lines tonight to see if I missed something. I do want to mention and see if it may be the vacuum line on the fuel rail filter because I broke that piece of plastic and bought a short lenght of rubber hose to connect the broken ends back together?

Any help would be appreciated. If I am not able to figure this out, I'm going to have to use the dealership and we all know how much I do not want to do that.

Thanks again!

[Ed_Strong]

I seems like a vacuum leak to me and judging by those high RPMs I would say it a big leak! Do you hear any hissing sound that weren't there before.

When I had my Corsica 3.1L I did an upper intake cleanup job and upon reinstalling the intake plenum one of the gaskets moved as I was tightening things up so I didn't realize it. When I got the engine started it started with the same high RPMs as you're describing.

Try to listen for a leak with a lenght of hose to your ear and run the other end around the manifold to hear for leaks. Or you could spray WD40 around the manifold and see if the RPMs change showing a sign of vacumm leak. Don't spray too much as WD40 is flammable... hope this helps.

[ilovemytracker]

In answer to your question, when we fired it up last night, there was a whistling sound coming from the engine compartment. It was actually rather loud. Is there something other than WD40 to help block air coming in for a moment? Then I assume that I am searching with my hose each of the intakes, right?

[Ed_Strong]

Actually the WD40 is not to block the air, but rather to see if there's a change in RPMs while sprying it around the manifold.
If theres a vacuum leak in the manifold then when you spray WD40 the vacuum will cause it to be sucked into the combustion chamber thru the leak. So as you spray it around you'll know where the leak is (front or back of the engine) as the RPMs change for that instant while you're spraying. Use the little straw that comes with the can so you can reach all tight spots around the mating surfaces.
Most people use Starting fluid or Carburator cleaner as it gives you a quicker reaction from the engine acting up to it, but those are too flammable and I don't suggest using it if your not too familiar with the procedure.

If you wanna try the hose first then run it slowly around the intake area to hear for the common hissing noise associated with a vacuum leak, similar to what your doctor does with a stetoscope while listening to your lungs when you breathe deep!
Keep in mind that when listening around the front of the engine (serpentine belt area) some of the pulleys sounds come thru the hose and it's similar in sound to a hissing, just so you don't get confused.

[Ed_Strong]

Forgot to ask if you checked for loose or disconnected vacuum hoses already?
Another option to try would be to take it to a trusty mechanic to have him look at it and he can tell you whats wrong so you can correct it.

[ilovemytracker]

I have finished searching for anything not plugged in and have found nothing. Still working around the intake to find where my hissing noise is coming from. I think I have localized it to an area surrounding the back, drivers side corner of the engine near the firewall. I'll be taking my peice of hose to that section next.

Also need to give an update on engine speed. It seems that as it warms up, it runs even faster. I am at almost 3000 RPM! However, again, when it goes into gear, it drops all the way to 1200 RPM.

[ilovemytracker]

Alright, I broke down and took it to a mechanic that came highly recommended to me. He diagnosed my malibu and told me that while I was doing my intake job, I some how damaged the gasket between the throttle body and the engine allowing more air into the engine. I have since had it repaired and it runs quieter now at 66,000 miles than when I bought it with 21,000. Thanks to all the threads that helped with these issues