Hello Everyone.

Alright, so I have a 2.4L 4 cyl 1999 chevy malibu. About a month ago I notice the car starts to hesitate while giving it gas. However, when I let go of the gas the car rolls along fine. At a stop signs or lights the engine runs fine. It starts up fine also. The problem only occurs when I am giving it gas. It also usually starts to do it when I hit 30 or 40 mph. I took it to my mechanic and he told me my vaccum pump hose is leaking. I just wanted to get a second opinion and does anyone know where this vacuum pump hose is located.

Thank You.

How expensive are we talking about? Maybe something is lost in translation. If it's a vacuum leak, your mechanic may not know the actual culprit yet. A lot of mechanics speak English as a second language which doesn't necessarily mean they are dishonest.

That is true about the english part. He said he would charge me 70 bucks to hook it up to the diagnosis machine and if it is just a vaccum hose leak then he said he would charge me like 2 or 3 bucks just to seal the hose up with 2 or 3 dollars worth of materials

So, the diagnostic fee is $70 which may or may not be reasonable, depending on your location and also whether or not you intend to maintain continuing relationship with this shop. It's up to you. I'd be happy to answer any questions on the diagnostic readout, though.

What is a vcauum pump anyways? I tried doing some research but I was nt able to find too much information on it.

I haven't got the foggiest. Your Malibu came with no "vacuum pump."

I see. Well ok then thank you for your help.

This sounds an awful lot like a plugged catalytic convertor, too.

A vacuum pump is a device that is mechanically driven by the engine to produce vacuum, used mainly on diesel engines. The only one I ever saw on a gasoline engine was on an old '64 Rambler with vacuum-operated windshield wipers. The vacuum pump on it was actually a vacuum enhancer since the wipers were hooked directly to the manifold. It gave them more vacuum when accelerating (when manifold absolute pressure=high/vacuum=low), but it was very old when I got it so it didn't work near as well as it should have.

As posted above, you do not have a vacuum pump.

You have a '99 but posted in the '08 up section.

Moving, PLEASE read where you are posting things guys....

OK guys I just happen to have a wrecked parts car from California. the california emissions Malibu V-6 3.1LTR HAS A Vacuum pump on it for emissions.
federal emissions cars dont...
Mike...

Hmm, is this a test?:confused: Translation problem? I think you mean air pump rather than vacuum pump.:D

What Starship suggests is most likely what you have - an air pump. I was taking you literally at what you posted, since it seemed to have come from a mechanics diagnosis. It's just a minor exchange of terms and I should have caught it.

The air pump, as I'm sure you're aware, just simply pumps extra air into the exhaust and/or catalytic convertor(s) to help burn off any unspent fuel before it exits the tailpipe. If yours never had it then it isn't required to meet emissions standards. But you're not doing any real harm if you hook it up, either. They run at very low pressure and take almost nothing to drive, so if it needs to be there to make the accessory drive belt fit it's a cheap solution. If it ever freezes up (sometimes they do) then you'll just have to decide if you're gonna replace it or put on a different serp belt.

Does anyone know what it means if you have a Vacuum Leak?

Yes. The intake mainfold is the ultimate source of vacuum on an engine. If there is a hose or fitting that doesn't make a tight connection then air from the engine compartment will be sucked into the engine through that hose or fitting. Depending on the size of the leak and the device that needs the vacuum to operate, it could be a minor or major issue.

Your power assisted brakes use vacuum to help you stop. If any fitting or hose from the engine to the booster developed a leak then it might not be too noticeable. But if the hose was gravely sliced then you would have little or no boost - serious indeed!

Other devices also use vacuum to monitor the operating condition of the engine or other devices, or they use it to operate things via vacuum motors.

Vacuum leaks can also cause the engine to run faster while idling, and they can affect the emissions.

Hello Everyone.

Alright, so I have a 2.4L 4 cyl 1999 chevy malibu. For some reason I noticed like when it is raining on a hot and humid day, my car will hesitate while I am giving it gas. When its sunny and hot the problem does nt really occur. It seems to happen only when it is hot and humid. Also, when it hesitate it hesitates really bad. I will be giving the engine gas and the rpm will shoot up to 4 rpm, but the car wont go past 30 or 35. After driving for about 10 mins at a slow speed of about 30 or 35 the car seems to go back to normal. Has anyone had this problem before. Another thing is my speedometer will bounce up and down from like 40 to 0 and all in between when the problem is occuring only.

I'm confused. Is this a new problem or continuation of the original problem? Care to share what's been done for the original problem?

Yes, this is pertty much the same problem. Since then I have pulled out the pcv hose and cleaned it up a little from both ends then made sure it was plugged in tight. That helped a little, but im not even sure if that was the solution or not. The car was running alright for about a month, then we started getting hot and humid weather like every other day. I noticed that the problem was occuring mostly on those days. If the next day was sunny and dry, then the problem would not occur. I pulled out the pcv hose and cleaned it up a little as I have done before and checked for any wholes in the hose but did not find any. This time the method did not work. Its very odd but I can almost guarantee the hot, humid and rainy weather is contributing to the problem.

Okay, I wouldn't call what you describe as hesitation (motor refusing to rev up). It sounds more like the transaxle refusing to upshift ("rpm will shoot up to 4 rpm, but the car wont go past 30 or 35"). If the only odd thing in the instrument cluster were the bouncing speedometer needle, I'd suspect the vehicle speed sensor (VSS) circuit. See the transaxle as seen from the passenger side at http://cid-54465800aad91b49.office.live.com/self.aspx/pub/87951085L.gif. There should be a two-wire harness connected to the OUTPUT SPEED SENSOR. The other end goes to the PCM and represents the VSS input (low-voltage AC pulses) which is needed for shift control. Due to its location, the connector at the sensor may be corroded and creating an intermittent connection.