2001 Pontiac Grand Am with 2.4 liter engine was brought in with the SES light on and a complaint of tip in acceleration problem and rough idle. The codes that were stored were P0105 for a MAP sensor malfunction, P0172 for a system rich fault and P0300 for a general misfire fault. I opened the hood for a visual inspection and heard an unusual hissing sound. I followed it to a vacuum hose that ran from the intake to the MAP sensor. Removed the damaged hose and replaced with a new piece and problem is now gone.
The above picture is of course the bad hose and it is just normal wear and tear that caused this. Below is a picture of the MAP (sensor three wire connector) at top right of picture and the new vacuum hose (the second hose down from the connector)
The P0105 was obviously caused by the MAP sensor hose, the P0172 system rich was also caused by the faulty hose because the computer thought that the engine was running under a heavier load and the P0300 was caused by the unneeded rich condition (particularly at low rpm). I was especially happy that this was a simple fix as it is my daughters car!
This page saved me!
I drive a 1999 Pontiac Grand Am SE, 4 cylinder, and over time I’ve had more and more trouble with the car stalling out, particularly at stop lights whenever the RPM’s would dip to 500 RPM’s while idling or coasting to a stop. I had to rev the engine to keep it going and after a while it would stall even as I was giving it gas to pull away when the light turned green.
Found the vacuum hose above just below the white connector at the front of the engine. It appeared to be cracked lengthwise all around. Had the mechanic replace that (he did it for free along with my oil change) and the car hasn’t stalled and has been riding much more smoothly since.
Before he replaced the hose, he recommended one or two new parts which would’ve cost a total of about $300 plus labor. I asked him to change this little hose specifically instead and that was all I needed.
Thanks!
I know this is an old thread, but wanted to thank you for this post. I checked our 1999 Grand Am (which has been suddenly stalling at stops) and this hose was cracked to pieces. I will replace and hope it helps! I appreciate the advice.
Has the battery been disconnected or dead recently? If so the throttle plate will likely need to be cleaned. You will need a pair of protective gloves, a can of throttle body cleaner, a rag and the tools to access the throttle body bore. After removing the duct work to expose the throttle plate, you will need to block the throttle plate open. An assistant is good for this. Also either disconnect the battery or at least make sure the keys are not in the car. Put on the gloves and spray the cleaner onto the rag. DO NOT SPRAY the cleaner into the throttle body. Using he rag clean all of the surfaces of the throttle bore and the throttle plate. You may have to clean it several times before it is clean. Reassemble and check your idle.
No service light. I was thinking maybe the hose was bend too much so i replaced with a little longer to give more of a curve.
Either way though when I come to stop it tends to bounce below 500 rpm and up.
Hi Chris,
Do you have a service engine soon light on? If so what are the codes associated with it?
The surging/stalling above 3000 rpms in park or neutral is normal and is being caused by a built in rev limiter in the pcm.