Is this an engine problem.

[Street-racer]

When mechanic hooked up the computer to the car today one of the thigns that came up on the screen that said "weak vacuum". What could that be? Because he tried to decline like hell that there was anything wrong with it. (but it has the check engine light on).

Anyone know what could be wrong?

[matts]

that could be something as simple as a vacuum line with a hole in it or something as serious as a.........something more serious than a small hole :lol:

i was gonna say more stuff, but evertytime i do i make myself to be an a*s because these engines are always as* backwards to what i say. but yeah :P

[cocobob]

Check for cracked vacumn lines at MAP sensor and the two at the Evap solonoid switch. Sometimes just by squeezing these old vacumn lines while checking connections can cause cracking as they become brittle from heat.

[93GASE3300]

generally low vacuum means either you have a vacuum leak of some sort or your compression is low from high mileage.

[rixGAphx]

It may indeed mean nothing.

A scan tool has no way to directly read the vacuum. Reading the vacuum requires a special gage be plugged into the intake manifold.

However, a scan tool WILL read codes that are stored in the car computer's memory.

One of the stored codes could have been a 'pending' code, meaning that for one instant the PCM (Powertrain Control Module, the car's computer) detected 'low vacuum' and it stored this code for future reference.
The stored code stays in the PCM thru 40 on-off driving trips.
If the condition that caused the original 'low vacuum' signal never recurs within 40 trips, then the PCM deletes it.
If the 'low vacuum' occurs again, and then a second time within the same or next trip, then the PCM will store the new code AND will set the "CHECK ENGINE" light.
When the technician checks the PCM, he may find several stored 'pending' codes; since they didn't recur and set the CHECK ENGINE" light, they really don't mean anything (unless several different pending codes can be associated with a specific device that might be failing).

If he said don't worry, I wouldn't worry.
He wasn't worried enough to charge you to replace a bunch of vacuum hoses, and your vehicle really isn't old enough for the rubber and plastic vac lines to be brittle with age (hell, mine are 7+ years old in Ari-freaking-zona heat and they're still fine).

Good luck.
-Rick