Q45 stopped on me the other night for the first time, all dash lights came on and died with no power. Before stopping it lost acceleration power. Subsequent inspection of Alt & Battery, revealed cracked vacuum lines and one missing. After replacing vacuum hoses, now experiencing rough idle, and misfire on acceleration. Is this related to vacuum hose replacements, is this coincidental? Please help me understand. Contemplating dropping off at Infiniti Dealer, but afraid of the costs.

It sounds like there may still be a loose or disconnected vacuum line.

Thanks sincerely for your response! If I may inquire further, how can I determine that, or find it? Keeping in mind that I've revisited lines involved with the maintenance that I performed, prior to this, the misfiring, or vacillating idle wasn't occurring.

OwnerCS wrote:It sounds like there may still be a loose or disconnected vacuum line.

Yep - or a replacement hose that got connected to the wrong vacuum port.

The customary way of finding vacuum leaks is to remove any plastic "beauty" trim on top of the engine (so that you have good access to all the vacuum hoses), start the engine, and then spray a little bit of WD-40 on any areas where you suspect there may be a vacuum leak.

When you find the leak, the WD-40 will temporarily plug it, making the engine suddenly run smoother. A few seconds later, the rough idle will return as all the WD-40 is sucked into the leak.

Occasionally, a small vacuum leak will actually make the engine idle faster, by increasing the amount of air available for combustion - in which case spraying WD-40 on the leak will slow down the idle, but will also smooth it out.

Awesome! I'll give it a try in the AM and update you. Thanks again!

In checking the Alternator & charging system, we discovered that the alternator is hitting below 12, closer to 11. In removing & replacing it, is better to do so from the bottom or top? What other components must be moved in the process?

Can anyone tell me why my "VDC" & "TCS" & "Slip" lamps will not go off? After about 15-20 miles, the transmission has a strained sound. Can anyone help?

If you're measuring 11 volts at the battery, your alternator isn't producing any charging current at all. It also means your battery is pretty heavily discharged:


(all voltages are measured with the engine off, after the battery has been setting for a while)

When the engine is running, a good alternator will keep the battery at around 14 volts at idle (assuming no no huge power-drawing electrical accessories are turned on), or a solid 13.5 volts with your headlamp high beams on.

Often, a bad alternator will make a whining sound that can be easily mistaken for engine or transmission noise.

Low battery voltage causes all kinds of dashboard indicator light problems, engine and transmission driveability problems, etc.

So, you should probably fix the alternator before attempting to diagnose any other problems you're noticing. If you're lucky, your other problems will disappear afterwards.