So occasionally when I try to press the start button with the foot engaged on the brake. The car lags and doesn't start up. I sometimes have to press twice or three times. I just changed the battery a month ago. Could it be the alternator that is out? Cant figure out why it doesn't start at times...

Thx

 

When you say it lags, does it sound like it's trying to crank but doesn't start up? Or when you press the button, there is no cranking noise at all?

If you want to check your alternator, you can use a voltmeter on your battery while the car is running. You should be reading about 14 volts DC if the alternator is working properly. If it's not, you'll read about 12 volts or less.

If it's trying to crank and doesn't start, it could be your spark plugs. You'll have to pull them and inspect them to find out if there ok.

If it doesn't crank at all, then it may be the switch or the foot pedal switch.

Hope this at least gets you started in the right direction.

 

Your description sounds like the motor cranks, but does not fire up.

Do you use premium fuel? How many miles on your IS? What year? 250 or 350?

 

If the motor isn't cranking when this happens - are you waiting till the light on the button turns green to push it? On some rare occasions there has been a lag on mine too where the light stays orange for a little longer than usual, but once the light turns green it always starts up perfectly fine.

 

Ok, here is a better description. I used 93 octane fuel. I basically press the pedal the car starts to crank and then shuts off. Then I try again and sometimes repeat process. Other times, it cranks fine and the engine starts. What is the process like checking out spark plugs?

 

I would check the battery again - hopefully it's not defective and check if the cable is not loose or something. When was the last time you changed spark plugs?

 

Once you press the button and release it the car should start. Are you inadvertently lifing up on the brake pedal before it fully starts? If the car hasn't started and it detects the foot is off the brake the starter will stop. And if you haven't driven it in a couple of days you sometimes have to pump the brake pedal a couple of times before starting, if the pressure in the system goes down a bit the system may not recognize your foot on the brake.

 

I always remove my foot from the brake the moment I hit the start button and I have never had to pump the brakes to get the car to start after it has been sitting for a few days or a week.

 

check the battery.

 

You should wait till your car starts to lift your foot up. I do and i highly doubt this has anything to do with it. I'm sure that you have waited till the light turns green (as you always should).

You have yet to answer us with mileage and spark plug change, the battery may have something to do with it but it sounds like its failing to turn over. It's not making a clicky noise is it?

 

Sorry, about 85K on the car, battery just change 1 month ago, though the problem was there before the battery change. Also, not sure when the spark plugs were changed as I got this car as a hand me down....but a complete service was recently done on the car...not sure if that entails spark plugs....

No clicky noise, occasionally when I press the start engine the car partially cranks up but then shuts off. A second attempt usually allow the engine to crank completely.

 

I am starting to have the same issue. My car has around 85K miles, and I changed my spark plugs around 60K. My battery drained about a month ago but the triple A guy told me the battery was fine and he jumped my car and I was good to go. Not until yesterday, did I having the similar issue as OP (I am stepping on the pedal, while pushing on the start button, and the crank feels really weak, although it has been starting up recently).... I'm thinking it's the battery maybe?

 

I have similar issue but unsure what is wrong (if anything).

My car recently started to have longer crank when I am at work's UNDERGROUND (p4). The car will start but just a feeling that it will not start and keep cranking. Please keep in mind this only happened at work and everywhere else I'm at it's perfectly fine (regardless if it's super cold or super hot).

Anyone can think why? thanks!