I have an '06 sedan 5AT and I was driving downhill on the freeway and put the car in neutral since I was going downhill. I've done this many times in the past but this was the first occurrence where while I was getting on the offramp, the steering wheel stiffened up and I see a bunch of lights on the dash (one's you'll see when you put your car in the ON position but don't start it).

Pulled over since I was next to the shoulder. Don't think the engine was running, hard to tell because of so much noise and I didn't bother to get out. Instead I turned it to off, waited a couple seconds, and started the car again. It started up with no problems at all and drove just fine. I put it in neutral again and no issues, but it wasn't near as long as the previous time.

My OEM cats need to be replaced. The honeycomb filter is loose and rattling, I just haven't had a chance to swap them. I don't know if that could be the reason (been driving with them like that for a couple weeks now). Or if it's something else. Other than this, the car has been running with no issues for quite a while now. Warranty has been exhausted as well. Any ideas?

 

First of all it's not smart to be doing that and is actually illegal in many states (how they know you do it is still a mystery to me). You're not really saving gas by coasting in N... In fact some might argue that you use even more because the engine needs to use gas to sustain it's idle, where as when you're foot is off the gas and you're going downhill, the ECU sense that and the only thing really turning your engine is the wheels of your car.

It's even worse when you do it with an AT transmission. For MT it's fine because you can manually engage/disengage gears using the clutch, but every time you shift from N to D in AT, you're shocking the tranny and damaging it because they weren't made for people to do that (and is quite unnecessary).

With that said, I don't think it's the the shifting from D to N that's is actually causing your car to cut out. It's probably your intake or a dirty MAF sensor. Have you ever cleaned them out before? Loose connection? Etc...

 

Ideas yes I have two, replace your wasted converters and quit coasting in neutral. That's strange your engine would just shut off by taking it out of gear, maybe the converters are effecting your G more than your realize....
Gary

 

+1 on the MAF. Clean it and you should be fine.

Also both above are correct about not shifting into neutral. It's unnecessary.

 

Didn't coasting in neutral was illegal. I thought it saved gas because every time I check mpg on the nav screen it goes up and so does the distance to empty.

MAF sensor and TB were cleaned over 6 months ago.

The car didn't shut off immediately, it was not for another good 30 seconds of having it neutral when it did.

I'll double check the MAF, but I'm guessing the cats are the root of the problem. Just wanted to see if it could be something else.

 

Sounds like your engine stalled when you shifted into neutral and the revs fell.

Even though your mpg goes up at idle engine speed, NO gas is used when you are in gear with your foot off the gas pedal. When you shift the car into neutral, the idle program in the ecu takes over. It does save gas, but not near as enough as staying in gear.

Go catless too.

 

Yeah, I had test pipes, but I got rid of them. They were non-resonated. I'll get resonated test pipes down the line when I do fully custom exhaust, but I need to do my custom rear bumper first since I'm doing a dual exhaust, quad tips.