chris j vurnis

I noticed something strange on my car that just happened last night.
I get in my car and start it up and it fires up and then almost stalled and then settled in at a 600RPM idle right away. Normal idle has always been 700rpm in my car.

Now when the engine is cold, it always idles above 1000rpm until warm and gradually comes down. So I figure that is odd behavior.

Then I put the car in drive and the tach dropped to 500rpms. I let off the brake and naturally the car creeped forward slower than normal.

Now here is the weird part; when I stepped on the gas, it took off noticeably quicker than normal. Its as if the typical wimpy response below 3K rpm has gotten a lot better. (by the way I have a knock sensor code and I have to get that fixed... checked out the code a week ago)

I've read in other posts that when a knock sensor is replaced, it takes the ECU at least a few hours or days to get used to the good readings and bring back the power. But this was like all of a sudden.

Anyway, I start it up this morning and I got the same behavior and also notice the unusually peppy response on the bottom end. Same this this afternoon after leaving work.

Could it be that the low idle speed generates a lot less heat in the torque converter and makes it run better when I get on the gas?

When the car is in Park or neutral, it seems to idle normally around 700 rpms. When I rev up the engine in neutral, it speeds up and then comes back down but sometimes too low an rpm. It will shake a little bit and then come back to 700. When I am in Drive and on the brake, it idles at 500rpm and sometimes there is a mild vibration that I can feel through the steering wheel. When I let off the brake, the vibration goes away. It will stay at 500rpm until I get on the gas and take off. And like I said, it does accelerate faster.


I tried to do a search on "low idle speed" but didn't come up with anything. Checked the battery voltage and it seems O.K.

What do you all make of this? Idle is low but car is faster... not tire shredding faster -- but maybe I guess 10%-20% faster at the bottom end... less bottom end lag for sure.

silvermax2k2

iTrader: (1)

intresting.... well i have no information for you, but all i can say is, hey as long as your car doesn't stall, then be happy for the extra low end boast!

chris j vurnis

Yeah...

I am going to take it to the dealer to figure out why its doing that.
But then I will tell them not to fix it. I just wanna know why.
So then if the car mysteriously fixes itself, I can go back in and disable that particular part so it runs good.

Nismo

iTrader: (18)

when you find out what the cause is, let us know. I had that problem sometimes when the idle drops down low and goes back up but It hasnt happened recently but It still has me wondering what the hecks going on.

Jamsan

iTrader: (2)

clean dat throttle body...same happened to me...and old friend that is into domestics was like, ya its juse your needle needs oiling..im like riiight....what would happen is, i would be going and when im coming to a stop, the rpms would drop well below 500, and then come back up.....so clean the tb and your good

silvermax2k2

iTrader: (1)

i was going to say clean the Tb as well, but he said that it was all of a suden, and it happened over night.... the tb gets clogged up over time. but yes, clean your tb.. you can pick up the cleaner at any car part place and it come in a spray can.

simply take off your intake, open the valve (not when the car is on! ) and spray alittle in at a time. then just wipe all the dirt out. depending on how dirty it is you might be there for a good 15 mins. and after every time you spray, and clean out dirt put the intake back on and start your car. then take it back off and spray/clean again. this solves the problem of your car having a hard start, or black smoke comming out of the tail pipe.

if you notice that it is extremly dirty, or alittle while down the road you clean it and it is very dirty, you need a new pcv valve. they cost approx. $4, and 30mins of your time.

well, that should solve your problem... and posiably help with accelleration. good luck, and let me know how everything turns out..

chris j vurnis

Thanks for the throttle body tips.
But I already cleaned it out two months ago. And it wasn't that dirty to begin with either.

silvermax2k2

iTrader: (1)

oh. damn. well now i am not so sure! sorry i couldn't help you out! good luck.

chris j vurnis

Well, the dealer figured it out for me.
My ECU was still in diagnostic mode after I pulled the knock sensor code. After they put it back to normal, the idle is O.K. now.
More idle rpms, more heat to kill the tranny oil faster, and more pollution at stop lights

Oh, well; I think the knock sensor made a mild difference.
Will have to drive it a few days for the ECU to get used to it and maybe then I won't get beat by wimpy cars...

silvermax2k2

iTrader: (1)

cool, glad you figured it out... and i hope it didn't cost you a pretty penny!