Caniac14

Hey all. So the car didn't stall and still ran fine, but today I noticed in D at a stop sign that the car was barely above the lowest needle between 1-200 rpm. In park is was at around 400. I know these are lazy motors but that seemed low. Is this normal. I haven't had any problems whatsoever(knock on wood) other than replacing my power steering pump and alternator. CEL came on briefly for cat efficiency last month but went away and hasn't come back. Oh btw. It's a 1996 LS400.

cgawelko

If the engine was truly at 1-200rpm, it wouldnt stay running, it would be incredibly rough and shut off. I would look for errors in the cluster needles.

Caniac14

I thought of that but it ran normal rpm at driving speeds.
Maybe it's just reading the idle wrong?

Can the scanners at places like advanced or autozone read idle rpm?
If so I guess my first thing to do is go up and there and see what the actuall idle rpm reading is.

cgawelko

The only person I could think of that knows all this is Yamae. But Autozone has nothing that can read your RPM, those guys are monkeys with internet access.

Yamae

I would clean the throttle body and also check the IACV.

Shmee

iTrader: (3)

Any decent OBD2 scanner with real-time data can output rpm on it's display.

Like Yamae has suggested, you likely need to clean the TB and IACV.

A proper injection system flush and new O2 sensors might also be worth doing if you have no record of either in the last 80k miles. Both can have an impact on the idle smoothness without any other symptoms.

Imolas4

I have a really low idle as well. Mine is around 4-500RPM and a 1997 . Not always but it happens. Especially nerve wrecking when sitting in traffic lol

Caniac14

I have yet to find time to find a place with a scan tool to hook her up and read true idle, but as of now she still hovers barely above the line when warm in D at a stop, and has no issues pulling off or misfires ect.
At this point I'm assuming it's probably the cluster since my speedo gets stuck every now and then and I have to rap on the dash to get it to move.

Once I get an exact warm idle rpm reading I'll update this thread.

Legender

No... not the cluster. Rapping on it is known to break it free from the grease that the needle sticks to. The cluster reads fine after it breaks free and has normal movement.
I had low idle also on a 95 I previously owned. Cleaning out the throttle body and replacing the plugs worked wonders... problem solved.
Coming off the freeway when really hot, the car would idle so low it would die on deceleration. It would start fine.
Again, cleaning the throttle bore and IACV and replacing the plugs will show marked idle improvement.

Caniac14

Got a friend with a scan tool to read it and it is the needle. At idle in park it was idling at around 800rpm and in D at around 500rpm.

So the needle is reading low. But how do those numbers look? Are the good/normal/fair/could be better?

AFLS400

Check or change out your coolant temperature sensor. I had some of the same issue on my 1998 and I changed out the CTS and all the issues (low idle, occasionally stalling at stops, low gas mileage (17-18 mpg) in city (now 20-21 mpg) and Bank1/system 2 CEL went away. Good luck.