1993 Camry low RPM at idle

[nemodat]

Hello,

I have a 1993 Camry 5SFE with 354k km. The engine has always run great, but for a long time it's had a minor glitch: if the engine is warm and I slip the transmission into neutral at a red light, the engine almost stalls. The RPMs drop to 250 or lower, then partially recover to the 250 to 500 range. Despite how close it comes to stalling, it has *never* stalled. If I shift back into drive with the brake on while this is happening, the idle increases to where it should be, somewhere around 800 RPMs I think.

This happens most often when the engine is particularly warm, like during a highway trip. I'm hoping this can be fixed with something simple and cheap. I remember something similar with an old Tercel I had, I replaced some type of sensor which attached to small rubber hoses, and the engine ran much better (O2 sensor?).

Any advice greatly appreciated.

Thanks,
ND

[fenixus]

do you have any error codes? CEL on?

it's hard to believe ECU didn't throw a code for something like that. it almost sounds like a bad MAP sensor, but why only in Neutral gear? does it do the same thing in Parking gear?

[nemodat]

Originally Posted by fenixus

do you have any error codes? CEL on?

it's hard to believe ECU didn't throw a code for something like that. it almost sounds like a bad MAP sensor, but why only in Neutral gear? does it do the same thing in Parking gear?

Fenixus: No, the Check Engine Light is not on and unfortunately I don't have a diagnostic tool so I can't say about error codes from the Engine Control Unit. As far as I know it's the same in Neutral and Park but I can't say 100% and I won't have a chance to test for a while.

I was hoping this was a well-known issue with the 5SFE and had a quick solution....

[LynchburgCSI]

My advice:
1) Automatic transmissions are designed to stay in DRIVE while at a red light. Putting it in neutral isn't good for at and normally will burn MORE gas.
2) Try leaving the battery disconnected (for pull the EFI fuse) for 5 minutes or so to reset the ECU. then go out and drive it. See if it still has the issue.
3) If that doesn't work, I'd suggest a seafoam treatment. It's probably due for one anyways, and that could remedy and types of buildup in the emissions system.

[Mister_Perkins]

thats weird it should idle higher in neutral. I would do like ken says and sea-foam first. Its simple and easy to do

[Mike Gerber]

I would clean the throttle body and idle air control valve first while still on the car. Here's a link to a DIY on your 5SFE engine:

How to: Cleaning Throttle Body -4 Cylinder Engines- With Pictures

Also, you mentioned "unfortunately I don't have a diagnostic tool so I can't say about error codes from the Engine Control Unit ". Your 93 5SFE engine is OBD1 not OBD2. That means you can check for error codes with a piece of wire or a paper clip. Any manual will have the procedure and what the flashes of the check engine light mean. I don't remember a particular thread covering the procedure here, but it probably has been covered so do a search.

Mike

[pmesfun]

+1 on seafoam. Sounds like the throttle body and idle air control valve needs a good cleaning also.
Edit: Mike beat me to it.

[Mister_Perkins]

error codes is E1 and TE1 on the Data link connector.

Flashes are

long = 10
short = 1

so four long flashes and two short flashes would be 42.

If it continuously flashes, that means no codes.

There are two DLCs on the car. One under the dash, and one on the passenger side Wheel well (Towards firewall with hood open)