Occasional Idle Problem

[rhash]

I have a 2001 RX300 (85,000 miles) that has started in the past few month OCCASIONALLY experiencing an idle speed problem at start. When the incidient occurs, the vehicle has difficulty starting unless gas is applied...then when I back off, idle speed drops and vehicle stalls.

So far, if I apply power (gas) while applying the brake, keeping engine speed up...until I can enter a road/highway...after a few minutes of running, the car is fine, as in it maintains proper idle speed the next time i come to a stop.

This problem is intermittent...probably only occurs once in every 10 starts or so at most.

There are no other symptoms (no check engine light or anything like that)

Gas mileage appears to be largely unchanged, and accelleration is basically normal.

It does not seem to be tied to any gas level in my tank at the time

Any ideas what this might be? (No, I have not take vehicle to a dealer yet) I'm going to put in some fuel injector cleaner into the gas tank tomorrow...but just curious if anyone as any experience with this. Clogged fuel filter?

Thanks for any help.

Randy

[Russ White]

Randy,

I had not experienced your symptoms, but if I did I might suspect some component of the systems that determine fuel richness at starting. In general, when an engine is started "cold", the fuel must be enriched to compensate for the condensation of the fuel on the side of the induction chamber on the cylinder walls and head. If there was some problem in that area the fuel might be too lean in some cylindars and not fire properly, requiring you to make the starting adjustment you describe. It may be hard to locate as long as it remains intermittent. A good scan tool that could read the value of the temperature sensor used to tell the ECU how much extra fuel to add would be helpful. Does the problem seem any worse when the engine is very cold? I don't think a fule injector cleaner would hurt - I use Techron. I would not suspect the fuel filter as that normally would show up first under full flow condtions like a long pull on a steep mountain or under sustained heavy acceleration. This could be a tough one. Good luck!

Russ

[92Lex]

That pedal you're stepping on has nothing to do with adding more gas...it actually adds more air.

Throttle:

FI- adds air

Carb- adds fuel

Check the idle air control valve or MAF sensor for problems.

[ColinBarber]

It is a common problem for the idle air control valve to become dirty and cause idling problems.

[SKperformance]

yup

iacv

look in the ES forum with the same engine on fixes and pics

[sgriffith]

I am now having similar issues. I cleaned the throttle body only about 10K ago and didn't really figure it would come up on me this fast. Has anyone with this problem noticed this when you are accelerating or crusing at a certain speed? I was driving 30 MPH downtown today and noticed it acting like it was cutting out on me. There would be about a 250 rpm drop and rise every second or so. I will clean everything again tomorrow before we head off on our Memorial day weekend and see if it clears things up & will post results. Thanks!