BobbyT

I have a 2000 Lexus RX300 with 90,000 miles which I have owned since new. It has recently developed a tendency to stall when first started in the morning with ambient temperatures ranging 40-55 F. It starts normally, but then stalls when placed in gear. Sometimes it repeats this behavior two or three times. Once it is warmed up a bit, the problem goes away.

Hot starts are normal. Driving performance is normal. I detected no fault codes with my code reader. Any ideas on how to troubleshoot and solve this problem will be appreciated.

salimshah

search on IACV

Salim

Lexspeed

BobbtT, definately include the idle air control value (IAC valve) as mentioned above on your short list of culprits. Clean that puppy and I'll bet you'll be good to go.

BobbyT

Thanks guys,

I got into it a bit today, cleaned what I thought was the IACV, but after getting it back together, and reading my shop manual a bit further, realized that I had cleaned only the solenoid control for the IACV.

The shop manual says to drain the radiator and remove the throttle body to remove the IACV, but I'm going to try leaving the throttle body in place and coolant hoses attached to the IACV, see if I can just drop it down a bit and hose it out with MAF cleaner.

Has anyone done it this way?

Lexspeed

I have a 99 with about 182k on the clock. Over 6 years ago I experienced stalling after a cold start and backing out of the garage. friend who owns an 8 stall shop told me that I could eliminate the problem if I removed the throttle body (TB) flex hose and sprayed the throttle plate and general area. After I did the problem was immediately fixed. I was pleasantly surprised. I have had TBs apart on other cars and have even rebuilt them before, but this was a quick and easy fix on the RX. I don't recall the details, but get some TB cleaner and go after the TB and the many orifices.

BobbyT

Thanks for the input, Lexspeed. While I was in there today, I did give both of the throttle body bores a good dousing with MAF cleaner, so tomorrow morning when I start it up cold should tell the tale.

BobbyT

I decided to take the throttle body out and give the IACV a thorough cleaning. Everything was pretty straightforward. I have the shop manual, which was helpful, especially in pointing out the hidden bolt for the brace rod on the back side of the TB (a real PITA to get to). The IACV had a lot of carbon build-up, so I'm glad I did this.

I also tested the operation of the IACV per the shop manual--the iACV in hand, connect the wiring harness, turn on the key, and observe that the valve cycles within .5 seconds.

No stalling now, but I'll check it again when the temperature is a bit lower. It was 50s this morning.

Lexspeed

That sure helps. I wish I had one for my RX. Did you need to remove the TB to remove and clean the IAC? I have never done that on my RX. On other vehicles I own or have serviced accessing the IAC is fairly easy with the TB in place.

BobbyT

After I was done, I found a copper wave washer, about 12mm diameter, where the car had been sitting while I did the work. I think this may have been in the space between the two parts of the IACV, that is between the black plastic solenoid part and the metal part which is the actual valve. Can anyone confirm this?

It seems to work perfectly now, so I'm not motivated to go back in and replace this washer.

BobbyT

Great thread with pictures on cleaning the IACV here:

http://us.lexusownersclub.com/forums...=30723&hl=

salimshah

Bad Idea. The wave washer is a needed component. The wave washers tend to compensate over time.

Salim

BobbyT

Hi Salim,

Thanks. I went back in and replaced the washer this morning. I'm getting so I can "undress" the top of the engine pretty quickly.

"The wave washers tend to compensate over time." Can you tell me in a bit more detail what this means?

Thanks again

salimshah

Wave washers are used to push (or keep) some moveable parts away from each other. As parts move and wear out, the tension is the washer compensates.

Unlike the flat washers which generally are used to spread the squueze force or prevent biding the nut/bolt.

Salim

BobbyT

Lexspeed,
The screws that hold the IACV to the TB are very difficult to access with the TB in place, and they are very tight. I won't say its impossible to get the IACV off with the TB in place, but pretty close to it. The only difficult part about removing the TB is the hidden 12mm bolt on the brace rod at the back side of the TB.

I got the shop manual as a download some time ago, and I don't remember the source, but it was far less expensive than a paper copy, around $30 IIRC.

caboxerguy

I have the 03 RX300 AWD and sometimes it will crank and like the motor will seem like it is going to start and then it just doesn't. It usually takes like 4 times to start it. No lights come on the dash and it only happens once a month or so. Any thoughts or suggestions?