vsop4me

*Meant to say "very hot days"*

Hi guys/gals,

Could use some help on this one. I have 99 GS300 that sometimes (and I mean rarely) stalls or struggles to stay at idle on very hot summer days in Denver (90+ degrees). It's happened both after parking in the hot sun and driving in the city for some time.

Here are some background on the car:
1. It has 200k, engine has 140k (long story short, car was purchased when pissed off wife poured cement into engine). Anyway, engine run great, still very smooth at speed an idle (except when it doesn't want to idle)
2. Car has P0440 evaporations code that's been on for 5+ years....there's a leak somewhere but nowhere obvious. I'm not sure if it's related to issue but thought you should all know. I've checked and replace the hoses int he engine to rule anything out that is easy but that's another story.
3. 2-3 years ago, I forgot...I replace the throttle body, driving home and car would accelerate but go home on limp mode. Found a cheap on on eBay, replaced it, still had some intermittent issues. So I got another used one that was in very good condition from a family friend who's a Lexus master mechanic and he said it got off a very low mileage car from wreck. That's the one that's been on the car.
4. When this started, a bout a year ago...I did some research and did come troubleshooting (lots of good info on this forum) and everything seem to check out. But I went ahead and replaced the OEM TPS as it was cheap.
5. One other thing to share, the electrical plumbing for the TB assembly has a broken tab so it doesn't lock in. It fits nice and snug, no play and I regularly check it and never found it to come loose. Is it possible maybe when it gets hot and loosens? I don't think so as it looks clean and the connections are tight fitting
6. NO CODE....besides the the P0440 that's been on there for years well before I started having this problem.

So I don't know if after years the evap leak is now becoming an issue and suspect I may need to take in to have it checked out/smoke test whatever it is that they do for evap leaks. Before I do that, I wanted to see if anyone has any information or advice on the issue. Again, it happens so rarely that it's hard to pin down.

Thanks
Dave

1of422

Maybe replace the maf, it's about $70 and in my specific case didn't throw a code, but fixed my hesitation problem. Best of luck.

vsop4me

I may have an extra MAF and will try that...hopefully, I can find a hot day and give it a shot...I truly hate intermittent problems.

Lliberty

What is a MAF for lexus gs300? I get the studders way to often now in my gs300.

tiguy99

Mass Airflow Sensor

Lliberty

Thank you!