roadielee

Alright, here goes:

I've been researching my Lexus' problem on here for a few weeks now, and can't seem to find a suitable answer that fits my exact problem.

First it started off with a power steering pump/white smoke issue, which, thanks to this wonderful Lexus bible of sorts, is now fixed. Sure wish I'd seen the post where I'm told that $110 air intake control valve could have been gotten at a junk yard for about $1.50, but hey, it stopped smoking.

So my car is a 1991, and it has a few over 300,000 miles. I bought it last January, and did all the normal stuff you do when you buy a used car, air filter and oil change, new plugs, new headlights, the whole 9. Ended up getting a new battery and new tires too. This car was well maintained before I got it, and I'm in love her.

I had the starter replaced a couple months ago, and when I got the car back, there were some unplugged hoses and it ran weird. Got those taken care of, but ever since then, the car idles kinda low, and tends to run really ragged and die when I come to a stop. Sometimes it starts, and dies immediately. It eventually does start though. I had the idle turned up, so it doesn't stall as much, but I'm sure my gas mileage is taking a hit, and I'm riding my brakes a bit.....It was idling at about 400-500 rmps (warm) and shoots down to about 200 and then up again, repeating until it just goes down so much it dies. It's trying to stay alive, but can't. Sometimes when I'm driving around and take my foot off the gas, the rpm's go down, and it seems like it wants to die. I was having to keep my foot on the gas with the brake on at stop signs until I had the idle turned up.

I hooked it up to a diagnostics computer, and came up with a 24, 31, and 71. Did some research, and the 24 is an air intake temperature sensor (what is that?) and the 31 is a VAF sensor (again, what?) and a 71, which has to do with the EGR messing up.

So, I've cleaned my MAF sensor, with the cleaner, (although it's still a debate on here as to what works and what doesn't) and it has the same problems. The air filter is clean, the plugs are fine, and I've cleaned some other parts as well.....checked for vacuum leaks, can't seem to find one, although there is some hissing....

I'm in California, and I have smog coming up real quick. I hate dumping tons of money into it, these prices for theses sensors ain't no joke. But because I've been so impressed with the information found on here, I want some of your guys' advice. Any hints? Ideas?

deanshark

Code 24 is for IAT and 31 is for AFM. The IAT (Intake Air Temerature) sensor is inside your AFM (Air Flow Meter). So you would need to change the whole AFM. You say you cleaned your MAF, that would actually be the AFM. They're supposed to be cleaned with a special cleaner so if you just sprayed any type of cleaner in it you probably hurt it more then helped. I did that and screwed it up. You can get a used one from the junkyard, if you can find one. Just take an ohm meter and make sure it's in spec before ya buy it. It's very possible that's your idle issue, also sounds like your IAC (Idle Air Control) valve not opening enough. It's been covered here and how to check and clean it. If you do a search for all these sensors you should come up with a lot of info on them. I'm not too experienced with the EGR so someone else will have to chime in on that. Hope that answers some of your questions and welcome to CL.

roadielee

Thanks!!! I will definitely go and try to find a MAF sensor, I actually found that information last night, and realized that the Code for the IAT is in my MAF. I did clean it with the special cleaner, although I guess that's not good either.

I just replaced my IAC, along with my power steering pump. I bought it brand new from the dealership. Do you think it could already be clogged/dirty, or do I have a different problem?!?! I'll go back through the power steering pump bible, there was a TON of good info in there...

Oh, and any idea to find the specs for the MAF sensor? is it in a thread on here? I'll google it and see if I can find it. Thanks for the welcome, you guys/gals on here are awesome possum!!! =)

deanshark

The IAC I'm talking about isn't the one on the PS pump, it's on the front of the engine. Here's a link that shows the specs on the AFM and the IAC valve. Even though it says ISC valve it's the same.
https://www.clublexus.com/forums/sc-...on-issues.html

roadielee

Well that answers my question now doesn't it? I figured that the IAC couldn't be it, since I had just replaced the one by the psp. Are they really both called the same thing? Thanks a million trillion for the link. I hadn't run into that one yet, and it seems to be exactly what I need to narrow the problem down. Those 3 items are ones I need to check.

deanshark

Actually you're thinking of the ACV (Air Control Valve), which is on the PS pump, some people and dealers call it the IAC . I came across that thread last month, someone posted it in another thread so I saved it. I wish I saw it last year.