92-93 Es300 Mass Air Flow Meter Warning

[lbinh]

How to clean the MAF meter in 1993 es300? I sometimes had hessitation during from stop acceleration. I tried searching the forum to no avail.

Search only resulted in MAF sensors for 94 and later models. After the fact, for 92-93 models, I found out they are aluminum meter boxes and not the typical black plastic sensor you can pull out and clean the filaments. I tried to clean my MAF meter using the MAF sensor cleaning guides on this board and elsewhere. Just a warning to those with the same model years. You can unhook the harness but do not unscrew the sensor and pull it out. You will tear out the contacts on the circuit board and lose your electrical conections if you do. No wonder Lexus no longer used the MAF meters and wen to sensors after 1993.

I found out the hard way and forcefully pulled out the connector part (after I removed the screws) which I thought was slightly stuck in the aluminum housing. Turns out it was held in by the soldered connections to the circuit board. What a crappy design. I had to open the silicone sealed black plastic on top of the sensor to try to reconnect the wires and solder the contacts that tore off the circuit board. There isn't anything to clean in there. I thought I did it and resealed everything and installed. Start the car and the CEL came on and the car dies while idling after warming up. :cries:

http://www2.lexpartsonline.com/parts/parts...er&dp=false

So much for trying to make my decent running car run better. Just picked up another used MAF meter from junkyard and hopefully that will bring back my car. $45 vs $350 local dealer.

[lbinh]

The junkyard MAF meter off a 92 Es300 worked. Engine is back to previous state before I messed up. Let's hope it lasts.

[2onthreeputt]

Thanks for this post...I was about to rip into mine this weekend..you just saved my bacon

..I think I'll look elsewhere for my acceleration problem (when cold).

[lbinh]

Thanks for this post...I was about to rip into mine this weekend..you just saved my bacon

..I think I'll look elsewhere for my acceleration problem (when cold).

Cool, glad to hear. I am in your boat also. Hessitation when accelerating from a stop when cold. Please share your fix if you discovered one.

[2onthreeputt]

Here is the thing..I had the problem BEFORE I blew a head gasket a few weeks ago...so I did both head gaskets, had the heads planed, cleaned the crap out of my intake manifold and air box..cleaned my egr valve and every other little orifice and hole attached to the intake manifold (about 6 cans of carb cleaner)...new plugs, new wires, new O2 Sensors..new gaskets all over the place....and it still does it.

I don't think this is the problem, but I'm going to change my fuel filter next as I think it's the original....maybe cold start valve??

[lbinh]

that's quite a bit of maintenance and problem still exist. gees. at least it sounds like you will pass emissions test if you require one. I did not pass mine and probably needing at least what you have already done. High NOX and HCs at low speed.

Have you tried the PCV valve and hose? Have you tried seafoam treatment? Maybe leaks in the intake air hose. Dunno about the cold start valve.

Keep us posted.

[Toysrme]

you should ahve never touched it; it's not a MAF, it requires no maintenance, ever.

now if you want, you can spin the cog about 5-10 clicks tighter to lean the engine out some & you'll pick up some horsepower.

AFA not runing correctly. change the plugs, cap & rotor & fix any vacuum leaks. the AFM has nothing to do with it...

[2onthreeputt]

Well, I changed my fuel filter and re-checked my ignition timing...this morning, the cold stumble seemed a little better, but not totally eliminated. I'm wondering if it might be one of the temp sensors....I'm going to date myself, but this thing runs exactly like a carbureted vehicle with the choke stuck open...kinda feels like it is running lean cold...once it warms up, it runs like a champ.

(Before you rip my head off, I'm fully aware that my car doesn't have a choke...just trying to draw on previous experiences with my outdated mechanical "abilities"..)

One thing I did notice..the theromstatic vaccum valve that connects to my vapor canister busted off at the nipple (the end that goes to the canister)...maybe that is it..but there is no real vaccum draw when cold..I checked it.

[lbinh]

you should ahve never touched it; it's not a MAF, it requires no maintenance, ever.

now if you want, you can spin the cog about 5-10 clicks tighter to lean the engine out some & you'll pick up some horsepower.

AFA not runing correctly. change the plugs, cap & rotor & fix any vacuum leaks. the AFM has nothing to do with it...

What and where is the "cog" that you can tighten to lean the engine?

[lbinh]

Well, I changed my fuel filter and re-checked my ignition timing...this morning, the cold stumble seemed a little better, but not totally eliminated. I'm wondering if it might be one of the temp sensors....I'm going to date myself, but this thing runs exactly like a carbureted vehicle with the choke stuck open...kinda feels like it is running lean cold...once it warms up, it runs like a champ.

(Before you rip my head off, I'm fully aware that my car doesn't have a choke...just trying to draw on previous experiences with my outdated mechanical "abilities"..)

One thing I did notice..the theromstatic vaccum valve that connects to my vapor canister busted off at the nipple (the end that goes to the canister)...maybe that is it..but there is no real vaccum draw when cold..I checked it.

I was about to change the fule filter like you but I thought would change the Distributor cap and rotor first. After removal, it did not look that bad as far as wear and carbon buildup. During the removal I decided to inspect the air intake hose I removed to get to the distributor. I used a flashlight and shined inside the intake hose and I discovered a 4 inch crack in one of the grooves as light peaked thru looking from the outside of the hose in a dark area. It was the first groove closest to the intake manifold connection. Apparently that was the stress point when handling the intake hose. I added clear silcone sealant/adhesive to the crack on the outside and on the inside of the intake hose crack. That was done last night and I drove to work this morning with so much more power and responsiveness at low speeds. It was like night and day before compared to before this repair.

So, now, I do not have the cold acceleration problems like before this whole MAF meter attempt to clean mess of mine. I think the main problem was a cracked intake hose leaking air into the intake. I did replace the cap and rotor but I think the biggest problem was the cracked intake hose. I might pass emmisions this year if this was an ongoing problem for me. I failed last year's emissions test due to High NOX and High HCs at low speed (15 MPH cruise). I passed the high speed portion and the car ran fine, no CELs. Crack must of been smaller last year not to cause hessitation like this year.

Leak might have contributed to dirty intake and carbon buildup plus messing up the fuel/air ratio mix causing High NOX, High HCs and hessitation. I think it definitely caused the hessitation during cold acceleration.

Will change the spark plugs with Denso plugs and Seafoam intake/gas tank/crankcase treatment and I think I will pass emissions this year.