After Cleaning The Throttle Body And Maf

[littlemouse]

After I clean the throttle body and MAF on my 92 LS400, the RPM start a little higher then 1000 and idle roughly. After 30 second, RPM start decrease (I can feel the car is shaking) then engine die. start it again and it die within 10 secounds. I wait for two hours and try again same thing happen (RPM start a little higher then 1000 and idle roughly. After 30 second, RPM start decrease then engine die.)

I unplug the MAF sensor nothing change.

I use CRC mass air flow sensor cleaner and CRC Throttle body & air-intake cleaner

Any one know why?

[Haylands]

After I clean the throttle body and MAF on my 92 LS400, the RPM start a little higher then 1000 and idle roughly. After 30 second, RPM start decrease (I can feel the car is shaking) then engine die. start it again and it die within 10 secounds. I wait for two hours and try again same thing happen (RPM start a little higher then 1000 and idle roughly. After 30 second, RPM start decrease then engine die.)

I unplug the MAF sensor nothing change.

I use CRC mass air flow sensor cleaner and CRC Throttle body & air-intake cleaner

Any one know why?

Could be any number of reasons from the maf to injectors to ecu to coils etc, you will have to get the car checked by someone with test equiptment, expensive if you go to the dealers, don't know where "ca" is under your location so can't advise who to see...

Good luck

Pete

[Mark W]

Assuming you didnt have the problem before cleaning?

In which case - check for debris in throttle body and make sure the butterfly valve isnt stuck.....I cleaned mine not so long ago and a tiny (and I mean tiny) thread of material from the cloth I used had got trapped between the valve and the body - Car ran like a complete pig - revving high and sounding like a bag of nails....

Removed the thread of material.....car back to normal ;o))

[runsgrateasanut]

Reviving an old topic. Having removed my MAF I was expecting to be able to clean it but it doesn't look quite how I expected. No thin wire.

Just cribbed this part of a thread on the US forum which suggests it can't be cleaned. In which case back it goes.

Quote " I went to my Lexus dealer today to asked them to clean my MAF. I was
told that MY CAR doesn't HAVE an MAF. It has - instead - a Karman Vortex
Airflow Meter. [i think that's what they said] NEVER EVER have I heard
ANYONE here at LOC mention that the 1st generation LS doesn't have an
MAF. Why didn't any of you say something?! Or am I confused? Apparently
the Karman Vortex thing can NOT be cleaned" Unquote.

Interesting. - any views on this?

[Rupert Dubreaux]

It is apparently unwise to clean the MAF or KVAM on a first gen LS with solvent cleaners they are easily ruined ,I have used a gentle waft of compressed air with no ill effects . The later models have a different MAF that can be cleaned as normal , it is also unwise to fit K an N type air filters to first gens as the oil from them can also cause problems .

As Mark says if you didnt have the symptoms before the cleaning it is most likely to be either some debris in the throttle body or a messed up MAF/KVAM .

Lets hope it is something simple to fix .

[ROYT]

Also check everything is fitted back securely, no air leaks etc.

check all wiring nearby in case something is disconnected.

[runsgrateasanut]

As I had to take off the Air box to get to the Spark plug cover to replcce missing Bolts, and a rubber strip my wife spotted under the Car - (my fault and not the mechanics) I thought I'd examine the MAF.

I have no issue with the running other than perhaps a higher than normal idle, perhaps a bit rich, and a smell of petrol when starting the Car. Possibly replacing the Caps as you experienced Rupert may solve these matters.

I didn't touch the MAF part but did clean the flat surface on the main runway and also the slight "Well" into which it almost sits. No significant dirt but to ensure the vortex flow is as good as possible. Took for 22 mile run this evening and seems OK..

[katana92_uk]

disconnect negative Battery terminal for 30 min and see if ECU reset helps.