I just got my 93 SC400 back from the mechanic after a replacement of my starter, plugs, plug wires and injector cleaning. As I left it was running a little rough and idling high when at a stop or slowed down.

I just thought the computers were having a hard time trying to figure things out now that everything was clean. I get home and pop the hood to hear a fairly loud sucking sound from what seemed to be the Air Intake Chamber. I took it back to the mechanic and we think we have found to general area, however we both gave up and said we'd look at it on Monday.

Here is what I think but really don't know. It looks as though in the fuel delivery pipe there are fuel injectors that seat into the Air Intake Chamber and just kinda float between the delivery pipe and the intake with seals. I've pulled the electrical from the injector..if this is what they are called and have found an insulator old and half gone.

This is right were the sound is coming from, however I can't be sure because the car will not run unless the electrical is plugged in.

Can this insulator missing create the sucking vacuum sound and rough idle?

Thanks for your help...

 

I found it. It was the front driver side fuel injector insulator. I purchased 8 of them from my local Lexus dealer. Check around because one guy sold them to me (Lexus Dealer Parts Department) for $3.93 each. Ft Wayne Lexus, Indiana... and Tom Wood Lexus in Indianapolis, Indiana wanted close to $7.00 each. I've only replaced 4 of them...only because too much to take off on the other side.

No more vacuum sucking noise and boy does the car run great!!!

Also Bell Lexus in Arizona, sell great discount internet parts..they seem to be really good people.

 

Glad you found it. Isn't funny when you find yourself replying to your own thread and solving your own issue? Happens to me. :-)