Ok, so I dabble in the automotive mechanics realm on this world, and I do know a little bit of what I am doing, I am ASE certified in brakes, but that is about where it stops (no pun intended). So I decided to help a friend out. He's got a 2001 Lexus IS300 w/ approximately 88K on the ticker. About 6 weeks ago, we changed the sparkplugs as per the DIY on IS300.net. Everything seemed great, we also changed the drivebelt, and the air filter, AC filter, and cleaned the MAF sensor. About 10 days ago, he called me complaining that the car was not running right. Indeed it is not. The car has as rough idle at times (below 500), and it feels like it is going to die. Upon takeoff, the car sputters. It feels as if it is out of gas, but after the sputter, it seems fine. On the highway it seems OK, unless you are below 2000 rpm, then you can feel it slightly doing the same thing. It is very noticeable at lower speeds, at idle, and on the initial takeoff. There is NO CEL. Car feels a little sluggish, but maybe that is because I am comparing it to mine which has a few goodies on it. Any ideas???

 

Hey Jeff!

Quick question, did you happen to gap the plugs to spec? My friend is having a similar same problem right now but w/blue smoke coming out of the tailpipe and running very rough (almost like a Subaru boxter engine).

O/T Is it normal for the IS' rear brakes to go out before the fronts? I'm close to 60k and im at 25% on the rear pads.

 

Plugs were pregapped, and rechecked by me. We got the plugs at the dealer. They are about .43-.44... I'm not smoking though. That sounds bad. If my buddy can get a loaner, its gonna go in. I just wish it didn't come down to that. I hoped I was going to be able to solve the problem.

For your question on the rear brakes, NO.. Typically, you should replace your front brakes twice before you do rears. Is your car a manual or auto? Manual fronts should get you about 50-60K, if you are under normal conditions. If I recall, you are not normal... I did my rear brakes about 3 months ago, which was about 45K. All my driving is traffic driving, stop and go. I figured this is about right. My fronts had 30K on 'em before I switched to the BBK, and they would have had to have been replaced if I kept them on there. So, to answer your question, due to the type of driving, I don't find it weird that your rears went first.

ANY OTHER IDEAS? I WANNA FIX IT FOR HIM AND NOT TAKE IT TO THE DEALER.

 

Do the symptoms include the idle dropping once you start accelerating? Did you guys clean the throttle body? It needs to be decarbed (or at least cleaned) every so often. The carbon build-up is usually the culprit in 2JZ vehicles. It's probably just a coincidence that it occured after you serviced his car.

Hopefully that helps out a little bit

 

I did take a little cleaner and and cleaned the throttle body out, and the intake manifold as much as I could...

Anything else? He says he can't get into his dealer and get a loaner for another week or so.

 

I was about to include Idle Air Control valve, but there isn't one on the IS... the only other thing it may be (not very likely at all) is a "lazy o2 sensor" where 1 o2 sensor goes out but doesn't recognized it went out. It will flux the a/f ratio at idle but the normal driving will be almost unchanged... it's a SUPER RARE occurence, but that's the only other thing I can think of... I've only seen that once in a 12-month period (Gen 1 LS 400, I believe)

 

I got some of the same problem on the IS and LS430 with no CEL, car runs sluggish and slow respone. Turn out to be a bad Air flow meter.

 

ur problem is right there. you destoryed the maff

the only real way to clean the maf is using air

 

how or why are you cleaning the MAF

 

thats what i was thinking...

 

Wrong! That was not the problem.


It is just a precautionary measure. After 85K miles, there is some stuff that can get in there and clog it up. I cleaned a lot of dirt out of the sensor plug using electric parts cleaner, and I used a little Brake Kleen to clean the MAF itself out. A lot of dirt came out of both parts. I hope you didn't think I used water to clean it out?









As for the problem: There was moisture in the spark plug casings on cylinders 3,4, & 5. When I was changing the plugs that part of the engine was so dirty, I decided to spray a little cleaner around and try to clean it up a little. I guess I was not so thorough in wiping it up. Problem is now solved, and the car runs just like she did when she was younger.

 

give it a month

 

OK, I will...

 

well glad to hear its fixed