It runs louder yhan should when excellerating only

5

Asked by Aug 21, 2012 at 11:48 PM about the 1998 Lexus LS 400 Base

Question type: Maintenance & Repair

Exhaust has been ruled out by dealer and another good shop.Low or high speed the noise is there. Dealer and another good shop dont know what it is but agree its not right. All major and minor maint has been done. Most exhaust parts are new. Im stumped. Dealer says there is no EGR valve for the 98. ? I have had many of this model 98-00 and never had this problem b4. Thier answer is wait for it to get louder to pinpoint the noise/problem. No engine lights go on. At times I hear a slight whistling noise when letting off the gas when leaving the house. Frustrated.

8 Answers

18,785

What does it sound like? Is the noise varying with the engine rpm or road speed?

5

Well it sounds like there is a exhaust leak and the rpm gage seems normal. It actually sounds slightly louder at a low speed. The noise is a huge mystery. There is no ticking.

18,785

So it will change pitch as your rpms go up or no

5

I would say its a lighter sound when x-pressway driving. But maybe the engine drowns it out a bit. If the car is still it is very quiet. The car has almost 130k on it. New timing belt, wtr pump. pcv valve. Everything flushed/gaskets. New valve cover gasket. At one point dealer said maybe a valve but there is no ticking. They do not want to take apart the pwr train to find it. Car shifts normal.

555

Hi Is the noise sound like a Wiesel or hissing .If it is it can b the brake booster or the hose or some vacuum hose . or the egr valve if ti has hard steal tub a small creak in it . PS I do not know if I;m right or not but its worth a look good luck.

Best Answer
5

Thanks dedell. I gotta feeling you are right with the egr. Its possible the shop dosen't want to do it because its supposed to be very hard to get to. Thanks to all who responed very much.

18,785

check the intake plenum for any loose parts or even cracked parts. the intake actualy does make noise during acceleration but with the stock plenum it muffles it to nothing. Maybe with an opening you could be hearing this noise. A vacuum leak should be more noticeable at idle or deceleration. During acceleration engine vacuum is redueced to little to none therefore wont leak out and hiss becasue it's not there already. EGR is a possibility, could make noise.

1 of 1 people found this helpful.
5

Andrew, Im taking the info you and dedell gave me to the shop tommorrow morning. Its a dam shame the Lexus dealer here in rochester, NY can't find the problem and its been a year. But it seems they dont really care and Im a pain in the rear even though I have dumped thousands in that place. THANK YOU!

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