98' Ls 400 Engine Noise

[Xkalaba]

Hey All,

I have an interesting problem, for about a week now my car has been running hard. It initially sounded like road noise coming from the tires. However, the noise (engine) is so loud that it sounds like I am riding in a jet airplane. I thought it was the spark plugs so this past weakened I changed them out. When changing the sparkplugs I notice that the plastic intake tube has a bad crake in it. The car idles perfectly and it is not throwing any codes. After the change of spark plugs there is no difference, still the same load noise coming from the engine. It feels like the car is losing power after 40mph, it shifts perfectly and at high speeds the rpm never goes over “3”. What can be the issue, is it the crack in the intake tube, vacuum hose, MAF???

Again it is not throwing any codes and I’m not getting good fuel mileage. This noise is so loud it’s driving me crazy. My LS was so quiet and smooth, and now this – what am I overlooking???

LS 400 1998 (125,000miles)…

[legendswraith]

Hey All,

I have an interesting problem, for about a week now my car has been running hard. It initially sounded like road noise coming from the tires. However, the noise (engine) is so loud that it sounds like I am riding in a jet airplane. I thought it was the spark plugs so this past weakened I changed them out. When changing the sparkplugs I notice that the plastic intake tube has a bad crake in it. The car idles perfectly and it is not throwing any codes. After the change of spark plugs there is no difference, still the same load noise coming from the engine. It feels like the car is losing power after 40mph, it shifts perfectly and at high speeds the rpm never goes over “3”. What can be the issue, is it the crack in the intake tube, vacuum hose, MAF???

Again it is not throwing any codes and I’m not getting good fuel mileage. This noise is so loud it’s driving me crazy. My LS was so quiet and smooth, and now this – what am I overlooking???

LS 400 1998 (125,000miles)…

jet airplane noise! does it go up and down with accelleration as in increase in volume and pitch if it does one of you connections onto the airbox/air filter is gone have you pulled the MAF sensor off and given it a clean if its the same as the GS then its only 4 screws to remove it and an electrical connector

[ColinBarber]

Have you got a picture of the crack? If it's after the MAF then you will get incorrect fuelling as the MAF will not detect all the air entering the engine.

[Xkalaba]

Hey All,

I have an interesting problem, for about a week now my car has been running hard. It initially sounded like road noise coming from the tires. However, the noise (engine) is so loud that it sounds like I am riding in a jet airplane. I thought it was the spark plugs so this past weakened I changed them out. When changing the sparkplugs I notice that the plastic intake tube has a bad crake in it. The car idles perfectly and it is not throwing any codes. After the change of spark plugs there is no difference, still the same load noise coming from the engine. It feels like the car is losing power after 40mph, it shifts perfectly and at high speeds the rpm never goes over “3”. What can be the issue, is it the crack in the intake tube, vacuum hose, MAF???

Again it is not throwing any codes and I’m not getting good fuel mileage. This noise is so loud it’s driving me crazy. My LS was so quiet and smooth, and now this – what am I overlooking???

LS 400 1998 (125,000miles)…

jet airplane noise! does it go up and down with accelleration as in increase in volume and pitch if it does one of you connections onto the airbox/air filter is gone have you pulled the MAF sensor off and given it a clean if its the same as the GS then its only 4 screws to remove it and an electrical connector

Hey Legends - thanks for the reply,

Actually it does get louder with speed (again over 40mph). I’m planning on cleaning the MAF and sealing the crack on the intake tube with some JB Weld.

You know I spoke to a friend of mine yesterday and he made an interesting diagnoses. He said it might be my cats or muffler clogged. Funny, because the feeling I am getting is one of no pressure being released. I know when I took it to the dealer couple months ago he told me I had a slight exhaust leak, but he said it not a big deal. Could my problem be there???

[Chris.S]

Might be the EGR pipe behind the engine that has corroded through

[cleverdick]

At a guess, I would say EGR pipe too. Had a similar problem on my '90 LS recently. To have it fixed is not as bad as they say - mine cost £600 (including new OEM exhaust front section) at an independent Lexus garage. That said, £600 is bad enough, so let's hope your problem is simpler than that.

Take care...

[Xkalaba]

Hey All,

Quick update on my noise issue, this weekend I went to Midas and they checked my exhaust system. Good news, it was not my EGR pipe, but it was a problem with the exhaust pipe. Apparently, the junction were both pipes come together (Y-pipe) which leads to the two mufflers have corroded and needs to be replaced. The bad news is the device on that pipe (resonator) and it needs to be changed? I was quoted $800.00 just the resonator and $85.00 for labor. The mechanic was very impressed with the design and overall look of the Lexus and said “Lexus makes great cars”, he also said my cats and mufflers are in good shape. Is that a good price for the resonator and can I just do with out one? Going to get a second opinion.

[Xkalaba]

At a guess, I would say EGR pipe too. Had a similar problem on my '90 LS recently. To have it fixed is not as bad as they say - mine cost £600 (including new OEM exhaust front section) at an independent Lexus garage. That said, £600 is bad enough, so let's hope your problem is simpler than that.

Take care...

I finally resolve my problem, My situation was not the exhaust system(resonator or EGR pipe). It was my WHEEL BEARINGS, and it cost me :D $220.00( a steal). I when to Good year and they charged my $98.00 for the bearings and $200.00 for the labor - over 2hours of work. I am very good with my hands and good DIY guy, but take it to a machanic. I personally feel that the labor on this type of work should be $500.00, just pressing the bearing out and in is a task. Especially, if your bearings were as bad as mine, the outer race was almost stuck to the actuall hub.

From a personal standpoint, I would pay that fee with a smile if it give me results like I am getting now. WOWWW!!!! I swear it feels like I am riding on a cloud, no road feel and I can't even hear my engine at all. Ohh my goodness, I never knew wheel bearings could cause such a problem. My car runs great!!! Thanks guys for your replies to my post, if anyone is having this problem, I hope my posting helps your diagnose and resolve your issue.

[chips229]

Glad to hear its all sorted out :)

and thanks for the Update.

The LS range is just so quiet when you do hear noises sometimes it sounds different from inside the car.

chips..