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Discussion Starter · #1 ·
I could barely keep up with a Prius and I got smoked by a Honda civic. I know this is sad ,but it is true. I don't know why my performance is going down the drain,but i need your guys help. Honestly, its like my car is running on 140 hp instead of 215 hp...

Whenever, I press on the acceleration the engine makes a loud moaning and it gets louder as my car slowly climbs up the RPM. Its not a pleasant sound. It sounds like the engine is dieing and trying its hardest to keep on going.

Another thing is that, the car has very slow acceleration from 30 miles and above. For example, lets say i am going 30 miles per hour and i want to reach 50 miles per hour it takes for ever. It doesn't make a difference if i floor the car. Its the same thing as pushing the pedal half way. When i floor it it doesn't even go above 3500 rpm... Its like it stuck there.

Now, i went to a mechanic and he said that this golden part next the engine is missed up or something. The part is circled with red.



What is that part? is that the reason why the car is slower and makes that loud moaning sound?
 

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Do you have a check engine light on?

Clean the MAF?
 

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That "gold" part is your exhaust manifold. I don't see why that would be the problem. I would reset your ECU and clean the MAF sensor on the intake. Also, do you have a check engine light?
 

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why is your master brake cylinder and abs in those locations?
Must be a right hand drive vehicle, note the steering column joint below the exhaust manifold. Wonder where the OP is located? England, Japan, Australia???
 

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yeah sounds like a possible air fuel issue? I don't see how the headers (exhaust manifold) would create a moaning sound. Also if your car won't rev past 3500 it sounds like its in "safety mode" or whatever they call it. Does the check engine light even work? when you turn your car into the on mode without starting the engine does it come on?
 

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It's likely your catalytic converters are plugged. It wouldn't be the first time for the IS, or Lexus's in general. And what you describe is typical of the problem. Basically,the engine is unable to breath and restricted from making power at higher rpms.

There are 3 cats though. I can be the 2 that are integrated into the headers (what you've circled), or the midpipe that contains 3rd cat. IIRC, the culprit is typically the 3rd cat in the midpipe. You can replace it with a stock replacement, knock out the cat substrate in the pipe, or just replace it with a race pipe that available rather cheaply on ebay.
 

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It's likely your catalytic converters are plugged. It wouldn't be the first time for the IS, or Lexus's in general. And what you describe is typical of the problem. Basically,the engine is unable to breath and restricted from making power at higher rpms.

There are 3 cats though. I can be the 2 that are integrated into the headers (what you've circled), or the midpipe that contains 3rd cat. IIRC, the culprit is typically the 3rd cat in the midpipe. You can replace it with a stock replacement, knock out the cat substrate in the pipe, or just replace it with a race pipe that available rather cheaply on ebay.
THIS but its not a diagnosis I want to give over the internet.
 

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Discussion Starter · #11 ·
It's likely your catalytic converters are plugged. It wouldn't be the first time for the IS, or Lexus's in general. And what you describe is typical of the problem. Basically,the engine is unable to breath and restricted from making power at higher rpms.

There are 3 cats though. I can be the 2 that are integrated into the headers (what you've circled), or the midpipe that contains 3rd cat. IIRC, the culprit is typically the 3rd cat in the midpipe. You can replace it with a stock replacement, knock out the cat substrate in the pipe, or just replace it with a race pipe that available rather cheaply on ebay.
I think you hit the spot right on. I am now convinced that it is from the catalytic converters. Thank Bro.
 

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who the hell was the mechanic who told you that "the gold thingy was messing your car up?" jesus. go to a lexus dealership to at least get a good diagnosis. you might not want them to do the repair because of the outrageous prices but at least find out what's wrong.
 

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like sebastian said , or just take it to a mechanic that specializes in working on toyota/lexus , whatever mechanic you took your IS too , never ever take it to him again.......lol
 

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doubt this is it but if you are going to clean your maf etc you should check the tension of your throttle cable. I snugged mine up and it was like driving another slightly peppy-er car.
 

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maintance is key.......oil changes ....change out sprak plugs...clean maf ....change or clean air filter...

And if your running the car with out the cover on the air box ...as i stated before thats a problem in its self....Also a must to clean MAF then also..
 

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due to the problems your describing i would check a few things such as clogged cats, stretched timing belt(common on toyotas if not replaced like it should be) or maf sensor. i had the same problem with one of my old celicas and a friend had the same problem on his es300. both ended up being the timing belt stretched enough for it to jump time so thats a big problem if it continues.
 

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I would say that your cats are definitely clogged. I had the same problem, poor acceleration, loud engine intake noise. I hooked an exhaust back pressure gauge (in the O2 sensor bung) and I pegged the gauge revving in neutral at over 15psi of back pressure. For reference, it should have been <4 or 5 psi revving in neutral at over 4000rpm. I removed the Y-pipe and the underfloor cat came out in pieces. Replaced with aftermarket header and everything was okay. Good luck!
 
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