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I really need some help from the forum members on this one. I have a 2003 IS300 with a 5 speed manual. Car is completely stock. It just turned over 57,000 miles. I have noticed two issues, that if can’t be fixed will mean selling the car. Here are the two problems:

1. Occasionally, while cruising down the highway the engine will lose power for a split second before returning. After that it’s fine. It usually happens while the cruise control is on, but sometime occurs under normal driving. I have not gotten ANY ‘engine check lights’, or other dashboard warnings:suspiciou . As stated above the car is totally stock. I cleaned the MAF sensor and the engine intake, but it didn’t help the problem. Any help would be grateful!

2. The other problem, is that the engine bogs down/hesitates when warm (not hot, not cold) when starting from a stop. After running on the highway for 10 miles when starting from a stop it’s perfectly fine. It’s almost like the drive train isn’t warmed up or something. Any help here would be great! Thanks!


Tim
 

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Dr. JDM
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try new spark plugs
 

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In 3000 miles you're due for your 60k maintenance which calls for spark plugs, among other things. See what the car's doing after you get that maintenance done.
 

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Do your 60k mile service at a Toyota dealership instead, if you are not making ends meet. It costs lower than $600 (Around $560-$585 range, without hookup) to do the 60k mile service versus Lexus, around $1100, i believe, for 60k mile service.
 

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maybe an injector is clogged? try injector cleaner as a cheap fix. if that doesnt work i think it could lead to spark plugs

THanks,

Jazzy
 

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It wouldn't have been the spark plugs. They are good for 120K miles and the OP has less than half of that.
 

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I just put my car in the shop for this problem. My plugs were just changed a few thousand miles ago. Could it be the fuel pump over heating?
 

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Could be fuel delivery issue, or spark plugs. Like suggested.
O2 sensor maybe on the fritz?
Make sure all the harnesses are tight and the coils are bolted down.

Try a leak down test. If you don't have access maybe try a compression tester.

Another idea...But probably not your problem...
Could be the coolant temp sensor. I am not sure how many are on our cars, but you need to test the one that goes to the ecu.
These are pretty important to controlling the fuel as well, especially during warm up.

There is probably a free and easy diagnostic test you can run on it with a multimeter in the Factory Manual to see if its functioning correctly.
 

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Could be fuel delivery issue, or spark plugs. Like suggested.
O2 sensor maybe on the fritz?
Make sure all the harnesses are tight and the coils are bolted down.

Try a leak down test. If you don't have access maybe try a compression tester.

Another idea...But probably not your problem...
Could be the coolant temp sensor. I am not sure how many are on our cars, but you need to test the one that goes to the ecu.
These are pretty important to controlling the fuel as well, especially during warm up.

There is probably a free and easy diagnostic test you can run on it with a multimeter in the Factory Manual to see if its functioning correctly.
If it were the o2 sensor he wouldn't have sudden powerloss. If it were the maf sensor he couldn't get passt 3000 rpm.

My guess is clogged valve/s. Try an injector cleaner as a cheap fix.
 
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