rpm drops during acceleration
Thread Starter
Driver School Candidate
Joined: Aug 2013
Posts: 23
Likes: 1
From: ca
rpm drops during acceleration
i have a 97 ls400 with 192k miles. all maintenance has been done.basically stock with coilover and muffler and resonator delete. when i accelerate up to 80mph around 3k rpms it drops 500rpms and then catches back up. what should i check? injector cleaner? ect? i noticed my pcv grommet is ripped and ill replace that.
Pole Position
Joined: Jul 2014
Posts: 217
Likes: 1
From: Can
I notice this on my 96 at around 3k, but only when force in 3rd gear. Let say I give it a bit more gas to pass someone it will drop RPM for half a second and then go just fine.
Since a few days it's much colder outside in the morning and when I first start the car there's now a strong smell of fuel. Wondering now if there's something wrong with the car and if those 2 issue could be related...
Since a few days it's much colder outside in the morning and when I first start the car there's now a strong smell of fuel. Wondering now if there's something wrong with the car and if those 2 issue could be related...
Check for any error codes first. That is a broad area to diagnose from fuel to ignition. If the ECU has not been checked, this is Yamae's test to determine if the caps in the ECU are in need.
https://www.clublexus.com/forums/ls4...-by-yamae.html
https://www.clublexus.com/forums/ls4...-by-yamae.html
Thread Starter
Driver School Candidate
Joined: Aug 2013
Posts: 23
Likes: 1
From: ca
I notice this on my 96 at around 3k, but only when force in 3rd gear. Let say I give it a bit more gas to pass someone it will drop RPM for half a second and then go just fine.
Since a few days it's much colder outside in the morning and when I first start the car there's now a strong smell of fuel. Wondering now if there's something wrong with the car and if those 2 issue could be related...
Since a few days it's much colder outside in the morning and when I first start the car there's now a strong smell of fuel. Wondering now if there's something wrong with the car and if those 2 issue could be related...
Thread Starter
Driver School Candidate
Joined: Aug 2013
Posts: 23
Likes: 1
From: ca
i observed that in first and second gear in lower speeds its smooth all the way to redline. but on the freeway when i try to pass someone as i step on the gas, it drops 500rpms at around when i hit 3k
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Pole Position
Joined: Jul 2014
Posts: 217
Likes: 1
From: Can
Sorry for the thread jacking, back to the RPM drop at 3k. Wondering if it's a "feature" or a real problem.
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From: Japan
Sounds like a pressure issue to me. Did you check the fuel pressure?
If it's OK, I will check the the negative pressure of the intake manifold and the positive pressure of the exhaust manifold. If the problem is started when you deleted the muffler and the resonator, it may be because of the back pressure issue. The cam overlap effects the exhaust line pressure to the intake line pressure.
If it's OK, I will check the the negative pressure of the intake manifold and the positive pressure of the exhaust manifold. If the problem is started when you deleted the muffler and the resonator, it may be because of the back pressure issue. The cam overlap effects the exhaust line pressure to the intake line pressure.
Pole Position
Joined: Jul 2014
Posts: 217
Likes: 1
From: Can
Humm nope didn't check the fuel pressure... Is there a release valve on the 1uz where I can plug the fuel pressure tester or I need to install a T adaptor?
Also just like OP I have done the muffler delete (not the resonator) but can't tell if the issue start after I've done the delete
Also just like OP I have done the muffler delete (not the resonator) but can't tell if the issue start after I've done the delete
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