The Problem With Engine @ Gs300/2003

[neza]

Good afternoon, dear L-owners,

I owe Lexus GS300 2003 car, with 2JZ-GE engine

Has noticed the following trouble:

When i'm driving in medium rate with a a traffic, i feel that my car is twitching in a range between of 1200 to 1700 RPM. The problem is definitely related to the engine. Above 1700 RPM, such symptoms is not observed.

When RPMs are go down, from above than 2000 to above-mentioned diapason, and then i push gas pedal to accelerate i hear some claps from exhaust.

At the same time, CHECK ENGINE doesn't indicate any problem.

Computer scan has shown that A/F ratio in short time period is correct (3-7%)

But in a long period, A/F ratio is 25%.

What i have did recently:

1) the New air filter

2) New maf-sensor

3) New sparks

4) New sparks wires

5) New sparks caps

6) the New fuel filter

7) Cleaned a grid on a gasoline pump

How can i solve this problem?

[intakerGS]

Can I interpret the 'claps' as some sort of backfiring?

Common suspect for backfiring when accelerating, is usually a timing problem. A leak in your intake manifold could also be cause.

[neza]

Can I interpret the 'claps' as some sort of backfiring?

Common suspect for backfiring when accelerating, is usually a timing problem. A leak in your intake manifold could also be cause.

U r right, "clap" meaens backfiring.

What means timing problem? What can be a reason of it?

PS: Will try to find leak in intake...

[TRDGS300]

timing= the gears that the timing belt sits on are not timed correctly anymore. If that is the case, get the timing belt changed. What causes the motor to go off timing? The timing belt could have skipped teeth or vice versa. One of the gears could have done the same. Either way, have a tech check it out for you.