little rpm bounce => phantom problem.......

[hondapowaa]

(first : scuse for my faults, i try to write english the best i can. i'm french.)

Hello,

my builded engine is actually under repair and i put a stock engine in my civic ek4, b16a2.
All is stock, i have just an intake, an exedy flywheel/clutch (stg1) and remove the catalytic.

You must know an important thing, with my last engine (other engine and ALL sensors was other sensors), the problem was same.

My problem is with no load at steady and in neutral position, when i rev the engine and try to have a stable rpm, this one bounce.

After some test, when i'm in open loop, my engine is really stable, but when i'am in closed loop mode, it bounce.

As i see, it bounce just a little (50/150rpm) but it's too much to pass the emission gaz test with success.

My lambda seems to work correctly and the correction seems to be also good.
(maybe lambda cycling too quickly?)

Each time my ecu inject more or less fuel, the engine rpm move same.
(with a little time delay of course).

All friends who have same car/same engine told me on theirs, they not have any boucing (maybe 10/15rpm but not visible and not audible)

I notice with a more important exhaust header/de-catalytic (more place for gas) this bouncing sims a little more.

Problem is also the same with my p30/s300 or my obd2b stock ecu...

I really don't know what is wrong and i need help if you can.

The map used is the stock p30jdm.
The log is a long log of 18mn, stationnary tests are made in the three last minutes.


I thank you very much in advance for the help, i wish, you will try to give me.

Best regards,

Alain
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***______________ Click here to download the log
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(when i want upload the file by your site it don't work so i put him on my ftp .)

[Spunkster]

Try changing the overrun fuel cutoff values in the TPS parameters.

[hondapowaa]

Try changing the overrun fuel cutoff values in the TPS parameters.

overrun fuel cutoff (TPS) or (MAP)???

However is read help but i don't understand very well what this will change?

When i want to stay at a desired rpm (like 3000) i must open the butterfly a little and don't move it anymore.

So, this problem is same with my obd2 ecu and we can't modify anything in a obd2 ecu, in a stock car.

I think you see my log, can you tell me if you see something wrong which explain why my rpm boucing with afr???

what can cause this trouble?
injection problem?
ignition?
lambda?

Thanks in advance for your response.

Alain