Z300 HELP - IDLE non stop Up and Down

[jaime300]

My name is Jaime, I live in Portugal and I just bought a 106 hours 04’ Z300AETO (6D0 X 1000862 P) and now… I need all the help I can get!



Thanks to the amazing online Yamaha community I’ve learn that this engine have some issues and decided to prevent before correcting.
I read has much as I could from all forums and started by…

1. Fuel filters - Changed the Racor 10M, the In-Line, the VST and the In-Line Medium PR with new hose clamp.
2. Spark Plugs - Replaced (all had a black laqeur accumulated on the center electrode and porcelian)
3. Oil Pump 6d004 - Mounted. Big time thanks to AndyJr (Yamaha Europe didn’t know about a Tech Bulletin, and they just gave me a pump AFTER I show them a copy that Andy kindly gave me when I was trying to buy a pump from his shop! No comments…)
4. Thermostats - Checked and OK
5. Water Pump Impeler - Replaced
6. Oil cleaner element - Replaced (68F-13440)
7. All Cylinder head anodes were in good conditions
8. TPS and oil rod set according the TSB02007-011 (0.51 without touching and after set to 0.62)
9. Spark Plug connectors cap resistance within spec (4K-6K ohms)
9. PR SENSOR reads consistent values with the local airport (20’ above MSL)

I did not clean/inspect water PCV pressure control valve grommets
I didn’t changed any of the injectors or mystery filters yet, because I’m trying to get them here instead of overseas.
Also didn’t change the fuel lift mechanical pumps because they look good and YDS reads Fuel PR around 6,60 MPa and HP around 970 PSI.

But my problem so far is IDLE.

The engine started well, but idled at 1200 RPM (recheck and TPS was/is at 0.62) and after a while started to vary RPM from 700 to 1500, up and down non stop.
When in gear all 6 cylinders fire, runs better but the up and down issue is still there.

Questions:
Why 1200 RPM with TPS at 0.62?
Can it be injector related at this low fuel flow?
Varying RPM… I could see fuel PR and timing changing slightly up and down, but I cant understand if it was the ECU trying to fix it or if it was causing it.


Thank you all in advance and please forgive my English,
Jaime.

[almetelo]

Se bem me recordo creio que já houve um post devido a um problema idêntico num Z300.

Já tentou fazer uma pesquisa nos tópicos anteriores por algo semelhante?

Há por cá quem consiga ajudar.

Boa sorte

[jaime300]

Cato almetelo,

Já procurei neste e noutros forums e até agora nada! Obrigado.


Update: forgot to mention that I've check cylinder PR, all 6 around 9.5 PSI.

[TownsendsFJR1300]

mucho gracias$

[jaime300]

UPDATE #2 Mystery filters replaced. (they looked clean)

No news... IDLE still up and down

if I set TPS to 0.62 without touching and then to 0.67 with the stopper,
I get a steady idle at 860RPM (1050 in gear)...

Is that acceptable? like this does the engine run leaner or richer?

[rodbolt17]

850 in gear is still to high.
are you doing this in the water or on a flusher?

any faults will cause a high idle.

the coolent temp sensor can cause a high idle.
that's where the laptop is nice, it may or may not show a code but it will tell you what the ECU is reacting to.
inrange failures wont throw codes but the ECU will react.

[jaime300]

Hi rodbolt,

I’m using a flusher.

Today I ruled out the possibility of air in fuel line below the fuel mechanical pumps.
Now I’m thinking that one bad reed valve could provoke this up and down behavior, but with 100 hours seems highly unlikely…

About the temp sensor,
I looked carefully to all the saved data from YDS and I saw some temp variations but I thought those to be normal and that the ECU would only react to a temp threshold signal. (above or below than)
I’ll try one temp sensor from my old OX66 and see what changes.


The laptop is nice and tells me a lot of things, but unfortunately I cant see it with your eyes :-)
I can see that a lot of parameters changing at the same time during that up and down loop, so far couldn’t find out which is causing what…

Could you take a look for anything abnormal to the file attached on the 1 post?


Thanks a lot,
Jaime.

[rodbolt17]

I think your chasing a ghost.
in N on the flusher two cylinders are shut down, couple 4cyl operation with no ex back pressure and that motors hunts and sounds rather ragged on the flusher.
set the TPS at .62.
then check ign timing.
once warmed up,above about 113*F, it should be about 3-7* ATDC.
if its anything BTDC start checking sensors.
if its fixed at 7*BTDC you definantly have a fault.

remember ATDC and BTDC are not my typos.

its why submerging the gearcase is always a good idea on HPDI.