Misfire and Datalog Info

[stang233]

I have been chasing many service engine alerts with no avail. Sometimes a misfire, sometime an alert with no code. I purchased the Rinda/Diacom to better diagnose.  I have done the following.

• Checked all grounds
• Rewired charging system
• Sent in injectors to Injector Rx for reman
• Checked for vacuum leakes
• New Batteries
• Cap/Rotor 3x
• Plugs
• Wires 2x
• Coil 
• Fuel Socks
• Checked fuel pressure. Holds at 59psi through all ranges.
• Checked all connectors under the helm and in the engine bay.
• verified cam angle.
• Had prop reworked and balanced.

I rarely get the code if we are say tubing or just idling around the lake. I get the code it seems with surf type speeds/loads or when I am jumping up onto a plain. Its so random I cannot remove variables.

I seem to always get the code if we are surfing and I pull back on the throttle fast when a surfer goes down. That code seems to be a ghost code and doesn't show up. Or its a repeat of the misfire, I am not sure.

I am hoping maybe something is glaring in the stills of my data log?

Gary and CSleaver have been very helpful.  I just had this data buried in an ECU/ECM forum and figured I would start a new one with specific data.

3900rpm

1500 rpm

 

Edited October 15, 2023 by stang233

[csleaver]

What does diacom show on the system info tab?

[stang233]

I am jutting getting familiar with the Diacom. Are you referring to what is noted in the bottom left corner as the system type or what system I selected. I selected the Monsoon 2009 up ECM motor.  Is there a better system tab to pull data? Thank you again. I have spent my whole life wrenching on mostly ATV and car motors. This one is challenging me.  Yours guys collective minds are great!

[oldjeep]

1 hour ago, stang233 said:

I am jutting getting familiar with the Diacom. Are you referring to what is noted in the bottom left corner as the system type or what system I selected. I selected the Monsoon 2009 up ECM motor.  Is there a better system tab to pull data? Thank you again. I have spent my whole life wrenching on mostly ATV and car motors. This one is challenging me.  Yours guys collective minds are great!

In your top picture - the far right tab

[stang233]

Hopefully this is it

Edited October 15, 2023 by stang233

[csleaver]

Use the Diacom TEST tab and select the clear the misfire data and select clear fuel adaption and counters before running the boat again.  That will give you a clean state of misfire data so it will be easier to determine if there are still misfires occurring and on which cylinders. 

Make sure there is nothing causing excessive vibration like a damaged prop, bent propshaft, improper engine alignment, damaged crankshaft damper, or even a loose/missing raw water pump bracket.  Driveline vibration can fool the ECM into thinking there is a CAV (crankshaft angular velocity) problem which is used to identify misfires.

[stang233]

Thank you. I will do that and see what we come up with.  I did have the prop into propellor works this winter for an inspection and balance.  I will take a look at the other items.

[csleaver]

I also suspect that your fuel pressure being at 54 PSI could be a root cause of the misfires.  It really needs to be at least 58 PSI or up to a maximum of 62 PSI.  Anytime I see it below 55 PSI it tends to be a problem. 

[stang233]

Quick update. The fuel pressure gauge was brand new, but only an $80 gauge. I had my suspicion it was off. I hooked it up to the Schrader valve on two of my cars and it is measuring five psi lower then indicated value from the TPMS system.  Meaning the psi is 59 at the rail.    I thought I was onto it with low fuel pressure

[stang233]

Well 4th of July was almost great. Boat ran great for about 10 hours. Tubing, surfing, ect.   Frustration is growing!!!

 

Back to misfire central.  Only variables. Fuel tank is lower than half and its hotter out.  Maybe a few hundred pounds more in the boat with people. It started with a cylinder 7 and 4 misfire. Now I am getting 7,4,5,3.   I data logged each run and was getting upwards of 5 percent misfire.  Does this screnshoot of datalog show anything. I would be happy to send my datalog for anyone to review if you would be so kind. 

It has to be a load issue.  If the motor is under too much load it starts to misfire. Yesterday was the most people I had on the boat this year…

Edited October 16, 2023 by stang233

[justgary]

Please verify that your data from June was taken at a different elevation than the current data.  June data indicates sea level and a perfect blue day.  July data indicates about 150 feet above sea level, or maybe sea level and a stormy day (in which case I doubt you would be out).

Does the System Info tab show non-zero adaptive learn data now?

I think I would grab a MEFI manual and perform the diagnostic tests of the distributor pickup coil and other distributor parts.  Maybe also try to rig up a timing light and a video camera to catch the spark jumping when the misfires occur.

[stang233]

Gary, the data was taken at the same elevation. The June date was a 70 degree day and the July day a 95 degree day.  Does this shed any light?

I will look into how to run distributor checks.  Thank you again!!!!!

[justgary]

5 hours ago, stang233 said:

The June date was a 70 degree day and the July day a 95 degree day.  Does this shed any light?

That could do it I suppose, especially if it was higher relative humidity in July.

[stang233]

Well I decided to check bleed off again on the fuel pump. After I prime the fuel pressure gauge and turn the key off I lose 2-3 psi a min.  I think the regulator is bad.  I am going to replace the whole pump while I am there.  Already ordered. Hopefully that rate or bleed off is out of spec 

Edited July 21, 2023 by stang233

[stang233]

Sadly the new fuel pump didn’t fix it.  The only real options left are new distributor or ecu for parts.   It might be cheaper to trade it in.  Feeling defeated. 

[stang233]

Can anyone help me understand the fuel adaptation. After replacing the fuel pump and clearing the fuel adaptation data the boat ran great for 3 hours with zero misfires. Surfing and tubing.  However, I did notice that the fuel adaptation tables had data inserted into them

Now we just tubed for 75 min and all cylinders had misfires again (upwards of 2000 on two cylinders). However the fuel adaptation data was back down to 0.00 across the board. It did not put me in limp mode but I have to believe that is way to many misfires to be okay.  

I ran the O2 sensor check in diacom and they passed.

Maybe my misfires are occurring because the ECU is not adjusting the fuel properly.  Is it worth throwing a new ECU on it yet?

 

 

 

Edited August 3, 2023 by stang233

[csleaver]

Fuel adaption is just a way for the ECM to use O2 sensor data during closed loop + adapt mode to accommodate for differences in engine build and wear to get the fuel trim as close to stoichimetric as quickly as possible for that particular engine.  Clearing the fuel adaption after repairs makes this process faster, but eventually the adaption will happen as the boat is operated over time.  Fuel adaption isn't really associated with misfire as the way the data is gathered for each comes from different engine sensors.  Misfire data is generated from the crank and cam position sensors and fuel trim or adaption data comes from the O2 sensors.

[stang233]

Well I re-ran a compression check with the Diacom which puts it at WOT.  Still good.

Cylinder 
1: 183
3: 171
5: 173
7: 175
2: 180
4: 174
6: 180
8: 178

Cylinder 7 and 4 are usually what I get a misfire for . Sometimes 1 and 5 as well.

I think I am going to have to get an appointment . only thing left for me to do is a new ECU or I have read a few folks needing exhaust manifold.  Idk. 

Edited October 16, 2023 by stang233

[csleaver]

The only thing I can see that you may not have verified is the condition of the crank position sensor and relutor wheel.  If the sensor is faulty, has been submerged, or if the sensor wiring or connector is loose or worn it could cause faulty misfire readings.  if the reluctor wheel on the crankshaft is loose, too close, or too far from the crank position sensor it could also cause faulty misfire readings.