Technical Troubleshooting power loss problems

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Technical Troubleshooting power loss problems

barneyfife

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Problem: Fiat Multipla 2009 1,9JTD 120HP 88KW has oil leak at turbo (huge), and intermittent power loss around 3200 RPM.

Actions: Sent original turbo out for repair, and reinstalled (24 hour turn-around). Scan tool (ECM Blutooth tool and app "car scanner pro") showed MAF faulty. replaced.
Turbo Variable vannes not moving. (No vac on line) Replaced waste-gate controller. (runs like a bat outta hell) for first 8 to 10 minutes. then feels like it goes into liimp mode, but not really. No codes or faults on the computer. It actually runs lean it seems. Power at 3200 RPM drops off a cliff. Voltage below 12V drops to 10V at sart. Replaced battery. Voltage now good to Computer.
Graphed all sensors in test drive. when working, Pedal position goes to 100% and fuel pressure rises accordingly. When not working, pedal position goes to 100% aand fuel pressure stays at 4000psi. Looks like a fuel pressure regulator is not working. Removed Fuel pressure regulator (PN: Bosch 0928 400 680). Worst case scenario is computer malfunction. Regulator connects directly to engine management computer.

Notes: The way it feels I'd say that the previous owner added a tune. Thus wearing out the turbo and fuel pressure regulator quickly. I saw boost pressure of 30psi !
This little regulator is the hardest part to change, other than the alternator on the Multipla.
Parts supplier for fuel injection parts at a great price: AutoRicambi | +421 323 217 202 | [email protected]
www.auto-ricambi.eu

Status: Fuel pressure regulator and gasket on order.
 
Egr valve sticking open?

If it does map reading will drop low because boost pressure will drop.

Does it have dpf?
 
Maf sensor faulty? Was that a code or readings looking wierd?

Did you fit a genuine Bosch maf sensor?

Stuck open egr will give unexpected high air flow readings because the turbo blows straight into exhaust via egr valve
 
Egr valve sticking open?

If it does map reading will drop low because boost pressure will drop.

Does it have dpf?
Hi Jackwhoo,
EGR is working properly. MAP readings were hit and miss before the change. DPF is installed and working properly. Boost pressure is not the issue. Plenty of boost. only a nosedive in power from lack of fuel...According to the data.
 
Map or maf changed?
First post states maf changed?
 
Maf sensor faulty? Was that a code or readings looking wierd?

Did you fit a genuine Bosch maf sensor?

Stuck open egr will give unexpected high air flow readings because the turbo blows straight into exhaust via egr valve
MAF readings linked by data to Throttle open position and MAF calculated power were the graphs I looked at. The MAF was not metering correctly, and the air lnlet temp was faultly. The MAF was definately not working properly, but it was not the issue for the non linear power curve.
I Bought a generic MAF. EGR @3% and if the EGR was malfunctioning i would not get 20psi boost. The manifold pressure remains high and even upto 30psi, however the data shows that fuel pressure on the rail does not map with the throttle position.
 
Look at getting multi ecu scan software
It can show desired rail pressure and actual rail pressure so they can be compared directly to see if there is a fault with rail pressure.

It can also show desired air flow and actual air flow.

I was also thinking about the boost and egr.....if boost remains high when fault occurs then egr must be closed
 
Map or maf changed?
First post states maf changed?
MAF. MAP Sensor reads correctly. MAP (Manifold Absolute Pressure) is a zero to 5V sensor. 4000 psi is about 1.3V output from the sensor.
Look at getting multi ecu scan software
It can show desired rail pressure and actual rail pressure so they can be compared directly to see if there is a fault with rail pressure.

It can also show desired air flow and actual air flow.

I was also thinking about the boost and egr.....if boost remains high when fault occurs then egr must be closed
So far, a 25Euro plug in reader from Amazon, and 5 Euro software app for my android has been able to datalog all signals and clear the faults. It also shows all the calculated load and power estimates driven by MAF and MAP and Fuel and THrottle position inputs. It also measures GPS and does provide accelerometer data from the phone sensors in real time. All that for 30 bucks seems like getting anything else for a shade tree mechanic like me is a waste.
 
Comparing The desired values being requested by the ecu to the actual values is very useful.
If you are reading a value that you think is not correct it can be compared to the value the ecu desires, if the values are the same then you can look into why the ecu is requesting a value you think is not correct.

If you have a laptop running on Windows,Multi ecu scan software free issue will give almost all functions you
would need . All you would need is an interface cable.
 
UPDATE:
ACTION: Fuel pressure regulator installed. No leaks. Now, fuel pressure tracks well with the throttle position. Definitely does work now.
STATUS: After 5 minutes of driving, the power drops out. Even with the Suction Valve installed and the fuel delivery correct!

AHHH!!! So, it seems that the PWM controller inside the computer is overheating after 5 minutes, and causes the power loss. I think that the PWM output to the SCV is weak, and with a new SCV, it draws less current, and so it works, but the Injectors also use PWM outputs. So, Looks like a computer malfunction. Boo.
 
UPDATE:
ACTION: ECU Scan with better tools. Overboost ON. DPF 1000% clogged.
STATUS: DPF replacement.
COMMENTS: Used cars can be expensive to repair! Car was completely worn out by previous owner. At least the computer is not dead.
 
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