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sprinkles08
sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 21604
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
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My name is ***** ***** I have a Jeep Grand Cherokee CRD

Customer Question

Hi My name is ***** ***** I have a Jeep Grand Cherokee CRD / 2006 150000 Km
JA: Thanks. Can you give me any more details about your issue?
Customer: While pressing throttle pedal to the floor, when the engine RPM are reaching 3600 - 4000 rps, there is an engine power cut if I keep full throttle, the car is like shaking a bit, then the rpm are going down to about 2700 RPM, is accelerating again, when reaching same rps range (3600 - 400) rpm, agai engine power cut I have been for a drive test, the Jeep Electronic Technician on the passenger seat, connected to the car control system the only thing he was able to notice was that whe the engine power was cut, a parameter called TCC was set to zero
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Submitted: 8 months ago.
Category: Jeep
Customer: replied 8 months ago.
While the engine was accelerating from 2700 rpm to about 3900 RPM, this TCC parameter was set to about 30, after reaching the 3900 RPM the TCC parameter was set again to Zero and the car was decelerating after shaking for a short while (foot still on full throttle)
Expert:  sprinkles08 replied 8 months ago.
Hello and welcome to JustAnswer! It sounds as if the engine controller is intentionally derating power. This can happen because of a number of reasons including the accelerator pedal position sensor, injector issues, the fuel pressure sensor, it may be a fuel delivery issue, or it could be boost related. A boost leak will often cause what you're describing as it sees mass airflow is incorrect for the amount of boost commanded.The first step in diagnosing the problem is to see if any fault codes are setting. If it is intentionally derating power then there will be a fault code set and it will need to be used as a starting point for diagnosis. Are there any codes setting?
Customer: replied 8 months ago.
Car VPN: 1J8HCE8M35Y581882 VFW
Thank you for the answer, it does not help, being very generic and not considering the details I have provided.
If there was an error code generated, things were much easier to troubleshoot.
But there is no error message / code generated.
As mentioned, during the road tests, the diagnostic laptop was connected to the car control system and the ET was monitoring the parameters.
Electronic throttle monitored, nothing seen that would explain the behavior.
Fuel pressure monitored, constant.As mentioned, the only thing identified was the TCC (Torque Converter Clutch) set to Zero when the engine power cut is happening. Before this is happening, the TCC parameter is set to about 30.
Again, no error code is being generated.
Expert:  sprinkles08 replied 8 months ago.
What is rail pressure and setpoint at the time the problem is happening?
Customer: replied 8 months ago.
As told to me by the ET, the rail pressure was +1600 Bar, steady / not changing when the problem is happening.
As already mentioned, the only abnormal thing the ET was able to notice was that when the engine power was cut, a parameter called TCC was set to zero.
Expert:  sprinkles08 replied 8 months ago.
What was seen with the torque converter clutch is not abnormal and the converter isn't relevant to what is happening.Rail pressure needs to bbe checked versus setpoint when the problem is happening. Pressure may very well be steady, but it needs to be compared to setpoint.
Customer: replied 8 months ago.
As told to me by the ET during the test drive, the rail pressure set point and the actual pressure did not change when the problem was happening.
Both were at +1600 bar, I do not remember exactly the values, it was something like 1630+.
Expert:  sprinkles08 replied 8 months ago.
What was commanded and actual boost? If no fault codes are setting then it's either a fuel delivery issue or lack of boost.
Customer: replied 8 months ago.
I have to go for one more drive test to be able to provide these details. As told to me by the Jeep ET, he checked all relevant parameters on engine, fuel, throttle, and found nothing abnormal, excepting the TCC dropping from about 30 to zero in the same time with the car chattering and the engine loosing power.
Expert:  sprinkles08 replied 8 months ago.
If the problem is being duplicated while someone is watching data and they're unable to see anything wrong then you're going to need someone more experienced. The data provided will lead in the right direction for diagnosis, saying the torque converter clutch state is an issue or even looking at it for these symptoms proves lack of familiarity.
Customer: replied 8 months ago.
Sorry about, I have missed to mention that the described issue occurred after the just performed 150K KM service, including the automatic transmission oil change.
Expert:  sprinkles08 replied 8 months ago.
The problem isn't related to the transmission. Was any other work done at that time?
Customer: replied 8 months ago.
Complete 150K Km service performed + change fluids not done with previous service. Basically all fluids and filters replaced. Gearbox filter replaced as well.
The problem seems to be related to the transmission.
The first oil used for the automatic transmission was the TUTELA T FORCE4 ATF+4.
With this oil and the car running since a while (gearbox fluid at operating temperature) for full throttle the gear shifting was erroneous each time from 2nd to 3rd and 3rd to 4th. Following my request, the gearbox fluid was replaced again with MOPAR ATF+4. Now the gear shifting is OK all the times 2nd to 3rd, very, very rarely erroneous 3rd to 4th (full throttle).
Customer: replied 8 months ago.
2005 - 2008 Jeep Grand Cherokee Service Repair Manual / AUTOMATIC TRANSMISSION FLUID
...
MoparT ATF +4, Automatic Transmission Fluid is the recommended fluid for DaimlerChrysler automatic transmissions.
...
Clutch CHATTER can result from the use of improper fluid.
Expert:  sprinkles08 replied 8 months ago.
Can you explain exactly what you are feeling when you say shifts are erroneous?
Customer: replied 8 months ago.
As written in my first message: "while pressing throttle pedal to the floor, when the engine RPM are reaching 3600 - 4000 rps, there is an engine power cut if I keep full throttle,the car is like shaking a bit, then the rpm are going down to about 2700 RPM"
In fact this is happening at the RPM when the automatic gear shift should happen.
It seems the car shaking is occurring first, followed by the engine power reduction, even if I keep full throttle.
Customer: replied 8 months ago.
The shifting 3rd to 4th at full throttle is at 4100 RPM / 160 Km/h, this would not happen in normal trafic.
Expert:  sprinkles08 replied 8 months ago.
I was aware of that but we've been discussing a lack of power. Your last post mentioned 'erroneous shifting'. Are you actually feeling a lack of engine power or is the transmission slipping?
Customer: replied 8 months ago.
After the car is shaking instead of shifting gear, if I keep full throttle, the engine RPM is going down to about 2700 RPM.
Expert:  sprinkles08 replied 8 months ago.
Is the engine running out of power or is the engine torque not making it to the wheels?
Customer: replied 8 months ago.
I could not tell if the engine torque is still going or not to the wheels after the car is shaking instead of smoothly shifting to the 4th gear ratio. All I see is that after the car is shaking for a couple of seconds, the engine RPM is going down with full throttle, and the car is slowing down. This seems being an effect of what's happening in the automatic transmission, not the cause of the issue.
This is why that TC parameter going to zero when this is happening seemed relevant. Strange that the car is performing better with the Mopar ATF+4 oil compared with the Tutela T Force4 ATF+4, this fluid being Chrysler / Jeep licenced same as the Mopar one.
Expert:  sprinkles08 replied 8 months ago.
It may be going into torque management if the trans is slipping, but again that's apparent in the data to someone knowledgeable. Are you able to upload a video showing the issue?
Customer: replied 8 months ago.
I need to have somebody catching this on video while I drive.
Considering the car age and the fact that the Jeep servicing shops are only since few years together with Fiat, the Fiat / Jeep ET is not an expert in Jeep WK/ WH's.
Expert:  sprinkles08 replied 8 months ago.
A trans tech at any Chrysler dealer will be familiar with this transmission. It has been in widespread use since 2004 and still is, it was used in a handful of other applications dating back to 1999.
Customer: replied 8 months ago.
Unfortunately there is no such thing as Chrysler dealer in Romania and Europe. The Fiat dealers have taken over Jeep for sales and service. The Daimler / Mercedes dealers technicians that were familiar with these cars are not doing Jeep anymore.
If the problem is not going to be sorted out after the second gearbox oil replacement with Mopar ATF+4, with special attention paid for the oil level, I am going to search for an independent Jeep service.
Expert:  sprinkles08 replied 8 months ago.
Do you have a Mercedes dealer?
Customer: replied 8 months ago.
There is a Mercedes dealer in my place, I was sent to Fiat / Jeep when I wanted to book the car servicing in their shop. The Mercedes dealer do not have anymore the diagnostic interface for Jeep
Expert:  sprinkles08 replied 8 months ago.
Did you actually go there and they sent you away? It wouldn't take anything more than a generic scan tool to communicate with it. The experience with this powertrain is more what you're after.