Technical Throttle body 2.8jtd
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Technical Throttle body 2.8jtd
Communicator
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Hi Rob,
The simple answer seems to be, no throttle body on the 2.8jtd, even when EGR is fitted.
May I answer your question with another. Is your engine fitted with EGR? Please see attached extract from eLearn for diagram of EGR installation.
My 2006 x244 2.8jtd does not have EGR, and differs considerably from the diagram. Back in 2006, I expected EGR, but I had not owned a vehicle with EGR for comparison. It took me some considerable time, to convince myself that EGR was not fitted to my vehicle.
The simple answer seems to be, no throttle body on the 2.8jtd, even when EGR is fitted.
May I answer your question with another. Is your engine fitted with EGR? Please see attached extract from eLearn for diagram of EGR installation.
My 2006 x244 2.8jtd does not have EGR, and differs considerably from the diagram. Back in 2006, I expected EGR, but I had not owned a vehicle with EGR for comparison. It took me some considerable time, to convince myself that EGR was not fitted to my vehicle.
Hi communicator. Thanks very much for the reply and information. It doesn't have an EGR valve. My problem is that the throttle response is still erratic and on occasion no throttle at all (dead stick)which makes it dangerous to drive. I have read that the throttle can stick but couldn't find a throttle body. Would you know how the engine is aspirated?
Communicator
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Hi Rob,
Do you have any engine alarms on the dash? If so a readout of stored codes would help diagnosis.
I am wondering if your accelerator potentiometer or connections are faulty. It is a two out of two system, but if not recieving similar outputs the ECU should give a fault indication. Is the connector by your right foot, properly inserted?
Another possibility could be the crankshaft position/rpm sensor. The ECU depends upon this for correct injection timing. Try searching on/off forum for reated faults.
As to your final question, I think that you are leaning too far towards carburettor petrol engine operation. See attached turbo charging description.
For further reading I am attaching other relevant file extracts from eLearn.
Do you have any engine alarms on the dash? If so a readout of stored codes would help diagnosis.
I am wondering if your accelerator potentiometer or connections are faulty. It is a two out of two system, but if not recieving similar outputs the ECU should give a fault indication. Is the connector by your right foot, properly inserted?
Another possibility could be the crankshaft position/rpm sensor. The ECU depends upon this for correct injection timing. Try searching on/off forum for reated faults.
As to your final question, I think that you are leaning too far towards carburettor petrol engine operation. See attached turbo charging description.
For further reading I am attaching other relevant file extracts from eLearn.
Hi Communicator.
Sorry again for the late reply I don't receive notifications.
I have the red injector light on the dash. When it is on the engine behaves normally which is strange because there isn't a reduction in performance (limp mode) When it goes out the engine behaves erratically and as mentioned before sometimes can floor the throttle with no response from the engine. The plug to the TPS isn't the best but couldn't see any of the pins touching. The two 5 volt references are next to each other at the end of the plug which I found a bit odd. I would expect them to be 5 volt,signal,ground. Ground,signal,5 volt. Instead I have 5volt,5volt,ground. Signal,ground,signal. I thought it may be the design of the TPS but not sure.
I did try a local garage to to get the codes but they couldn't get their equipment to communicate with the ECU (seems a common problem)
I could swop out the sensors CPS,MAP and TPS but don't want to throw good money after bad. I have heard the MAP sensor can suffer from overheating. The fault did occur last summer after a long hill climb which caused the radiator fans to turn on. Although it happened the next day and symptoms were mild. I'm still trying to get my head around how a diesel engine is throttled by the turbo rather than a petrol type butterfly valve.
Thanks again for the information.
Sorry again for the late reply I don't receive notifications.
I have the red injector light on the dash. When it is on the engine behaves normally which is strange because there isn't a reduction in performance (limp mode) When it goes out the engine behaves erratically and as mentioned before sometimes can floor the throttle with no response from the engine. The plug to the TPS isn't the best but couldn't see any of the pins touching. The two 5 volt references are next to each other at the end of the plug which I found a bit odd. I would expect them to be 5 volt,signal,ground. Ground,signal,5 volt. Instead I have 5volt,5volt,ground. Signal,ground,signal. I thought it may be the design of the TPS but not sure.
I did try a local garage to to get the codes but they couldn't get their equipment to communicate with the ECU (seems a common problem)
I could swop out the sensors CPS,MAP and TPS but don't want to throw good money after bad. I have heard the MAP sensor can suffer from overheating. The fault did occur last summer after a long hill climb which caused the radiator fans to turn on. Although it happened the next day and symptoms were mild. I'm still trying to get my head around how a diesel engine is throttled by the turbo rather than a petrol type butterfly valve.
Thanks again for the information.
Communicator
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Hi Rob,
I think that in your situation you should get any stored codes read.
Multiecuscan is frequently recommended, and as one forum member (Ocwobio?) put it "speaks fluent Fiat".
Does your vehicle have have the standard OBD2 port, or the earlier 3 pole connector with 2 wires connected? I have read that this connector is to be found close to to the ECU on the inside of the LH front wing. See link below.
Another avenue for you to investigate is that on early versions of the 2.8 jtd, the injector leads were too short, leading to intermittent injection failure.
As regards basic diesel engine operation, forget all about throttles. A basic turbo only pushes air into the cylinders upto the maximum boost pressure. The injection system then injects the required amount of fuel to maintain the set rpm. To elaborate, prior to the jtd, the idTD had a mechanical injection pump, with internal govenor. Accelerator pedal acted upon the govenor setting. Fuel injected as required, to achieve set speed.
https://www.fiatforum.com/ducato/104856-diagnostic-port-2001-2-8jtd.html
I think that in your situation you should get any stored codes read.
Multiecuscan is frequently recommended, and as one forum member (Ocwobio?) put it "speaks fluent Fiat".
Does your vehicle have have the standard OBD2 port, or the earlier 3 pole connector with 2 wires connected? I have read that this connector is to be found close to to the ECU on the inside of the LH front wing. See link below.
Another avenue for you to investigate is that on early versions of the 2.8 jtd, the injector leads were too short, leading to intermittent injection failure.
As regards basic diesel engine operation, forget all about throttles. A basic turbo only pushes air into the cylinders upto the maximum boost pressure. The injection system then injects the required amount of fuel to maintain the set rpm. To elaborate, prior to the jtd, the idTD had a mechanical injection pump, with internal govenor. Accelerator pedal acted upon the govenor setting. Fuel injected as required, to achieve set speed.
https://www.fiatforum.com/ducato/104856-diagnostic-port-2001-2-8jtd.html
Hi Communicator and thanks again for the reply.
I'm trying a few things at the moment. I'm going to use a 5k resistor as a jumper between the the 5 volt reference and the signal wire to establish if the signal is shorting to ground. I found the method on YouTube. Also I will test the TPS for resistance. If I can establish or eliminate the TPS circuit it will be a step forward.
When the garage tried to connect to the ECU they used the 3 pin 3 wire connector. I did mention to them i thought the 3 pin 2 wire was the correct one but they insisted it was the 3 wire and yes it is adjacent to the air filter. I've also checked the injector wires but can't find a problem. I did however secure the cables better where they return to the ECU. They are quite heavy bunched together in the loom and could pull if driving over rough ground. Seems a poor design.
I'll let you know how I get on.
I'm trying a few things at the moment. I'm going to use a 5k resistor as a jumper between the the 5 volt reference and the signal wire to establish if the signal is shorting to ground. I found the method on YouTube. Also I will test the TPS for resistance. If I can establish or eliminate the TPS circuit it will be a step forward.
When the garage tried to connect to the ECU they used the 3 pin 3 wire connector. I did mention to them i thought the 3 pin 2 wire was the correct one but they insisted it was the 3 wire and yes it is adjacent to the air filter. I've also checked the injector wires but can't find a problem. I did however secure the cables better where they return to the ECU. They are quite heavy bunched together in the loom and could pull if driving over rough ground. Seems a poor design.
I'll let you know how I get on.
Communicator
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Hi Rob,
I came across the attached info while trying to build a corrected set of eLearn diagrams. Thought that it may be of interest.
I came across the attached info while trying to build a corrected set of eLearn diagrams. Thought that it may be of interest.
benchmark51
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This is something I have been considering too. Also that the air going though the MAF gets pushed through a plastic pipe that varies down to about 40mm as it enters the turbo inlet, goes through the turbo and out into another larger pipe into the intercooler then out again to get reduced to another smaller pipe. Eventually getting to the inlet manifold. So many connections and potential for leakage.
Hi Communicator. Hopefully you can help with this. I have tested the TPS plug when removed from the TPS. Both 5 volt reference good. Both signal wires tested by connecting a 5k ohm resistor from 5 volt reference to signal wire(ScannerDanner Youtube) No shorts to ground found. There however appears something wrong with the ground wires. P1 ground no continuity when ground to chassis ground. P2 ground has continuity when grounded to the chassis. Obviously there is a problem but not sure which circuit. Should a TPS ground show continuity when ground to the chassis? Is the ground showing no response the good ground? Any help appreciated.
Communicator
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Hi Rob,
Sorry, but I cannot help with your latest question.
I am however attaching part of the engine management wiring diagram, which while perhaps not fully relevant to your x230, will give the general connection method for the accelerator sensor. Please note that the text annotations are mine and not original, also the file name is temporary
All wires connect into the ECU. which is an electronic "black box".
In general, I would advise against using anything other than the diode test range of a multimeter, when testing into an electronic module.
Sorry, but I cannot help with your latest question.
I am however attaching part of the engine management wiring diagram, which while perhaps not fully relevant to your x230, will give the general connection method for the accelerator sensor. Please note that the text annotations are mine and not original, also the file name is temporary
All wires connect into the ECU. which is an electronic "black box".
In general, I would advise against using anything other than the diode test range of a multimeter, when testing into an electronic module.
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Hi RobL. I found an old thread on this forum which deals with this issue. I don't know the "clever" way to link to it, but it was dated 09-10-2007 and titled "Ducato 2.8 JTD 2001". Might be worth a look.
To summarise, there can be problems with the wiring between the throttle (accelerator) position sensor and the ECU. I would recommend disconnecting at both the TPS and ECU ends and checking the 6 relevant wires for resistance from end to end (which should be extremely low) and resistance to each other (which should be extremely high)
All the 6 wires from the TPS go to the ECU. It's not safe to assume that the two "signal low" wires will have a low resistance to chassis ground, as it's anybody's guess what the designers did inside the ECU. The ECU should be able to determine if either of the two potentiometers (plus their associated wiring) is faulty and log a code.
An engine management light indicates that the engine may be producing higher than acceptable emissions. It isn't always associated with a limp mode; that is only brought in to play for the more serious faults.
To summarise, there can be problems with the wiring between the throttle (accelerator) position sensor and the ECU. I would recommend disconnecting at both the TPS and ECU ends and checking the 6 relevant wires for resistance from end to end (which should be extremely low) and resistance to each other (which should be extremely high)
All the 6 wires from the TPS go to the ECU. It's not safe to assume that the two "signal low" wires will have a low resistance to chassis ground, as it's anybody's guess what the designers did inside the ECU. The ECU should be able to determine if either of the two potentiometers (plus their associated wiring) is faulty and log a code.
An engine management light indicates that the engine may be producing higher than acceptable emissions. It isn't always associated with a limp mode; that is only brought in to play for the more serious faults.
Hi Communicator and Anthony489.
Thank you so much for your help. The wiring diagrams were invaluable and your right Anthony it is a wiring problem or rather it isn't now it's fixed!!! The problem was (P1 TPS Circuit)Blue ground wire 3 to pin 76 on the ECU. The wire is broken somewhere no continuity so fitted a temporary jumper wire from the TPS plug to the ECU. No fault light on the dash engine runs fine and seems a lot more responsive. Just need to fit a permanent jumper wire. So many red herrings but got there in the end. Thanks again people.
Thank you so much for your help. The wiring diagrams were invaluable and your right Anthony it is a wiring problem or rather it isn't now it's fixed!!! The problem was (P1 TPS Circuit)Blue ground wire 3 to pin 76 on the ECU. The wire is broken somewhere no continuity so fitted a temporary jumper wire from the TPS plug to the ECU. No fault light on the dash engine runs fine and seems a lot more responsive. Just need to fit a permanent jumper wire. So many red herrings but got there in the end. Thanks again people.