Hi,
So as the title says, I'm getting a P0401 code, insufficient flow. However I'm reading the actual amount as far higher than the requested.
The duty cycle almost always stays at 15.1%, even under load. When you press the accelerator there is a very brief spike, then back down to 15.1%.
Also MAF vs EGR Actual shows the EGR Actual as being the same value as the MAF, which presumably should mean that the engine is breathing 100% inert exhaust, and therefore shouldn't run... it does run a tiny bit rough, and feels like it misfires occasionally. There are no error codes relating to this.
The vacuum pipe going to the EGR is fine, and it pulls a good vacuum. I can feel the vacuum changing as the egr cycles, so the solenoid operating it is presumably fine as well.
I have a replacement EGR on the way so I will start by replacing that, I was just wondering if anyone else seen this pattern. I've done a fair bit of reading but I've not seen anything that matches this pattern (at least to my untrained eye). The car is too old to have a DPF fitted.
Other than replacing the EGR and checking the supply pipe, is there anything else I can do? All tests performed stationary, so not under load.
Thanks!
This shows EGR Actual, Spec, RPM, and Duty Cycle under varying RPM.
The coolant temp sensor is also faulty, this shows the coolant temp dropping, the engine RPM being increased automatically, and then the EGR spec increasing. The EGR Actual stays constant.
EGR Spec, Actual, RPM under rapid rpm increases
EGR Spec, Actual, Duty Cycle under rpm changes.
MAF and EGR Actual
At present all I can think is the EGR is jammed and unable to properly close, so is delivering more than the engine wants. This is causing the engine to drop the duty cycle as low as it can, in an effort to reduce the EGR flow? Brief duty cycle increases seem to be when the EGR Spec exceeds the EGR Actual, or when the pedal is released.
If there is anything else useful I can provide or investigate, let me know. Thanks for any help and advice on the topic. I will report back with findings if/when I solve the issue, in case anyone gets brought here by google for the same pattern!
So as the title says, I'm getting a P0401 code, insufficient flow. However I'm reading the actual amount as far higher than the requested.
The duty cycle almost always stays at 15.1%, even under load. When you press the accelerator there is a very brief spike, then back down to 15.1%.
Also MAF vs EGR Actual shows the EGR Actual as being the same value as the MAF, which presumably should mean that the engine is breathing 100% inert exhaust, and therefore shouldn't run... it does run a tiny bit rough, and feels like it misfires occasionally. There are no error codes relating to this.
The vacuum pipe going to the EGR is fine, and it pulls a good vacuum. I can feel the vacuum changing as the egr cycles, so the solenoid operating it is presumably fine as well.
I have a replacement EGR on the way so I will start by replacing that, I was just wondering if anyone else seen this pattern. I've done a fair bit of reading but I've not seen anything that matches this pattern (at least to my untrained eye). The car is too old to have a DPF fitted.
Other than replacing the EGR and checking the supply pipe, is there anything else I can do? All tests performed stationary, so not under load.
Thanks!
This shows EGR Actual, Spec, RPM, and Duty Cycle under varying RPM.
The coolant temp sensor is also faulty, this shows the coolant temp dropping, the engine RPM being increased automatically, and then the EGR spec increasing. The EGR Actual stays constant.
EGR Spec, Actual, RPM under rapid rpm increases
EGR Spec, Actual, Duty Cycle under rpm changes.
MAF and EGR Actual
At present all I can think is the EGR is jammed and unable to properly close, so is delivering more than the engine wants. This is causing the engine to drop the duty cycle as low as it can, in an effort to reduce the EGR flow? Brief duty cycle increases seem to be when the EGR Spec exceeds the EGR Actual, or when the pedal is released.
If there is anything else useful I can provide or investigate, let me know. Thanks for any help and advice on the topic. I will report back with findings if/when I solve the issue, in case anyone gets brought here by google for the same pattern!
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