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EGR delete trouble
clarknova Offline

Posts: 7
Joined: Sep 2016
Location: Alberta
EGR delete trouble
My '99 E300TD was starting to sputter and threw a code P0400, EGR valve. I cut a circle out of an aluminum can and placed it in the junction between the EGR tube and the intake manifold, but the engine still sputtered occasionally and the P0400 came back.

Next I removed the plastic coupler from the vacuum host leading from what I believe to be the actuator to the valve. It's the yellow coupler piece seen in this video at 1:51: After removing the couple I plugged both ends of the vacuum hose with a bolt. This ended the sputtering, but the P0400 code returned. Sometimes the car would have boost, sometimes not, as if the wastegate was being held open. Usually (but not always) the car would have boost after starting the engine, but after a few minutes it would lose boost, not to return until the key was cycled.

My next intervention was to install the resistor-diode device as described here: I did this today and cleared DTC again. Now the car will drive longer with boost and no check engine light, however the engine light still does come on occasionally, at which point again, no boost. The DTC that accompanies this is P0100, MAF sensor.

Identifix indicates that a P0100 code is normally corrected by replacing the MAF sensor or cleaning the intercooler. It also says that "The Air Mass Sensor on this engine is used to verify EGR operation. The P0100 code can set if the amount of volume going past the sensor is not in spec.". I should note that I have a cheap scanner that shows what appear to be reasonable airflow values while I drive, so I suspect that the MAF sensors is at least partially functional.

Given the timing of the occurrence of this DTC, it seems likely that the installation of the EGR delete device has contributed to it, but I don't know. Can anybody suggest what the cause of the problem is at this point? Have I installed the diode backwards? Did I kill the MAF sensor? Do I need to reconnect the vacuum hose or remove the EGR obstruction?
09-08-2018, 11:00 PM
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AlanMcR Offline
mind - blown

Posts: 330
Joined: May 2009
Location: USA
RE: EGR delete trouble
Even with the resistor/diode fix, the MAF has to produce a roughly accurate value. The fix is there so fake the effects of the EGR valve opening and closing. You can leave the fix in place, but you will need to get a new MAF to be rid of limp mode.
09-09-2018, 11:42 AM
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