Can PCM be fooled into thinking EGR is present?

Rangstang · May 15, 2015

I've got a 99 Ranger with 3.0L that I recently purchased. Intake has been swapped to a later model composite, throttle body swapped, and JBA headers, but he removed the EGR valve, EGR solenoid, DPFE, and capped off the port in the LH header. He lived in Tonopah, AZ where emissions are not required. I live in Mesa (suburb of Phoenix) where emissions are required.

Is there a circuit I can install which will take the EGR solenoid signal and process it to send out a DCV (would be the DPFE signal) to the PCM so that it believes everything is present and working correctly?

If not, I don't mind adding the parts back in if necessary, but I don't know where to begin since it's a bastard with different years of parts. I don't even know where the EGR mounts on the later model composite intake motors.

Anyone out there with experience in this area? Any help is greatly appreciated.

Rearanger · May 15, 2015

Your state may not allow emissions equipment to go missing then cover it with computer tinkering - if you could even do that. They may check to see what's there or not.

I'd put it all back. Truck will run fine.

RonD · May 15, 2015

EGR system is a real time feedback system for the computer, so don't think it would be easy to trick the computer.
EGR modulator is a 12volt valve the computer opens to send vacuum to the EGR valve
The DPFE sensor monitors exhaust manifold pressure in two places, one close to or on EGR valve's tube.
As computer pulses 12volts to EGR modulator partial vacuum is sent to EGR valve and it opens a little.
Computer watches for DPFE pressure change to see how much it opened.
Computer has EGR tables for RPMs and load and for how much to open EGR valve.

So while you may be able to trick it for awhile, few hours, I would suspect you would get a CEL regarding EGR over time.

2002 Rangers with 3.0l, didn't have the EGR system, but I think dealing with the PATS issue when swapping PCMs would be more of a pain than EGR issue

Rangstang · May 15, 2015

They don't even open the hood much less know what's going on. They only interface with the OBD port. It's a real scam. In fact I failed a vehicle last week with no codes but because the check engine light wasn't functioning.

As I said, if I can determine what I need and where it needs to go, I don't have a real issue with putting the parts back.

As for fooling the system, it wouldn't be hard if I knew what the duty cycle on the EGR solenoid was in relation to the DPFE voltage. Probably be fairly simple.

RonD · May 15, 2015

Some have said hooking up DPFE sensor's "ref" hose to the EGR modulator's EGR valve hose will give PCM reasonably correct feed back, in that DPFE sensor "sees" pressure drop as vacuum is applied to "EGR Valve"
Never tried it

Rangstang · May 15, 2015

RonD said:
Some have said hooking up DPFE sensor's "ref" hose to the EGR modulator's EGR valve hose will give PCM reasonably correct feed back, in that DPFE sensor "sees" pressure drop as vacuum is applied to "EGR Valve"
Never tried it

Previous owner had done this, but I had the battery disconnected for a few hours before thinking to check for codes (CEL out) and haven't driven it yet, so I don't even know if it had any codes. Just researching prior to driving it so I don't have any major challenges when I need it.

Can PCM be fooled into thinking EGR is present?

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