Ok gents ive been having problems with my egr not opening. Thought I had it fixed, but I guess not this sucks I know I have good vacuum 17hg to the evr but a big fat ZERO to the egr valve. I disconnected the vacuum hose to the Egr With the engine running at a steady throttle and revved it And no vacuum. What could cause this? bad evr or wiring, or even a bad computer I was going to try to drive it but my hood was going to pinch my gauge hose any other Ideas on how to check it this way? I know this is why my truck is running this way oh I have mentioned this before i can open the evr By grounding the green wire to the battery Please try to help me out guys. I appreciate so much! Thanks Robert.

 

That is normal operation. The only time the PCM should open the EGR valve is under part throttle cruise conditions.

If you are getting an error related to the PCM not sensing the EGR is opening then you need to check the EVP sensor output. Attaching a vacuum gauge to the EGR side of the EVR is a great idea. I have run a vacuum line through the firewall a time or two. I have even closed the hood just enough to engage the safety latch then driven very carefully to watch the gauge too.

 

Yes sir I tried to do that just latching the hood but it was going to pinch the vac gauge hose so i will test the evp sensor and try running the vac gauge through the firewall. But what sucks is my evp sensor is new, so that tells me its either wiring or the darn pcm itself Thanks Robert

 

What code #? The reason I ask is because I had a similar problem, but my code was 33. It only appeared after converting my SD 302 to Mass Air. Tried everything, swapping another good EVP sensor, good non-Motorcraft EGR valve, still same code. Lots of research led me to replacing with New Motorcraft EGR valve, and since then (7 months, 4,000 miles) never came back.

Trust me when I say, I'm cheap cuz I didn't want to spend $177.xx, but it got that darn CEL to stay off.

Just a thought...

 

Hey bro Im getting code 33 but my cel is not on this is from key on engine running ive even tried to clear it disconnecting batt. pulling the jumper wire during test. I know the EGR will open manually by grounding it From the EVR but i do not believe it is opening while driving it. I do not have a MAF sensor But I do have a MAP sensor though, i replaced that a year or so ago. I do have the original Motorcraft egr valve back on. Oh and it will open with straight vacuum to it. Please let me Know what you think? Robert.

 

Code 33: EGR valve opening not detected. This is a CM and KOER code.

It simply means the PCM is sensing no change in the EVP output when it has commanded the EGR to open via the EVR.

Use a DVM to measure the EVP output with the engine off/key on. Record the value. Repeat with the engine running. The values should be very close. If not, you have a leaking EVR. Replace if necessary.

For this next test I prefer to have the engine off/key on. Keep your DVM connected to the EVP then manually apply some vacuum to the EGR. The EVP output should increase from the closed value. If you cannot manually apply some vacuum, using a hand held vacuum pump, then you could do this with direct manifold vacuum (engine running).

Assuming the EVP value increased in the last test then repeat with the engine running, but this time momentarily ground the EVR to apply manifold vacuum to the EGR using the normal vacuum supply route.

If the EVP output never changes, or very little then you need to look at the EVP itself as well as the EGR.

If everything checks out then you need to rig up a gauge and drive the truck. You may have a leaking vacuum reservoir located on the passenger side fender. This metal coffee can looking device is well known to rust out. If you run out of vacuum the EGR will close....

 

I was doing a open loop check on all the wires to the EVP Sensor they all checked good and the green wire to the EVR, that had good continnuity also. and good 12v. to the red wire, and i can open the EGR by grounding the EVR to the battery. So to me that would say my PCM maybe shot? is that possible any one think so? Thanks Robert.

 

Please define that statement in bold. That means absolutely nothing to me. What were the measured voltage values and under what conditions?

 

All I meant was all the wires have good continuity To the EVP, EVR no broken wire to these parts so I think my computer is not telling the EGR valve to open when it is supposed to I guess. I'm sure I probably don't know what I'm talking about this is just driving me insane.

 

Continuity between the computer and sensor/solenoid is vital. Go the next step and verify the EVP output using your DVM set to DC Volts as I outlined above.

For reference: Fuel Injection Technical Library » EGR Valve Position sensor (EVP)

 

I guess my point would be i dont think my EGR is not opening unless i manually open the evr itself by grounding it momentarilly But I probably said that already I think? Thanks for the help.

 

Quit guessing...measure it . Verify what the PCM thinks is going on.

 

I have 4.9 volts between vref signal return which should be good right? My friend

 

That's good. That means the PCM is sending out the correct VREF signal and it is getting to the EVP. Now measure the signal output in reference to Signal Return.

Reference the output voltages in the link I previously sent.

 

.31 volts is what I got with the connector to the sensor and If I remember that should be ok to I think thanks again.