EGR? Running rough.
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EGR? Running rough.
I have a 1994 5.8. It was running rough when I received the truck a couple of months ago, so I replaced:
plugs
wires
cap
rotor
fuel filter
(All Motorcraft because I didnt want to replace again any time soon)
Ran great for a couple of weeks.
NOW I have:
rough idle
seems to have VERY little power
barely makes it up ANY incline
A/C cuts off when working to climb any incline (A/C returns once I fully let off the gas)
I have not found any vacuum leaks (sprayed carb cleaner meticulously, but no RPM changes)
Tried to test EGR:
Motor was warm
Son held RPM @ 2500 while I was under hood
There is no vacuum from line that plugs into EGR
EGR diaphram doesnt move
I can move EGR diaphram freely with finger
Any ideas??
plugs
wires
cap
rotor
fuel filter
(All Motorcraft because I didnt want to replace again any time soon)
Ran great for a couple of weeks.
NOW I have:
rough idle
seems to have VERY little power
barely makes it up ANY incline
A/C cuts off when working to climb any incline (A/C returns once I fully let off the gas)
I have not found any vacuum leaks (sprayed carb cleaner meticulously, but no RPM changes)
Tried to test EGR:
Motor was warm
Son held RPM @ 2500 while I was under hood
There is no vacuum from line that plugs into EGR
EGR diaphram doesnt move
I can move EGR diaphram freely with finger
Any ideas??
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The vacuum line is there, but there is no vacuum (suction) from that line.
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So I ran through the video and got the following:
1ST key on/engine off
Current code-
539
Saved code-
327
334
543
Key on/engine on
Code- 116
2ND key on/engine off (wanted to triple check codes)
Current code-
111
Saved code-
327
334
543
1ST key on/engine off
Current code-
539
Saved code-
327
334
543
Key on/engine on
Code- 116
2ND key on/engine off (wanted to triple check codes)
Current code-
111
Saved code-
327
334
543
Elder User
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The EGR vacuum regulator meters vacuum to the EGR valve. It doesn't always hold vacuum on the EGR. It is not a lot of vacuum either, so it might be hard to "feel it".
Check the plug for the EGR valve position sensor (EVP). Then check the sensor. That's your codes 327 and 334. https://www.fullsizebronco.com/threa...cement.218407/
ECT (code 116) is probably fine. The truck might not have been warmed up all the way.
Edit: the AC cutting out is almost certainly a vacuum leak somewhere. Could be vacuum reservoir. Another common culprit is the white vacuum line for the AC blend door actuator (passenger side near the firewall). Lots of threads / videos on it.
Check the plug for the EGR valve position sensor (EVP). Then check the sensor. That's your codes 327 and 334. https://www.fullsizebronco.com/threa...cement.218407/
ECT (code 116) is probably fine. The truck might not have been warmed up all the way.
Edit: the AC cutting out is almost certainly a vacuum leak somewhere. Could be vacuum reservoir. Another common culprit is the white vacuum line for the AC blend door actuator (passenger side near the firewall). Lots of threads / videos on it.
Last edited by mark1986F150; Aug 13, 2020 at 01:26 PM. Reason: AC / vacuum leak
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The EGR vacuum regulator meters vacuum to the EGR valve. It doesn't always hold vacuum on the EGR. It is not a lot of vacuum either, so it might be hard to "feel it".
Check the plug for the EGR valve position sensor (EVP). Then check the sensor. That's your codes 327 and 334. https://www.fullsizebronco.com/threa...cement.218407/
Check the plug for the EGR valve position sensor (EVP). Then check the sensor. That's your codes 327 and 334. https://www.fullsizebronco.com/threa...cement.218407/
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Check the harness connector very carefully. Check that wires are held in tightly and contacts look okay. You might measure voltage that is correct when the sensor is unplugged and no current is flowing. But high resistance in the connector will affect voltage when current is flowing when the evp is plugged in. My guess is it's sigrtn wire issue.
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Out of curiosity I started the truck and let it warm up. I increased the throttle and held for several seconds (using throttle cable) and watched the EGR diaphram. It did raise up on it's own but only held for a second or 2 before falling. This was with no change in throttle. Does this mean bad EGR?
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Check the harness connector very carefully. Check that wires are held in tightly and contacts look okay. You might measure voltage that is correct when the sensor is unplugged and no current is flowing. But high resistance in the connector will affect voltage when current is flowing when the evp is plugged in. My guess is it's sigrtn wire issue.
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Maybe... probably not though. The EGR is not always open. I seem to recall the vacuum regulator sends 4 to 8 inches of vacuum to it... oscillating back and forth (somewhat rapidly) so the "average" EGR position matches what the computer wants. Keep in mind the vacuum regulator also "leaks" vacuum (that's by design though).
What you observed may have been the computer trying to figure out where the EGR valve actually is sense the EVP sensor is out of range.
What you observed may have been the computer trying to figure out where the EGR valve actually is sense the EVP sensor is out of range.
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One more thought... You may want to check the vacuum reservoir. IIRC there is a check valve on the engine-connection to hold vacuum when you open the throttle. You may not have any actual vacuum to send to the EGR when you open the throttle if the checkvalve is bad. That would explain AC too.
The computer wouldn't know the difference. It has an idea of what the EVP should read based on the signal it's sending to the EVR to control the EGR opening. So if there's no vacuum to actually move the EGR, it will read high or out of range.
The computer wouldn't know the difference. It has an idea of what the EVP should read based on the signal it's sending to the EVR to control the EGR opening. So if there's no vacuum to actually move the EGR, it will read high or out of range.
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