Code 334
#1
Code 334
The Actron code reader said I have a 334 KOEO. Looks like a problem with the EGR...
334:
EGR Valve Position (EVP)
sensor – signal voltage
higher than expected
(closed valve position).
I got a 334 for the CM too.
The truck idle is smooth when warming up, but rough at idle when warm. It's been this way since I got it 4 years ago. I passed smog 2 times but the last time just barely. I need to pass again now.
What should I change, or should I take it off and clean any deposits. From searching it could be either the sensor or the actual plunger thing on top of the EGR.
Thanks for the help.
334:
EGR Valve Position (EVP)
sensor – signal voltage
higher than expected
(closed valve position).
I got a 334 for the CM too.
The truck idle is smooth when warming up, but rough at idle when warm. It's been this way since I got it 4 years ago. I passed smog 2 times but the last time just barely. I need to pass again now.
What should I change, or should I take it off and clean any deposits. From searching it could be either the sensor or the actual plunger thing on top of the EGR.
Thanks for the help.
Last edited by CraigK; 01-11-2013 at 02:10 PM. Reason: more information
#3
I cleaned the egr and cleared the code. The egr wasn't very dirty and the egr pressure feedback plunger moved freely. The truck ran great for a bit, shifted really nicely, but the code is back.
With a warm engine, I tested the voltage at the vacuum solenoid and I get 12+. I think I read that it's supposed to drop as the engine warms up, but I can't find the link someone posted.
What do I do next?
Thx.
With a warm engine, I tested the voltage at the vacuum solenoid and I get 12+. I think I read that it's supposed to drop as the engine warms up, but I can't find the link someone posted.
What do I do next?
Thx.
#4
#5
I'm not sure about the voltage, but if you can, cap the line running to the EVP with a golf T. Or if you have a vacuum gauge, attach it to the line running to the EVP. If you are pulling vacuum above 1"-Hg, there is a problem with the EVR. There should be at least 10.5 volts on VPWR terminal with ignition switch in RUN position.
It could be the EVR is allowing vacuum through, therefore allowing vacuum to pull the pintle up on the EVP, pulling the plunger up on the EGR, allowing exhaust gases back into the intake.
Also note there are 2 different EVR's. One gray and the other black. Only replace with same color if diagnosing points to malfunctioning EVR.
It could be the EVR is allowing vacuum through, therefore allowing vacuum to pull the pintle up on the EVP, pulling the plunger up on the EGR, allowing exhaust gases back into the intake.
Also note there are 2 different EVR's. One gray and the other black. Only replace with same color if diagnosing points to malfunctioning EVR.
#6
I cleaned the egr and cleared the code. The egr wasn't very dirty and the egr pressure feedback plunger moved freely. The truck ran great for a bit, shifted really nicely, but the code is back.
With a warm engine, I tested the voltage at the vacuum solenoid and I get 12+. I think I read that it's supposed to drop as the engine warms up, but I can't find the link someone posted.
What do I do next?
Thx.
With a warm engine, I tested the voltage at the vacuum solenoid and I get 12+. I think I read that it's supposed to drop as the engine warms up, but I can't find the link someone posted.
What do I do next?
Thx.
As noted before the VPWR supply to the EVR is always there with the key in the On/Run position. The PCM (computer) turns the EVR on/off by supplying a ground to the return side of the EVR. This on/off process modulates the EVR which in turn controls the amount of effective vacuum supplied to the EGR valve.
For reference:
Fuel Injection Technical Library » EGR Valve Position sensor (EVP)
Fuel Injection Technical Library » EGR Vacuum Regulator (EVR)
#7
The OP has an 1995 model which uses the older style EGR position feedback. Yours uses the newer, and still used, DPFE (pressure) EGR feedback setup.
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#8
That's the page I was looking for...
I removed the green line and applied vacuum to the EGR and it held vacuum. I could see it move. The idle got rough and it wanted to stall.
I connected that back up and put the vacuum on the green line at the EVR and the gauge showed no vacuum.
From the library page above:
With everything connected and the engine running ground out the pin 33 side. The EGR vavle should open and the engine RPM should change.
Ford EGR valves will open 50% at 4 inHg of vacuum, and 100% at 8 inHg of vacuum.
Auto electrical is not my strong point. How do I do this?
I removed the green line and applied vacuum to the EGR and it held vacuum. I could see it move. The idle got rough and it wanted to stall.
I connected that back up and put the vacuum on the green line at the EVR and the gauge showed no vacuum.
From the library page above:
With everything connected and the engine running ground out the pin 33 side. The EGR vavle should open and the engine RPM should change.
Ford EGR valves will open 50% at 4 inHg of vacuum, and 100% at 8 inHg of vacuum.
Auto electrical is not my strong point. How do I do this?
#9
That's the page I was looking for...
I removed the green line and applied vacuum to the EGR and it held vacuum. I could see it move. The idle got rough and it wanted to stall.
I connected that back up and put the vacuum on the green line at the EVR and the gauge showed no vacuum.
From the library page above:
With everything connected and the engine running ground out the pin 33 side. The EGR vavle should open and the engine RPM should change.
Ford EGR valves will open 50% at 4 inHg of vacuum, and 100% at 8 inHg of vacuum.
Auto electrical is not my strong point. How do I do this?
I removed the green line and applied vacuum to the EGR and it held vacuum. I could see it move. The idle got rough and it wanted to stall.
I connected that back up and put the vacuum on the green line at the EVR and the gauge showed no vacuum.
From the library page above:
With everything connected and the engine running ground out the pin 33 side. The EGR vavle should open and the engine RPM should change.
Ford EGR valves will open 50% at 4 inHg of vacuum, and 100% at 8 inHg of vacuum.
Auto electrical is not my strong point. How do I do this?
Use this for reference:
courtesy of oldfuelinjection.com
#10
#12
#13
#14
#15
You are much better off measuring the output voltage of the EVP. The values are listed on the page I linked to before.