Code 334
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Senior User
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From: Burbank, CA
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; Jan 11, 2013 at 02:10 PM. Reason: more information
Thread Starter
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Senior User
Joined: Dec 2008
Posts: 142
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From: Burbank, CA
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.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
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.
Fleet Owner
Joined: Oct 2005
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From: Kentucky
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)
Fleet Owner
Joined: Oct 2005
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From: Kentucky
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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From: Burbank, CA
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?
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Fleet Owner
Joined: Oct 2005
Posts: 20,783
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From: Kentucky
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
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Senior User
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From: Burbank, CA
I hooked up a wire to Pin 33 and ground to the negative terminal of the battery. The EGR opened. I could see it and the truck began to stumble.
The EVR makes noises when I turn off the truck. Is that normal?
The EVR makes noises when I turn off the truck. Is that normal?
Fleet Owner
Joined: Oct 2005
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From: Kentucky
Some make more noise than others, but yes it is normal.
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Senior User
Joined: Dec 2008
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From: Burbank, CA
I'm still not sure which is causing my problem. If the EVR is working properly, it seems like the problem is the EVP.
How do I test this part? Nothing is mentioned on that fuel injection page.
How do I test this part? Nothing is mentioned on that fuel injection page.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
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From: Mexico, Missouri
Check resistance if the evp. I don't think it should be above 5k ohms when the pintle is resting and no more than 100 ohms when completely pushed up. I don't have my book, but will check this morning after work. I may have it opposite in regards to its position in ohms.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
After reading the article, it says that, "At idle, the EVP sensor signal should be apprx. 5000 ohms(EGR valve closed), reducing to 100 ohms when the EGR valve is fully open."
Hope that clears my prior statement up.
Hope that clears my prior statement up.
Fleet Owner
Joined: Oct 2005
Posts: 20,783
Likes: 1,751
From: Kentucky
You are much better off measuring the output voltage of the EVP. The values are listed on the page I linked to before.