'94 problems
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'94 problems
I'll start out saying I have a 1994 F-150 with the 4.9L big six and the E4OD automatic trans.
While going 30MPH -and- while Vacuum is at 10hg and holding my truck will start running very rough like it's starving for fuel and the CEL will come on, there's two codes from this it seems, one that the O2 sensor is reporting rich and the other is an EGR code. Any ideas?
While going 30MPH -and- while Vacuum is at 10hg and holding my truck will start running very rough like it's starving for fuel and the CEL will come on, there's two codes from this it seems, one that the O2 sensor is reporting rich and the other is an EGR code. Any ideas?
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codes that are being thrown are 334 O(EGR closed valve voltage high), 179 C(HEGO sensor fault unable to switch/rich during part throttle), 327 C(EGR valve position circuit below minimum voltage), 334 C(EGR closed valve voltage high).
The O2 sensor is a new Denso that I replaced when getting the code, the EGR valve and valve position sensor were replaced, the original issue was the EGR vacuum solenoid went up and I eventually got it. I also have a new exhaust from the manifold back
The O2 sensor is a new Denso that I replaced when getting the code, the EGR valve and valve position sensor were replaced, the original issue was the EGR vacuum solenoid went up and I eventually got it. I also have a new exhaust from the manifold back
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From: Easton,Ks
The 334 means the EGR valve is not closing so it is stuck and needs to be cleaned or replaced.
It also sounds like you may have some old codes.
Ground the STI wire and turn on the key and when the MIL stars to flash remove the ground from the STI wire and your codes will be cleared.
Do not unhook the battery to clear the codes as that will cause another code and cause a driveability problems for about 10 miles.
Then run the code test again after you drive it and post back what you get.
It also sounds like you may have some old codes.
Ground the STI wire and turn on the key and when the MIL stars to flash remove the ground from the STI wire and your codes will be cleared.
Do not unhook the battery to clear the codes as that will cause another code and cause a driveability problems for about 10 miles.
Then run the code test again after you drive it and post back what you get.
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It looks like your EVP signal is all over the board, below 0.2VDC then above 0.67VDC when the EGR should be closed. Did you clear the codes after replacing the EVR?
I question if the EVR you installed might be leaky? That could be the root cause of the 179 code.
I question if the EVR you installed might be leaky? That could be the root cause of the 179 code.
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How do you mean leaky? As in leaks out vacuum or leaks out exhaust gas into the engine?
I haven't had much of a chance to work on this since I haven't had a day off but I picked up an auto-ranging voltmeter so I'll at least be able to start troubleshooting.
I'll also probably get my timing checked just for good measure, I need to bump my timing up a little bit anyhow but I don't have the guts to just turn the distributor without checking my current timing.
I haven't had much of a chance to work on this since I haven't had a day off but I picked up an auto-ranging voltmeter so I'll at least be able to start troubleshooting.
I'll also probably get my timing checked just for good measure, I need to bump my timing up a little bit anyhow but I don't have the guts to just turn the distributor without checking my current timing.
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From: Kentucky
The EVR is the EGR Valve Regulator. The PCM sends a signal to the EVR to modulate the EGR valve open/closed. If the EVR is not closing completely vacuum may be applied to the EGR valve when it is not supposed to.
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I see. I'm fairly sure that also was replaced. Would a good test be to plug the vacuum line to the EGR for a day or two and see if that helps?
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Stick a voltmeter on the EVP signal output, turn the ignition key to the on position. Note the signal voltage output. It should be below .67 VDC. If it is not, then you need to start looking at the EGR valve itself or a bad EVP sensor. If the voltage is in range, start the truck, see if the voltage output from the EVP is close to the same (it should be) as when the truck was not running. If the voltage rises then you know there must be vacuum getting through to the EGR valve.
If you have a vacuum gauge, install it inline with the vacuum line running to the EGR valve from the EVR solenoid. Start the truck, the vacuum reading should be zero. If it is not then you know the EVR is letting vacuum through to the EGR valve when it is not supposed to be there.
If you have a vacuum gauge, install it inline with the vacuum line running to the EGR valve from the EVR solenoid. Start the truck, the vacuum reading should be zero. If it is not then you know the EVR is letting vacuum through to the EGR valve when it is not supposed to be there.
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Well, waiting on my new red haynes to shine light onto sensor checking I did some playing around with my vacuum lines.
Removing and plugging the line to the EGR solves the driveability, the Vacuum _AND_ the spark knock but it causes a CEL
There's no apparent change at idle though but it's a huge difference from there on out. I'll put a gauge on it and see what it says for idle and higher.
Removing and plugging the line to the EGR solves the driveability, the Vacuum _AND_ the spark knock but it causes a CEL
There's no apparent change at idle though but it's a huge difference from there on out. I'll put a gauge on it and see what it says for idle and higher.
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The EVR looks like it starts putting a little vacuum out at 1,000RPM and puts out 6hg at 2,000RPM and the 6hg will stay when gracefully slowed to 1,500 RPM. When it loses vacuum it makes my vacuum gauge needle hit the 0 stopper peg hard enough for a little sound though both the needle and the peg are metal I believe but the truck does not do that in any other normal operation.
I also cleared the codes the way it was suggested and I'll see what comes back up. I hope I'm starting to get somewhere now
I also cleared the codes the way it was suggested and I'll see what comes back up. I hope I'm starting to get somewhere now
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EVR Re-replaced, after driving it for a while with it disconnected it initially drove better until it "re-learned" now it's back to square one. Someone told me that the computer should affect how the EGR works according to the engine temperature. Is that true?
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temperature doesn't seem to make a difference currently, so I'm wondering if the ECT for the computer is bad.It opens any time the engine's RPMs get higher, 1,500RPM starts off with lower vacuum(2-3) then slowly opens up more and more until it's at the full 6 even if staying at 1,500RPM and with no more gas pedal movement.