Getting error codes 327 and 334

Popped Vacuum hose off top of EVP and put hose on and sucked.

Engine was running

No change in idle at all when I sucked or blew in vacuum hose.

Does this mean bad EGR?

93 5.0, Auto.

 

Considering the fact that the those two codes have nearly opposite meanings, I would be more concerned about the EVP and/or the wiring to it.

Code 327 - EVP circuit BELOW minimum voltage. With this Code, make certain you are getting +5VDC (VREF) at the BROWN/WHITE wire before you try to troubleshoot any further. Check the connection to the EVP as well.

Code 334 - EVP circuit (closed valve) voltage higher than expected. This means one of two things. Either the EGR valve is not closing all the way or the EVP sensor is bad.

 

Thanks, Grey,

I am getting +4.97 VDC.

I can pull the vacuum hose off the top of the EGR and it feels like there is a good amount of vacuum.

How do I test the sensor vs testing the actual EGR now?

 

4.97 VDC is just fine.

Connect your meter to the BROWN/LT. GREEN wire coming from the EVP sensor and take the reading again. With the EGR valve closed (no vacuum) the voltage through this wire should only be about 0.5 VDC. As vacuum is applied, the voltage should rise and it should rise as smoothly as vacuum pressure increases. In other words, there should be a direct correlation between the amount/magnitude of vacuum applied and the change in voltage. At no time should the voltage exceed the reading you already got from the test you have already done.

If the voltage jumps around or doesn't change as vacuum is applied, the sensor needs to be replaced. If the voltage ever drops BELOW 0.5 VDC replace the sensor. If the voltage ever spikes above 4.97 VDC... um... well you have stranger problems than a bad sensor because its a virtual impossibility.

If the voltage does not change at all, make sure the EGR valve is actually moving when vacuum is applied. You can apply vacuum and observe the diaphragm and pintle through the small holes in the side of the valve. If you apply and release vacuum quickly, you can hear the valve snap shut as well.

 

I tested it again. VDC doesnt change to any of the wires, hot or cold, vacuum or not.


Far right wire/prong stays at 5.0
Top middle stays at .01
Left one stays at 3.7

this is standing in front of the motor looking at the plug.

 

Make sure the valve moves when vacuum is applied. If it does, replace the sensor. If it doesn't, replace the valve.

 

Thanks Grey, hooked a new hose up, sucked in and out and I could hear the EGR valve popping up and down when I sucked and released.

Getting new sensor to be installed on Saturday. I will report back to see if my codes goes away.

Thanks for all the help.

 

New problem EVP/EGR after EVP replacement!!
Put new sensor on after testing old sensor and not getting right voltage.

Now my error code 327 is gone.

Car starts and idles fine, when I rev it up, when it comes back down it dies.

When I unplug the connector to the EVP and Rev motor it comes back down and Idles fine....

Pulled codes getting 334 still, no CEL.

Clean IAC as next step?

1993 FSB, 5.0, A/C, E4OD. Stock.

 

With the new sensor in place and the valve closed, the voltage at the BROWN/LT.GREEN wire (the LEFT one from your previous description) should be no more than 0.5 VDC. If this voltage remains higher, about the only thing that could cause it (short of getting a bad EVP right out of the box) would be an EGR valve that is not closing fully. Carbon deposits and crud in the seat for the pintle or a weak return spring would be the culprits.