The code won't just go away after you change a sensor, you have to clear the codes and check them again later to see if it came back.

The EVR(egr vacuum regulator) controls vacuum to the EGR valve, this solenoud is over by the coil.. should be on the same bracket as the TAB and TAD solenouds. Sounds like yours is not operating correctly or the vacuum supply to this solenoid is missing.

 

I was thinking, What is your thermostat rated at? If you are running a 160F or 170F (or stuck open),you might never see the EGR move. It would also explain your s**tty MPG!

 

Im not sure what the thermostat is rated at. pretty sure it is the original one. Planning on changing it as soon as it warms up around here. I also ran the KOEO test and got the code along with a 44 (i think thats the right code), but its "Thermactor Air Injection system inoperative (Right side)." not really sure on what to do here, but there were some other posts in the other thread, about this though.

 

When you supply vacuum to the EGR valve the engine should run rough because of the addition of exhaust gas, (basically it leans out the fuel mixture). So it sounds like you either have a bad diaphram or a very and do note very small obstruction in the orfice. Your truck should do the exact same thing your dads truck did when you applied vacuum and I doubt the IAC is at fault. Also the EVP sensor on top of the EGR valve, EVP= (EGR Valve position sensor) tells the computer what position the EGR valve is in. Usually a code is set because the computer "sees" that either the EGR valve is not opening or staying open when the EEC wants it off. So if it were me I would replace the EVP and the EGR with one from ford and be done with it.

 

If the amount of fuel injected remained the same, the mixture would actually become richer because there would be less oxygen available for combustion. But the computer dials back the fuel to maintain the proper ratio, even with the exhaust gases present. If the EGR valve is sensed open and no exhaust gases are present, then you are right, the mixture would be lean.

 

after taking off the EGR to check for obstructions, i replaced the EVR and the gastket and put it back on the truck. After this i applied vacuum to the EGR and the motor almost stalled. So, as was said before, i have no vacuum to the EGR from the green vac hose. The hose is not clogged and it has no kinks/cracks in it. Maybe bad EVR?

 

What temp thermostat should I be running? I believe the one in it is the one from the factory and I ws thinking that maybe i should be running a 180 degree one. Correct me if im wrong.

 

Stock is 192-195 degree. Have you tested the EVR by momentarily jumpering its negative wire to ground? How does the EGR behave? Did you monitor vacuum signal to the EGR valve while driving?

 

Okay, im went and got a new 190 degree tstat and asked about picking up a new EVR. The autoparts store didnt have any and said that they cant even order one. I went to another parts store and asked them, they said they can order one for $88. Before i go throwing the money at em, I want to test the EVR. Im really not sure where this selinoid is.. I went and looked for it breifly and couldnt find anything that resembled the picture on FFI.com. Also, how would you monitor the vacuum to the EGR while driving?

 

If you're not measuring vacuum to the EGR while driving, then how did you come to this conclusion?: The EVR solenoid will only supply about 8 inches of vacuum to the EGR valve at maximum. I've never been able to get vacuum to the EGR valve while the truck was sitting still, and it should never be active at idle or wide open throttle. So unless the vacuum signal is being measured, there's really no way of knowing if the EVR is functioning properly or not and replacing it would be a shot in the dark without testing the valve and monitoring the vacuum supply to the EGR valve while running and driving.

The EVR solenoid is on a bracket with the TAD and TAB solenoids, usually near the ignition coil on the 351.

 

Well im still getting a 33 but I replaced the EGR, the gasket, and the EVP, tested to make sure the new EGR held vacuum, and it did. I started up my dads '94 and took it to the parts store to get some headlights for my truck and when i got back, i popped the hood and removed his hose and felt vacuum on his at a standstill. On mine, there's nothing.

 

Narrow things down until you find the problem. Try to pull a vacuum on the green plastic tube at the EVR and see if the line and EGR will hold vacuum since you know the EGR itself will. Then either with the engine running or with a vacuum pump on the EVR supply side, momentarily ground the EVR negative wire and see if the solenoid energizes and passes vacuum to the EGR. Have you measured the voltage output or resistance of the new EVP to make sure it is within range and is working properly?

 

The voltage output was in range. I have been looking for the EVR and the TAB/TAD along the passanger firewall/panel and cant seem to find them. Can someone post a picture of exactly where this bracket is so i can see if it was removed from the truck or not?

 

The bracket is mounted to the engine above the driver side valve cover near the ignition coil.

 

Well today in our 65 degree weather in the unpredictable state of Ohio, i started looking around the motor for other possibilities of why the EGR may not have been getting vacuum. I finally found the culprit. The vacuum lines between the EVR and the plastic adapter were almost melted together. I dont know how i missed this, but probably because it was back almost behind the motor. I now have a little vacuum at idle and it increases with RPMs. So, i have the computer resetting (this takes around 20 mins with battery cables off, correct?) and will drive the truck about 40 miles or so to see if the code will clear!

QUESTION:
Those other two hoses that are in the same connector, what do they control? I believe one is black and the other is red? do these have something to do with the operating TAB/TAD selinoids?