EGR system not operating correctly...
 

Here are the details... please read everything before you offer any advice.

1. The car is a '92 5.0 with a consistent rough idle and rich fuel mixture problem. It bogs at tip in/low RPM.

2. The following parts have been replaced and have been tested as good.

EGR valve
EGR position sensor
ECT sensor
IAC valve

3. Running codes produces:
034 (EGR Valve position sensor voltage above closed unit)

Here's the rundown on the EGR system. The EGR valve and position sensor are new and test out. The green vacuum line coming from the EGR vacuum regulator solenoid actually pushes air out into the EGR valve at idle and produces very little vacuum at higher RPM. I can see no visible movement of the bladder in the EGR as I rev the motor with the vacuum line attached. With the EGR valve disconnected, the car seems to smooth out and power is regained.

Does it sound like the EGR vacuum regulator solenoid is bad? What are the symptoms? How would the car run with the EGR staying in the closed/open position?

The EGR valve needs to open going down the road just cruising around and in theory will open about 15 sec into a WOT run down the track trying to keep emision levels low. If EGR opens at an idle you will get a lean condition. Thats why with what is mentioned above when you are running a supercharger or even N/A high horse combos you dont want an uncontrolled gas coming into the combustion chamber when at WOT. Otherwise it may turn ugly if you dont tune around it(ex. richen up strategy at wot to save the engine.) In all actuallity EGR will not open just reving it up in the driveway. You would actually have to put a vacum gauge on it driving down the highway to tell whether or not the EVR(EGR Valve Regulator) is comanding on the EGR valve. You can simulate this effect in the driveway. Go to the parts store and rent a hand vacum pump and attach it to the EGR valve. When you pull vacum at an idle the car should die. Bring up idle a bit and pull about 10in of vacum. The car should rough up for a bit but then smooth out once the 02 sensors catch up. Another thing to check would be EGR Valve Position Sensor voltage on the feed and return side. The feed should be 5v reference and the return side to the ECU will vary by applying the vacum pump. As far as the EVR goes I have really never seen one go bad. It works similar to a Idle Air Control valve. 12v input from the ECU varying in voltage depending how much EGR the ECU needs. Be sure to check the input vacum source. Not that the line is pinched off or broken somewhere it should be manifold vacum at that point. Make sure it is plumbed correctly and that it is wired correctly not that the TAB and TAD solenoid wires are connected to it. Those would be on the strut tower right next to the EVR. Thermactor Air Bypass and Thermactor Air Diverter used for the smog pump located below the alternator. If you choose to skip the whole process and just want the car to run remove the egr from the manifold and block the hole. But make sure to leave the EGR and EVP connected to not set the check engine light on again. I think anything beyond that is going to start looking at 02 sensor voltage, wiring, ect temp, act temp, and vacum line routing. Hope this helps. I do have more info if you need it.


Brad

It's all a little overwhelming to me. My car is running cool. Usually around 170 to 180. This is a result of using a 180 thermostat and waterweter. I also recently installed an aluminum radiator. I will install a factory thermostat tonight. I did get an ECT code (21) along with the 34 code. However, I'm confused as to what this may have to do with my current problem. When you first start the car it's not going to be instantly at running temp. I can see it affecting the car once at operating temp because it never reaches the factory temp. I'm also confused with how the vacuum should be plumbed. I have Power Plus intake. I'm thinking we may have the vacuum set up wrong.

Do you still get the ECT code with EGR code? The ECT temp is very important to the ECU and runs fuel and timing tables off of the ECT temp. There is no problem to just running a 180degree tstat. That should keep the ECU and cooling system happy. As far as getting the vacum lines routed incorrectly I know from personal experience that it can be a real treat. I just installed that intake on my own setup. Let me know if you need assistance on where everything is routed to. Also the EGR and ECT temp sender are related because it will only operate EGR when up to operating temp so if it was cold and it tried to operate EGR it tried to make a difference soooo much that it reached its limit. So you may not even have EGR problems it could just be related to the ECT temp. So replace the ECT temp sender in the intake manifold(short one that goes into the water jacket of the lower intake) and get rid of that problem first. Then work from there. Also when you are all said and done disconnect the battery for five minutes and reconnect. Then start it back up and drive it. Let me know if this works out for you. Sorry for being so detailed it can be very overwhelming to me at times to.
Hope this helps.

Brad

Actually I took the ECT module and the EGR to Autozone and they both checked out okay according to them. I guess I could swap out one from my other foxbody and see if it makes a difference. Also, could you tell me how you routed your vacuum lines from the intake? Pictures would also be great.

ECT module? Lost me there. I was talking about the Engine Coolant Temp sender that the ECU uses to know where engine temp is at located in the lower intake manifold. As far as vacum line routing goes it will take a bit I think I even wrote it down somewhere. I did include a pic but its kind of hard to tell. The little vacum line out of the back of the intake goes to the EGR vacum regulator and to the fuel pressure regulator. The big one out of the front goes to the Canister Purge canister located on the front pass apron near the air intake. The large one located right rear of the manifold goes to the vacum tree that is on the firewall for brakes, A/C, and heater and stuff. The one located underneath the intake goes to the PCV valve on the back of the lower intake. I wish I could draw a pic but man I am horrible at that. Hope this helps.


Brad

Ok bear with me here. This is bad but it may help. I attached the file on how it should look. Hopefully it helps.


Brad

I was talking about the ECT sender. Thanks for the drawing.

Ok I understand. Hopefully you can get that straightened out.


Brad

I give up! Everything I have done so far has made it worse. I guess I will have to take to a shop. Thanks for all your help.

What What What????????????? What have you done?

Mainly just reroute vacuum lines. I also checked the mass air meter filament which was not dirty. I changed out the ECT sensor with another car I have. It seems like the vacuum lines have impacted the car in terms of running. I would still have had a rich problem but at least the car would run. Now it bogs down and back fires.

How long have you had this combo together? Was it ever running good? Do you still get the codes? What is fuel pressure set at? What type of fuel pressure regualtor do you have?


Brad

I have had this setup for about 6 months. I can't really recall when I started having a rich condition. I had an injector with a broken pintle. I replaced it thinking this may have been dripping fuel or something. I have an after market FPR (can't remember the brand) fuel pressure is at 38. This is the first time I have gotten the codes because I just got the computer recently. I replaced the EGR valve, IAC. I have a PRO M 75 mass air meter and had a C&L 76 before. Timing is at 14 degrees.

Are you still running rich? Just curious to see how it was going on your end.



Brad

I made some improvement. It's not backfiring anymore. But it's still not running right. It's not responsive. Kinda feels like something is holding it back. So yes, I guess it is still running rich. I guess I will fiddle with it a while but my trouble shooting experience is limited. It just seems like to many possibilities to narrow it down. I will probably put the computer on it to see what codes it is giving. I'm sure I will see an EGR code.

Thanks for asking though. Are you a Packer's fan? Man you guys got a gift and maybe the hottest team in the NFC right now. I'm a Dallas fan but I doubt they beat the Panthers. I hope the Pack get's to play Philly. I think you will beat them there. I love Brett Favre and did so when we had Aikman. I would take Favre over Aikman any day!

Your right there are a lot of possibilities to your problem. I just probably made it worse by making a bunch of ideas run through your head. Sometimes basic beats out overwhelming information. Let me know what codes you get again.

I am a jump on the bandwagon packers fan. I love watching there games on sunday but I dont get into it until they start playing good again like now. One thing good though is that it does bring a lot of revenue to the state. As far a Favre goes. Man hes like his own team. If he could throw to himself it would get real interesting.


Brad

Well I have some more progress but It's still not running right. I have replace the EVP and EGR (Autozone Warranty) and have the vacuum lines correct. I checked for vacuum leaks by listening with a vacuum hose. I also swapped the EGR solenoid from another working car. I'm still getting code 12 and 34. Car now idles rough when started the improves as car warms up. Car still runs lean. Code 34 (orc): EVP or PFE voltage above closed limit during operation. I don't understand what this means and I don't know what the PFE is. I'm also wondering if it could be the Barometric Pressure Sensor. I understand that this sensor does impact the mixture but I'm not getting a specific code. I have the luxury of having a 93 Cobra to swap parts with. I guess tomorrow I will swap this sensor. Is the MAP the same as the BAP? I think I'm getting close.

Your car only has a BAP sensor.