Keith Browning Posted January 5, 2008 Share Posted January 5, 2008 I have a repeat offender in the shop. The truck was towed in after stalling leaving codes P0404 and P1335 in memory. Started up immediately as it had the last two times in the shop with the same codes and complaint. I could not verify any fault either time. Shop manual leads to a new valve each time. First time I had no problem with replacing the valve. Came back 3 months later, same problem, manual says its the valve so I contact the Hotline. They suggested a broken EGRDOC or leaking EGR cooler - nope, no DOC debris or wetness. Just light carbon which is dry. It got another valve which I did not agree with but I'll try anything once. So now the PCED is telling me the valve is bad again. I thought perhaps the PCM might be malfunctioning after running for a while so I set the EGRVPDES to 30% and went to lunch. When I came back to it and started to open and close the valve with IDS the valve stopped working. Cool! I verified it!!! I decided to test all of the circuits from the valve to the PCM - all good. But this left me with more questions than answers. First, If I verify all circuits and find no shorts to power - ground -each other the PCED always points is to replacing the valve. There is not a single test that checks the circuits for power and or grounds during operation - VPWR or ground switching. Second, how does the EGR valve actuator function? I cant find this documented anywhere in Ford's literature. I even looked at the web training courses again. I recall being told this valve has a DC stepper motor with a position sensor. Should I assume that the EGRVCL and EGRVCH circuits power the motor as per commands by the PCM and the PCM changes polarity of the circuits to move the valve open or closed accordingly? The HotLine was shut down yesterday so I had no access to an engineer... I am hoping one of you fellas especially one of our resident instructors could shed some extra light on this. I am thinking the PCM is failing as it gets hot. Three faulty valves? I don't think so! Quote Link to comment Share on other sites More sharing options...
DamageINC Posted January 5, 2008 Share Posted January 5, 2008 I actually thought that the 6.4 EGR valve was utilizing a bi-directional motor this time, that actually opens AND closes the valve, as opposed to just opening the valve and letting spring pressure close it. I could be wrong (which is usually the case) but I am pretty sure it "goes both ways" like that via reversing polarity. Seeing as you're getting used to removing these things anyway, why not yank the bastard out, and try to open & close the sucker on the bench with your own 12v source? Dave Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted January 5, 2008 Author Share Posted January 5, 2008 I actually thought that the 6.4 EGR valve was utilizing a bi-directional motor this time, that actually opens AND closes the valve, as opposed to just opening the valve and letting spring pressure close it. I could be wrong (which is usually the case) but I am pretty sure it "goes both ways" like that via reversing polarity. I believe this to be the case but I want confirmation from someone who "ACTUALLY" knows of has documentation. I had the valve out while testing, I see no need to bench test it. I know the valve is good. What I want to do is test/monitor the control circuits via the module with the scan tool to verify power to the valve and a ground but all I get on either circuit is a constant 12-volts. I compared that to a known good truck... same thing so I really want to know how the module is controlling this valve. /forums/images/%%GRAEMLIN_URL%%/scratchhead.gif Speaking of pulling the valve out, how many of you have had the pleasure of using the tool? I have used it four or five times and it still takes me a couple of minutes to get it assembled correctly but I think I am good with it now. What a contraption! Quote Link to comment Share on other sites More sharing options...
DamageINC Posted January 5, 2008 Share Posted January 5, 2008 I recall having a wonderful time trying to get that thing to stay together while I was in the class, however I've not been fortunate enough to have any reason to use it in the field yet. To be honest, we've been very good with our 6.4's so far... only real problem was one with the radiator tanks seperated and another with a TERRIBLE front crank seal leak. Oddly enough, the new seal came with a wear sleeve. ..but now it's changing subjects, so, meh.. I'd be interestd if we can get any definitive answers as to the actual operation of the EGR valve. I couldn't find anything in the classroom books, or the "coffee table" book either.. Dave Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted January 5, 2008 Share Posted January 5, 2008 Sounds like Bruce will be interjecting at anytime now... Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted January 5, 2008 Share Posted January 5, 2008 Quote: What a contraption! Keith do you have a picture of said tool??? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted January 5, 2008 Share Posted January 5, 2008 I'm a little short on time right now and don't have any good answers for you. I did e-mail you the current IH MaxxForce7 (6.4) service manual. The EGR looks very similar to the 6.4 Ford unit. I hope this helps. Good Luck! Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted January 6, 2008 Share Posted January 6, 2008 I, too, recall the mention of this being a stepper motor.... Not compelling evidence on it's own but let's consider the circuit. If it was duty cycled, we'd have V_BATT to one terminal and the PCM would duty cycle the ground.... But you have measured V_BATT at both EGRVCH and EGRVCL.... odd names for the circuits... and it is obvious "something" is different with the way they are controlled.... PNP transistors are expensive to make and (AFAIK) don't switch real quick or real clean.... We rarely see power side switching transistors in automotive applications for this reason. And here, I'm going to stick my scrawny neck waaaayyyyyy out and opine that the EGR is a stepper motor and is controlled by some variation of an electronic "relay". V_BATT is supplied to each "leg" of the motor through a PNP device.... If the PCM wants to "step" the motor in one direction, it can turn off the power once..... the faster, cheaper NPN device can then step the ground circuit however many times needed and then the slower PNP device can turn on again. Looking at the differences in the design of the basic circuit... I feel safe in saying that assuming this is a stepper motor arrangement isn't a bad thing. If you hook up your scope, I would envision a pattern that traces both above and below your base line volts as the valve cycles in or out.... I might also expect some goofy sh!t to happen when the V_BATT to one leg is turned off and the ground circuit is not complete.... Of course, I could be some drunk old fool that's ticked off because he got called in to work to put out more "fires" on his day off /forums/images/%%GRAEMLIN_URL%%/frown.gif Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted January 6, 2008 Share Posted January 6, 2008 Quote: What a contraption! Keith do you have a picture of said tool??? It's a bitch to assemble, as it comes in about 20 parts. I had to get a picture of it to look at as I put it together. There is NO FRIGGIN WAY that EGR comes out without this tool. It is not optional like a 6.0. /forums/images/%%GRAEMLIN_URL%%/rolleyes.gif Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted January 6, 2008 Author Share Posted January 6, 2008 NO FRIGGIN WAY that EGR comes out without this tool. It is not optional like a 6.0. Except maybe a big lag screw pounded into it and a slide hammer! /forums/images/%%GRAEMLIN_URL%%/scratchhead.gif I could swear I made the exact same post as you Bruce with a similar picture, just not as good. WTF! Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted January 7, 2008 Share Posted January 7, 2008 /forums/images/%%GRAEMLIN_URL%%/scratchhead.gif I could swear I made the exact same post as you Bruce with a similar picture, just not as good. WTF! You did post it, about a year ago. I didn't look for it, though. My brain's a little fried right now as I drove 1400 miles since yesterday. (teaching here in Tampa tomorrow) Normally I fly to distant jobs like this, but I figger I'll stay down here a few weeks and enjoy the sunshine. /forums/images/%%GRAEMLIN_URL%%/smirk2.gif Here's a couple of EGR scope waveforms taken with a low amp clamp showing a PWM command at 1KHTZ (1000 hertz, or 1000 cycles per second) and very low amperage, about 74.48ma average. I know this ain't gonna help you much, but until the fog clears it's all I can offer. I'm in a hotel and don't have all of my stuff with me. I'll give it some more thought tomorrow after a good nights sleep. Also, I gotta read all of that soapbox stuff Jim wrote..... Were you able to open the IH stuff? Quote Link to comment Share on other sites More sharing options...
DwayneGorniak Posted January 7, 2008 Share Posted January 7, 2008 /forums/images/%%GRAEMLIN_URL%%/scratchhead.gif Speaking of pulling the valve out, how many of you have had the pleasure of using the tool? I have used it four or five times and it still takes me a couple of minutes to get it assembled correctly but I think I am good with it now. What a contraption! I have used this "FRIGGIN CONTRAPTION" about five times now and it still sucks the big one. But damn Keith, I love that idea of the slide hammer. I think I just heard of a new flatrate EGR removal tool. /forums/images/%%GRAEMLIN_URL%%/thumbup.gif /forums/images/%%GRAEMLIN_URL%%/hammer2.gif Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted January 7, 2008 Author Share Posted January 7, 2008 Yeah Bruce, I got the information - still reading through it though. I am calling the HotLine in the Morning. Maybe they will tell me to put a fuel pump in it. /forums/images/%%GRAEMLIN_URL%%/shocked.gif Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted January 7, 2008 Share Posted January 7, 2008 As far as I can tell, you guys have it correct. The IH WSM shows it to be a stepper motor with the PCM changing polarity to reverse the direction of the motor. They call it a bipolar H-Bridge that forces the valve open or closed. The position sensor shows in the IH service manual to be a Hall Effect device, but in the output chart it shows a 0v-5v output of the sensor, which does not make sense. The EGR valve consists of a valve and an actuator motor. The IH book says in another area it says it is a regular potentiometer sensor. My guess is they were experimenting with a Hall Effect sensor and didn't correct the WSM before it went to print. I believe the EGR uses a standard potentiometer sensor. The current IH 6.4 service manual is marked "DRAFT" on all of the pages and is dated May, 2007. The EGR valve receives the desired EGR position from the Electronic Control Module (ECM) to activate the valve for exhaust gas recirculating. The EGR valve provides feedback to the ECM on the valve position. The ECM interprets the feedback signal and sends the command using a pulse width modulated signal to the actuator motor. I'm running short on time again: Go to IH document "B" page 285 and see if the diag steps and voltages are the same for the Ford manual. Comments: Pin 2 and 6 are EGR high/low that you state are 12v hot. The IH service manual also shows these should be 12v hot. I'd hook a small light bulb to them to verify available amperage and do a wiggle test on the harness. Perhaps you have a bad harness. My 6.4 motor clearly has 6 wires going to the EGR, but the schematic only shows 5. Does yours have 6? Unfortunately, I only have one 6.4 EGR so far, so I have not made a cutaway yet. I will comment that a DTEGR engine uses a somewhat similar EGR with 2 valves inside. An interesting thing about this DT valve is that if the valve itself sticks, the ECM may not see it. The valve portion is spring loaded against the actuator portion and can become unattached. Thus the ECM can command the EGR open and closed, see the correct position voltage, but have the valve be hung open. I've proved it. If the 6.4 is built the same way, the same problem could occur. This is a DT EGR valve: Good Luck! Quote Link to comment Share on other sites More sharing options...
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