News Flash...

I replaced the DPFE with the second unit and got the 336 again (I still have the 214 but we'll look after that later). I checked the voltage to the DPFE and it was within range. It calls for 4-6 volts and it was 4.89volts. I checked the voltage on the EVR (EGR solenoid) and it was battery voltage. Also checked the EVR reistance and it was within spec (33ohms I think). Vacuum lines seem to be OK.

According to Haynes it is likely that the engine will idle roughly, surge or stall if the EGR is completely open. My idle is rough, rough, rough, with the system hooked up. It smooths out if I disconnect the EGR vacuum tube.

It seems to be running on full open EGR. I guess I could have 2 non-functioning DPFE's but that would be real bad luck. Could it be anything else I wonder? Any thoughts?

 

Since these things seem to die rather frequently, I would not be surprised if both are bad. DPFE range is from 0-5 V nominally. My information has 4.75V maxed out as wide open. So yes you are right, if you read 4.89V, your EGR valve is wide open - that would mess up your idle. EGR is not supposed to be open at all at idle.

Remember, the DPFE is a sensor and it sends the V back to the PCM. PCM sends the initial 5V, DPFE adjusts the V due to EGR flow and returns it back to the PCM. The PCM then knows how much fuel to cut out since burned exhaust gasses can burn anymore fuel. You have a double whammy. EGR when you're not supposed to have it and less fuel when you need it fairly percise - at idle.

My question though is how are you reading the DPFE voltage? If you simply remove the connector, turn on the key and check voltage, you'll get about 5V. The correct way is to run your volt meter in series with the retunr line back to the PCM, after the sensor. Then you'll know exactly what the sensor is telling the computer. Another way is with a code reader/scanner that gives you real time fedback. My Autoxray does this. I plug it in and it tells me what all the sensors are telling the PCM.

Your 336 code is interesting. PCM is saying, I'm not opening the vacuum solenoid but the egr valve is flowing full. Are your vac lines backwards? Maybe I lied to you the other day. Try swapping them.

 

I have only read the voltage to the DPFE at the connector not while running the vehicle. It is supposed to read 4 - 6 volts at the connector so at least I figure the fault is not in the wiring harness. I need to back probe the DPFE while it's running to see how it reacts. I think it starts near 0 volts and then increases as the vehicle warms up? I have the procedure so I'll run this test soon.

I found the vacuum harness for the EVR/EGR/manifold tree so I can install this and be sure of the vacuum routing (I had one from a U-Pull truck I'd been working on but it must have fallen out of my truck as I found it laying on the garage floor).

I'll get some information back to you soon!

P.S. I also got a CMP out of a truck in one of the local boneyards. It took a little time but I did get it! It cost me $20.00 which included a few other odds and ends I needed but it sure beats Ford wanting $675.00 for the unit.

 

Gil - PM me your email address and I'll send you a document I put together with all the sensor values. Yes the DPFE feedback starts at 0V and goes up to the full PCM supplied voltage, which should be 5V. In any case, the PCM does not open the EVR/EGR valve at idle. So if this is physically happening, then either the EGR is connected right to engine manifold vac or the EVR solenoid leaks. You shold get 0V at the EVR connector at idle. All of this is independent of the DPFE since, again at idle, the PCM should never tell the EGR to open.

 

woops. I did lie to you about the EGR lines. The top one off the solenoid goes to the valve not vacuum. I took a better look at it yesterday. So if you hooked it up backwards, you might have been getting EGR flow al the time. I'm not sure how the little solenoid valve works. It might allow the engine vacumm to open the valve and then pull vacuum on the EGR valve opening it up. If so, this would explain the PCM codes. But know that you got the OEM vac lines, they kind of only go one one way and you're probably OK now. I think you said it was working OK now. Sorry for the mix-up.

 

From what I have seen with the "new" vacuum harness thing seems to have worked things out. That is to say it runs smooth at idle. I believe you are right top goes to EGR. You can't mess it up with the OEM harness. I can't find my Code Reader so I can't check for codes yet. I'll still get the 214 due to the CMP though (obviously).

I finished the front end on the weekend and took it out for a drive and everything seemed fine with both the suspension (I may need to check alignment to be sure) and the motor/drive train.

I also did had to rebuild my 4x4 motor (engage motor) and found that the poly "stop" had been ground to pieces as most people state in there posts (you also I believe). When I originally rebuit the unit I cleaned the electrical components and I thought they were talking about the white shaft bushing being ground up (which was OK on mine). Upon further review I found the problem with the "stop" and I replaced it with a piece of tubing re-assembled, re-installed and she's pure now.

 

Sounds right on the t-case shift motor assembly. The 3/4" or so diameter plastic shaft bushing you mention I don't think will ever wear out. With all that worm gearing, that shaft is all torque and no speed, very slow anyway. But the stop screw bushing goes - as you mentioned. I think because the controller drives all the way to the 2WD position and adds a few more pulses to make sure it's full disengaged from 4WD. Runs to stop all the way hard and evetuanlly the plastic bush falls apart. I used az piece of 1/4" ID poly urethane tubing.

 

FYI

I found my code reader and the 336 code is no longer present. I'm only getting the 214 from the CMP. It seems it needed to be run a little for the EGR system to settle. It may be a good thing that I misplaced my code reader.

Only one to go!! I may have a try at the CMP this weekend.