dpfe trouble code

blk94xlt · Post by **blk94xlt** » Tue Dec 18, 2007 5:22 pm

I am working out the bugs in my swap and I still have a trouble code of 1400 that I can't seem to get rid of. The code 1400 is for 'DPFE sensor circuit low voltage'.
I have read that the dpfe sensors are pretty common to fail so I did replace the sensor. I cleared the trouble codes and drove it again and the same code reappeared. Does anybody that is familiar with the newer OBDII diagnostics systems have a suggestion where I should start the troubleshooting?
CJ, you are pretty familiar with these systems correct? Do you have a troubleshooting process that you would go through to eliminate possibilities? ...any other information that I could get to help narrow it down?
Maybe I should mention that the truck does not have the greatest idle. I changed the cam to the E303 and had to get an IAC bypass plate to bump the idle up to around 900rpm so that it would not die. Then I got one of those IAC restrictor plates so that it would not idle at 2000rpm when it is first started and cold. I don't know if those mods matter but they are there.

Dave · Post by **Dave** » Tue Dec 18, 2007 6:17 pm

Hey, I Was just wondering how things were going with you out there, hadn't heard anything from you lately. Any problem getting it tuned to ignore the auto functions with a program change? Did you do the suggested 4 deg retard when using the E-303 cam and the Explorer computer?
Dave - Cold/Snowy Wisconsin

cjcnomor4 · Post by **cjcnomor4** » Tue Dec 18, 2007 7:55 pm

If your still @hotmail, I sent you an email that might help. Let me know if you need more help.

blk94xlt · Post by **blk94xlt** » Wed Dec 19, 2007 4:49 am

Hi Dave, I haven't taken it to get the controls for the auto trans deleted yet. I am trying to get the other trouble codes taken care of before I take it somewhere. I may have them try and tune it a little to smooth out the idle so I don't need the stuff installed at the IAC. This DPFE trouble code is the last one remaining other than auto trans related. I did install the adjustable timing set to give it a little help. I don't know if it helped or hurt though.

CJ, thanks for the diagnostic info. I checked the DPFE voltage and it looks like it is correct. Key On Engine Off voltage is 0.5V so that looked good. I even applied vaccum to the REF input to the sensor and the voltage climbed correctly according to vaccum. If the sensor is working right I am wondering if it is the PCM. That would suck. This is the second PCM that I have tried. I don't have a scan tool that will read the voltage from the PCM so I am reading them from the wires right where they go into the PCM, I'm not sure what the PCM actually sees. Any other possibilities or suggestions?

cjcnomor4 · Post by **cjcnomor4** » Wed Dec 19, 2007 7:50 am

make sure you have vref at the sensor, across the connector.backprobe the connector. your meter in vref and sig rtn should be 5v. if you measure dpfe signal and sig rtn with the engine idling you should see your .5v. same set up engine running pull a little vacuum on the egr valve, about 10 in/hg (it will run rough and possibly stall if you pull too much). your voltage should go to 1-2v. if it goes down your hoses are backwards. if it doesnt change, but idles rough your dpfe is bad. if it doesnt change and the idle doesnt change you have no egr flow. if all that is ok do a real good check of the wiring to the pcm. wiggle and bend the harness to make sure there are no breaks. if all that is ok try a pcm.

stranger · Post by **stranger** » Wed Dec 19, 2007 8:22 am

since it measures egr flow,sounds like egr is sticking or not working(ps the hose connections matter,try swaping them).
all the idle stuff i tried worked a little but when i tuned it i reduced the iac duty cycle.
i would leave what you have done and let tuner fix any little idle problems by pcm.
glad your working thru it.good luck

cgrey8 · Post by **cgrey8** » Wed Dec 19, 2007 8:45 am

I thought about the tubes being backwards too. The "polarity" of the tubes on the DPF sensor is a big deal. However to help eliminate them being put on backwards, Ford does size them differently. IT doesn't mean you can't force them on backwards, but you'd have to be ignorning a very loose and very tight fit of the hoses on the sensor for that to happen. Notice in this pic the diameter difference:

What year EEC and year engine are you using? Based on previous comments, I assume it's an Explorer motor of some type. Those details might be good info for your signature including all the mods like the E303.

As for the E303 on Explorer EECs, this is a known problem that the Explorer EECs don't like the E303 cam that much. However I don't have any further knowledge as to exactly why. Until reading this thread, I wasn't aware that retarding the E303 was a technique to help make the E303 more acceptable to the Explorer EEC. Retarding any cam delays the opening of the intake valve until the piston is further along in it's travel downward. This has the effect of stabilizing the intake manifold pressure, but with the E303's big duration of 220Â°/220Â°, it's not going to eliminate the pulses in the intake at lower RPMs & light loads. What causes those pulses can be discussed later if someone is curious, but for now suffice it to say that wider duration cams cause vacuum instability/pulses in the intake at low RPMs. Likewise, the wider exhaust duration is going to create similar pulses in the exhaust manifolds. I may be going wildly out on a tangent here, but these could be what the DPF Sensor is picking up and thus what's confusing the computer. However I'd think for this to happen, the EGR valve would have to be open. Is this a code you only get after driving the truck for say 30 minutes at sustained cruising loads or is this code something you get just sitting still and idling for a few minutes?

If you are driving it at cruising loads, do you ever feel a slight jerking or surging in the motor at light loads that seem to go away if you push on the gas or let off? If you do, that's the EEC cycling the EGR valve open and closed. The surging is the effects of different amounts of EGR gas being let into the intake as you drive down the road. The EEC is looking for change in DPF Sensor readings so it knows where it is at. However if the DPF is delivering erratic feedback, the EEC may not be able to stabilize the EGR and thus the source of the problem. I don't know this, but I could see it being a possible explanation for the code.

If that is the problem, you MIGHT be able to help stabilize the DPF sensor readings by installing Mass Accumulators between the sensor and the EGR pipe. This wouldn't eliminate the pulsing, but it would smooth/dampen them especially if the pulses are high frequency. Mass accumulators are nothing but holding tanks. You can make them out of PVC pipe with pipe caps and taps to fit hoses on. Since the DPF sensor doesn't actually flow any of the exhaust through those tubes, you wouldn't have to worry about hot exhaust getting into the accumulators and melting them. However you would need to locate them sufficiently far enough away from the motor that they didn't pick up engine/exhaust heat and melt (assuming you used PVC).

cjcnomor4 · Post by **cjcnomor4** » Wed Dec 19, 2007 9:49 am

they get swapped rather often. the fit isnt as loose or tight as you would think. you get someone that goes to an outside shop, has work done and still has a problem. then the aftermarket shop has the ability to tap out and say take it to the dealer, we cant fix it. most previously repaired egr problems are clogged ports or hose reversal. make sure they didnt get switched at the tube too.

blk94xlt · Post by **blk94xlt** » Wed Dec 19, 2007 1:20 pm

The hoses are on right, that's the first thing that I checked.
I checked VREF and sig return and those voltages are correct so it looks like the sensor is doing what it is supposed to do. I just used a vaccum pump to simulate what it would see if there was exhaust gas flowing through the oriface tube. All that was with Key-On-Engine-Off conditions. I haven't looked at the voltages with the engine running yet to see if there is actually any egr flowing through the tube when it thinks there should be.

I'll try monitoring the DPFE voltage with the engine running, apply some vaccum to the EGR valve and see what happens. If EGR works and DPFE voltage changes accordingly I would lean more towards this being the DPFE voltage not getting to the PCM correctly. I tried the wiggle test with the harness but no intermittant readings.

I don't know exactly when the code is set. I have the other codes from the auto trans not being there so the MIL is lit for those. I do get the surging and jerking at light loads. I freakin hate that... My mustang does it too and it drives me crazy sometimes. Driving through a parking lot I look like a teenager that hasn't quite learned how to drive a stickshift yet. Since the truck has more power now I look even more retarded... and I'm not talking about my valve timing. I hope solving this problem will help that!!

cgrey8 · Post by **cgrey8** » Wed Dec 19, 2007 1:56 pm

Violent surging and jerking isn't usually caused by EGR gasses, I can almost bet that's the engine running lean. Excessive spark advance can also cause this, but that's not likely if you are running 93 octane with and engine and computer designed for each other.

I've become so dependent on my datalogging ability to give me feedback as to what's happening when that I couldn't imagine trying to deal with and engine management problem without one of these jewels. The problem is I wouldn't recommend the TwEECer for your EEC. Despite the TwEECer website claims to support hundreds of different EECs, the truth is all those EECs require the use of the included software which to put it bluntly SUCKS @$$! The software is buggy, far from intuitive, misspellings, mislabelling of things, and most of the tune settings you need to do advanced level tuning isn't exposed making the purchase of the TwEECer a fat waste of money if you don't have a more mainstream EEC. But worst of all, the developer you pay $500+ to has no interest in fixing the bugs that get reported nor in continuing to develop his software with new features.

If you really want control of the EEC, you have to spend more money buying aftermarket software called Binary Editor for the TwEECer. BE is written by a different developer that knows how to write software AND knows how to support his customers. Unfortunately, his software currently only supports the popular EECs which include any of the 5.0L Mustang EECs from 89-95, some of the 4.6L 96-99 GTs, and a few scattered niche EECs like the ones for the Thunderbird 2.3L turbo or Thunderbird 3.8L supercharged. New support is always growing, but it's slow and is mostly based on volunteers donating knowledge to BE's developer to include for others to take advantage of.

cjcnomor4 · Post by **cjcnomor4** » Wed Dec 19, 2007 2:27 pm

I've seen dpfe voltage stuck at more than 4.75v cause a buck/surge at steady cruise. not at parking lot speeds but 30-45. the pcm sees load and commands egr flow but doesnt get the feedback fromthe dpfe and it starts varying evr hence the surge. It never feels like more than a light misfire, but once you feel it you get tuned in and can get it everytime. the last one I had do it was an 02 taurus 3.0 2v and it never set a code.

cgrey8 · Post by **cgrey8** » Wed Dec 19, 2007 2:48 pm

cjcnomor4 wrote:I've seen dpfe voltage stuck at more than 4.75v cause a buck/surge at steady cruise. not at parking lot speeds but 30-45. the pcm sees load and commands egr flow but doesnt get the feedback from the dpfe and it starts varying evr hence the surge. It never feels like more than a light misfire, but once you feel it you get tuned in and can get it everytime. the last one I had do it was an 02 taurus 3.0 2v and it never set a code.

Yeah, 30-45MPH light load surge is what I was referring to. It's not quite as intrusive as a misfire, but it is a hesitation that you can't really ignore. My 97 Ranger did that when the DPF Sensor went out. I never checked the voltages to see if it was stuck one direction or another. I just verified that the EGR would flow gas, and it would. So I assumed it was that DPF sensor and replaced it. No problems since. But in this case, the DPF sensor seems to be working just fine since he can get the voltage to fluctuate with vacuum.

However surging at parking lot speeds just sounds like the engine running lean to me.

blk94xlt · Post by **blk94xlt** » Wed Dec 19, 2007 5:43 pm

I do also get the truck into this condition where the idle jumps up to around 1500-2000 rpms and sits there for 3 or 4 seconds before returning to a normal idle. This only happens when I am playing with the gas and clutch to get going or when driving at really low speeds like coming to a stop with the trans in second gear this would happen after using the clutch for a stop. I don't know if that is related to the DPFE problem though.

cgrey8 · Post by **cgrey8** » Wed Dec 19, 2007 6:06 pm

That just sounds like typical idle tuning issues that most modded motors do when there's a head or cam change that the EEC isn't programmed to handle.

I hope you can find a good dyno tuner that can get it working for you. Otherwise, there may be too many little driveability issues for you to put up with on a regular basis forcing you to abandon the Explorer EEC in lieu of a Mustang EEC & TwEECer. If messing with computers and stuff like that is something that appeals to you, you'll love tuning it yourself. But if that just sounds like too much work, then you are better off leaving the tuning to people who know how. But even they aren't likely to get all the issues worked out since they aren't going to be the ones to see what's happening while it's happening like you could with a datalogging tuner.

Dave · Post by **Dave** » Wed Dec 19, 2007 6:29 pm

I'm the one that sold blk his wiring harness and first computer, the wiring came right off my Explorer crate motor. The computer came right from Downs Ford as a rebuild unit, both for a '97'. Don't think blk changed sensors from his '99' motor to the '97' ones, would that be a problem? Was there a difference between the early and later '97' computers?
I had to go do a "Google" just to find out what you all were talking about a dpfe sensor. Found one site that right at the bottom, they mention that an air leak in the EGR tube might cause surging and slight mis-firing. Good explantion and some good diagrams for someone like me!
Dave
http://www.fordscorpio.co.uk/egrmonitor.htm