Hey guys,

Getting a Check Engine light on my 1994 Explorer, 4.0, auto, A/C. Anyway, the code is (ODB-1) 332, which is "Insufficient EGR flow detected."

What are the troubleshooting steps for this, or is it just not worth my time (better to bring it to a garage)?

Mike

 

Is that 332 a KOEO code (1st set of codes output during the KOEO test), a CM code (2nd set of codes output during the KOEO test), or a KOER code (assuming you performed the KOER test)? Because KOEO codes are set with the engine off, they almost always have to be electrical. In this case, check the wiring between the PFE/DPFE and the computer. If the wiring checks out, then replace the PFE/DPFE. If you got a KOEO 111, then you'll also need to check the vacuum hoses and such between the various EGR components.

 

Hi,

I only did the KOEO test, this was the only code it gave me. What does that tell you?

Mike

 

It tells me one of two things:

1) You are inexperienced at pulling EEC-IV codes, and are operating with a very poor set of instructions, because it doesn't tell you how to distinguish between KOEO (Key On Engine Off sometimes called hard fault codes) and CM codes (sometimes referred to simply as memory codes). I posted a decent set of instructions in a competing forum, but FTE doesn't like competing forums. You might find a better set of instructions
2) That the 332 is both a KOEO and a CM code.

Questions: How many 332's did you get? If the latter scenario, there should have been four 332's output. Did you get any 111's? Did you get a separator pulse (some code readers output a 10 for this)?

 

Ouch! Little harsh especially since you're wrong about a 332 code, LOL.

ford fuel injection dot com says it is a CM and KOER side. Thus under normal operation, the PCM did not detect the EGR opening. The DPFE sensor did not return the proper voltage as the PCM was expecting. He was able to pull the code without the truck running because it was stored in continuous memory (CM).

Since the code is in memory, you can disconnect the battery and see if the CEL comes on and if so, check the codes again. Check the codes anyways since sometimes codes are stored without a CEL.

If is does come back, you can check the circuit for mechanical failure. Maybe the vacuum line came off and the valve truely is not opening, maybe the rubber line came off the venturi tube that the DPFE is measuring flow through (this happened to me), maybe the EGR valve itself is bad and truely not opening, If mechanically it checks out OK, there is a solenoid that opens to allow vaccum to the EGR valve diaphram (opens the valve) and the DPFE sensor itself. Those are the only 2 electrical components.

It is important to get this fixed since the PCM uses the EGR open signal to adjust the A/F mixture. It will wack out your performance a little.

 

You guys crack me up...

Anyway, thanks for pointing out the obvious, I'm a rookie with the code reader, and the Haynes manual I am using is great at telling you what the code is, but terrible at telling you how to troubleshoot (leaves you to part-swapping, which I hate, both at work and on my truck).

I have disconnected the battery overnight (had a bad cable) and the same code came back, so I'm thinking it's real. I may run the test again and do a better job of documenting the codes (I think I ignored how many times I got the same code, and whether or not I got a 111, thinking that was a separator).

Can you point me in the right direction to find the EGR and solenoid on this 94 4.0L engine? I think it's on top of the engine on the passenger side, but the book doesn't show good pics or drawings. Also, the nuts and bolts look extremely rusty (did I mention 260,000 miles?).

BTW, what's the DPFE sensor, where is it, what does it do, etc.?

Mike

 

Sorry, Didn't mean to be harsh. Maybe blunt, or gruff, or otherwise less than diplomatic, but not harsh.

The code lists I've looked at say the same thing. But I don't accept everything those on-line, generic EEC-IV code lists tell me as absolute truth. If it truly is only a CM code, then he should have also got a 111 pass code (or something else, perhaps a 335) from the KOEO set of codes. Since he reported only a 332, I have to assume that that's all he got.



PFE/DPFE ((Differential) Pressure Feedback EGR) sensor measures the exhaust backpressure/pressure drop. Computer uses this information to determine how much the EGR valve is open and whether to open it more or close it down. My '92 doesn't have an EGR system, so I'm not exactly sure where it's located or what the parts look like exactly.

 

DPFE = Differential Pressure Feedback EGR

It is a sensor that returns 1-5 v back to teh pcm depending on how much flow is sensed in an oriface tube tha runs from the exhaust manifold to the EGR valve. So in theory (and actual practice) if the EGR valve is open and exhaust gases are flowing into the intake manifold, this sensor reads how much and feeds that back to the PCM so it can lean out the mixture appropriately. That's how EGR's gt better fuel mileage.

The EGR valve is on the back Driver's side of the intake manifold and the actuating solenoid is just beneath it. The solenoid gets a vibrating 5 V signal from the PCM to open when the right conditions are present per the PCM software program. The vibration frequency varies to control how much the valve opens and thus the flow into the intake manifold. There is no feedback to the PCM on this circuit. So if the PCM says go open EGR and it doesn't, it has no way of knowing.

I t only knows if there is flow through the orafice tube from the DPFE. If the PCM syas go open EGR and the 0-5 V feedback from the DPFE matches the amount the PCM told the EGR to go open, eveything is happy and you don't get a CEL. In your case, something did not report back right.

It could be any of the things I mentioned earlier. So you see, the codes don't tell you what is wrong at all. Just that some feedback didn't match expectations. You need to fully understand the controls system of the device that the PCM is pointing to to then be able to troubleshoot. Better than the pre-computer days but certainly not artificial intelligence yet.

The DPFE is located on the drivers side near the oil dipstick tube, 1/2 way between the intake and the exhaust manifolds. It has 2 silicon rubber (not vacuum line) hoses going to the orafice tube, they are different sizes znd only go on one way.


Oh and MrShorty..I was only razzing you. Your description to trouble shoot this if it were a KOEO only code was exactly what I would do since that would indicate a system check issue, not a running condition issue.

 

Our Cyber notes crossed in space - your link works MrShorty.

 

Hi guys,

Here's an update. I checked the "other forum" and found a lot of useful info.

Anyway, I have a 1994 4.0, which has a PFE sensor. Went to the store to get one, but the one they showed me had input tubes that were side by side. Mine are one in front of the other, so I figured this was wrong (this was the computer lookup even though I gave them the FMC number from the original part). Then, he looked in a book and said I must have an early 1994, and I need the 1993 model year sensor, which they did not have in stock. Part was about $80.

So, I took another look at the sensor, which has two rubber lines, different sizes, 1/4 and 5/16. The 1/4 line was disconnected, and both lines were old and brittle. I replaced them with new line (use fuel line), and added a spring clamp to the 1/4 line where it connects to the sensor, because the plastic inlet tube seemed to be damaged (and I can't get a replacement unless I wait).

Took a test drive, no CEL so far. Ran the code checking again, here's what I now have:

KOEO: 111
CM: 332
KOER: 111

I cleared the CM, and I'll run it for a week or so to be sure the code doesn't come back. Big thanks to MrSki and MrShorty!

Mike

 

That is what I thought. I got the same code on my 1993 X (Ca model) and when I looked, one of the lines was blown off the orafice tube. You went a step further with the worm ger clamp, I just used tie wraps. I am a little concerned about usine rubber fuel line. I don't think it will hold up to the temp's. As I mentioned before, there stock lines are a silicon rubber compound. Well anyways, it's awesome you found the problem and fixed it. If the code comes up again, you know where to go to look. makes me a little more happy, more X-mas cheer, to know we could help you out here in cyber space. Cheers!

 

Hi guys,

It seems my tube fix was temporary at best (no CEL for about a month). Now the CEL is back.

Good news is, I'm not getting a 332 error anymore, bad new is, I am getting this:

KOEO: 337, 337
CM: 336, 337, 336, 337
KOER: 337, 337

When I looked this up, the book tells me:

336: "Pressure Feedback EGR (PFE) sensor or EGR Pressure Transducer (EPT) - signal voltage higher than expected (exhaust pressure high)"

337: "EGR Valve Position (EVP) sensor, Pressure Feedback EGR (PFE) sensor or EGR Pressure Transducer (EPT) - signal voltage too high

Again, 1994 Explorer, 4.0L, automatic, 260,000 all original!

What is the test procedure for this (without part-swapping)?

Mike

 

Mike, I think you have a shorted DPFE, giving a full 5v to the PCM. Replacing it should fix your problem. It's the gizmo on which you replaced the hoses.

Might also be shorted sensor wiring or plug-in, but not likely.

 

It sounds electrical because the codes talk about signal voltage. But it could also be correct that the voltage is too high because the flow is in fact too high. A bad EGR valve (leaking diaphram) or a bad vacuum solenoid (leaking vacuum and opening the EGR valve) could also be the problem.

 

When diagnosing EEC-IV DTC's, start with the KOEO codes. Because KOEO codes are set with the engine off, they are almost always electrical in nature. Specifically, they either indicate a problem in the DPFE itself, or in the wiring between the DPFE and the computer.