EGR Problem/Codes

[sjjones]

Folks,

ISSUE: I have a 4.0 4WD 1994 Explorer with 140K. My Check Engine Light (CEL) has been coming on after 5 minutes and stays on mostly thereafter. When I first checked the codes with Key On Engine OFF (KOEO) I got 335, 327, 332, 336, and 337 (all EGR related). After resetting the computer by taking off the negative termial, then driving around until the CEL came on again, I then used the code reader again and just got the 327 and 332 codes. Along with the CEL issue, I also have a pinging when the motor get hotter (a problem I had and solved just last year as explained below).

HISTORY: Last year I had the pinging with no CEL and no codes displayed. After messing around for months trying to resolve the "pinging" issue, I finally took to a shop and they replaced the DPFE sensor which completely cured my pinging - so my DPFE sensor is only one year old. Now, a year later, the pinging has seriously returned and I'm getting the CEL and above mentioned codes which all seem to be EGR related.

DONE SO FAR: I've only visually checked the vaccum lines and wiring on the DPFE, EGR Valve, and the EVP solenoid. They appear fine. No removal or testing of individual components. Have not removed the EGR valve to check for carbon build up.

QUESTION: I checked with CarQuest locally and with discount can getthe DPFE, EGR Valve, and EVP solenoid for about $155 which seems exceptionally reasonable after reading related threads. I'm tempted to just buy the three major components, take all three off the Explorer, clean things up and look for carbon in the EGR Valve ports/holes, put on new parts and take a run with my fingers crossed. Does this sound reasonable way to proceed? I hear that the EGR Valve seldom is the actual problem; however, once I've taken the time to get it off and replace the gasket - for $58 bucks it seems prudent to replace at 140K. Since the DPFE is only one year old, perhaps the most likely culprit is the EVP solenoid (what CarQuest calls a "position sensor solenoid" - however, I've read nothing about the solenoid being a lkely cause.

I can take the parts off and try and figure out, or have someone help me, individually test them, or I can just replace at what I'm thinking is a very reasonable $155. Would very much appreciate more experienced folks suggestion.

P.S. - It looks to me like the large exhaust hose going to the EGR Valve is solid (not flexible). Attaches to the EGR Valve with large nut fitting. Can the EGR Valve be removed by just loosening the hose nut and EGR mounting bolts? Is it a difficult task? I will of course soak the hose nut and bolts with some penitrating oil a day or two in advance (I know just a little).

Many thanks.

Welcome to contact me PM at seamansjones@hotmail.com

 

[MrShorty]

Are those codes KOEO codes (before separator pulse of KOEO test) or CM codes (after separator pulse) or both? KOEO codes almost have to be electrical in nature, and KOEO 3xx codes relate to the DPFE circuit.

 

[sjjones]

Codes came with KOEO. Don't know exactly what you area asking, but the codes came one after another after I pressed "test" button. First one number came up, then it blinks awhile (few seconds) and another code comes up. Eventually, it started repeating a couple of the codes.

Anyway, even though I got a new PDFE less than a year ago, I figured it was most likely causing the codes, so replaced it with a new one. I now have 111 code only - which of course what I want.

However, I still have some pinging that was completely gone last time I replaced the PDFE. I'm seriously considering replacing the solenoidand EGR valve just to see if it helps and because of the mileage.

 

[MrShorty]

You might want to read through my "notes on pulling EEC-IV codes" to understand how to distinguish KOEO and CM codes. Both sets of codes are output during the KOEO test with a separator pulse between.

There are a few common causes of ping on the 1st gen 4.0. Among the common causes: 1) Dirty MAF (a simple cleaning is in order)
2) Leaking lower intake manifold (usually can be fixed by simply tightening the bolts).
3) Other vacuum leak/air intake leak.

These are discussed quite frequently here -- see what details you can find with the search function. I would start there rather than replacing EGR components.

 

[sjjones]

Thanks for taking the time to respond Shorty. Several years ago I spend a lot of time on this forum researching my pinging. I did the MAF, tighten bolts, and a half dozen other things, including seafoam treatment.

Eventually, the pinging got to a point I went to a shop that does a lot of work on Ford trucks. The only thing the mechanic/owner did was to replace my DPFE EGR sensor. Replacing that part totally eliminated my pinging. Then a year later, the pinging returned and I got the codes. Although replacing the DPFE turned off my CEL and reflect no problems codes - the pinging is still there.

The pinging is pretty specific to a hot engine. I'm suspecting it may still have something to do with the EGR system. An EGR valve that is not opening/closing properly can cause pinging.

My pinging nearly drove me crazy a year ago and having it completely dissapear by just replacing the DPFE sensor - and then having a DPFE sensor go bad in only a year and the pinging returning - all seems rather odd - but it is impossible not to believe there is some relationship.

Anyway, I plan on installing a new solenoid and EGR valve now. My cost is real reasonable and I need to exercise my tools BTW, I know I can test the EGR valve with a simple suction test - but I will never know if the ports or clogged unless I take it off. If I'm going to go to the trouble to take a 140K EGR valve off, I'd just as well put a new one on - and I'm sticking to that story

 

[pitbulldell]

Thanks for taking the time to respond Shorty. Several years ago I spend a lot of time on this forum researching my pinging. I did the MAF, tighten bolts, and a half dozen other things, including seafoam treatment.

Eventually, the pinging got to a point I went to a shop that does a lot of work on Ford trucks. The only thing the mechanic/owner did was to replace my DPFE EGR sensor. Replacing that part totally eliminated my pinging. Then a year later, the pinging returned and I got the codes. Although replacing the DPFE turned off my CEL and reflect no problems codes - the pinging is still there.

The pinging is pretty specific to a hot engine. I'm suspecting it may still have something to do with the EGR system. An EGR valve that is not opening/closing properly can cause pinging.

My pinging nearly drove me crazy a year ago and having it completely dissapear by just replacing the DPFE sensor - and then having a DPFE sensor go bad in only a year and the pinging returning - all seems rather odd - but it is impossible not to believe there is some relationship.

Anyway, I plan on installing a new solenoid and EGR valve now. My cost is real reasonable and I need to exercise my tools BTW, I know I can test the EGR valve with a simple suction test - but I will never know if the ports or clogged unless I take it off. If I'm going to go to the trouble to take a 140K EGR valve off, I'd just as well put a new one on - and I'm sticking to that story

PLEASE UPDATE THE REPORT ON THE EGR CHANGE ?

 

[sjjones]

Update

Gosh, its been a month and I haven't received a call from the parts department on my solenoid part for the EGR system. When it comes in, I'll replace it.

However, since I last posted, I noticed the No. 5 plug is oily which is a clue that I may have a lower manifold gasket problem - or worse, cracked head. I've had the pinging problem for many years and it hasn't gotten worse. Before I tackle the job of replacing the gasket and all else that is worth doing during the process, I'm probably going to try some sea foam just for the heck of it.

Why the new EGR sensor corrected the pinging before is beyond me. I do notice that it hasn't been pinging last week or two and this I believe is do to the rainy season and more moisture in the air - go figure

P.S. - I've also had some antifreeze uses since I got the X back in 1996. This is another clue it may be a manifold gasket.