327 error code pain

[nelwill]

Hello folks.
New member here. 94xlt.
327 code is killing me. Replaced DFPE and PCM. No relief. Have tested EGR valve, selenoid valve, MAF, TPS. All good. Cleaned IAD and verified function. PCN connector pins #46, 27, and 28 all ohm out O.K. between PCM connector and DFPE connector.

At the DPFE connector w/ KOEO:
(Brn/LGrn)(PCN#27)= 5V
(Brn/Wht)(PCN#28)= Variable voltage (with EGR valve vac input variance)
(Gry/Red)(PCN#46)= 0V....problem.

Any thoughts?

 

[Iron Weasel]

Is it a KOEO, CM (Continuous Memory), or KOER code?

Measure voltage between pin 27 (BR/LG) and pin 46 (GY/R) at the PCM (not the DPFE sensor)...backprobe it or pierce the insulation on the wire with a straight pin or something so you can get to it. With the engine idling in Park or neutral, if the voltage is less that 0.2v - replace the DPFE sensor.

EDIT: OK, I'm a moron...skipped over the part where you said you already replaced the DPFE.

Did you clear the KAM (Keep Alive Memory) at any point during parts replacement?

Also, still need to know if it's coming up KOEO, CM, or KOER.

 

[nelwill]

Iron, thanks for the response.

CM

Yes, cleared memory.

 

[Iron Weasel]

I hate being redundant, but it helps to start at the beginning...so here we go.

1) Does the vehicle start?

2) Any other codes aside from KOEO Memory 327?

If an EGR fault exists at the time of this test (hard fault), then an EGR DTC should also be received in KOEO or KOER or both depending on the DTC. If the EGR DTC is NOT received in KOEO or KOER but only retrieved from Continuous Memory, this could be due to an intermittent EGR system fault which occurred sometime in the past.

If there aren't any other codes:
Key "OFF".
Conduct a thorough visual inspection of the Pressure Feedback EGR (PFE) / Differential Pressure Feedback EGR (DPFE) system for any potential failures. Use the following check list for possible causes:
Obvious physical damage.
Loose connectors.
Pushed out connector pins.
Corroded connector contacts.
Damaged wiring insulation.
Incorrect harness routing.
Incorrect component mounting.
Road salt or rust accumulation.
Damaged vacuum hoses.
Incorrect vacuum hose routing.
EGR Vacuum Regulator (EVR) solenoid filter contamination.
Vacuum hose restriction.
Road splash or icing.
Incorrect service parts.

If everything looks good, go around and do a "wiggle" test - just grab the wiring harness at the DPFE, EGR, PCM, and pretty much anywhere you can reach and just shake the wiring around.

Possible causes of DTC 327:
Open in PFE/DPFE Signal circuit.
Open in PFE/DPFE VREF circuit.
Short to GND in either PFE/DPFE Signal or VREF circuits.

You might have to hook meter or test light up to each circuit and have someone else watch the meter / light while you go around and do a wiggle test on all the components. If all else fails, disconnect the PCM and DPFE connectors and stick a lead of a meter in each end, and then do continuity checks while doing a wiggle test. It'll probably be time consuming to check each circuit, but it's always better to troubleshoot than randomly throw parts at it.

If you still can't find the problem, lemme know.

 

[nelwill]

Thanks Iron.

"1) Does the vehicle start?" - Yes. Idles just a little bit rough although acceleration is very poor. Feels and sounds like I am towing something under acceleration. CEL comes and goes under normal driving. (Mostly on)

"2) Any other codes aside from KOEO Memory 327?" - Have not checked KOER in a while. Been focused on the KOEO 327. Will run KOER again, maybe tonight.

"If an EGR fault exists at the time of this test (hard fault), then an EGR DTC should also be received in KOEO or KOER or both depending on the DTC. If the EGR DTC is NOT received in KOEO or KOER but only retrieved from Continuous Memory, this could be due to an intermittent EGR system fault which occurred sometime in the past."
- If I just clear the error and retest (KOEO) without running the engine I get no error code.

As for your list of things to check. I have been through about all of it multiple times but, will go at it again along with the "wiggle test". One point of interest in your list- "EGR Vacuum Regulator (EVR) solenoid filter contamination"- I am unaware of a filter for that solenoid? Where would I find it?

Thanks again.

 

[Iron Weasel]

The EVR solenoid looks like the diagram below.



The filter is internal on the solenoid, but the solenoid itself should be on the driver side of the upper intake near the actual EGR valve.

Speaking of the EVR solenoid, any of the following could also cause DTC 327 to show up without any accompanying codes:

EGR valve sticking open.
EGR Vacuum (EGRV) solenoid sticking open.
EVR solenoid vent restricted.
EVR solenoid driver shorting to GND.

You've already replaced the EGR valve itself, so we can probably rule that out as the cause. If the EVR filter is clogged or sticking, it will be sending the incorrect volume of vacuum pressure to the EGR valve so the EGR in turn will be showing a lower voltage than what it should be. I would check the wiring a little more thoroughly, and if all the wiring checks out, my attention would turn toward the EVR solenoid.

 

[LiKuiD]

Good luck with this, i've been fighting this code for over a year and a half and no luck. Luckly, I dont feel any degraded engine performance, but the code flashes on randomly after driving for about 10 or so minutes.

Replaced EGR/DPFE/hoses, etc. no luck. If you search, theres a thread with Williard who had the same problem and couldnt solve it either.

Maybe you can be the first!

 

[Twenty8000]

I'll chime in with my 327 experience. (94 Ex Sport)

I was having no luck with the 327 code, did lots of reading through the threads to find that many people were having problems with auto-parts-store DPFE's (mine was a Duralast). I swapped it out with a Standard Motor version...code went away and hasn't returned.

At the very start I was getting 335, 336 codes with my original very old DPFE. Swapping with the Duralast cleared those but added the 327 code. Then, swapping that with the Standard Motor version cleared everything.

If all the other troubleshooting doesn't do the trick, it might be worth trying...

 

[nelwill]

Folks, thanks for the input.

Iron,
Just FYI, I have not replaced the EGR valve yet. Tested and all was well. Just went ahead and replaced the EVR solenoid... no help. 327 remains after clearing mem and a short drive. KOER - 111 no faults. Will try the "jiggle test" tomorrow. Keep you posted.

Li,
No worries. Will let you, specifically, know when I get this one.

20,
Interesting as I also replaced with a Duralast. Gonna pitch that if the "jiggle test" gives me no relief. Stay tuned.

Thanks for hanging with me.

 

[Iron Weasel]

Not saying that this applies in your particular case, but you'll get a CM code if the condition that caused the DTC to be set was seen within the last 50-60 key cycles. If you aren't getting 327 as a KOEO or KOER, then that means it's not a hard code.

Continuous Memory codes are stored in the KAM (Keep Alive Memory) and the best way to clear that is to disconnect the battery for at least 15 minutes. That clears out all operational data. Then you'll need to drive it about 10 miles under various operating conditions to force the PCM to relearn all the parameters.

Point being, if it's coming up as a memory code and not a KOEO or KOER hard code, then it's an intermittent issue.

 

[nelwill]

Iron,
Point taken. Batt disconnected as we speak. Morning drive. Keep you posted.

As always, thanks.

 

[Iron Weasel]

Not trying to come off sounding like a dick....I just tend to ramble a lot and I have to remind myself to get back on topic sometimes.

 

[nelwill]

Iron,
Did not take it that way at all. You have been nothing but helpful and it is appreciated. Thanks.

 

[nelwill]

Okay folks my 327 saga continues.

Left the batt disconnected overnight. Reconnected and drove today. CEL showed up again. Did not even bother to get the fail code.

As another step I measured the voltage between pin 27 (BR/LG) and pin 46 (GY/R) at the PCM (not the DPFE sensor as I had done earlier.) Result was 0.59v @ idle. While I had it hooked up, I jiggled about evey wire under the hood including all the connectors attached to anything EGR related. Voltage remained solid at 0.59 throughout.

My plan for tomorrow is to drive it while I have the DVM still attached to the PCM ,as I previousy described, and see if the CEL relates to any change in the voltage between pins 27 and 46. Any thoughts?

Again, thanks all.

 

[Iron Weasel]

Do you have a vacuum gauge?

Also, if you're measuring the DPFE voltage, the voltage between pins 27 & 46 should be less tha 0.2v and you're getting almost 0.6v - the manual says to replace the PCM at that point, but you've already done that so that makes it a little more complicated. Anyway, I was going through the steps and from here....according to the shop manual, you're supposed to start checking the EGR valve and DPFE sensor with a vacuum gauge.

Key "OFF".
Disconnect vacuum hose at EGR valve and plug end of hose.
Connect a hand vacuum pump to the EGR valve.
Apply 34 kPa (10 in Hg) of vacuum to EGR valve and release while observing movement with inspection mirror if possible. Look for binding of the valve pintle.
Does the EGR valve function in a smooth manner?

NOTE: Repeat test as necessary to ensure accurate results.

Yes -- Go to DL97. See: DL97 - Check EVR Solenoid and Hoses
No -- Remove and inspect the EGR valve for signs of contamination, unusual wear, carbon deposits, binding, and other damage. Service as necessary (use Rotunda EGR valve cleaner 021-80056 if needed). Clear continuous memory. See: Reading and Clearing Diagnostic Trouble Codes\Clearing Diagnostic Trouble Codes


DL97 - Check EVR Solenoid and Hoses

An EGR Vacuum Regulator (EVR) solenoid that is not functioning properly can cause the EGR valve to open or remain open when EGR is NOT demanded (such as at idle).

Key "OFF".
Inspect the EVR solenoid vacuum hoses and solenoid closely for the following:
Restriction in the vacuum hoses.
Signs of contamination, icing or moisture at EVR and in hoses.
Excessive contamination in the EVR filter.
Is a fault indicated?

Yes -- Isolate fault and service as necessary. Reconnect all components. Clear continuous memory. See: Reading and Clearing Diagnostic Trouble Codes\Clearing Diagnostic Trouble Codes

Rerun quick test. See: Reading and Clearing Diagnostic Trouble Codes\Reading Diagnostic Trouble Codes\Quick Test Appendix (Detailed Testing Instructions)

No -- Reconnect all components. Go to DL98. See: DL98 - Check EVR Solenoids For Shorts

DL98 - Check EVR Solenoids For Shorts

An EGR Vacuum Regulator (EVR) solenoid or EVR driver circuit short could cause the EVR to open supplying the EGR valve with vacuum.

Key "OFF".
Disconnect vacuum hose at EGR valve and connect hose to a vacuum gauge.
Run engine to operating temperature and stabilized idle.
With the engine at idle, tap the EVR solenoid and wiggle the EVR connector while noting vacuum reading.
Does the EGR vacuum remain below 3.4 kPa (1.0 in Hg) with no sudden increase?
NOTE: EVR leakage below 3.4 kPa (1.0 in Hg) is normal.

Yes -- Leave vacuum gauge connected. Go to DL99. See: DL99 - Check EVR Harness Circuit For Intermittents
No -- Inspect EVR solenoid connector for shorts. Service as necessary. If OK, service or replace EVR solenoid. Reconnect all components. Clear continuous memory. See: Reading and Clearing Diagnostic Trouble Codes\Clearing Diagnostic Trouble Codes
Rerun quick test. See: Reading and Clearing Diagnostic Trouble Codes\Reading Diagnostic Trouble Codes\Quick Test Appendix (Detailed Testing Instructions)

 

[nelwill]

Iron,
Do not have a gauge but, can probably get one in a day or two. What are you thinking?

Do not know what to make of the .6V. Was going to redo the measurment tomorrow to see if I did something stupid (i.e. wrong pin or something)

Your thoughts are much appreciated.

 

[nelwill]

Sorry, posts must have crossed paths. Let me read your latest and respond.

 

[nelwill]

Iron,
EVR solenoid and DFPE have both been replaced.

I will make sure my PCM connections/measurements are correct and get the vacuum gage tomorrow and get after the testing you have posted. Thanks much and keep your thoughts/knowledge coming.

 

[LiKuiD]

I'm going to pull codes again this weekend and see if theyre still 327...after having the CEL on for a year with this code I stopped checking.

I'll also pull voltage readings on the DPFE and see what I get. I'm so tempted to go to a yard and replace the entire EGR assembly, but the prices are outrageous in NJ.

 

[nelwill]

Todays events:
Not sure what this means but, am hoping somebody does.

From yesterday:
(As another step I measured the voltage between pin 27 (BR/LG) and pin 46 (GY/R) at the PCM (not the DPFE sensor as I had done earlier.) Result was 0.59v @ idle.)

From today:
1) Re-measured at DFPE sensor at idle = 0.59v @ idle.
2) Hooked up DVM at PCM connector (pins 27 to 46) and drove. Measurement was 0.59v coasting and would decrease to 0.0v with minimal acceleration. If I went WOT the same 0.59 to 0v. Min acc or WOT was an almost digital 0.59 to 0v.
3) When CEL came on, measurement remained 0.59 during coast and also at min acceleration. If I went WOT the voltage would increase, linearly, to 0.65v.
4) Repeated running with CEL on/off 3 times with the same results.

Other:
Iron,
Have the vac gauge, just no time today to run the tests you suggested. Maybe later tonight. For my reference, what should the vac be at the vac tree during idle?

Thanks again all.