EGR issues

[99sho-time]

Ive noticed lately that I get a sort start/stall when cold. I ended up finding out that it doesnt do this with the egr vacuum line unplugged from the valve, furthermore as its idling with vacuum line unplugged if i plug it back in for curioisty sake while idling it almost stalls the car. So I changed the solenoid that seemed to stop the starting issue for a lil while but seems like once the PCM learns the new part the issue returns. I also notice that theres alot of misses with egr plugged in under light load when cold. egr valve is new motorcraft.

Am I missing something here? the egr valve has an effect on starting and idling? i thought egr was suppposed to open only under light load medium load. could it be a dpfe?

the fuel trims at idle are near perfect with no vac leaks. And one other weird thing I noticed is if i reset the computer it starts fine almost like once the OBDII mon's pass then the issue starts again. if i unplug it and leave it it drives better for a time once the car learns the egr is unplugged the car shifts harder no idea why.

 

[GEN 3 SHO FAN]

I have some misfires too at idle. I made some searches and yes ERG can have bad effet on idle (at least misfires).

I can confirm your precise trouble is truly linked to ERG but here is what I tryed on mine (with mitigated succes). The EGR pressure sensor could be cloggled, if its happens it can create a bad idle. Its the number 1 on the photo. #2 is also related to EGR IIRC.

Which solenoid you changed ? (1 or 2, or other thing)


This one is coming from a SLO with 50 000 km (same part).

It help a little with my misfires but I still have some. Maybe these very small hoses are cracked somewhere or I have a leak elsewhere.

 

[99sho-time]

I changed 1 and cleaned that sensor with contact cleaner (2) i did some musing around with it today I think its just that for w/e reason unrelated to a vacuum leak the car runs lean under load because I see the trims go +.
I'm unsure of why it does this It may be my intake/mafsetup + my open exhuast. I also deleted the solenoid that opens the SAI check valve mines tuned i see no need for that to be part of the vac system anymore but this has no real effect on the egrother than that it is linked to it.

My car does not misfire at idle at all it idles very very smoothly.

 

[gamefanatic]

Do you get a lot of registered misfires? If so are they random?

Do you have stalls only at idle, or other times like deceleration?

 

[99sho-time]

the misfires don't register or throw a coat i pretty sure theresa misfire thing on forscan that picks them up somehow.
It's stallish at cold startup or most startups but bigest one is cold start. it does act sorta droopy the rpm's after revs I ahvent seen any stalls on decell lately.

 

[GEN 3 SHO FAN]

Humm, maybe a faulty IAC valve ? Carbon deposits with time will interfere in their operation. Too much open, misfires, too much closed choke and stall... ? I changed my IAC this week too and it was doing no strange behavior on idle but when I decelerate, the rpm going down until a near stall at around 200. The valve wasn't able to open enough fast to keep the engine at 600 rpm. But once stopped, the rpm climbbed at 600-700.

If your car want to stall after you asked some rpm, the TB is closing and the IAC opens to compensate. It could open at the good level but not at the good speed... However, the strange thing in that its heat related...

The fact that the car can stall also indicate that many cylinders are in cause, probably random. This engine can turn on 4 cylinders (don't ask me why I know this). The problem is probably affecting all cylinders.

Otherwise :
"it idles very very smoothly" : at which rpm ? 600-700 seems the good range.

Is your ERG is correctly bolted ? When I unbolted mine the first time the small gasket falls without noticing it... (Will also affects idles normally.)

If its heat related it can be an electrical contact going good with dilatation. Or a fluid is accumulating somewhere and with heat, it dissipate (oil on plug, water on cylinders) but the idle will be affected too...

A coil is going crazy sending false signal to the EGR sensor ?

Bad Throttle position sensor (TPS) ? They can have bad behavior at a precise load.

Sorry, to not helping you that much...

 

[99sho-time]

I appreciate your reply. I think what you said about the IAC has some truth i noticed after my tuning the motorcraft iac worked the best. My egr seems to bolt up and vacuum free. my coils are all new motorcraft. my valve covers and sparkplug seals are all rtv'd. I noticed that the dpfe sensor cleaning helped. the car drives very well. so far after mt battery reset changes/cleaning hasnt start/stall'd yet crossing fingers.

 

[99sho-time]

Yeah I'm just not sure why my egropens when cranking. I can hear the car overcranking to fast due to intake being open. It does this with or without tune. i dont understand.

 

[gamefanatic]

If the EGR is operating as necessary check the vacuum regulator #1 in Gen3 SHO fans pic. Make sure its not leaking. That's what the PCM used to open the EGR.

Finally if those are all working check the DPFE #2. This is what tells the PCM to open the EGR. Do you have another DPFE you can put in? EGR should not be opening under cold conditions / startup. Are your DPFE hoses Ieaking? You might be able to tell while the car is running just feeling for air / hot air moving. If the EGR isn't operating as normal there is a problem with one of these parts.

I'd probably need more symptoms to suggest another route... Are you receiving any P-codes?

 

[99sho-time]

No egr codes only codes i get are key fab codes.

I did notice that my tachometer bugs out sometimes when i start the car it glitches and sticks at 3k rpm if i tap on it goes back to normal operation.

I do have another dpfe sensor that has the same shape and looks the same but the part number is different

Update. Looks like the DPFE is reading 2.05 im guessing thats over 2 volts.

any idea what your dpfesensor voltage is at?

 

[gamefanatic]

EGR DPFE Sensor - Voltage Range Revision

Article No.
97-22-1


10/27/97

DELTA PRESSURE FEEDBACK EGR (DPFE) - DIAGNOSTIC TIPS

FORD:
1994-97 MUSTANG, THUNDERBIRD
1995-97 CONTOUR, CROWN VICTORIA
1996-97 ******, TAURUS


LINCOLN-MERCURY:
1990-97 TOWN CAR
1994-97 COUGAR
1995-97 CONTINENTAL, GRAND MARQUIS, MYSTIQUE
1996-97 SABLE, TRACER


LIGHT TRUCK:
1994-97 EXPLORER
1995-97 ECONOLINE, F-150-350 SERIES, WINDSTAR
1996-97 AEROSTAR
1997 EXPEDITION, MOUNTAINEER
1998 NAVIGATOR


ISSUE:
The current DPFE sensor diagnostic reference values as published in the Powertrain Control/Emissions Diagnosis (PC/ED) Service Manual, and also accessed by either the Service Bay Diagnostic System (SBDS) or Service Bay Technical System (SBTS), can lead to the replacement of good DPFE sensors.

Fig. 1


Fig. 2



ACTION:
Use the following revised DPFE sensor voltage ranges for all (black plastic or aluminum) DPFE system applications when checking the PID (Parameter Identifier Display) value "DPFEGR" or when measuring the DPFE sensor input directly at the breakout box. Refer to Figure 1.

NOTE : THESE LISTED VOLTAGE RANGES SHOULD BE USED FOR ALL (BLACK PLASTIC OR ALUMINUM) DPFE SYSTEM APPLICATIONS WHENEVER CHECKING THE PID VALUE "DPFEGR" OR WHEN MEASURING THE DPFE SENSOR INPUT DIRECTLY AT THE BREAKOUT BOX

 

[gamefanatic]

From this TSB I'd say yours is high for idle.

I will try to make a point to check mine tonight.

 

[gamefanatic]

Forgot the important part...

 

[gamefanatic]

Found I was able to monitor the DPFE via Forscan. Voltage was consistently below 1.9v when driving at normal speeds/throttle, and below 1v at idle. Of course the app is still unstable so, would recommend the PC version for actual monitoring.

 

[99sho-time]

think im gonna go ahead and just swap at the dpfe not like its that hard to do. Now im wonder if i would able to use the newer plastic ones or one from a regualar taurus. I wonder if its a sho speciifc dpfe sensor.

 

[gamefanatic]

Considering they all use the same voltage, I doubt they are any different. I suppose just make sure the inlet/outlets are the same and in relatively the same place. There isn't much wiggle room...

 

[GEN 3 SHO FAN]

I do have another dpfe sensor that has the same shape and looks the same but the part number is different

It could be useful to have your 2 different part numbers to resolve this.

This part eat a lot of heat (rear bank) + aging, #2 may be a part to watch over time too.

 

[99sho-time]

stuck in a used one from a mountaineer or something and its def reading a much lower voltage. started up nicely but time will tell. went from 2.05 at idle to like 0.60 at hot idle. i didnt reset the bettery or anything but i doubt it will just start getting higher voltage. I'll check back if the issue returns.

 

[GEN 3 SHO FAN]

OK thanks.

I checked my spare today (coming from a 97 or 98 SLO) and its the same as the right one (yours original SHO one ?).

F48E-9J460-BB (96-97 SHOs)
F7UE-9J460-AA (98-99 SHOs)

The hoses going on this aren't tightened by clamps, some leaks could appear there over time possibly. Also according to the size of these hoses, dirt can easely go into this sensor and false any measurements.

 

[99sho-time]

the left is the sho one and those hoses i dont think they need clamps those are hard to get on as it is. putting clamps on them would be a difficult task. they really fit very firmlyu that material they used is very resilient

I drilled and punched out the rivets on the original part it appears that water was in there on both sides. imguessing from the natural combustion process. not sure.

So far the car is driving even better havent gotten crap start yet. the dpfe can most def effect performance becase the dpfe will lean the car out.