Sensor issues

[Thatdude]

I just got a 1994 mazda b4000. It has codes 118 and 327(koeo). Im trying to test the wiring for both the ect and evp circuits. If i did it right the ect is only getting .5v instead of 5v and the evp is getting 1.5v instead of atleast 2v. So either im not testing it right or there is a wiring issue. If someone could help me make sure im performing the tests correctly and/or a likely spot to have issues in the wiring harness I would be very appreciative.

 

[RonD]

Welcome to TRS

Its good to post the codes with the definitions you are using, no one has then all memorized and we can see if Fords definitions match yours
118 ECT sensor is/was high or open - ECT
327 EGR feedback signal is/was low - EVR or PFE


test ECT sensor with OHM meter first, readings seen here: https://www.explorerforum.com/forums/data/xfmg/thumbnail/24/24365-f43791dd2506145a330fe2baceeba107.jpg?1583516355

Try testing for 5volts by reversing polarity on the meter, its a pull down circuit(or pull up) which means it won't test as 5volts(key on) on all Volt meters
TPS and air temp sensor use the same grey/red wire with same 5volts, shared wiring, so if it was a voltage issue you would also get codes from these sensors, just FYI

327 is EGR code, not sure 1994 4.0l would have an EGR except in Calif., but maybe NY too?
EGR Pressure feedback sensor also uses the same grey/red wire with 5volts

With key off you could test continuity between grey/red wires at the 3 other sensors that share it

 

[Thatdude]

The wires did have continuity, but i pulled the ect sensor and it had no continuity so i replaced it and now the code 118 is gone but i still have the 327. Ive been reaserching how to test the dpfe and egr system but havent had much luck

 

[RonD]

Get a longer vacuum hose for EGR valve, so you can apply vacuum just by sucking on the hose, assuming you don't have a hand held vacuum pump, lol

Unplug the vacuum hose that is on the EGR valve now
Put the longer hose on the EGR valve's vacuum port
Start engine
EGR system/valve is NOT USED at all when engine is cold or idling
Feel if the hose you unplugged from EGR valve has vacuum, it shouldn't, if it does then the EGR solenoid/modulator is leaking and will need to be replaced

But still testing
Suck on the longer vacuum hose, EGR Valve should start to open
Engine should start to run rough, stumbling, because exhaust gases are being added
If not then EGR valve is either not working, if it can't hold vacuum then its broken, or valve and/or EGR tube are clogged up with carbon, need to remove both and clean

If EGR valve tests OK, engine starts to run rough, then EGR sensor is most likely bad

 

[Thatdude]

The egr solenoid is not leaking, if i pull vacum on the egr engine runs rough. On the wires going to the dpfe, if i test between the ground and signal wires there is nothing, but if I use the battery for ground i get about 1 volt on each of the signal wires. If I put vacum to the egr, both signal wires continue to show 1 volt, so it seems to me that i have a problem with dpde and/or the wiring. Thank you for your help thusfar.