96 winnie 3.8L cel codes

hello all, hoping someone can help me diagnose what's going on with this car. got the car last year form my in-laws with less than 10K on a jasper engine. they had to park it because it would not pass emissions and wound up giving it to us. the cel was lit, codes were 1407,0170,0174, after much research here and much hair pulling decided it was the dpfe sensor. wrong guess, was still getting the same codes. after much searching and much more hair pulling looking for a vacuum leak i found the problem. hose barb on the vacuum regulator that controls the egr was broken off. ordered the regulator and put in on, voila problem solved. had to have the tranny rebuilt a couple of weeks ago and the guy that did it got my battery mixed up with someone else's. i returned there today to get my battery back and not 5 miles after the battery change i got 0402(egr flow excessive) and 1407(egr, no flow detected) codes. i'm just a little puzzled here, everything on the egr system is fairly new. egr valve, dpfe sensor and hoses, vacuum regulator, anyone here have any ideas? thanks in advance

Any chance the DPFE hoses are reversed?

Any chance the DPFE hoses are reversed?
i wouldn't think so, the sensor and hoses were done last summer. that wasn't my real problem though, it wound up being the vacuum regulator for the egr. after i replaced that, i haven't seen the cel again until today.

i wouldn't think so, the sensor and hoses were done last summer. that wasn't my real problem though, it wound up being the vacuum regulator for the egr. after i replaced that, i haven't seen the cel again until today.

Just a thought. However, the DPFE's job is to monitor the EGR flow via differential pressure. It is either getting/giving bad info or the EGR is open, and closed at the wrong time which would point back to the control solenoid I would think.
You could do a "ballpark" evaluation of the solenoid: with the key in run you should see 12V across the solenoid and it should be closed - no EGR flow. The manual states that the solenoid controls vacuum via a variable voltage signal from the PCM. With the engine running you should see the voltage vary (decrease I believe) with RPM. I'm not totally sure if the EGR will be commanded open under static "revving" situations however so you may need long leads and a test drive?

Just a thought so you can begin to track down the problem.

Just a thought. However, the DPFE's job is to monitor the EGR flow via differential pressure. It is either getting/giving bad info or the EGR is open, and closed at the wrong time which would point back to the control solenoid I would think.
You could do a "ballpark" evaluation of the solenoid: with the key in run you should see 12V across the solenoid and it should be closed - no EGR flow. The manual states that the solenoid controls vacuum via a variable voltage signal from the PCM. With the engine running you should see the voltage vary (decrease I believe) with RPM. I'm not totally sure if the EGR will be commanded open under static "revving" situations however so you may need long leads and a test drive?

Just a thought so you can begin to track down the problem.
ok thanks, i cleared the codes out and will just drive it tomorrow and see what it does. i did pull the hose off the egr valve and was getting vacuum there at idle, it wasn't very much vacuum, but it was at least getting there. i know it's as you say, it's variable and changes with rpm's so the low vacuum at idle may very well have been normal. i'm hoping if it does show back up that it'll turn out to be a defective dpfe. i actually have the one i took off last summer which i believe was good. so i may just switch the dpfe out and see if anything changes and if not, i guess i can just rule that out and move on. thanks a lot for the advice