1991 f150 4.9 5spd 2.73 rear end. (axle 12)
Code 33: Egr opening not detected.
I am getting about 13 mpg doing mixed driving. I am not driving like a douche
I am cruising between 60-65 mph on the freeway.



Truck runs fairly decent except at part throttle in 1st and 2nd gear around 1600-2k rpm she seems to buck and stumble a little bit. I've also noticed that when you first start up the truck and you tip in the throttle a little bit she has a small stumble too.


What I have done. I have seafoamed the truck, put in motorcraft copper plugs, new cap and rotor and now I am waiting for my kingsborne wires to get in (did all this to eliminate any other issue just in case, plus old rotor looked alittle burned out). I have applied vacuum approx 4in hg to EGR with truck running. Truck started to stumble.


Tested the EVP according to oldfuelinjection and the EGR closed was showing .49v (in spec) on a centech dmm. Applied vacuum and voltage went up like it should.

I have checked resistance on the EVR and that was within spec. Also grounded out pin 33 on it and the EVR did apply vacuum to the EGR

Am I missing something else?



Also vid of what truck is doing.
www.youtube.com/embed/Nb8VLROSLYU

 

When u apply vac the evr is suppose to hold it and not leak down. Test the hose for leaks.

 

I didn't have an issue with vac leaking. Ill double check.

 

Sorry that should have been egr not evr.

 

Ok cool that makes more sense. I was a little confused hahha. Ill double check that.

 

Ok I have an update and some codes. I get the typical 33, then it goes to a set of codes that flash faster. CM codes? Anyways I get 334. EVP circuit above the closed limit of .67 volts

I also did a koer test and got code 172. HEGO sensor circuit indicates system lean (right side)



Currently I am reading through a thread that was started a few years back by aliens8mycow and see if I see anything in there that I am missing.

 

Everything is sounding consistent with an EGR or vacuum leak. Check all your lines make sure nothing is pulling outside air.

 

yes sir will do. ill finally have time tomorrow to do more testing and looking around and what not.

 

The egr gets the command to open and close from the evr. Should have two hoses and both need to be tested for leaks. Also clean the egr may help. The egr may not be closing all the way because it is dirty. Pull engine vac and if it is not 17-22 test all the lines with a hand vac pump. There should be a sticker under the hood showing the driveability vac lines. 172 could be a o2 sensor.

 

Ok just found out that I was over counting the first code. I am actually getting 111 when I go to CM I get 334. KOER is 172.

Engine vac is around 20 inhg