WTF EGR valve plugged in, but no vacuum hose to it.

Discussion in 'Fox 5.0 Mustang Tech' started by Rerun, Jun 28, 2004.

  1. Okay cool will try after work. Where does the "vacuum leak" take place if an egr is stuck open? Is it where the valve attaches to the upper intake? Or is at the tube that goes from the lower to the valve? Reason I ask is because if the valve WERE stuck open (I dont think it is) wouldn't there still be a leak even with the sensor unplugged?
  2. Only if there was an intake leak. Without the EGR ports on the heads, there is nowhere for airflow to travel up through the intake manifold and into the EGR and into the manifold airflow. basically with the EGR stuck open, you'd have a big empty chamber of stagnant air...unless you have a leak in a gasket somewhere. Spraying carb cleaner around should help find that.

    Without EGR ports in the heads, you might as well delete the EGR. Remove it and buy an EGR block off plate and install that.

    When you get a tune, have the tuner turn the EGR function off permanently to get rid of the CEL

    But with the EGR should get a CEL
  3. Okay, so just for clarification, since I'm dumb: If I unplug the egr sensor, and it still bogs down under light acceleration, then I have crossed the egr off the list as a possible cause and there is absolutely no way any of it has to do with the egr or a vacuum leak related to the egr?
  4. I wouldn't say no way, but it would lead me to beleive the EGR is unrelated. however, i'd be more convinced if I saw a code generated by it and a CEL letting me know the EEC has disabled it.
  5. Alright, I have to ask... Who is in your avatar lol

  6. Denise Milani.

    Google search and you'll easily find her :)
  7. :hitit:

    Anyway, back to tech talk, lol. Unplugged EGR sensor, cant really tell if its any better or not (which leads me to believe it's not). It did give me a CEL.
  8. So I guess now the question to be asked is, what could cause poor performance and throttle response... At partial throttle under light load, lol.
  9. Do you know how to run the cylinder balance test funtion in the EEC check engine testing? basically after all the codes are spit out, you give the engine a good 1/2 throttle rev to enter the CBT mode. It will turn off the injectors to each cylinder 1 at a time, and verify each cylinder is contributing 100% by measuring the exhaust with the 02 sensor. At the end, it spits out a number 1-8 if a cylinder has an issue, or a 9 if all ok.

    Run that. Will tell you if an cylinder is weak or injector is dead.

    I drove around for a year on a dead injector and couldn't even tell. The engine had a light stumble at part throttle that I couldn't figure out
  10. Do I do this after the KOEO and KOER tests are done? For instance, after the KOER test gives me all the codes, do I leave the scanner plugged in and then press the throttle to the floor?
  11. After the last KOER code is spit out. They usually repeat, so wait until everything is all done. Then blip the throttle fast.

    The engine RPM will rise up to about 1500 RPM on it's own for about 1-2 mins. At that point it will drop and begin blinking or give you a number (depending on how you are doing the test). 9 means all good. A number 1-8 means issue with that particular cylinder.
  12. SO, I did a cylinder balance test. Twice. 90 both times. So I'm good there. I've had a compression test done recently as well, all between 160-170. Good there.

    Something curious to note: I've dumped both KOEO and KOER codes at least half a dozen times in the last month. Always at the beginning of KOER I get the 8 for # of cylinders. However, today when I dumped them (after running the truck with the EGR sensor unplugged) it gave me a 6... Said what the ****, dumped codes anyway, ran cylinder balance anyway, passed with a 90.

    Pulled negative terminal and turned on headlights after to clear eec. Plugged EGR sensor back in, dumped codes a second time. Back to 8 cylinders again, okay... Ran balance test again, passed with a 90.

    Also, something to note that has gone unanswered in @jrichker 's surging idle thread: All 3 of the MAF's I have tried (original & two reman'ed Cardone units) have measured high voltage between pins c & d at idle. According to his thread, I should be at .6 at idle. I replaced the original because I got a high voltage code for the MAF. Since then I have tried two different reman'ed units, both measured .9-1.1 at idle between c & d. Is there a chance there are different parameters for my truck vs. stangs? Or perhaps I'm so lucky that I got two defunct reman'ed Cardones (they don't have a very good reputation). Same engine.

    I refuse to believe that my truck is just a dog at partial throttle after the tfs heads, custom cam, and ported lower, lol. Something is going on, and by god I'm determined to find it.

    #32 Benboi92GT, Mar 18, 2014
    Last edited: Mar 18, 2014
  13. Hard ot say at this point. In terms of the computer, it's happy with everything it sees. You do still need to have the EGR turned off when you tune.

    Could be something in your combo as well? Without knowing the mechanical parts, it's tough to say. Could be the grind of the cam just doesnt have good midrange torque??
  14. Shouldnt be the cam. Cam is ground for maximum torque throughout the powerband from idle to ~4500. Guess I'll just have to bite the bullet and take it to a tuner and hope I don't get it there (3 hour drive) and have him say nah something aint right cant tune it till it is lol
  15. General consensus seems to be that it is leaning out at partial throttle. First thing tuner said over the phone when I explained what was going on, and same thing some other people said.

    A.K.A tune time lol
  16. Just for fun, here is the truck you've been helpin me figure out =P








    Any Ford fan should appreciate :flag:
  17. Nice clean ride
  18. Thanks! One would be hard pressed to find a cleaner 92-96 truck anywhere.

    I guess until I get it tuned there's nothing else I need to know. Thanks for your help :nice:

    Now I shall let this thread sink back to the depths from whence it came :runaway: