EGR Help
02-21-11, 04:27 PM
#1
Pit Crew
Thread Starter
EGR Help
So my car has been having a misfire issue at idle and I've replaced every component on the ignition side (plugs, wires, coil, cap, rotor) and even the MAF. Can someone help me understand why unplugging the "Q" vacuum hose on the EGR seems to make my idle better and misfire disappear? I unplugged and it seemed to get better and when I plug the hose with my finger the car dies. I'm confused. What's the difference between the EGR and the other valve looking thing to the right of it.
Here's a vac. diagram.
Here's a vac. diagram.
02-22-11, 08:01 AM
#3
Pit Crew
Thread Starter
idle doesnt seem to change much but just sounds like it just gets smoother. isnt that hose connected before the throttle plate? im thinking either something is wrong with my egr valve modulator or the vsv? im so lost lol
02-22-11, 10:56 AM
#5
Lead Lap
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Not sure if it should have vac at idle (and it may be dependent on whether the car is warm or cold); but so far as the FSM advises checking operation on the vacuum modulator by:
1) Disconnect P Q and R from it. Block P and R with your finger, blow air into Q; air should flow freely.
2) Start car, rev up to 2500rpm, repeat previous test, it should be hard to blow air.
That's pretty much all they give. I hope that helps some!
Edit: Since at low/no RPM you can blow into Q; it would seem the vac is okay (to me anyway)
1) Disconnect P Q and R from it. Block P and R with your finger, blow air into Q; air should flow freely.
2) Start car, rev up to 2500rpm, repeat previous test, it should be hard to blow air.
That's pretty much all they give. I hope that helps some!
Edit: Since at low/no RPM you can blow into Q; it would seem the vac is okay (to me anyway)
02-22-11, 11:03 AM
#6
Pit Crew
Thread Starter
Not sure if it should have vac at idle (and it may be dependent on whether the car is warm or cold); but so far as the FSM advises checking operation on the vacuum modulator by:
1) Disconnect P Q and R from it. Block P and R with your finger, blow air into Q; air should flow freely.
2) Start car, rev up to 2500rpm, repeat previous test, it should be hard to blow air.
That's pretty much all they give. I hope that helps some!
Edit: Since at low/no RPM you can blow into Q; it would seem the vac is okay (to me anyway)
1) Disconnect P Q and R from it. Block P and R with your finger, blow air into Q; air should flow freely.
2) Start car, rev up to 2500rpm, repeat previous test, it should be hard to blow air.
That's pretty much all they give. I hope that helps some!
Edit: Since at low/no RPM you can blow into Q; it would seem the vac is okay (to me anyway)
Thanks for the testing procedure. I kept finding the same procedures but nothing about whether or not there should be vacuum at idle or not. It sucks because I feel like I've tested tried everything for this stupid misfire and now I have to go through the entire EGR system to check. I wish I could just remove it and call it a day but VA has strict emission laws.
02-22-11, 03:35 PM
#7
Pit Crew
Thread Starter
EDIT: Problem solved! Previous owner had the EGR vacuum hose switched up instead of it going to the VSV causing the EGR valve to stay open during idle. And to answer the vacuum question at idle, there shouldn't be vacuum from "Q"
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