EGR question

[1dollardog]

I've had this posted in the Tech section for a few days but have had little response. (Maybe because it is on a hot air engine) My 84 GN has been idleing like crap for the last month. It would seem to run ok short of being a little sluggish and stumbling somewhat out of the gate. No codes and numbers seemed to be in the OK range (Via my otc2000). I thought it might be a vacuum problem so I was trying to chase down a bad vacuum hose. When I unplugged the EGR valve hose it smoothed out. Idle ran just a bit high (around 1400 rpm) but it was smooth as silk. It made little change when I blocked this hose with my finger. Throttle response seemed to be better as well. Does an EGR valve go bad? Is it worth replacing or is there another option?

 

[TurboRegal84]

Have you adjusted your IAC and TPS lately? Sometimes when they are little out of whack the symptoms you listed will happen.


EGR valves can go bad but rarely do. You can test the EGR valve by pressing the bottom of the diaphragm up (from the bottom of it) and while it is up put your finger over the part of the it that the vacuum hose connects to. Then release the bottom of the egr valve and it should hold the pressure.

 

[1dollardog]

Have you adjusted your IAC and TPS lately? Sometimes when they are little out of whack the symptoms you listed will happen.


EGR valves can go bad but rarely do. You can test the EGR valve by pressing the bottom of the diaphragm up (from the bottom of it) and while it is up put your finger over the part of the it that the vacuum hose connects to. Then release the bottom of the egr valve and it should hold the pressure.

No adjustments to the iac or tps. I have recently switched over to the 87 ecm,coil/module,maf. It ran fine after this conversion though. It was a gradual change for the worse in the idle. It wasn't all at once.

 

[mrfixit49]

Sounds like a bad vacuum solenoid.

The EGR valve itself works off vacuum that is allowed at certain times by the EGR vacuum solenoid which is controlled by the computer. When you pull the vacuum hose off the EGR, is there constant vacuum on that vacuum hose? If yes, you could have a stuck open solenoid or the computer is sending a constant signal to keep the solenoid open.

Reconnect the vacuum hose to the EGR. Follow the hose back to the solenoid and unplug the electrical connector. Check engine light comes on but the car still runs poorly? Stuck open solenoid. Check engine light comes but it smooths out? Post back, I'll have to do more research.

You can test it yourself, connect a vacuum tester to the EGR and apply vacuum while idling. Notice the stumbling. Only if you don't notice a stumbling of the engine while you are pumping that vacuum tester, you have a bad EGR. Vacuum on the EGR is supposed to make it stumble, that still a good EGR.

Good Luck.

-Michael

 

[1dollardog]

The EGR valve itself works off vacuum that is allowed at certain times by the EGR vacuum solenoid which is controlled by the computer. When you pull the vacuum hose off the EGR, is there constant vacuum on that vacuum hose? If yes, you could have a stuck open solenoid or the computer is sending a constant signal to keep the solenoid open.

Reconnect the vacuum hose to the EGR. Follow the hose back to the solenoid and unplug the electrical connector. Check engine light comes on but the car still runs poorly? Stuck open solenoid. Check engine light comes but it smooths out? Post back, I'll have to do more research.

You can test it yourself, connect a vacuum tester to the EGR and apply vacuum while idling. Notice the stumbling. Only if you don't notice a stumbling of the engine while you are pumping that vacuum tester, you have a bad EGR. Vacuum on the EGR is supposed to make it stumble, that still a good EGR.

Good Luck.

-Michael

Ok now we are getting somewhere. There is constant vacuum on the hose. It isn't much vacuum but it is constant. To give you an examplt, there is about 5 times as much vacuum pressure on the fpr hose than on the egr hose. I'll check the solenoid when I get home this evening.

 

[DKNIS85]

I just bought the EGR blockoff plate from jegs and deleted the egr it was alot cheaper