EGR Idling Problem

[brownbag]

I am still unable to connect the vacuum hose from Port Q of the EGR vacuum modulator to the EGR valve without the engine idling roughly.

According to the emissions manual, above 2500rpm the EGR vacuum modulator should apply enough vacuum to open the EGR valve.

Here's the issue. There is a small amount of vacuum at low idle at Port Q that opens the EGR valve enough to cause a rough idle. I am running the cruiser now with the EGR disconnected and am getting some slight hesitation and bucking when I change RPM's at highway speed.

Note- that I have already replaced the intake/exhaust manifold, gaskets, carb insulator and vacuum hose with new OEM parts. I am pulling a neg 18 on my vacuume guage at idle.

Also, I suspect I may have a dying brake booster, as when depress the pedal, I lose some vacuume pressure and the pedal will progressively get softer. Brake fluids are at right levels and not leaking.

Any thoughts?

 

[dallen341]

What condition is the modulator? New? Old? Clean?

The bottom comes off and there is a filter element within the housing.

Don

 

[Pluton]

Sounds like you might want to sort out that vac booster before anything else. I had an EGR that was open at all times, problem was traced to incorrectly rebuilt carb. Carb was supplying too much vacuum to EGR system at idle, and way too much at higher rpms. Replacing the carb instantly fixed it. BUT, if your carb is stock and working fine, this wouldn't apply to your case. When did it start doing this? Did it always have this problem? Anyway, hope this helps.

 

[FJ40Jim]

I am still unable to connect the vacuum hose from Port Q of the EGR vacuum modulator to the EGR valve without the engine idling roughly.

According to the emissions manual, above 2500rpm the EGR vacuum modulator should apply enough vacuum to open the EGR valve.

Here's the issue. There is a small amount of vacuum at low idle at Port Q that opens the EGR valve enough to cause a rough idle. I am running the cruiser now with the EGR disconnected and am getting some slight hesitation and bucking when I change RPM's at highway speed.

Any thoughts?

Thought: the idle speed is set too high.
All of the vacuum for the EGR valve comes from two ported vac fittings on the carb. At idle, both of these fittings are dead. When the throttle butterfly is opened up a little bit, these ports begin to see vacuum. If carb idle is adjusted properly, there cannot be vacuum to the EGRVM.

 

[brownbag]

I purchaed all the smog equipment off of a running Fj60 that was being parted out. I was able to try a different EGRVM with no change.

I am going to check the vac connections at the base of the carb, as I did remove the carb when I installed the intake/exhaust manifolds and new insulator plate.

I also will check the idle speed.

Will check back...Thanks

 

[brownbag]

Problem solved. Thanks

I had the vacuum lines that come out of the base of the carb crossed. What a huge difference - No stalls, stutters runs better than ever