Swapped in motor is running, but EGR problem.

[jeepinrandy]

tongue.gif The engine I swapped in is running tongue.gif But, the EGR stays open while running. :( I put in new temperature vacuum switches and, by the diagram I have, the vacuum lines are all hooked up right. :confused:

Anybody know if certain EGR valves use more vacuum than others? Anybody have a vacuum diagram for an 88, the one I was using was for an 89. Anything else you can think of?

[Jeepzilla]

EGR valve is supposed to be open when warmed up and with high manifold vac ops. The CTO valve will do this. Supposed to be closed at idle and when cold. If you have manifold vac to the EGR (just pull off the line and check with your finger), then check to see that the pintle is not frozen. Shoot thoroughly with penetrating oil and work it loose. There is a big diaphragm in there too, I suppose it could fail...

[jeepinrandy]

smile.gif Learned something new :cool: So I have vacuum at the EGR, not allot, but some. The EGR stays open until the vacuum is released, bad EGR valve? Wrong valve ?

The EGR valve is the one that was on the Holley Street Dominator intake when I bought it, so it could be the wrong one. Next step is to swap the one on from the original engine.

[Jeepzilla]

I'm confused. The EGR is not on the carburetor, it is on the manifold. There is a manifold vac line connection to carb, that's all. Shouldn't make any difference what carb you have. There is a thermal vac switch in your air cleaner. It controls vacuum passage between the EGR and the CTO. When cold the TVS blocks vac to the EGR and prevents its operation. There is a dump valve between the EGR vac source and the EGR. It prevents the EGR from operating at low manifold vac levels.

Test your EGR as follows:
1. At normal operating temp. and at idle, rapidly open the throttle to 1500 rpm and close. You should see the diaphragm move. If it does not, you have a vac line leak or a bad EGR. If that is OK then,
2. At op temp amd idling, depress the EGR diaphragm (opens the valve). RPM should drop quickly. proving the the valve was closed correctly. If there is no change in RPM, and you have proven that the EGR is working (above), then you have a plugged passage from the EGR to the manifold.

BTW, if the engine idles badly, and you do not get RPM changes by pressing the diaphram, then the EGR is not preventing exhaust gases from entering the combustion chamber during idle. Exhaust gases are contaminating the mixture, making it run rough. Check for bad hoses, wrong routing or bad EGR. When buying new valve specify the engine, not the carb.

[ March 23, 2003, 04:53 AM: Message edited by: Jeepzilla ]

[jeepinrandy]

Sorry for the confusion, my fault.

EGR is on the manifold, which happens to be made by Holley.

At operating temperature the engine is running rough at idle until I un-hook the EGR. This indicates that it is open until I un-hook it. I think the wrong EGR is on the manifold and I was mixed up because I thought it should be connected to ported vacuum.

[Jeep Craze]

Your EGR valve is suppose to be hooked to ported vacuum NOT manifold vacuum. That is why you have rough ideling. It needs to get its vacuum from a ported port on the carb. It can't get any vacuum until the motor is up to operating tempature, then it can only get vacuum when under acceleration(at a cruise) once you dump it, you will be able to feel when it closes again once you get close to full throttle. It will fell a lil slugish and then when its closed it will feel like you kicked another 4bbl in. Craig

[Bob Barry]

Here's an obscure condition that can cause your EGR to be activated, EVEN IF you've got it hooked up properly to ported vacuum.

Another item hooked up to ported vacuum is the "VAC" port on your evap canister on the passenger-side fender. According to the factory diagram, I believe that port taps into the same line as the EGR valve, after all the thermal switches.

Gently disconnect that vacuum fitting to the evap canister and see if you are getting vacuum when the engine is warmed up and idling, not off that vacuum-line, but rather off the port itself.

There is a rubber diaphragm in that little housing under the port; if it tears (as mine did), the line to the PCV valve, which draws in fumes from the evap canister to the intake plenum, and which is a manifold vacuum source, starts sucking in through that port. Any line connected to the charcoal-canister port will then see a bit of manifold vacuum. That was enough to pull open my EGR valve and cause rough running.

To test it, see if you have a vacuum signal at idle off the evap canister port.

If it does show vacuum, the fix is as simple as popping off that plastic cap that the port is part of, pulling off the spring and replacing the diaphragm. I don't know if they sell these repair kits; I pulled a good diaphragm off a spare canister I had.

If you can't find the repair part, you'll have to replace the entire canister.

[Bob Barry]

Originally posted by Jeepzilla:
Ported vac of sufficient strength would open it.A ported vacuum should not show any signal when the engine is idling. If the engine is improperly tuned, such that the idle-speed is attained solely by adjusting the throttle-opening rather than the mixture screws, a ported vacuum source might show a vacuum signal, but that's only on a misadjusted engine.

But you're absolutely right about an EGR valve being closed at idle.

Of course, a backpressure-design EGR gets a lot more complex.

[jeepinrandy]

Hmmm, something else to check. Thanks Bob, I don't know if they make the canisters anymore. I know they don't make one for my CJ7s anymore and I believe they are the same P/N. I am going to try the correct EGR valve first, then I will check the other systems. smile.gif