EGR details please

[scottyb]

After reading thru some cold start hesitation threads, I supected my EGR. I took off the black cover, put my thumbs on the top and forefingers on the bottom so I'm holding it like a sandwich. Nothing moves if I squeeze. I went on to the center of the bottom. Feels like a little arm that would push-pull the valve. No motion if I push up or down. I blew into the vac hose and I could feel the rubber diaphram around the edge move, but no metal parts move. ??

I am assuming that the arm is just stuck and I need to remove and clean it up. Is this possible?

Car runs great after 3 minutes of warming up, just a hesitation when cold. Also, it doesn't hesitate cold if I crank it up and run the AC. Would a stuck valve affect WOT performance and knock? I don't know if it open or closed.

Thanks,
Scott

 

[Steve Wood]

egr normally only functions at part throttle and is closed at idle and wot.

If stuck open, it would affect cold and hot idles..normally running very badly.

If stuck closed, it could cause detonation at cruise under light loads.

 

[PsychoBuickBoy]

Steve,
I installed a Powerplate a while back and did not drill the hole for the EGR port. My car seems to be running fine, some drivability problems at times. Can this have adverse effects on my car? Should I take the powerplate off and drill the hole? I have (or had) a functioning EGR before and it is still all there.

 

[Steve Wood]

If you have emissions testing, it will probably make you fail the NOx portion. It may run better at cruise with it drilled as the car may be too lean otherwise.

 

[gofstbuick]

PsychoBuickBoy
It looks like Arizona recently implimented a smog check program that consist of remote sensing devices and random checks. Further review seems to point to the fact that the smog test of choice (for AZ) is I/M240. If this is implimented or in pilot, you're better off to drill your powerplate for EGR function. Because as the car is accelerated to 58mph on the dyno, your engine is going to need as much help as possible to pass the NOx portion of the test. The cat will take care of a max 1200ppm of NOx and the EGR will take care of another 800-1000 ppm of NOx. Just my 0.02. So I hope there is at least a three way cat on the vehicle

 

[PsychoBuickBoy]

Yes, she passed the IM240 here just a while back but that was without the powerplate (first try!). I do have a cat that I throw on for testing purposes but the rest of the time I run a test pipe. I don't need to be tested again until 2003 and by then I will probably get around to drilling that dang powerplate out.

 

[gofstbuick]

Another comment on this subject. I hope your engine is not excessively rich, because the one of the EGR ports gets its source from the exhaust system. Over time it will plug or carbon up that port. Then to soften or loosen the carbon build up you'll have to let TEC or oven cleaner sit in the port for a day or so and then follow it with a frayed speedo cable (attached to a drill) to clean the carbon out, or you'll have to remove the intake and have it dipped and clear the crossover passages on the cyl heads. Jus my 0.02

 

[Ormand]

Emissions

I believe that without EGR you MIGHT fail an emissions test, depending on the chip, the injectors, and the test. Our engines are fairly low compression, so I'm not sure what the NOX would be without EGR. Don't think not having it will "lean out" since the O2 sensor and the chip will correct for it, but there is probably too much spark advance at part throttle, at least in the stock chip, for an egine without EGR. That would lead to part throttle knock, not good, but not as bad as detonation. Chip Gurus, do you change spark advance for engines without EGR?
George W
Raleigh, NC

 

[gofstbuick]

Ormand
Please remenber that some states (AZ being one of them) is running a I/M240 type test. A smog test that 1, uses a dyno, and 2, test at various speeds (not steady state or at a specific mph) basically from 0-35mph-0-58mph-0 over a 240second period. Believe you me, the egr must function for this type of test, and if you get a operator that can't drive the trace too well, that will also affect the results. Also, this test measures in grams/mile, so the whole exhaust sample is store in a bag and processed through a $150000 gas bench (a very accurate gas bench). These are the same type of emission test systems that the feds use for emissions certification of a car model.