What are the symptoms.....
Thread Starter
Instructor
Joined: Jun 2005
Posts: 243
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From: Lakeland Florida
Originally Posted by Dale1990
Rough idle/stalling is one of the major symptoms. Also failing emissions testing (NOx specifically, I think).
I appreciate it.
Jesse
Thread Starter
Instructor
Joined: Jun 2005
Posts: 243
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From: Lakeland Florida
Originally Posted by C4396roadster
if its not leaking and just shows symtoms you can try to remove and clean it and reinstall before you replace it I usually do this step first
Alan
Alan
"at times", I have a very rough idle and under light throttle (just above idle) the car seems like it's missing and about to die, if I give it a little gas, it smooths right out.
I have replaced everything in the ignition system Plugs, wires, cap rotor, module, coil and it made no improvement.
I then checked fuel pressure which is very good and changed the fuel filter. Nothing has made a differance.
I recall having an issue like this on my old F-body and if my memory serves me it ended up being the EGR valve. I just wish I had remembered this sooner.
Does this sound like an EGR to you?
Thank you,
Jess
Le Mans Master
Joined: Apr 2002
Posts: 5,726
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From: Waukesha WI
St. Jude Donor '15
If you have a small vacuum pump (Mity-Vac or similar) you can try pulling a vac on the valve to see if it leaks and if the diaphram moves as it should. This will be quite difficult on an L98 w/o removing the upper plenum but I think it is possible. Pulling the valve and cleaning it would be a good first step.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
With your 180deg T-stat the coolant should get hot enough (>175deg) for the ECM to call for EGR while cruzin. So it it's not responding or stuck open the ECM should be throwing a code.
That would leave only the possibility of a leaking diaphram which could cause rough idling (I had this problem with the LB9 in my IROC). A manifold vacuum test may show up such a problem.
That would leave only the possibility of a leaking diaphram which could cause rough idling (I had this problem with the LB9 in my IROC). A manifold vacuum test may show up such a problem.
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Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by 85A4Coupe
What are the symptoms.....
a failing EGR valve?
I have no codes
Thank you,
Jess
a failing EGR valve?
I have no codes
Thank you,
Jess
There are some interesting and confusing suggestions in this thread. The symptoms you eventually described sound like the valve is opening too far, too soon and causing a lean misfire.
Originally Posted by 65Z01
That would leave only the possibility of a leaking diaphram which could cause rough idling
RACE ON!!!
Thread Starter
Instructor
Joined: Jun 2005
Posts: 243
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From: Lakeland Florida
Originally Posted by drochau
I would have the injectors tested. I chased a similar problem for weeks and it turned out I had two injectors going static.
-Dave
-Dave
I have also suspected the injectors. I pulled the injectors last week and the only thing I found wrong was a missing cap on the end of one injector. I think it fell of in the intake and probobly got sucked on through the system.
I just spent about an hour checking the EGR valve and vac switch and they "appear" to be working properly. The switch is open with the key off and closes when the key is on. I made sure vacuum didn't pass through the switch when it was activated. I then had the car idling and i unplugged the vac switch which opened it and the engine began running horrible which leads me to believe the EGR is opening. The only question I couldn't answer was if it is closing All the way.
The more I mess with it the more frustrated I get. My mileage has dropped from a 22.5 average to 16.8 just in the last two weeks.
I appreciate everyone's replies. Hopefully I'll find it soon.
Jesse
