jamesg Posted February 16, 2004 Report Share Posted February 16, 2004 My 93 STS has a slight vibration? Is it the egr valve, o2 sensor or what? Link to comment Share on other sites More sharing options...
Jan Olsson Posted February 16, 2004 Report Share Posted February 16, 2004 What kind of vibrations? Harsh shifts? Poor idle quality? If your car has made 100 000 miles+ it´s likely time to clean the EGR valve, throttle body, phenolic spacers etc, change fuel and air filter, change plugs and perhaps plug wires too. The are lots of posts in the old Cadillac message board about these topics. Reguards Link to comment Share on other sites More sharing options...
jamesg Posted February 16, 2004 Author Report Share Posted February 16, 2004 A slight vibration on the steering wheel and you can barely feel it in the driver's and passgenger seats. I had a tune up at 100,000 new wires plat plugs, the whole nine yards, new fuel filter, cleaned throttle body, new air filter after each oil change. Have not cleaned or replaced egr valve yet or changed O2 sensors or cleaned phenolic spacers yet. Link to comment Share on other sites More sharing options...
loucar1 Posted February 16, 2004 Report Share Posted February 16, 2004 Check for codes first, but I would clean EGR valve and Plates as the next step Lou 94 Seville STS Link to comment Share on other sites More sharing options...
Jan Olsson Posted February 17, 2004 Report Share Posted February 17, 2004 Check for codes first, but I would clean EGR valve and Plates as the next step I´ll agree. And while you´re at it, clean the electrical connections to the ignition module with anti-corrosive "oil", and make sure that the ignition coil connections for the spark plug wires aren´t burned or corroded. That could happen if the former wire set was bad. The ignition system is quite sensitive ie it needs good connections. I would be surprised if these things together wouldn´t make some difference. Make sure that you hold the EGR valve in upright position when you spray solvent into it. You don´t want the solvent to get passed the sealing inside because it can damage the electrical insulation. Link to comment Share on other sites More sharing options...
KHE Posted February 17, 2004 Report Share Posted February 17, 2004 Check for codes first, but I would clean EGR valve and Plates as the next step At idle, there is no EGR flow so I wouldn't think that the EGR system is causing the problem as long as the pintle position code is not set. Have you checked the fuel pressure regulator? With the key on (DO NOT start the engine), there should not be any fuel leaking out of the nipple on the FPR. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Poobah Posted February 17, 2004 Report Share Posted February 17, 2004 And while you´re at it, clean the electrical connections to the ignition module with anti-corrosive "oil", and make sure that the ignition coil connections for the spark plug wires aren´t burned or corroded. I installed timeserts and replaced my head gaskets about 3000 miles ago. While the engine was all apart, I had had new plugs and wires installed, had the EGR passages including phenolic spacer cleaned and all that sort of routine 100,000 mile type maintenance done. The EGR valve itself was replaced about 5000 miles ago. Ever since I've had the car back, the idle has occasionally been a little rough as if there is a slight intermittent ignition problem. Often, it's fine and it is entirely possible that I'm just overly sensitive to it. (There have been no codes set.) I'm wondering if the above suggestions might be worth looking into. If so, please tell me where the ignition module is and what type of anti corrosive "oil" should I use to clean the connections? Should I use the same stuff to clean the ignition coil connections for the spark plug wires? What about the connections at the spark plugs? Any information or suggestions would be appreciated. Happiness is owning a Cadillac with no codes. Link to comment Share on other sites More sharing options...
KHE Posted February 17, 2004 Report Share Posted February 17, 2004 I would use dielectric grease on the electrical connections. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Barry94 Posted February 17, 2004 Report Share Posted February 17, 2004 Not to frighten you, when I bought my STS, I had a vibration in the engine. Long story short, it was a burned exhaust valve. Compression on one cyl was down to 55 lbs. It was 1000 mi. over the warranty. GM would do nothing !!!!!!!!!!! I suspect the previous owner had carbon build up under the valve and it eventually burned. If you can't find the problem, get the compression checked. Barry 2008 STS V82016 Colorado Z711970 Corvette LT-1 Coupe Link to comment Share on other sites More sharing options...
Jan Olsson Posted February 18, 2004 Report Share Posted February 18, 2004 I think my STS idles better than any Volvo I´ve had, including the 6-cylinder 960. As bbobynski says "it´s the nature of the beast" to get a slight vibration with a high output engine like this I´ve done some major tune up and for everything I´ve changed, cleaned etc the car runs better and better and idles quite smooth now, almost as good as my -88 Eldo The only thing I want to do is to change my EGR-valve beacuse of a rattling noice. It helped a great lot when I cleaned it, the idle went better and the shifts are so smooth now! Link to comment Share on other sites More sharing options...
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