up2ng Posted October 13, 2004 Report Share Posted October 13, 2004 My 85,000 mile 1997 deville has been having a problem with misfiring. I changed the plugs(Bosch Platinum) when I got the car in June as part the "I don't know what the old owner did or didn't do tuneup" along with wires,PCV Valve, clean EGR valve pintle & passages underneath(code 340`?). The car started misfiring so I pulled the plugs and they had ash on them with a coating of carbon. I put Autolite Dbl Platinums on 2 weeks ago (on recommendation from friend) due to misfiring and found ash on the plugs. Fast forward to today I put new Bosch Platinum +2's in and within 50 Miles I am,getting the same problem with misfiring !. I am going to pull the plugs tomorrow morning and see which cylinder is the culprit but my question is how can I clean the carbon out without spending $400 at the dealer for their procedure (TSB spray, leave for 2 hrs, vac out cylinders) ? I have tried SeaFoam, dumping water in at 3000 rpm and niether seemed to work(I did both through the Brake Booster hose). I did shine a light through the plug hole and found the tops of the pistons looked like charred steak and the car has been using 1 quart of oil per 300-400 miles. I am currently not the richest person in the world (between jobs) but I do need the car to get around and $400 is a deal breaker at the moment. ANY help would be appreciated. P.S. I beat the snot out of this car as per Guru and others to clean carbon but my front motor mount is shot (if anyonehas tips on replacing this doodad feel free to enlighten me) and don't really wan't to chance dropping the drivetrain on the highway Link to comment Share on other sites More sharing options...
JasonA Posted October 13, 2004 Report Share Posted October 13, 2004 With all the plugs you've changed, you've not once put in plugs that were DESIGNED with the engine -- AC-Delco Platinums. If you don't have a lot of carbon rap, I don't think carbon buildup is your problem. The problem is the multitude of aftermarket plugs that are in there. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
up2ng Posted October 13, 2004 Author Report Share Posted October 13, 2004 With all the plugs you've changed, you've not once put in plugs that were DESIGNED with the engine -- AC-Delco Platinums. If you don't have a lot of carbon rap, I don't think carbon buildup is your problem. The problem is the multitude of aftermarket plugs that are in there. Ummm. I guess the plug eat the oil too, but Delcos wont. I knew this would be one of the answers I would get. It is not the type of plug. I get code 300 when it misfires, otherwise there are no codes. And I do have the rap noise, and I did all 8 plugs together each time, no mix-and-match And I'm not being a smartass Link to comment Share on other sites More sharing options...
JasonA Posted October 13, 2004 Report Share Posted October 13, 2004 My point was that plugs with wrong heat ranges can run very wrong in a particular vehicle. For example, I put a set of Bosch Platinum plugs in my Nissan truck, when everyone tells you to put in the OE NGK plugs (like we advise OE Delco plugs). What did they do? They didn't misfire, but they spark knocked terribly. The very plugs that are supposed to work in the truck ran very wrong. I put the OE plugs back in that I took out and the truck was back to normal. Relating this back to your current problem, based on the oil consumption, it sounds like you may have rings that are sticking. This can draw oil up into the combustion chamber and make quick work of a set of spark plugs. Back to the aftermarket/OE debate, perhaps the aftermarket plugs aren't the correct heat range afterall (like the Bosch's were wrong for my truck), and perhaps they're fouling badly were Delcos wouldn't. Then you could separate the ring issue and deal with that problem separately. Thanks for adding that you have the carbon rap. You didn't list that first, so I figured you didn't have it. But that's germaine to the situation and sheds a new light on it. I don't think carbon buildup itself is your problem, especially if you really do drive the pee out of it, and have done the water and Seafoam methods. I'd say your problem could be sticking rings. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
Scotty Posted October 13, 2004 Report Share Posted October 13, 2004 One of the most amazing things that I have experienced was how poorly a 96 Corvette ran with Bosch plugs, the idle was really bad. I put in ACs, perfect! I should have known better! Link to comment Share on other sites More sharing options...
up2ng Posted October 13, 2004 Author Report Share Posted October 13, 2004 Did some searching and found 1 plug (#5 under the coil pack) that was wet, the boot on the plug wire had an arcing cut in the seam complete with white powder around the edge (these are 4 month old Delcos !). The plug hole had no edges that were sharp, nothing that would boot could tear on it must have been defective. So I went to the local dealer, raised hell and they gave me replacements ($150 for wires and no warranty would have really pissed me off). The real reason for the post was to find out if there is an alternative to GM/Cadillac's Carbon Removal Routine done at the dealership. That was the $400 comment and the explaination of 1 quart of oil every 300 miles. The other 7 plugs that were not misfiring had ash/carbon all over them. The oil has to go somewhere and its not leaking on the ground or in the coolant (yes I use pellets). I would like to cut the cars insatiable appetite for 10w30 ! Thanks for your help ! P.S. The OE plugs locally here are $8-9 each, and I have always used the Bosch Platinums in every car I have had since 1986 without issue. Link to comment Share on other sites More sharing options...
JasonA Posted October 13, 2004 Report Share Posted October 13, 2004 P.S. The OE plugs locally here are $8-9 each, and I have always used the Bosch Platinums in every car I have had since 1986 without issue. I have no doubt you've had good luck in the past with Bosch plugs. Obviously, they've got to work for some people becaues they keep selling them. I've found that parts and mods for cars are like medicine for us. Each specimen reacts differently to the same part/medicine, and each specimen has slightly different side effects. Glad you found the misfiring problem. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
up2ng Posted October 14, 2004 Author Report Share Posted October 14, 2004 P.S. I beat the snot out of this car as per Guru and others to clean carbon but my front motor mount is shot (if anyonehas tips on replacing this doodad feel free to enlighten me) and don't really wan't to chance dropping the drivetrain on the highway I used to do it Link to comment Share on other sites More sharing options...
wake Posted October 14, 2004 Report Share Posted October 14, 2004 One of the most amazing things that I have experienced was how poorly a 96 Corvette ran with Bosch plugs, the idle was really bad. I put in ACs, perfect! I should have known better! That's funny, my previous 96 Corvette, my previous 94 NS ELdo, my 98 ETC, all ran perfectly fine with Bosch platinum plugs... My current 96 Vette is running copper NGK plugs because it's not a daily driver and the 98 ETC is running +2 plugs instead of the +4s I had in my 94 Eldo... Both vehicles are purring along quite nicely... Honestly I don't think your choice in plugs is going to cause you drivability problems unless you choose something way out of the OEM heat range... Link to comment Share on other sites More sharing options...
growe3 Posted October 14, 2004 Report Share Posted October 14, 2004 I have run the Bosch Platinum 4 plugs in my 93' STS. They work fine. Until I get a few thousand miles on the car. Then they seem to "misfire, shudder". I changed back to my Champion Dual Platinums, the power is back and the shudder is gone. I'm not an expert on what is happening, but the Bosch Platinum 4 plugs just do not seem to work right in the Northstar. -George Drive'em like you own 'em. - ....................04 DTS............................ Link to comment Share on other sites More sharing options...
Scotty Posted October 14, 2004 Report Share Posted October 14, 2004 One of the most amazing things that I have experienced was how poorly a 96 Corvette ran with Bosch plugs, the idle was really bad. I put in ACs, perfect! I should have known better! That's funny, my previous 96 Corvette, my previous 94 NS ELdo, my 98 ETC, all ran perfectly fine with Bosch platinum plugs... My current 96 Vette is running copper NGK plugs because it's not a daily driver and the 98 ETC is running +2 plugs instead of the +4s I had in my 94 Eldo... Both vehicles are purring along quite nicely... Honestly I don't think your choice in plugs is going to cause you drivability problems unless you choose something way out of the OEM heat range... Who knows, all I know is what I saw and experienced. If the plug was the wrong heat range it is what was handed to me over the counter. All I know is that the car ran like crap and hardly idled. Put in the ACs and it ran fine. It is doubtful that it had to do with ANYTHING else but the plugs since I am a total fanatic about details, fit and perfection. That means that I checked each wire, wire connector (both ends), their routing, cap, rotor, etc. When I do something it takes twice as long as I leave nothing to chance. That quirk in my personality is both a horrible trait and a very good trait at the same time. Since I have heard and seen non OEM plugs cause problems often in GM engines, I do think there is something to it. I have seen GM especially Caddy's run crappy over and over if you don't use AC plugs since I was a kid. Champions are the worst in a GM car. Link to comment Share on other sites More sharing options...
JasonA Posted October 14, 2004 Report Share Posted October 14, 2004 This is the reason why we whole-heartedly recommend AC-Delco parts. Sure, you might have a third-party part (like a Bosch or Champion plug) run great in your particular car, but it's going to be hit-or-miss. Many times, the third-party parts don't run as well, and you spend more money in the long run to go back and buy the correct parts. Buying GM parts up front saves the expense of potentially buying parts that don't work...then having to go back and correct. While we've heard many stories here about third-party parts not working, I don't believe we've had anyone to say, "I put in Delcos and they ran like crap." Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
up2ng Posted October 15, 2004 Author Report Share Posted October 15, 2004 While we've heard many stories here about third-party parts not working, I don't believe we've had anyone to say, "I put in Delcos and they ran like crap." Maybe not the plugs but the wires (OEM Delco w/defective boots) I got seem to have been made Monday morning or on Friday Afternoon Link to comment Share on other sites More sharing options...
bigfoo Posted October 15, 2004 Report Share Posted October 15, 2004 I use vitek plug wires and denso plugs.. have had no problems at all so far Link to comment Share on other sites More sharing options...
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