PAUL T Posted October 11, 2004 Report Share Posted October 11, 2004 I have had an ongoing stumbling on light acceleration in my 94 Concours and it is driving me nuts. I have replaced the Delco spark plugs and wires, fuel filter, and air filter and it still stumbles. It is not setting any codes. There is no stumbling on WOT and it does it when the engine is cold or warm. I have read where the gas cap could possibly affect this and or maybe crank sensor? It idles fine but just stumbles or misses on light acceleration. Gas mileage does not seem to be affected I still average about 20-21 mpg. What about fuel pressure regulator? Link to comment Share on other sites More sharing options...
KHE Posted October 11, 2004 Report Share Posted October 11, 2004 Have you cleaned the EGR valve lately? When I had the hesitation/stumbling on my '96 Seville, that was one of the items I was advised to check. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Regis Posted October 11, 2004 Report Share Posted October 11, 2004 Paul, I had the same problem a couple years ago. I agree with KHE about checking/ cleaning the EGR valve. I would also check/clean the phenolic spacer plates. My plates and passage ways were almost completely clogged. Scraped out enough carbon to neatly fill a large beer can. Below you'll find links to the old discussion board archives that go into more detail. By the way only 93/94 northstars have the phenolic spacer plates. http://caddysearch.netgetgoing.com/mbarchi...id=caddymb-9080 http://caddysearch.netgetgoing.com/mbarchi...id=caddymb-9077 http://caddysearch.netgetgoing.com/mbarchi...id=caddymb-3680 One of my favorites: http://caddysearch.netgetgoing.com/mbarchi...id=caddymb-1290 Should read this too: http://caddysearch.netgetgoing.com/mbarchi...?id=53366a53502 http://caddysearch.netgetgoing.com/mbarchi...?id=51024a51108 http://caddysearch.netgetgoing.com/mbarchi...?id=49906a49930 Well these should get you started. Post back if you need more info and good luck. -kg "Burns" rubber " I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. " Link to comment Share on other sites More sharing options...
PAUL T Posted October 11, 2004 Author Report Share Posted October 11, 2004 When the EGR starts plugging up doesn't it throw a code? I have no codes. I do WOT very often, will it still carbon up the phenolic spacers an passage ways? The car does almost have 114,000 miles, I guess it won't hurt to clean the EGR and passage ways. It does do all of the stumbling when it pulls a slight grade then it drops down a gear and goes away. Thanks for the info, anybody else got suggestions? Link to comment Share on other sites More sharing options...
Regis Posted October 11, 2004 Report Share Posted October 11, 2004 If the EGR canister is getting fouled up it should throw a PO36 i believe. However if the phenolic spacer plates are gunked up with carbon I don't believe you'll get a code. I didn't. It's been suggested that decarbonizing of the phenolic spacer plates be done every 100,000 miles. So you're probably due at 114,000. After mine were cleaned I immediately had more power and my mileage went from 19-23 (highway) to 24-28mpg. Oh and no more stumbling. -kg "Burns" rubber " I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. " Link to comment Share on other sites More sharing options...
BSchlossmann Posted October 11, 2004 Report Share Posted October 11, 2004 The 93/94 4.6L Phenolic spacers carbon up about every 100k miles. It takes a couple of hours and can be done without removing the intake manifold. I used 2x4 blocks as spacers to hold the passinger side of the manifold up far enough to gain access to the spacers. Don't lift the manifold up too high or you may cause fuel line damage. The spacers come out easily. You will also need to spend a lot of time scraping the manifolds. Stuff some rags in the ports to prevent loose carbon from dropping into the valve area. Otherwise, when when you go to start it back up it will run crappy for a couple of minutes. I scrapped and used a vacuum at the same time. This solved the stumbling problem. Link to comment Share on other sites More sharing options...
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