Guest doorman99 Posted April 5, 2015 Share Posted April 5, 2015 First of all I replaced the lifters in my 2004 grand prix 3800,now when I reassembled the intake and all the components it won't idle,as long as I give it throttle it'll run at high rpms,and after a few seconds it'll choke off and read on the dash display "reduced engine power"can anybody help me out? Link to comment Share on other sites More sharing options...
Guest Posted April 5, 2015 Share Posted April 5, 2015 First of all I replaced the lifters in my 2004 grand prix 3800,now when I reassembled the intake and all the components it won't idle,as long as I give it throttle it'll run at high rpms,and after a few seconds it'll choke off and read on the dash display "reduced engine power"can anybody help me out?[/quoteProbably a big vacuum leak somewhere - intake gaskets slipped/not sealed or a hose off somewhere. Check all hoses carefully and if good, spray some WD40 or starting fluid around the gaskets and see if it makes the engine rev. If so, there's your leak. I don't know anything about your engine as far as whether it uses individual rocker arms or rocker arm shafts, but I assume you initially turned down the nuts to "preset" the hydraulic lifters as called for in your service manual. Link to comment Share on other sites More sharing options...
bhambulldog Posted April 5, 2015 Share Posted April 5, 2015 Does that 3800 have a plastic intake manifold?The plastic manifold can warp causing vacuum leak. Link to comment Share on other sites More sharing options...
TexasJohn55 Posted April 5, 2015 Share Posted April 5, 2015 (edited) Codes? Have you put a scanner on it and read the codes and live data stream? Sounds like it may be the Idle Speed Control but would likely continue to run with throttle held open if that was the cause. Huge vacuum leak would cause what you are seeing. Need a live data stream to diagnose with associated codes. Edited April 5, 2015 by TexasJohn55 (see edit history) Link to comment Share on other sites More sharing options...
Guest doorman99 Posted April 5, 2015 Share Posted April 5, 2015 Codes? Have you put a scanner on it and read the codes and live data stream? Sounds like it may be the Idle Speed Control but would likely continue to run with throttle held open if that was the cause. Huge vacuum leak would cause what you are seeing. Need a live data stream to diagnose with associated codes.no,I haven't put a scanner on it yet,I figured when I had the intake off some anti freeze maybe got in the idle air control valve and maybe caused it to go hay wire! Link to comment Share on other sites More sharing options...
RansomEli Posted April 5, 2015 Share Posted April 5, 2015 From personal experience, the 3.8 V6 gives you a lot of ways to introduce a vacuum leak. First of all, try to isolate the problem. Gently spray WD-40 along the injector rails and other possible vacuum leak areas. If the engine starts to idle faster then you have located a vacuum leak. If you did not seat the fuel injector o-rings properly, then that can cause problems. Spray around the o-rings first - you may catch the problem right off. Link to comment Share on other sites More sharing options...
Guest doorman99 Posted April 6, 2015 Share Posted April 6, 2015 Yes,I put a code reader on it and it showed no codes,I sprayed wd-40 and carb cleaner around the intake and no dofference,so I'm gonna call a professional in the morning, it's something that I've done,cause I ran when I pulled it in the shop Link to comment Share on other sites More sharing options...
John348 Posted April 6, 2015 Share Posted April 6, 2015 I worked with a guy who was real big on 3.8 Pontiacs, he built one that runs in the low 10's front wheel drive also! I remember he was active on a forum that was dedicated just to these engines, it might be worth asking these guyshttp://www.grandprixforums.net/ Link to comment Share on other sites More sharing options...
RansomEli Posted April 6, 2015 Share Posted April 6, 2015 Whatever happens, let us know. I've learned a lot from this forum. Link to comment Share on other sites More sharing options...
John348 Posted April 6, 2015 Share Posted April 6, 2015 How did it run before you replaced the lifters? Could it be a clogged cat, and you are noticing it more now that you are taking in and exhuasting more air with the improoved valve lift? If you remove the O2 sensor (it will sound like a tractor) and if the idle improoves the cat is clogged. Link to comment Share on other sites More sharing options...
Harold Posted April 6, 2015 Share Posted April 6, 2015 I think the 3.1's had different-sized pushrods for intake and exhaust. The 3.8 may be the same design and you got some pushrods mixed up when reassembling.Another good site for these cars is w-body.com . Link to comment Share on other sites More sharing options...
Guest Rp1967 Posted April 7, 2015 Share Posted April 7, 2015 Did you reattach the brake booster vac connector on the back of the plenum, thats one big vac leak . Link to comment Share on other sites More sharing options...
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