cetheri Posted December 5, 2004 Report Share Posted December 5, 2004 Lately, when I start my '97 STS after it's been sitting for a while, it runs very rough - a shake that you can actually feel. This lasts about 45-60 seconds and then it smooths out (back to normal). At first, I suspected a fuel injector, but now I'm not so sure. The plugs are only a year old and are the 41-950's. No driveability problems after it's warm and no check engine light. This began after the weather started to cool down this fall. Also, I had the fuel rails replaced under the recall and had them go ahead and replace the FPR. This had no effect on the behavior. Anyone have any experience with such a problem? Link to comment Share on other sites More sharing options...
Ranger Posted December 5, 2004 Report Share Posted December 5, 2004 I developed a misfire right after the fuel rail replacement as I think several others reported as well. Mine was under light load. A new set of wires cured the problem. There seems to be some correlation between moving the old wires around and ignition problems immidiately afterwards. Link to comment Share on other sites More sharing options...
JasonA Posted December 5, 2004 Report Share Posted December 5, 2004 I developed a misfire right after the fuel rail replacement as I think several others reported as well. Mine was under light load. A new set of wires cured the problem. There seems to be some correlation between moving the old wires around and ignition problems immidiately afterwards. Larry, did you have to put new wires on after the recall as well? I bet yours were the original ACs...like mine. The Autolite Professionals are still running good on mine, but it's only been a few months. I hope I get a similar life out of these as I did the ACs. 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...
Ranger Posted December 6, 2004 Report Share Posted December 6, 2004 Yes, right after the recall I developed a misfire. They were the OEM wires with 92K on them. I replaced them with A/C Delco's. My '92 had 125K when I traded it and never a problem with the wires. Link to comment Share on other sites More sharing options...
cetheri Posted December 6, 2004 Author Report Share Posted December 6, 2004 Mine was actually behaving this way before I had the recall work done. I was hoping (wishful thinking) that the work, or possibly the new FPR would correct the problem. Again, it just runs rough right after I start it. A moment later it runs fine(???). Link to comment Share on other sites More sharing options...
cetheri Posted December 9, 2004 Author Report Share Posted December 9, 2004 Has anyone replaced a full set of fuel injectors in the Northstar? If so, how much did they cost and what prompted the change? Link to comment Share on other sites More sharing options...
Ranger Posted December 9, 2004 Report Share Posted December 9, 2004 I think the injectors are about $95 ea. but it is highly unlikely that all 8 injectors would go bad at the same time. Link to comment Share on other sites More sharing options...
cetheri Posted December 9, 2004 Author Report Share Posted December 9, 2004 Right, but I was thinking about just replacing them all instead of just 1. I also though about going through and testing each of them to see if one is actually bad. This is the only thing I can think of that would be causing this particular problem. Link to comment Share on other sites More sharing options...
JasonA Posted December 9, 2004 Report Share Posted December 9, 2004 Right, but I was thinking about just replacing them all instead of just 1. I also though about going through and testing each of them to see if one is actually bad. You would certainly want to do that latter (testing them) before you do the former (replacing all of them). You'll spend WAY more money replacing all of them when none of them might be bad in the first place. 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...
cetheri Posted December 21, 2004 Author Report Share Posted December 21, 2004 Does anyone have the injector test procedure they could pass along? Link to comment Share on other sites More sharing options...
cetheri Posted January 10, 2005 Author Report Share Posted January 10, 2005 Problem Fixed(???) I have resolved this problem and wish to pass on the solution, however temporary it may ultimately turn out to be. In my original post I remarked that the engine only ran rough after having been shut off for a period of time (a few hours or even all night). Last week I noticed an unusually heavy amount of steamy condensation exiting the exhaust. I'd been experiencing a mysterious loss of coolant and at that moment I began thinking that a head gasket may be failing, thereby allowing coolant into a combustion chamber or exhaust port. After doing a tremendous amount of research on coolant loss issues on this board I decided that 3 tubes of Bar's Leaks Golden Seal may help. I installed it in the upper radiator hose, drove the car about 40 miles to get it circulated well, and now the problem seems to be gone. The rough running when cold condition is gone, exhaust condensation has returned to normal levels. I can only wonder what it was exactly that the Bar's Leaks Golden Seal fixed. Might it be a faulty head gasket that will eventually open up again, porosity in the block, or perhaps even a crack? Bar's Leaks Golden Seal, or GM Coolant supplement, appears to be absolutely essential in the life of a Northstar. Bbobynski provided the clue from a previous post regarding the correction of a crack in the lifter valley discovered in a disassembled engine. My STS has 109K miles. Anyone have any thoughts? Link to comment Share on other sites More sharing options...
Ranger Posted January 10, 2005 Report Share Posted January 10, 2005 My only thought is that if it is indeed a head gasket it will certainly be a temporary fix. Link to comment Share on other sites More sharing options...
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