GrandRegal Posted January 29, 2014 Report Share Posted January 29, 2014 I have a misfire in my 1993 Regal Series I. The misfire is noticeable at start up but gets worse as the engine warms to operating temp or when the a/c is turned on. It has been this way since I got it. What I've done: -I have checked the coils both cold and warm and they are all within range between 5 and 6 ohms. -Sparkplugs look fine and wires are new. -checked the fuel injectors they are all working. -I noticed the radiator level is never all the way full when I check but no external leaks after pressure test I'm thinking a possible cracked head with water in the cylinder causing a miss and crack opening wider at op temp, Maybe bad intake valves. Any input would be great. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted January 29, 2014 Report Share Posted January 29, 2014 Did pressure bleed off when you did your pressure test? Quote Link to comment Share on other sites More sharing options...
ConvertibleRoy Posted January 30, 2014 Report Share Posted January 30, 2014 My work van did that and it was a bad computer board.... good luck..... Quote Link to comment Share on other sites More sharing options...
Schurkey Posted January 30, 2014 Report Share Posted January 30, 2014 EGR passage in the manifold burned? Defective EGR valve? Defective intake gaskets? Is that a common problem with the Buick V-6 like it is with the Chevy 60-degree V-6? Cylinder leakage test will easily point out poor valve sealing. Quote Link to comment Share on other sites More sharing options...
GrandRegal Posted January 30, 2014 Author Report Share Posted January 30, 2014 It only lost .5 psi in an hour on the coolant pressure test while then engine was cold. I do see occasional bubbles in the coolant reserve tank when the car reaches temp. EGR passage in the manifold burned? Defective EGR valve? Defective intake gaskets? Is that a common problem with the Buick V-6 like it is with the Chevy 60-degree V-6? Cylinder leakage test will easily point out poor valve sealing. I don't believe the EGR passage is in the manifold on the series I 3800. Also this car was pre-dexcool so i'm thinking the intake gasket might still be ok. I don't have a leakdown tester or I would have checked the valves. Is there any other way to do this? Also would a bad egr cause a specific cylinder to miss? thanks again Quote Link to comment Share on other sites More sharing options...
redgrandprix Posted January 30, 2014 Report Share Posted January 30, 2014 compression test, maybe a local parts store can rent you a kit, it won't tell you where(if) the leak is but it will rule out any compression issues Quote Link to comment Share on other sites More sharing options...
GrandRegal Posted January 30, 2014 Author Report Share Posted January 30, 2014 I did a compression test on the front bank and everything seemed fine but don't have the clearance to screw the hose in the sparkplug hole on the back. Any suggestions on how to do this? Quote Link to comment Share on other sites More sharing options...
redgrandprix Posted January 30, 2014 Report Share Posted January 30, 2014 i'm unfamiliar with the engine setup/placement where there is a will there is a way? Quote Link to comment Share on other sites More sharing options...
Schurkey Posted January 30, 2014 Report Share Posted January 30, 2014 this car was pre-dexcool so i'm thinking the intake gasket might still be ok. My Lumina is pre-Dexcool, and the intake gaskets were a common problem. Quote Link to comment Share on other sites More sharing options...
GrandRegal Posted February 2, 2014 Author Report Share Posted February 2, 2014 *Update* Alright guys checked the spark to all the wires with a spark tester and got nothing at 35,000 volts on cylinder 4. Switched the coil with the 3-6 coil and the problem moved to cylinder 6 so looks like a bad coil even though the ohms were in spec. I will replace it and give another update. Still don't know what's causing the small coolant loss though. Thanks again. Quote Link to comment Share on other sites More sharing options...
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