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buick misfiring problem


agairob's Avatar
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04-10-04, 06:48 PM   #1  
agairob
buick misfiring problem

This has been ongoing problem for over 1 year now. I have a Buick century 98 the engine rattles at idle while at gear, especially when brake is realized and car starts to inch forward with no gas applied. Sometimes it gets so bad that it only fires on 5 cylinders, but it is not consistent. I had someone replaced 5-th and 6-th injector and still the problem exists. It is driving me nuts! Avery time I take it to the shop they keep on telling me that it is a injector problem. Because that problem has been not solved for such a long time, I have noticed lately that it does gets worst in summer time and than almost disappear in winter when air temperature is low. I wonder now if that mite be pointing towards different problem than injectors. I also have replaced fuel pressure valve, just for the hack of it. Please help!!!

 
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04-11-04, 04:12 AM   #2  
Just a quick thought. Try pinching off brake booster supply hose just to check idle. Be careful driving it that way.

 
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04-11-04, 10:35 AM   #3  
agairob
I am not sure, what would pinching brake booster line do? Would it help me diagnose the problem? What can I expect when I do it at idle, and how can I use the extra information to point me toward the right solution? Sorry for being so stupid, but car repair is not the same as it used to be 20 years ago. Any help is greatly appreciated. Thank You!

 
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04-11-04, 12:16 PM   #4  
Originally posted by agairob
I am not sure, what would pinching brake booster line do? Would it help me diagnose the problem? What can I expect when I do it at idle, and how can I use the extra information to point me toward the right solution?
If, by chance you have a hole in the booster diaphram, every time you step on the brake, it will create a large vacuum leak that you can't hear because it is inside the booster housing. If you pinch off the vacuum line and your car runs better, it would point to a leaky booster. If the booster gets it's vacuum anywhere near the offending cylinders, it will effect the mixture. It's just one more thing in the process of elimination to determine the problem. Not real likely but needs to be checked.

 
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04-12-04, 04:17 PM   #5  
agairob
Thank you Desi501
I will check it today.

 
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04-12-04, 06:19 PM   #6  
Check the fuel pressure and for corrossion on the coils and wires.

 
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