engine misses and sputters
07-07-2010, 10:47 PM
#1
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Join Date: May 2007
Location: Fort Atkinson, WI
Posts: 344
engine misses and sputters
Today my 1989 firebird formula with a 305 tbi started to miss/sputter at about 55mph. When I slowed down it was still doing the same thing and I was able to get the car home. I thought maybe the spark plugs were bad so I changed them and no change. Also, I checked the egr valve and it appears to be working ok. I did a complete tune up on the car about 3 years ago ( 5000 miles ) so I don't really think it's any of those components. I am not getting a service engine soon light and the exhaust smells really bad.
07-09-2010, 10:42 PM
#2
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Join Date: May 2007
Location: Fort Atkinson, WI
Posts: 344
Well, I have checked everything I could think of and found nothing. I'm thinking about taking it to the local muffler shop and have them check to see if the cat. is plugged. To my knowledge it is the original one on the car.
07-12-2010, 01:18 PM
#3
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Join Date: Jun 2004
Location: Austin, TX
Posts: 151
You can check the basic things first: fuel pressure, ignition base timing, fuel injector spray pattern (visually) etc.
Fuel pressure for TBI units varies, the typical range is 9-11psi.
Base timing on the TBI engines could again vary, from 4 to 8 degrees BTDC, depending on what the last mechanic set it to, because each engine likes a different base. Don't forget to disconnect the single-prong connector (tan/black wire) by the blower motor.
The fuel injection pattern should be nice and conical and should look the same from both injectors. No dripping or stream spray.
Let us know what you find.
Lou
Fuel pressure for TBI units varies, the typical range is 9-11psi.
Base timing on the TBI engines could again vary, from 4 to 8 degrees BTDC, depending on what the last mechanic set it to, because each engine likes a different base. Don't forget to disconnect the single-prong connector (tan/black wire) by the blower motor.
The fuel injection pattern should be nice and conical and should look the same from both injectors. No dripping or stream spray.
Let us know what you find.
Lou
07-13-2010, 11:34 PM
#4
Registered User
Thread Starter
Join Date: May 2007
Location: Fort Atkinson, WI
Posts: 344
You can check the basic things first: fuel pressure, ignition base timing, fuel injector spray pattern (visually) etc.
Fuel pressure for TBI units varies, the typical range is 9-11psi.
Base timing on the TBI engines could again vary, from 4 to 8 degrees BTDC, depending on what the last mechanic set it to, because each engine likes a different base. Don't forget to disconnect the single-prong connector (tan/black wire) by the blower motor.
The fuel injection pattern should be nice and conical and should look the same from both injectors. No dripping or stream spray.
Let us know what you find.
Lou
Fuel pressure for TBI units varies, the typical range is 9-11psi.
Base timing on the TBI engines could again vary, from 4 to 8 degrees BTDC, depending on what the last mechanic set it to, because each engine likes a different base. Don't forget to disconnect the single-prong connector (tan/black wire) by the blower motor.
The fuel injection pattern should be nice and conical and should look the same from both injectors. No dripping or stream spray.
Let us know what you find.
Lou
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