Corvette C4 Forum 1984 through 1996

85 missing under load

Old May 4, 2007 | 08:21 AM
  #1  
redsox's Avatar
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Default 85 missing under load

Hey everyone, My 85 has a noticeable miss under load, it seems to run fine at idle or at crusing speeds.I have replaced the distributor cap , rotor, wires and plugs and it is still the same, please help
 
Old May 4, 2007 | 09:19 AM
  #2  
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Default RE: 85 missing under load

I dont know if this will help, but mine ran so much better after cleaning the carbon build up in the throttle body.
 
Old May 4, 2007 | 07:43 PM
  #3  
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Default RE: 85 missing under load

A weak ignition coil will make one buck or surge under load. Try the coil, the way to test it is with a scope watch kilovolts. The coil should be able to put out at least 20 kv or better. The only other thing that would make it miss is an injector.
 
Old May 5, 2007 | 08:32 AM
  #4  
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Default RE: 85 missing under load

Thanks for the info, I will replace the coil and look at the throttle plate and clean if needed. Is there a way to test the injectors?
 
Old May 5, 2007 | 09:26 AM
  #5  
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Default RE: 85 missing under load

You can ohm each one. Should not be more than .5 ohm difference in reading. The other way require a fuel pressure gauge and injector tester to run a balance test. I do not think throttle body is the problem. It will give you idle problems that are more prevelant. Have you checked codes to see if you might have any TPS or MAF probs?
 
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