Engine & Internal Cams, heads, valvetrain, rotating assemblies. Chat about beefing up your insides here.

Miss fire problem. Please help!

Thread Tools
 
Search this Thread
 
  #21  
Old 05-13-2010, 09:41 AM
Join Date: May 2010
Posts: 16
Default

Has anyone thought about maybe a burnt valve? Of course, it wouldn't have gotten worse with the wire change if it was a burnt valve. Has to be crossed wires to be worse after the install of the new wires. Firing order is 1-8-4-3-6-5-7-2.
 
  #22  
Old 05-13-2010, 10:16 AM
18436572's Avatar
1st Gear Member
Join Date: Apr 2010
Location: quebec , canada
Posts: 127
Default

for sure it could be a valve but that is why the cylinder balance test will help find the bad cylinder.
or new test ...
now that you have run a while on the new plugs,
take them all out ( pop them into a card-board to keep them in order ) to see how they are burning, should all be the same ... black on the sides and light to drark brown in the middle.
if you have a plug that is wet in gas and white still , it could be a bad or mixed wire.
with all the plugs out you can do a compression test to check for bad valves.
 

Last edited by 18436572; 05-13-2010 at 10:19 AM.
  #23  
Old 05-15-2010, 05:55 PM
82 z28's Avatar
In the Staging Lanes
Thread Starter
Join Date: Mar 2010
Posts: 63
Default

Its not croosed wires i checked and checked the firing order...and all the plugs looked fine when we took the other ones out and replaced them.

How do you do a compression check to check for bad valves
 
  #24  
Old 05-15-2010, 07:07 PM
18436572's Avatar
1st Gear Member
Join Date: Apr 2010
Location: quebec , canada
Posts: 127
Default

a cylinder with a bad valve will have little to no compression.
you need to screw a guage in place of the spark plug and crank the engine to measure the pressure
 
  #25  
Old 06-04-2010, 03:56 PM
82 z28's Avatar
In the Staging Lanes
Thread Starter
Join Date: Mar 2010
Posts: 63
Default

Hey its been a while and i just think i should say that the miss has gotten a little worse. It does it all the time now when i downshift, deccelerate, or rev it hard. If i step on it it will miss for a second, if i rev it quick it misses alot. Ever since it has started doing it, it has progressivly gotten worse and i am afraid it will continue to only get worse. I know for sure its not the plugs, wires, cap, button, or wrong firing order, those have all been changed like i said and the firing order has been checked. Please does anybody know what else it could, let me know even if its bad, i have to know because i dont wanna wait and slowly watch my car get ****ty.
 
  #26  
Old 06-05-2010, 01:20 PM
82 z28's Avatar
In the Staging Lanes
Thread Starter
Join Date: Mar 2010
Posts: 63
Default

It could definately be a vacuum leak couldnt it? It is the most noticable at idle...it is pretty rough, sometimes it comes close to dying when i put it in gear.
 
  #27  
Old 06-05-2010, 01:25 PM
Camaro 69's Avatar
Senior Moderator
January 2010 ROTM Winner
Join Date: Oct 2007
Location: The 'Burbs of Chicago
Posts: 18,306
Default

Is it ok or semi ok when the engine is cold, then gets progressively worse as it heats up? Or is it the same, cold or hot engine?
 
  #28  
Old 06-05-2010, 01:39 PM
82 z28's Avatar
In the Staging Lanes
Thread Starter
Join Date: Mar 2010
Posts: 63
Default

Well when its cold it acts like its gonna die for a second after i start it up but if i rev it once or twice it doesnt die but it keeps idling rough...if i put it in gear when its cold it will either die if its real cold or chug real badly if i let it warm up for a few minutes (worse in revererse). But for the most part it always is rough at idle hot or cold.
 
  #29  
Old 06-05-2010, 02:00 PM
18436572's Avatar
1st Gear Member
Join Date: Apr 2010
Location: quebec , canada
Posts: 127
Default

so you basically haven't done any tests then?
your just still listing symtoms.
just reread the three pages of advice, do the tests, or get them done and if you still have a problem ... it would be easier to give more advice.
basically every possible problem with an engine is listed .... lol
 
  #30  
Old 06-05-2010, 05:04 PM
Camaro 69's Avatar
Senior Moderator
January 2010 ROTM Winner
Join Date: Oct 2007
Location: The 'Burbs of Chicago
Posts: 18,306
Default

Might wanna look at the carb next then to rule that out, or in.
Has it ever been rebuilt, or does it need to be?
Is the choke opening all the way?
What kind of fuel filter do you have?
Have you checked to see if your carb still has the built-in filter in the carb? It's usually a real fine sintered bronze and is located under the big fitting where the fuel inlet line is connected.
Whatever you do, DON'T horse that fitting back onto the carb, they can strip out very easily. Often times, that filter can be forgotten about and could be clogged and restricting fuel flow.
It's worth a look anyway.
 


Quick Reply: Miss fire problem. Please help!



All times are GMT -5. The time now is 04:38 AM.