LS1LT1 Forum banner

1 - 2 of 2 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
I have a 1994 Firebird Formula. The car has a miss in it that I can't figure out. I changed all the plugs and wires, plus put a new coil in it. I even put a new fuel filter in it. The miss is noticeable, because at low RPMs and idles you can feel the vibration. The weird thing is that there isn't a check engine light on. Any advice would be appreciated. I'm also going to use some fuel additive to see if that helps. (We also checked the injectors, and they all seemed fine.)
 

·
Global Moderator
Joined
·
13,110 Posts
Welcome to the forum.

The check engine light doesn't light up for some of the codes. So you need an obd 1 scanner to check for codes.

Because it is a pita to change the opti rotor & cap, it probably has never been done. Only way to 100% diagnose the opti low & high resolution signals is with an oscilloscope. It will show if low & high res sigmnals are present & the proper 5 volt square wave.

You can buy a PC based scope for around $70 on ebay, amazon,etc.

Has your air filter & fuel filter been changed? If not, do so. And get a fuel injection pressure tester and check your fuel pressure. It should be around 43 psi @ key on prime. Above 30 psi @ idle and around 40 psi during other driving conditions.

When you say you checked out your fuel injectors, did you pull fuel rail and make sure your injectors had a good spray pattern. And they didn't leak when not spraying fuel? Always change o-rings when fuel rail pulled. And have FIRE EXTINGUISHER at hand when testing injector spray pattern.

As a resource we have the 94 factory service manual at the following link. It has everything you need to know about your car. www.mediafire.com/?40mfgeoe4ctti
 
1 - 2 of 2 Posts
Top