'94 civic ex mixture adjust?

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flyboy

New Member
How do you adjust the mixture in a 1994 Honda civic ex? I know, I know, I need to get a Hanes manual already. My spark plugs are grey on the exposed parts, think I’m running lean. Is there a mixture screw I can turn or do I have to bring it in and have it tuned? It runs really rough in the low rpm’s especially when it is cold. I installed a test pipe and a cat back, also a ram air intake. My car hasn’t run the same since I tightened up my old leaky exhaust, but I’m not getting a check engine light like when my O2 sensor went out. Also, I can’t feel my VTEC kick in any more. Can the solenoid get stuck open on the high rpm cam?
 
your car is fuel injected, there is no way to change the mixture without having a tuneable ecu, or a piggy back system such as an apex-i afc.
if you felt the vtec kicking before you tightened the manifold then no vtec after; then maybe you have a plugged cat (unlikely) or you may have done damage to the engine when the manifold was loose (cold air hits hot valves and warps them) if you think you need a tuneup (per your other post) then I would do it, fouled or worn ignition parts can make all sorts of problems.
As far as your o2 sensor it will not throw a check engine light unless the o2 sensor fails alltogether. o2 sensors do however do all sorts of other things like give false readings and act lazy, both of which will not throw a check engine light but will cost you gas mileage and poor performance.
Without a CEL, you are stuck with the basics, check your timing, especially your ignition timing since you replaced the distributor, then check your ignition parts like the plugs wires cap and rotor, also check your fuel filter, fuel pump and air filter.
I would possibly start with a tuneup, plugs, wires, cap, rotor, fuel filter. then take it from there.
 
Thanks for the help welfare. Guess I'm gonna have to break down and bring it in to have it tuned. It bet it needs a new fuel filter, and my manifold separated right above to 02 sensor so I'll probably have to change that too. The distruibuter has a new cap and rotory button and I put in Bosch platnum plugs not long ago, but the wires have been on there for at least 7 years. Would the VTEC solenoid give me a check engine light if it failed?
 
Would the VTEC solenoid give me a check engine light if it failed?

possibly, I have seen them throw CEL if it's not hooked up, but I don't know about anything else.
 
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