Hey I just picked up a 2003 Civic SI Coupe, 4cyl, vtec, 1.7L about a month ago.
The last couple days it started acting up like no power and bogging out and misfiring. So I picked up some new spark plugs and put them in, still doing the same thing. Any ideas on what I can check to see what's causing the car to do this? I tried searching on here, but I can not seem to find too much. Now where I changed the plugs do I need to reset the ECU or anything? maybe check some fuses? Also there is no engine light on and the car idles fine its only while driving?

If someone could let me know that would be wicked!

Thanks,

Adam

 

How many miles are on it?

What spark plugs did you use? They should be Denso PKJ20CR-M11 or NGK PZFR6F-11

Check the freeze data and also scan for stored codes. Sometimes codes will be stored even though there is no MIL. (check engine light)

No, you don't have to reset the ECU when you change spark plugs.

 

You try changing the fuel filter yet?

 

There are 140,000 miles on it, the new spark plugs I used were recommended from the dealer and they are "NGK IRIDIUM IX - ZFR6FIX-11". How do I go about checking the codes myself on this type of car? is there a way I can jump the thing and pull them myself like I used to do on my old 1994 Accord?

Also the fuel filter is the original. Is it recommended to have that changed after so many miles?

Thanks a lot guys

 

It's really hard to explain what the car is doing, but I just went for a burn on the highway. The car seems to be lacking power like its bogged right out and picks up speed really slow. Also there is some slight backfire/misfire? you can hear it really faint. I'm not sure what would cause the car to do this? maybe try changing the coils where I just put new plugs in?


Thanks,

 

Wait, are you saying that you have mismatched plugs?

Have you checked the air filter? When is the last time it was replaced?

Have you changed the timing belt yet? It's overdue.

Are the valve clearances within spec? You're overdue for a valve inspection / adjustment. (if it hasn't been done)
Intake: 0.18mm - 0.22mm (0.007 - 0.009 in.)
Exhaust: 0.23mm - 0.27mm (0.009 - 0.011 in.)

Checked the fuel pressure? It should be 40 - 47 psi.


I've heard (meaning I've never tried it myself) that you can jump the DLC to retrieve codes, but it's easier to just have it scanned. Many auto parts stores will do it for free.

 

Mismatched plugs? no, I just put in brand new spark plugs that were recommended by the dealer (I thought that was my problem). The air filter is brand new, short ram air intake with a K&N cone filter. Timing belt was changed at about 120,000 miles. Also I just got this car and I don't think the valves been adjusted, that is on the to do list. Never checked fuel pressure yet either.

Thanks

 

So I finally got a CEL on, got it scanned was pulling a code P1259 - VTEC malfunction/initial timing issue? Called up Honda to see what the most common thing was for this code they told me to change my oil. So I got my oil changed and so far so good the cars back to normal again and the CEL went out. Just wanted to let everyone know just in case they run into this problem. Again thanks for all the help over the years its been greatly appreciated.