Civic VX with miss at 2k rpms
 

I just purchased a nice 130,000 mile VX (Canadian version). All orig except aftermarket distributor and add-on A/C that looks factory installed. New NGK ZFR4F11 plugs. First two tanks avg 55 mpg. No worries, right? Well not quite. Engine has miss at approx 2k rpm (no CEL). Looking for troubleshooting recommendations. I do not own a scan tool, but would consider buying one if it help identify component failure. Not real enthusiastic about poking holes in factory wiring so also considering ECU extension harness to test with Multimeter.

I know you probably did but, did you use anti-seize on the spark plugs and torque them to proper spec? Because if one wiggled loose it would allow compression to blow past the spark plug, but wouldn't throw a CEL.

The problem with the miss was happening before the new plugs. New plugs did not help. But I do need to go back and put anti seize on them. Thanks

Hey Gatorsby7, if your new, welcome to the site. By chance, is the mis-fire your feeling just the VX engaging into "lean burn". I ask, because I have found that around the 2000K mark, the engine either wants to enter/leave burn, OR to leave Lean Burn and engage into Vtec, depending on how I modulate the throttle.

Lean burn feels like a misfire. The engine will run rough, but you'll burn a lot less gas than in a stoichiometric burn. It's why the VX trim has such a better EPA rating than the CX, which shares the same transmission and displacement.

Most of the VXs at that mileage would benefit from a EGR passage cleaning unless it has already been done.

regards
mech

OG VX,

It could very well be what you said. I've only noticed it after it is warm.

Lean burn at 2k? Dang

Lean burn in my car feels like the car just loses all power and takes twice the throttle to get anywhere.

Really? Wow, weird. Yeah, there is definitely a sensation of loss in torque as the car goes into Lean Burn on the VX. However, the way the gearing is on our tranny's, it does work out OK that it kicks in at that 2K rpm mark. It can kick in during 3rd, 4th, or 5th gear. I've never had it kick on in 2nd, but that's b/c I use that as a gear primarily to get up to speed.

It should also be noted that I've had good success doing the following for high-traffic scenarios: Power quickly through 1st and 2nd, fairly agressively, using VTEC in 2nd (only) to get up to speed. Don't go "all out" but just be agressive to get up to speed. Then I enter 3rd at a speed where I can nearly instantly get into Lean Burn. I've found this to be more beneficial as the car gets up to speed faster, and I end up using less gas during my acceleration to speed overall. This can seem counter-intuitive, as you feel like you are using a good bit of gas in the VTEC part of your acceleration. You are indeed, but not as much as you may use "eekking" it out to get to 3rd the slow way. Plus, more importantly, you get there faster, and don't piss off others behind you. :thumbup:

Also, important to this thread, doing the above steps will help you avoid having to cross that awkward bridge where the FI computer can't decide if you want to be in Lean Burn, a standard condition, or VTEC. You "power through" and past that bubble-moment. Does that make sense?

Yep last sentence cleared it up pretty well. The hx only engages in 5th gear and it is a seamless transition, from what you're saying it would be pretty rough transition from lean burn directly in to vtec.

It does that at 78mph in the hx but it feels like a turbo kicking in as it does vtec very gradually