HELP Honda Civic LEAN burn issue

[add|ct]

^Your O2 sensor 'could' be lazy and tired, not throwing a code yet?

It is the 5-wire and your ECU is the 49-State FED not CALI?

[Kendaddy126]

It's a brand new o2... It is a 48 state five wire. I'm thinking fuel????

[benfrogg]

How about vacuum leaks? Have you done the "spray test" with a can of cleaner at all hoses/joints with the car running?

Can you be more specific about how the car acts in lean burn? You said it is kind of like a skip. The transition into and out of lean burn can sometimes feel like a skip....

Did you buy the ngk ZFR4F11's for your plugs?

B

[Kendaddy126]

That's a good idea about the vacuum leaks... I'll try that. I do feel the "stumble" going into and out of lean burn... but it stumbles repeatedly when in lean burn. It feels like a skip, but more like a clogged EGR or a bad fuel mixture. The thing that gets me is that it runs PERFECT out of lean burn. That's why I was shying away from a vac leak. It's really got me puzzled. I had the NGK's in, but I also have Bosh that I have swapped around... the Bosh are in it now... but it did the same thing with either plug. I will try to check for vac leaks though... hadn't thought of that. Thanks

[add|ct]

^My car is similar, I have to give it more gas because it wants to 'hesitate' or 'hiccup'(not backfire)...but I also have a clutch that badly needs replacing, so???

[Kendaddy126]

OK... I sprayed all the hoses and so forth... no air leaks. Back to the basics. Any ideas?

[djenyc]

Originally Posted by Kendaddy126

OK... I sprayed all the hoses and so forth... no air leaks. Back to the basics. Any ideas?

2 things:

First of all if you have a vacuum leak you'll almost certainly have high/uneven idle.

Second, if you do have a vacuum leak, experience tells me that just spraying cleaner is not gonna do it. I had 2 VXes, both came with vacuum leaks that were significant enough to cause drivability problems, yet the cleaner method did nothing to uncover them. Eventually I was able to find source of vacuum leaks by swapping components back and forth between 2 Civics - one vacuum leak was in throttle body by the throttle plate shaft, second at intake manifold to cylinder block gasket.

If you do have high/uneven idle - go to a shop with a smoke machine and they'd be able to tell you where you problem is for not much money.

[Kendaddy126]

Idle is perfect... when cold, about 1200. when warm maybe 600 steady. NO ISSUES OUT OF LEAN BURN. None.. perfect always... in lean burn mode.. it stumbles. My only thought would be a leaky fuel injector.. they look clean.. but original with 200k on them. My next step will be to replace them.... unless anyone has any other ideas... i'm open.

[benfrogg]

Ken-
Pull em' and clean em' first. If you do it in your garage (as i did) you'll see improvement but can't really test them all that well. If you send them out (<$100 or so) they will before/after test them for spray as well as test them for leaks, failure, etc. Way cheaper than buying new. If OTOH, you have a used set you want to swap in to try it out, go for it. You'll probably end up replacing injector o-rings when you do it. Most rebuild shops will include those with the cleaning price.
B

[honerscivic]

Maybe the best way would be to tap into the o2 wires to see how lean its getting before misfiring? I have an extra sensor that came with a spare motor that I tried and had the same issue, power mode is fine, lean burn feels like a misfire ( no ping/detonation sound) so much that I couldn't stand it. I put the percieved good one back in and runs fine. Sounds like you need some hard data at this point.