Setup: B16A, I/H/E, Skunk2Stage1 cams, ITR valvetrain, stock fuel system.

FYI: I have a working AEM wideband with gauge. And there are no vacuum leaks.

Here is the deal:
A while ago, my car started running real rich. Changed o2-sensor and it lasted two days. Who thought that would be broken again? So instead I borrowed a map-sensor, tps, fpr and changed the fuel filter - measured fuel pressure after the filter and it checked out ok. Since there were no improvement with all this I borrowed another o2-sensor and guess what - the car ran fine and AFR was fine.

The story goes on. "Oh, it is the new lambda that is broken - I can put my own parts back on since it is the lambda anyway, right?" Wrong! The new o2-sensor lasted a good three weeks and the same **** happens all over again... Can't really go to the shop and say that even this lambda is dead from the factory

Driving around town today I got a bright idea. Tested with light and heavy load on the throttle and it seems the AFR sometimes stay correct with nearly no throttle(cruising at constant speed). As soon as I push the throttle a little or vary the throttle the AFR plunges to below what my AEM Uego can display(=VERY rich). If I lift off the throttle completely so that the injectors close and then apply light throttle and resume cruising speed, the AFR may most often stabilize around 1 lambda(14.7:1)

"It must be the map sensor then, it is vacuum dependant :D I'm a genious..." Wrong! Borrowed a known working one, no difference still.

--> Long story, I know, but as far as I can see now, the only vacuum dependant thing left is the oem FPR that I put back on after the second o2-sensor change.

Is anyone able to tell me if the FPR is the obvious problem or have I screwed my head up with this idea so far that I can no longer think clearly and have wandered too far into BS?

 

No opinions, people?

 

where are you tapping into for power and ground to the wideband?

 

Well, the FPR seems like the next step so why not try it. I can definately be it, if you are discovering that it's vaccum-related.

 

Which ECU are you using?

 

Don't see the relevance but the wideband is powered on the ignition and grounded in nearby chassis. (the wideband is used only for monitoring as of now)

Will be changing the FPR today - can a fubar FPR result in damaged o2-sensor? (clogging the 02 with carbon or something?)

ECU is a virgin P30-G (standard in EUDM Civic VTi)

 

Because if you were running a Skunk2 ECU for example, which runs rich as ****, then there is a lot of relavance to the Q.

What's your fuel pressure at? Burning oil and coolant will quickly kill one. Running rich for extended periods of time...or running with leaded race gas will do the same.

Have you ever gotten a fuel supply too lean/rich code yet? Are you using OEM O2 sensors? If not, are you at least using one that has an OEM connector already attached to it? O2 sensors that come with stripped wires needing the connector soldered/crimped onto it are the worst, it seems, for Honda's.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote"> What's your fuel pressure at? </TD></TR></TABLE>
Measured after the fuel filter, well within spec.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">Burning oil and coolant will quickly kill one. Running rich for extended periods of time...or running with leaded race gas will do the same.</TD></TR></TABLE>
Oil and coolant is not burning at all. About the running rich, seemingly it got worse and worse until the mixture went mad rich finally. Also at startup(cold engine), the mixture was way rich and making it difficult to hold the AFR at a level which would retain proper idle.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">Have you ever gotten a fuel supply too lean/rich code yet? Are you using OEM O2 sensors? If not, are you at least using one that has an OEM connector already attached to it? O2 sensors that come with stripped wires needing the connector soldered/crimped onto it are the worst, it seems, for Honda's.</TD></TR></TABLE>

No code other than 43 which is Fuel Supply System. Always OEM 4-wire O2 sensors.

I'm going to the garage now, will be replacing the FPR first and check AFR. If that does not help immedeately I will replace the o2 sensor. Then it will be fixed I know, but for how long, I don't know Guess it will last if it turns out to be the FPR.


PS. Anybody see a problem using an FPR from a 2.0i Accord 1990? The labels on the FPR are the same (NR-1) - the only difference is that the Accord FPR hasa somewhat bigger return.