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-   -   Car idles RICH when warming up, but LEAN when on gas. Intermittant (https://www.homemadeturbo.com/forced-induction-7/car-idles-rich-when-warming-up-but-lean-when-gas-intermittant-117965/)

XpL0d3r 10-20-2010 05:45 PM

Car idles RICH when warming up, but LEAN when on gas. Intermittant
 
Specs:

97 Civic, converted from auto to manual
JDM B18B, still running auto y7 harness
Harness was modifed for a y7 to y8 mini-me, as well has CKF sensor bypass due to JDM engine with USDM ECU
450cc DSM "Blue Tops", cleaned and flow tested, running to resistor box
Walbro 255lph fuel pump
4 bar OMNIpower MAP sensor
Garrett T3.T4 60 trim .48 a/r
3" downpipe & exhaust, cat-less.
Tuned on NEPTUNE, o2 sensor is disabled (running open loop)
Wideband A/F Gauge, with its own o2 sensor right in the downpipe


Here's the problem:

Car will idle fine from cold start, and drive fine. Once it gets warmed up, it idles at MAX RICH (10.0AFR). When I step on the gas, it goes LEAN (mid 16's to low 17's). When I'm driving this way, car bogs down and makes it VERY tough to drive. Letting off the gas (but coasting in gear), AFR goes down to a 10.0 rather than the 20.0 it should be going to. BUT, when I turn off the car then back on, it runs fine again most of the time.

I noticed this problem would even occur when engine was warm, when I turned on my HID's. I removed the HID's, and was fine with halogens. It ALSO happened when my sub would hit, so I removed the sub to fix that.

However, when the car warms up, it still has this rich idle/lean on gas issue. I've had the tuners re-check the tune, make sure battery offsets were fine, as well as check the injector wiring and resistor box, and all is good.

I now keep blowing fuse 15A under dash, alternator/speed sensor. I checked for wiring short (I know about the Service Bulletin), but cannot find a short. Using a 10A fuse rather than 15A works, though is dangerous, and still doesn't solve the rich/lean issue.

Could this be the alternator? It's a re-manufactured Napa alternator, though as it has a warranty I got a new one and will replace this week. The tuner keeps telling me to replace the engine harness. Just got a hold of a nice uncut one (for a y7, 5 speed) and will be replacing that as well.

I do NOT have a CEL on, though when I jump the connector I have code 20 (ELD). It is rare that ELD's go bad, but I just got a new fuse box with ELD and will put that one in. This is another reason it leads me to believe alternator because the ELD controls voltage from the alternator. When it needs more power (aka turning HID's on), it gets it from alternator. However, the subwoofer is wired to battery, so it does NOT go though the ELD. Since both issues caused the same problem, I can assume the ELD is good, though both of those (HID's and Subwoofer) use the alternator.

Also, I have cleaned and checked grounds, they are good. However I noticed my bottom radiator hose is cold, suggesting bad T-stat. Would coolant temp sensor affect any of this either?

If anyone has any insight to this PLEASE help me out.

Thanks for reading.

EDIT: Due to.. certain people.. running off and telling my tuner that me posting this stuff online means I am second guessing their work.. I AM NOT. I am simply looking for suggestions on other ideas in case the stuff they recommend does not fix the issue. Thanks.

busa4 10-21-2010 09:08 AM

the computer uses a base map until the vehicle is in closed loop. when the vehicle is in closed loop it will look at sensor readings such as the o2 sensor and the map sensor. if you have is set to never be in closed loop the computer is not going to look at these sensors. during tuning you want the system in open loop so the computer doesnt adjust afr's but once the tune is done then you need to turn the closed loop function back on.

XpL0d3r 10-26-2010 07:48 AM

It's always running open loop. I thought at first it was tuned in open loop then runs closed loop afterwards, but according to the tuner I am always running open-loop, so it's taking no o2 sensor input.. ever, I guess.


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