Just curious as to what other people read from afr's on a cold start.
I read 21:1 until the temp needle begins to move, then it steadies at 14.7:1

Can someone confirm this as being normal?

 

I would have thought it would be the otherway around...

ie 21:1 is VERY lean, 9:1 is rich... normally coldstart = rich...

 

I've seen some cars do that, My car actually was doing that when my battery was weak (Mini Battery Kit) before it was fully charged..

However look at your fuel trims, if at idle and when the car is somewhat warm, it has to add quite a bit of fuel, it means your background map is lean.. There are several ways to adjust this after you determine what your actual issue is (Aftermarket filter, low MAF reading, etc..)

I want to add before I confuse anyone, that I was assuming this is after the 15-20 second warmup cycle of your Wideband..

 

Your wideband simply hasn't heated up. Completely normal. It would misfire even when warm at a real 21:1.

 

I don't think he's referring to a wideband not being warm yet.. But I keep forgetting most widebands don't have a countdown timer like the TurboXS does that keeps you from mistakenly assuming its operating.

But I have seen what he was describing so lets wait to hear a bit more detail..

 

It seems to vary depending on the type of wideband sensor and controller, so some just show 14.7 until they warm up, some show completely lean, narrowbands usually show zero volts. Also depending on sensor positioning (and again the controller and the sensor), the wideband heaters often don't seem to be sufficient to read on many examples without some exhaust gas even if you power up the sensor a little while before you start the engine.

I've not induced lean misfire on the Evo, but on Subarus 16-17:1 is decidedly ropey, and on cold start a bit of a disaster.

You've played with more widebands than me on Evos, but I don't see how it is anything other than a misread from cold - ie sensor not warm.

 

The one i have the most experience with reads a count-down on its display.. On my externally connected gage, it reads a flat voltage representing 14.7 so I can see what your saying..

I should have clarified (I edited my post) that I was assuming this was after the sensor was actually reading properly... Which definitely would result in misfiring on tip-in and idle, which is what I was experiencing until I found the problem (Surprisingly a bad battery, and low voltage, low voltage led to being in a cell I never adjusted for the injector voltage latency, which resulted in a very lean idle with my aftermarket injectors)

 

Curious, does the countdown give a fixed time or is it getting feedback from the lambda heater circuit?

 

I know the innovative lm1 warms up first before any readings are given and after that it is on the money at like 15.3 dropping to 14.6 - 14.7 at idle.

 

Mine goes to 10.0 then slowly comes back up to 14.6

 

Its Zietronix ZT2- This is as soon as the car is turned on. The Car will idle at 1k-1.2at cold start but then increase to 1.5k and the afrs will drop to 15-17 and then when the idle steadies again then afrs go back to 21.

 

how many miles do you have on ur o2 sensor? how did you route it to your downpipe? i had an o2 sensor a while back ago. readings didn't seem accurate, i'd see 21 often during startup and even sometimes while driving. i ended up checking the connection between the extension harness and the sensor and noticed some moisture inside the connector. i ended up purchasing a new sensor and harness and everything was fine after that. oh btw, i have zeitronix.

 

On mine its definitely been a fixed count-down...

 

You really can't rely on the O2 sensor as soon as the car starts, its not warmed up, thats what JCSBanks was referring to. The Zt2 does appear to have a fairly short warmup cycle though.. you really have to look at your fuel trims and other adjustments to see what is going on.

 

or maybe it's something with the connection... :P the zt-2 is probably not getting a proper signal from the sensor. i dunno. no one seems to really care what i have to say (even in other threads. pfft), just stating what happened to me and almost everything in the first post was what i had. bah, yes i'm having a bad day at work.