Coldstart AF Reading
- Thread starter cbird77
- Start date
Eric Stage I
TurboTweak Guy
- Joined
- May 25, 2001
Depends on how cold, but it could be down in the 10's. If you have the capability to tune cold start, we generally go as lean as possible while keeping it smooth, and without causing it to stall when dropped into gear.
Eric
Eric
I installed new NGK UR-5 plugs @ .032 gap, changed oil, started up and black smoke coming from exhaust. The plugs I pulled were fouled severely. AFR shows 14.5. Fumes burn your eyes. It's around 70 degrees here in TN today. I'm beginning to think there is something wrong with the wide-band (PLX). What symptoms should I look for or other ideas. Attached file is a cold start log....
I'm not familiar with the PLX. Does it have to be calibrated? How old is the sensor and where is it located on the DP?
What does the Narrowband read?
Will look at your PL file when I get home. Is there a variance between ECM AFR and WIDEBAND AFR? Is the correct Wideband selected in the PL?
Something is certainly weird because nothing in that file indicates an overly rich condition. Not the narrowband nor the wideband.
What chip are you running? Why is the highlighted BLM cell #10 at idle?
You've got some weird "jittery" crap going on in that ECM! Pull up the gauge screen and scroll through the file with your arrow keys and watch the gauge dials jumping around. That's NOT normal, even at idle. I know it's not worth looking at but.... the ECM AFR is showing 0.1:1 which is not a reading that a normal ECM/CHIP should be indicating.
Which plugs were fouled?? All of them? One or two?
Your wideband indicates about 14.7:1 throughout, and as your narrowband heats up, it's pretty close to agreeing, so both O2 sensors agree with each other, but why 14.7:1 at cold start up. They should be indicating richer than that.
You could have one or more injectors stuck open.
delcowizzid
newzealand turbo 3.8
- Joined
- Mar 3, 2010
If its massively rich and missfiring you will read lean on narrow and wideband o2s and have fuel smoke out the pipes
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Sent from my C8660 using Tapatalk 2
I pulled the computer and checked the connections and all seemed ok. Reseated the chip...still rich...I did lower my idle fuel to 126 and it leaned out 15.2 afr. While watching the PL I did notice the narrowband O2 pop low from .500 down to .150 a few times.
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Eric Stage I
TurboTweak Guy
- Joined
- May 25, 2001
Cell 10 is cold start, that's why its highlighted.
If it's rich, then the AFR can't be 15.2. So make sure all your wideband input wiring is correct. You might need a new sensor. The reading looks very inactive, so the sensor might be dead.
The IAC is too high, so that's also adding fuel (the SD chips have IAC fuel compensation). Open up the throttle blade a bit with the screw to get the IAC down.
Do you also have a stock O2 in there?
You can try to continue to reduce idle fuel (cell 9), but it would be nice to see the real AFR.
If it's rich, then the AFR can't be 15.2. So make sure all your wideband input wiring is correct. You might need a new sensor. The reading looks very inactive, so the sensor might be dead.
The IAC is too high, so that's also adding fuel (the SD chips have IAC fuel compensation). Open up the throttle blade a bit with the screw to get the IAC down.
Do you also have a stock O2 in there?
You can try to continue to reduce idle fuel (cell 9), but it would be nice to see the real AFR.
Eric, why is his MAF reading so high at idle? (more than 20). Even though this is SD, the fake maf signal should still be somewhat real I would think. Mine is with SD2, and it also was with Translator Pro. After all, we're still talking about a stock ECM here. It still needs something of a realistic MAF reading whether it be generated by a real MAF or generated by a piggyback SD system.
I definitely want to know the real AFR. I'm going to get a new wideband on the way. It has a stock O2 as far as I know. I will work on getting the IAC cts down. Below 20, warm in park, correct? We'll see what she does then.....
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