01-15-2011, 07:37 AM | #743 | |
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When a car is started, the computer is in open loop until certain criteria is met. The o2 sensors need to be heated to work properly, so this is the main reason there is a delay. After the sensors are heated up, the car goes into closed loop and the O2 sensors make their corrections. The computer will go back into open loop under a variety of conditions. Throttle Position (TP) is one way. There are parameters in the computer that determine what the TP is for Open Loop, and other things. When that TP is reached, and the car goes open loop, and richens up. In closed loop fueling, the computer takes readings from the oxygen sensors which read +/- of 14.64 AFR (Stoich) and makes corrections for it. If your car is idling @ 13.5 AFR, the 02s can see this, and will know to pull out enough fuel to get back to stoich. In open loop, the fueling is purely based off the MAF transfer function and the open loop fuel table. This table has to be calibrated any time you make MAF changes, and changes that affect the airflow of the MAF. With that being said.....as long as the 02 sensors are warm, he's in the loop..given the fact they are heated, it's likely the car is in fact in closed loop. |
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01-15-2011, 07:50 AM | #744 |
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But he is running CAT Less. The sensors are not reading anything.
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01-15-2011, 08:06 AM | #745 | |
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That is incorrect....there are 2 sets of 02 sensors on the car, one set before the cats ( which will be in the collector of the header ) and one post cat ( in the cat or the off road pipe ). The rear 02 sensor are disabled in the PCM so they don't throw codes...the front 2 are still sending info the PCM to determine A/F ratio. |
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01-15-2011, 09:08 AM | #746 |
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He told me he did not hook anything to the headers. Made it sound like the cables and sensors are just tied up on his car in a loop.
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01-15-2011, 09:12 AM | #747 |
Go Blue!!!!!
Drives: 2012 Cruze LT Join Date: Mar 2009
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01-15-2011, 09:12 AM | #748 | |
Drives: 2010 Camaro SS/RS Join Date: Oct 2009
Location: Lincoln Nebraska
Posts: 1,754
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__________________
2010 IOM SS/RS LS3, Hennessey HPE550 Polished Magnuson TVS2300 Supercharger. 3.4 Pulley. Kooks long tube headers / high flow cats. GHL Full exhaust. ZL1 Fuel Pump/ADM FPCM. MSW Bap. JRE ZL1 Race cam with new springs/pushrods/Trunion Upgrade. FIC 850cc injectors. ZR1 Map sensor. CAI Induction. JRE Tune.
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01-15-2011, 09:21 AM | #749 |
Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009
Location: Mich
Posts: 4,483
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Before running much more, I'd check the oil. Make sure the oil doesn't smell like gas. Just to make sure it's not way overfueling and washing down the cylinders. You can get a rough idea if the stall is from rich or lean by blipping the throttle while its starting to die. If it chugs, revs real slow, and puffs out dark smoke.... way too rich. If it stumbles, hesitates, pops, revs quick, no dark smoke, no gas odor, then way too lean.
A few more run times (as long as it's not flooding the oil with gas) should be enough to set a code. If the oil is good, I'd give it a few more warm up runs, check the data and codes. If it's not setting codes, maybe it is just the tune. But normally it takes quite a significant mechanical change to a motor such as a big cam to not even be able to stay running on the stock tune. Fuel pressure should be fine if it idles good in open loop. The O2 readings, short term fuel trim, when the problem is happening should tell the story. |
01-15-2011, 09:52 AM | #750 |
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01-15-2011, 10:12 AM | #751 | |||||
Booooosted.
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All of my sensors are plugged in. Quote:
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Everythings plugged in. |
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01-15-2011, 11:24 AM | #752 |
Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009
Location: Mich
Posts: 4,483
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One quick check you can do to make sure all the pcv stuff is hooked up right... While it is idling relatively stable, take the oil cap off real quick. The engine should falter slightly and a small drop in rpm. Stick it back on and it should stabilize. It is very slight but noticeable. If there is absolutely no change when popping the oil cap on and off at idle, something in the PCV is not right or vacuum leak somewhere.
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01-15-2011, 11:30 AM | #753 | |
Booooosted.
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01-15-2011, 11:42 AM | #754 | ||
CamaroFans.com
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I believe if left at idle the time is an 88 sec delay which coincides w/ shutdown in the video... |
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01-15-2011, 08:12 PM | #755 |
Psssssssssshhhhhhhhhhhhh!
Drives: under contruction Join Date: Nov 2009
Location: Marysville, Ohio
Posts: 12,996
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Mighty quiet in here. I can hear crickets.
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01-15-2011, 08:15 PM | #756 |
Go Blue!!!!!
Drives: 2012 Cruze LT Join Date: Mar 2009
Location: Indiana
Posts: 23,290
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