Help with a diagnosis please
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Help with a diagnosis please At times the car sputters, the check engine light starts flashing, smoke starts coming from my exhaust, the car goes to a 10:1 A/F, then usually stalls. The car is giving misfire codes(300), is telling me I have issues with both of my 02 sensors (even though one was just replaced) and is injecting way too much gas (evenly on both sides). My wide band will not hold 14.8. It stays between 12:1 and 13:8 when idiling, and while cruising at low speeds.
So Kool Rays and Darkformula came over last night to help me with the car. At first I though I had a 918 issue, but my springs and valves are fine. Rutan TA told me to see if the K&N was coating my maf in oil. I cleaned it off and the results are still the same. I'm trying to think of what changed that could have caused the issue because my A/F held 14.8 last year fine. Since then I added a rossler tranny, a custom y-pipe, removed the egr's, changed from Tr55's to TR6 spark plugs, and had 2 degrees of timing pulled (for nitrous).
Can anyone point me in the right direction?
So Kool Rays and Darkformula came over last night to help me with the car. At first I though I had a 918 issue, but my springs and valves are fine. Rutan TA told me to see if the K&N was coating my maf in oil. I cleaned it off and the results are still the same. I'm trying to think of what changed that could have caused the issue because my A/F held 14.8 last year fine. Since then I added a rossler tranny, a custom y-pipe, removed the egr's, changed from Tr55's to TR6 spark plugs, and had 2 degrees of timing pulled (for nitrous).
Can anyone point me in the right direction?
Can you post a data log?
You probably have an 02 sensor signal return circuit thats intermittently pulled to ground, and the computer sees that, and floods it with fuel (+25%) to try and get it to come back up. Seen it before. Smokin exhaust and all.
Also, any chance you been runnin leaded fuel in it? That will kill the 02s and have the same symptoms.
You probably have an 02 sensor signal return circuit thats intermittently pulled to ground, and the computer sees that, and floods it with fuel (+25%) to try and get it to come back up. Seen it before. Smokin exhaust and all.
Also, any chance you been runnin leaded fuel in it? That will kill the 02s and have the same symptoms.
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Originally Posted by edcmat-l1
Can you post a data log?
You probably have an 02 sensor signal return circuit thats intermittently pulled to ground, and the computer sees that, and floods it with fuel (+25%) to try and get it to come back up. Seen it before. Smokin exhaust and all.
Also, any chance you been runnin leaded fuel in it? That will kill the 02s and have the same symptoms.
You probably have an 02 sensor signal return circuit thats intermittently pulled to ground, and the computer sees that, and floods it with fuel (+25%) to try and get it to come back up. Seen it before. Smokin exhaust and all.
Also, any chance you been runnin leaded fuel in it? That will kill the 02s and have the same symptoms.
Originally Posted by xxtheonlyxx
Thats pretty much exactly what the data log showed. I was running leaded gas all last year.
PS I'm surprised you ran it for a year without any problems til now.
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Originally Posted by edcmat-l1
Did you replace one or both 02s? If only one, then replace the other. And stick to 100 octane unleaded.
PS I'm surprised you ran it for a year without any problems til now.
PS I'm surprised you ran it for a year without any problems til now.
I did only replace one. Thanks!!!! I'm praying it will work
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Originally Posted by Billiumss
Brian, you could always bring the car over to me, I know a thing or two about LS1 cars and engine tuning.
Bill
Bill
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Originally Posted by xxtheonlyxx
Thanks Bill. We went through the tune and thats ok. I hope its just a bad O2.
Not saying that it could be the tune but since you said you were running leaded fuel, it makes sense now. Replace both O2 sensors their shot, I've seen this before. Just be 100% sure that the leaded fuel is out before you replace the O2s or you'll be replacing them again.
Never use leaded fuel in a car that has O2 sensors.
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Originally Posted by xxtheonlyxx
Thats pretty much exactly what the data log showed. I was running leaded gas all last year.
(arm hurts from pattin self on back, sports injury)PS thats for tblu92's benefit. He knows why.
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I was supposed to get 109 but it was 112. I didnt realize it until I had already gone through about 20 gallons of it. Then I came on hear and heard of all those guys running leaded with no issues, and the others who used it once and it destroyed their sensors. I went from June through November them my tranny broke and the car didnt move for 3 months. After the tranny was replaced the car still ran fine, but at that point I was running 107(unleaded). They worked fine for 2 more months, then took a crap on me. I didnt think about the o2's because the last time I ran leaded was November of last year..... wierd huh?
The only way I will ever run leaded will be in my fuel cell at the track a few times a year.
The only way I will ever run leaded will be in my fuel cell at the track a few times a year.
His o2's were not switching when we logged it the night I was over and the LT's were as high as 25. always over 10 and even on both sides. Brain you failed to mention you ran on leaded gas last year LOL. All the more fuel that you use in the nitrous cell I would run the VP 109 in it and forget the leaded gas altogether.
