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swathdiver
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Well, I guess I'm having reading comprehension issues again! LOL I about drove an ebay seller crazy the other day.
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I had a lean idle issue on my C5 vette for years and it drove me nuts, and yes it was adding fuel trim up to +25 then CEL if idling a lot. Turns out one day I had my ex gf watching the O2's graph going up and down and I busted out the propane torch (NOT lit) and sprayed. Second I got near the injectors (ALL of them !!) they went rich. Turns out all of my injector orings were hard as glass. $9 later and car was purring like a kitten again.
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swathdiver
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You know that has been in the back of my mind. I did buy new o-rings for the injectors when I replaced the intake gaskets but was rushed and didn't install them. Thanks for bringing it up, I'll change them out when it starts to cool down.
George B
¯\_(ツ)_/¯
How about the MAF sensor. If it is not reading the correct flow at idle it will trow off trims. I tried a search but want to confirm its your LTFT thats climbing right?
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swathdiver
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Yes, it is LTFTs at idle. Reckon I could find the acceptable values for the MAF and watch it while idling after it is warmed up. I run the thicker, HD ACDelco air filter A3085C and this one has been in since Christmas Eve, about 10K miles. Shouldn't clog up the little 5.3.
Is there a way to compare values between the MAF and something else to see if the air intake or MAF is a restriction or reading correctly? I seem to remember LT Holman mentioning something like that when he was testing his orange pickup out.
With all the mistakes I've been making lately, I'm a little reluctant to even pop the hood!
How much do your LTFTs change at idle? Seems like you'd have to be idling a long time to affect them much. Normally they're a mix of all your driving, over time -- hence "Long Term" -- so probably a high percentage of above-idle rpms.
Now your STFTs will change instantly, so if they're good at idle, time to look elsewhere for your issue.
Now your STFTs will change instantly, so if they're good at idle, time to look elsewhere for your issue.
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swathdiver
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Before we changed the O2 sensors, the LTFTs while cruising down the highway for example would rarely get to zero. They were usually -3% or so on both sides. Coming to a stop they would begin to creep up into the negative upper single digits.
Now the LTFTs on the highway usually hit zero and creep into the upper negative teens coming to a stop or pulling into the driveway and sitting there for a few minutes.
George B
¯\_(ツ)_/¯
Found one similar issue online
https://www.silveradosierra.com/thr...uel-trim-at-idle-only-flat-43psi-fuel.722357/
https://www.silveradosierra.com/thr...uel-trim-at-idle-only-flat-43psi-fuel.722357/
As your LTFTs are dropping into the negative bracket, what are your STFTs doing? It seems like they'd also be very negative.
What's the name of this truck, Christine?
What's the name of this truck, Christine?
George B
¯\_(ツ)_/¯
Probably would be good to graph that.As your LTFTs are dropping into the negative bracket, what are your STFTs doing? It seems like they'd also be very negative.
What's the name of this truck, Christine?
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