valve float??
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12 Second Truck Club
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From: Jacksonville FL.
valve float?? i have a 2004 tahoe with a trick performance front mount with FMIC. i've been working on the tuning and all. well the other day i got on it fully for the first time racing a mustang. well it went through 1st gear nice and easy ana fast (beside AWD torque steer
) then through second real good til about 5500 rpm or so then it felt like it took a loooooong time to get to 5900 shift. then when it shifted to 3rd it felt like i hit it with a shot of N2O. it started pulling really hard again. so was this maybe valve float? the fueling was between 11.3-11.5 through the whole thing. i have a data log photo i can put up from HPT
good news is i wipe the plate with the mustang. i let out and he got beside me and down shifted on me. so i hit it again. it down shifted and away i went.
) then through second real good til about 5500 rpm or so then it felt like it took a loooooong time to get to 5900 shift. then when it shifted to 3rd it felt like i hit it with a shot of N2O. it started pulling really hard again. so was this maybe valve float? the fueling was between 11.3-11.5 through the whole thing. i have a data log photo i can put up from HPT good news is i wipe the plate with the mustang. i let out and he got beside me and down shifted on me. so i hit it again. it down shifted and away i went.
hm...nice to see another HP tuner user....
what turbo you running at 47lb/min at 4570rpms???
also, its hard to tell in that log if its valve float or not. Best way to know is either on a dyno, or actually driving it. When you get valve float.....it will pull like a train and then feel like it stops pulling and lost power....if it kinda feels like it stopped pulling, but you have alot more rpms to go, that there my friend is valve float.
what turbo you running at 47lb/min at 4570rpms???
also, its hard to tell in that log if its valve float or not. Best way to know is either on a dyno, or actually driving it. When you get valve float.....it will pull like a train and then feel like it stops pulling and lost power....if it kinda feels like it stopped pulling, but you have alot more rpms to go, that there my friend is valve float.
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12 Second Truck Club
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From: Jacksonville FL.
its similar to a t67. is 47lb/min at 4570 good? still learning here alittle. it did kinda feel like it just stoped pulling. i guess i should lower the shift rpm in 2nd until i can get some springs. ?
DO you have a cam in it? If you look at your injector duty cycle, you are at peak HP way before you shift. I would shift right after that point, just wasting energy and building needless intake air temp.
No, I am saying to shift just after that. You really need to lay your gearing and power out and figure out where you would need to shift from second to land just 100 or 200RPM over torque peak. It will really help out.
I am not sure if a truck is the best at catching the next gear for power, but it looks like you are really just dragging out 2nd way to long like you thought.
I am not sure if a truck is the best at catching the next gear for power, but it looks like you are really just dragging out 2nd way to long like you thought.
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Thread Starter
12 Second Truck Club
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From: Jacksonville FL.
here is the latest log. it really sems like it maybe valve float. it pulls really hard in first then it slowly drops off from there. i race a viper on the street. i left him behind in first gear and part of second then he pulled me and past by the time i hit third. now i know it was a viper and he has way better top end. but just useing this to make a point. at the track you can watch it slow down in acceleration.
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From: England UK
I know you cant really tell by reading regular O2's on WOT, but one of them is reading about 800mV. You could possibly be running a little lean on one bank, I know you said it was 11.3 - 11.5 AFR which sounds fine, but if your two pipes merge to one and back into two then the Dyno is going to measure the average. Of course it may be something else, just thought I'd bring this up.
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From: Jacksonville FL.
that run was mid to high 10's afr. i have a wideband, if you look up in the graph the green line is wideband. i think the one narrow band reads bad do to high back pressure in the crossover pipe. when the other sensor is not in the crossover but rather the down pipe.
If you have stock valvespring's then that is without a doubt a problem. You can also attach the full log so the people who are willing to help can look at the scan as if it was thier's. You have to go to "manage attachments" under the "additional options" section when you reply.
Those 2 logs show completely different data. The first one you can see from the inj duty cycle that something was wrong 1/2 way thru 2nd as it started dropping. Second screen shot looks normal. You could be blowing thru the converter or having tranny slip is the first one. Could also be blowing out the spark.
