Still Bucking Around 1500 RPM.
#1
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Still getting the bucking around 1500 at 0% TP. I am running SD mode. Bucking has been there since the cam was installed (before and after SD). VE Table is within 2%. I am also running EFILive OS 3. I have tried: Increasing Spark; decreasing spark; increasing the AFR. My idle cells are right on. Below is the last log in the bucking are. MAP is around 50kpa.
Car runs great except for this bucking which is getting to be a pain
.
Can anyone help?
Bucking Area 11-03-05
..Frame ..Time GM.KR SAE.ECT SAE.IAT SAE.MAP SAE.RPM SAE.SPARKADV SAE.VSS GM.TP GM.AFR GM.DYNAIR CALC.AFR_LC12
754 13:00.1 0 172 73 53 1621 26 53 0.4 14.63 23.24 14.55
755 13:00.3 0 172 73 49 1596 26 53 0.4 14.63 21.36 14.56
756 13:00.5 0 172 73 48 1575 26 53 0.4 14.63 21.15 14.58
757 13:00.7 0 172 73 48 1615 25.5 53 0.4 14.63 21.51 14.46
758 13:00.8 0 172 73 48 1573 26 53 0.4 14.63 19.78 14.34
759 13:01.0 0 172 73 48 1622 26 53 0.4 14.63 21.2 14.51
760 13:01.2 0 172 73 47 1555 26 52 0.4 14.63 20.09 14.48
761 13:01.4 0 172 73 48 1595 26 53 0.4 14.63 20.41 14.77
762 13:01.5 0 172 73 46 1592 26 52 0.4 14.63 20.29 15.15
763 13:01.7 0 172 73 47 1575 26 52 0.4 14.63 19.77 14.77
764 13:01.9 0 172 73 47 1544 26 52 0.4 14.63 19.11 14.74
765 13:02.1 0 172 73 47 1543 26.5 52 0.4 14.63 18.98 14.34
766 13:02.2 0 172 73 47 1498 26.5 51 0.4 14.63 18.95 14.86
767 13:02.4 0 172 73 48 1526 26 50 0.4 14.63 19.44 15.18
768 13:02.6 0 172 73 48 1496 26.5 50 0.4 14.63 18.98 14.84
769 13:02.8 0 172 73 48 1471 26.5 49 0.4 14.63 18.78 14.87
770 13:02.9 0 172 73 49 1461 26.5 48 0.4 14.63 18.78 14.64
771 13:03.1 0 172 73 49 1441 26.5 47 0.4 14.63 19.09 14.17
772 13:03.3 0 172 73 49 1421 26.5 47 0.4 14.63 18.53 14.01
773 13:03.5 0 172 73 49 1412 26.5 45 0.4 14.63 18.65 14.11
Car runs great except for this bucking which is getting to be a pain
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Can anyone help?
Bucking Area 11-03-05
..Frame ..Time GM.KR SAE.ECT SAE.IAT SAE.MAP SAE.RPM SAE.SPARKADV SAE.VSS GM.TP GM.AFR GM.DYNAIR CALC.AFR_LC12
754 13:00.1 0 172 73 53 1621 26 53 0.4 14.63 23.24 14.55
755 13:00.3 0 172 73 49 1596 26 53 0.4 14.63 21.36 14.56
756 13:00.5 0 172 73 48 1575 26 53 0.4 14.63 21.15 14.58
757 13:00.7 0 172 73 48 1615 25.5 53 0.4 14.63 21.51 14.46
758 13:00.8 0 172 73 48 1573 26 53 0.4 14.63 19.78 14.34
759 13:01.0 0 172 73 48 1622 26 53 0.4 14.63 21.2 14.51
760 13:01.2 0 172 73 47 1555 26 52 0.4 14.63 20.09 14.48
761 13:01.4 0 172 73 48 1595 26 53 0.4 14.63 20.41 14.77
762 13:01.5 0 172 73 46 1592 26 52 0.4 14.63 20.29 15.15
763 13:01.7 0 172 73 47 1575 26 52 0.4 14.63 19.77 14.77
764 13:01.9 0 172 73 47 1544 26 52 0.4 14.63 19.11 14.74
765 13:02.1 0 172 73 47 1543 26.5 52 0.4 14.63 18.98 14.34
766 13:02.2 0 172 73 47 1498 26.5 51 0.4 14.63 18.95 14.86
767 13:02.4 0 172 73 48 1526 26 50 0.4 14.63 19.44 15.18
768 13:02.6 0 172 73 48 1496 26.5 50 0.4 14.63 18.98 14.84
769 13:02.8 0 172 73 48 1471 26.5 49 0.4 14.63 18.78 14.87
770 13:02.9 0 172 73 49 1461 26.5 48 0.4 14.63 18.78 14.64
771 13:03.1 0 172 73 49 1441 26.5 47 0.4 14.63 19.09 14.17
772 13:03.3 0 172 73 49 1421 26.5 47 0.4 14.63 18.53 14.01
773 13:03.5 0 172 73 49 1412 26.5 45 0.4 14.63 18.65 14.11
#2
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same thing for me man, the thing that has helped me the most is proportional fuel. the o2s were switching so slow it was making the fueling odd. since then a lot of bucking has gone away. still have some though. main things i found with mine were idle airflows but mostly fueling. how is it if you throw the car in open loop when its hot?
#3
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Originally Posted by WS6FirebirdTA00
same thing for me man, the thing that has helped me the most is proportional fuel. the o2s were switching so slow it was making the fueling odd. since then a lot of bucking has gone away. still have some though. main things i found with mine were idle airflows but mostly fueling. how is it if you throw the car in open loop when its hot?
Bill
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#5
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i just seem to notice it most when the o2s switch bad or i get in that part of the ve that wont lean out on me. doesnt seem to do it when the car is cold either. i did notice that my idle airflow values are way off depending on the oil temp. maybe that has something to do with it for me, but i dont know. but it has gotten a lot better since i lowered the proportional fuel. bill, what injectors are you running?
#6
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Originally Posted by WS6FirebirdTA00
i just seem to notice it most when the o2s switch bad or i get in that part of the ve that wont lean out on me. doesnt seem to do it when the car is cold either. i did notice that my idle airflow values are way off depending on the oil temp. maybe that has something to do with it for me, but i dont know. but it has gotten a lot better since i lowered the proportional fuel. bill, what injectors are you running?
Bill
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#7
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i started a thread about bucking issues a few days back and it seems that no one has a cure for this issue..i know what you guys are going through..it sucks when the car starts shaking like ****..just pisses you off..
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I noticed that your min TPS voltage is 0.4 just like mine. I changed a parameter called "min tps voltage for idle" to use 0.5 instead of 0.0 to help fix some erratic stalling behavior at lower speeds. You can give that a shot...
#10
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Originally Posted by technical
I noticed that your min TPS voltage is 0.4 just like mine. I changed a parameter called "min tps voltage for idle" to use 0.5 instead of 0.0 to help fix some erratic stalling behavior at lower speeds. You can give that a shot...
#11
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Originally Posted by technical
I noticed that your min TPS voltage is 0.4 just like mine. I changed a parameter called "min tps voltage for idle" to use 0.5 instead of 0.0 to help fix some erratic stalling behavior at lower speeds. You can give that a shot...
Bill
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#13
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A lot of the bucking can be a result of the IAC motor fighting with the PCM. Try unplugging the IAC motor (after the car's warmed up), then see if the bucking gets better (or worse). If it changes, then you have a pretty good indicator that additional work needs to be done with the IAC effective area table.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
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Originally Posted by WS6FirebirdTA00
what issues did you experience with the tps voltage issues?
#16
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Originally Posted by ninobrn99
Bill, what does your injector duty cycles look like?? stock injectors should be maxed or close to shouldnt they??
Bill
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Last edited by Bill Bowling; 11-09-2005 at 02:10 PM.
#17
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Originally Posted by GuitsBoy
WS6FirebirdTA00 - when you say your lowered proportional fueling, what exactly did you lower?
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Originally Posted by WS6FirebirdTA00
the closed loop prop fuel, it has values in the 100's. i droped them down becuase my oscillation was very slow and hanging. my values are extremely low now, but bucking has gone away a lot. between that and fixing the throttle cracker table. if you need a hand with seeing how yours is let me know. just get a driving scan at constant throttle and scan o2s to see how the oscillate.
I've been tuning my ve table the last few days in OL/sd mode, I have very minimal surging at 1500 rpm and some very random surging while slowing down between 1000-1900rpm. Very little left but I'd like to get it better if possible.
thanks for any advice
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I definitely found that IAC operations were a big part of my cam surge. Through tuning spark and VE and all that good stuff, I was able to keep the surge to under 1200 rpm. Once I nailed the IAC vs Effective Area and RAF tables, it now only starts to surge at 900 rpm, and then only in 1st or 2nd gear. I can cruise all day in 6th at 800 rpm with no surging. I have the same cam you do, so you should be able to get similar results.
Definitely make sure your idle stuff is dead on, and also the idle proportional fueling like WS6FirebirdTA00 mentioned.
Definitely make sure your idle stuff is dead on, and also the idle proportional fueling like WS6FirebirdTA00 mentioned.
#20
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Originally Posted by Checkmate
What did you 'fix' with the throttle cracker table?
I've been tuning my ve table the last few days in OL/sd mode, I have very minimal surging at 1500 rpm and some very random surging while slowing down between 1000-1900rpm. Very little left but I'd like to get it better if possible.
thanks for any advice
I've been tuning my ve table the last few days in OL/sd mode, I have very minimal surging at 1500 rpm and some very random surging while slowing down between 1000-1900rpm. Very little left but I'd like to get it better if possible.
thanks for any advice