Bucking in low RPMs...
01-27-2011, 07:29 PM
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Bucking in low RPMs... Cam is a 236/242 114LSA... sometimes between 1500-2000 RPM, the car wants to buck bad unless I give it more gas in gear or throw it into neutral. Is this a tuning issue or just the nature of a cam of this size?
Thanks,
Adam
Thanks,
Adam
01-27-2011, 07:38 PM
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Damn... Motor mounts are brand new polys... 
That's dissappointing. I had it dyno tuned twice too.
It's more of a hopping when it's decelerating... it's not like a stalling feeling. Maybe I didn't describe it well. I dunno.
That's dissappointing. I had it dyno tuned twice too.
It's more of a hopping when it's decelerating... it's not like a stalling feeling. Maybe I didn't describe it well. I dunno.
Last edited by Adam2001WS6; 01-27-2011 at 07:52 PM.
01-27-2011, 11:58 PM
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Yes it's a tuning issue. There are a lot of threads on it over in the PCM Diagnostic & Tuning section, like this one: I'm still working on it with my tuner since I put my cam in. The problem was that it wouldn't buck/surge for him when I took it over last time 
Don't rely on a dyno tune, he has to tune it while you're driving the car normally on the street.
Good luck
Don't rely on a dyno tune, he has to tune it while you're driving the car normally on the street.
Good luck
01-28-2011, 12:10 AM
#6
If you have the ability, run a data log and try to duplicate the environment where the problem happens. My problem only happened after I had been on the road 25 minutes or so and was random during part throttle under 2500 RPM after that. I have HPT and found my issue was an intermittently bad (would randomly drop to 0% only when the engine was hot) throttle position sensor. $35 and a new sensor later, all is cool. 
Just another idea, HTH
Just another idea, HTH
01-28-2011, 08:42 AM
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Unfortunately I don't have an tuning heldheld/software to make a data log and I know zero about tuning cars. I guess I'll just have to deal with it for the time being until I can pony up another ***** of money to get a street tune.
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01-28-2011, 09:32 AM
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I guess I'll just have to deal with it for the time being until I can pony up another ***** of money to get a street tune.
01-28-2011, 10:03 AM
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Unfortunately, the shop that did the tuning is located in DE, about 2.5 hrs away from me and it's just a pain to get up there and then it has to sit up there the whole week. Not to mention ive already done the trip several times, gas money, and tolls. They are a good shop, but I need to find someone more local. I'll probably send them a quick email though.
01-28-2011, 11:00 AM
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Unfortunately, the shop that did the tuning is located in DE, about 2.5 hrs away from me and it's just a pain to get up there and then it has to sit up there the whole week. Not to mention ive already done the trip several times, gas money, and tolls. They are a good shop, but I need to find someone more local. I'll probably send them a quick email though.
01-28-2011, 12:42 PM
#12
I agree with Paul, I have a ms4 in my 99ss m6,now my tune is perfect,my buddy really put a lot of time to get it right,but when i got the car back it did buck just a lil at low rpms,we did some work on it while driving,now I still have a very,very lil bucking but its so minor its not worth messing with it anymore,I was really shocked on how well my buddy tuned my car,never ever died at idle,drives fine,and idles really well, imho bucking,cam surge,etc is all issues people deal with when running a big cam,but some street tune time will help ya out,also what gear are you running?I'm swapin out the ms4 pretty soon for a eps cam so I can run the heads I have just chillin here in my garage,good luck man,
01-28-2011, 01:07 PM
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how do u gauge what a lot or little? even the stock cam/tune bucks at a low rpm if you get it to get into a fit and once it starts it doesn't stop unless you manually interrupt it. reminds me of a divergence series in calculus...haha
01-29-2011, 07:25 AM
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My tuner spent a lot of time tuning the surge out of my car and I have a smaller cam. It still bucks a tiny bit. 411 gears helped a lot, because I'm now above that 15-1700rpm range rolling through parking lots, etc. Under load, cruising in 6th, It doesn't buck any more. I think he said that he pulled a couple degrees of timing at those rpms. I just push in the clutch when it starts, then ease back into it.
