Tuning gurus....have a question
08-22-2010, 10:56 AM
#1
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Tuning gurus....have a question I have a narrow knowledge of tuning. I need some help understanding.
Had my tune tweaked yesterday. Had an issue with surging and bucking at low speeds. My local tuner looked at the tune that the shop in Detroit installed and we noticed that the idle spark tables were all set to 17 degrees up to 800 rpm anything over 800 was 4 degrees (WTF). The car was bouncing back and forth from the high octane spark table to the idle table and it ran like ****. We reloaded the stock idle spark tables and the surging at low speeds went away completely. We picked up the idle to 975 from about 800 and the car gets underway smoothly with an 11 lb flywheel. Car is a head and cam motor with a 90mm Fast LSX set up. The cam is very mild (GM Hot Cam 112LSA). The only remaining issue is the hunting it does to get back to idle after deceleration (mostly at parking lot speeds) and although it will stall only occassionally, it can dip to 400 rpms and recover after several bounces. It will idle pretty steady when just sitting still. This is the last issue we need to solve as the car performs quite well other than this hunting back to idle thing. What are the tuning approaches to this problem?
Had my tune tweaked yesterday. Had an issue with surging and bucking at low speeds. My local tuner looked at the tune that the shop in Detroit installed and we noticed that the idle spark tables were all set to 17 degrees up to 800 rpm anything over 800 was 4 degrees (WTF). The car was bouncing back and forth from the high octane spark table to the idle table and it ran like ****. We reloaded the stock idle spark tables and the surging at low speeds went away completely. We picked up the idle to 975 from about 800 and the car gets underway smoothly with an 11 lb flywheel. Car is a head and cam motor with a 90mm Fast LSX set up. The cam is very mild (GM Hot Cam 112LSA). The only remaining issue is the hunting it does to get back to idle after deceleration (mostly at parking lot speeds) and although it will stall only occassionally, it can dip to 400 rpms and recover after several bounces. It will idle pretty steady when just sitting still. This is the last issue we need to solve as the car performs quite well other than this hunting back to idle thing. What are the tuning approaches to this problem?
Last edited by Big Bu Bu; 08-22-2010 at 11:01 AM.
08-22-2010, 11:23 AM
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If you get on the HPTuners or EFILive forums there are a lot of LS guys over there. They might be able to help you out. Or CTSMapper or something like that over on caddy forums sounds like he runs a shop and knows a lot about tuning. May hit him up.
08-22-2010, 11:31 AM
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The only remaining issue is the hunting it does to get back to idle after deceleration (mostly at parking lot speeds) and although it will stall only occassionally, it can dip to 400 rpms and recover after several bounces. It will idle pretty steady when just sitting still. This is the last issue we need to solve as the car performs quite well other than this hunting back to idle thing. What are the tuning approaches to this problem?
If anyone has any insight to this issue please advise.
My V is cammed, supporting mods in signature.
08-22-2010, 11:56 AM
#4
Need a little more info about your tune. Were the idle airflow tables tweaked too? Or just the idle speed? Were the MAF and VE tables tuned using a load bearing dyno or on the street (or at all?)? The basis to a good WOT cam tune is an EXCELLENT street tune. Did your tuner spend time with the car on the street or did they jump straight to the dyno?
08-22-2010, 01:59 PM
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send me your tune to
rhett.castillo@gmail.com
I'll tell you exactly what you need to change in the tune to make it stop hunting. I'll send you some HP Tuners screen shots so it makes it easy for your tuner to make these changes.
rhett.castillo@gmail.com
I'll tell you exactly what you need to change in the tune to make it stop hunting. I'll send you some HP Tuners screen shots so it makes it easy for your tuner to make these changes.
08-22-2010, 03:55 PM
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Need a little more info about your tune. Were the idle airflow tables tweaked too? Or just the idle speed? Were the MAF and VE tables tuned using a load bearing dyno or on the street (or at all?)? The basis to a good WOT cam tune is an EXCELLENT street tune. Did your tuner spend time with the car on the street or did they jump straight to the dyno?
08-22-2010, 03:59 PM
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send me your tune to
rhett.castillo@gmail.com
I'll tell you exactly what you need to change in the tune to make it stop hunting. I'll send you some HP Tuners screen shots so it makes it easy for your tuner to make these changes.
rhett.castillo@gmail.com
I'll tell you exactly what you need to change in the tune to make it stop hunting. I'll send you some HP Tuners screen shots so it makes it easy for your tuner to make these changes.
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