ITB tuning questions

For discussing B&G MS-I/MS-II set-up and tuning of fuel parameters (including idle valves, etc.).
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Underdog51
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ITB tuning questions

Post by Underdog51 »

Well i am having some problems tuning my 4 throttle body 4ag. I can get it tunned pretty well for all out full throttle, but then its rich as heck for cruising. I am getting 90+ kPa at cruise. I have heard this is typical of ITBs because of the low vacuum area. I have had some thoughts, is there a way to switch over to the VE3 table with TPS? So my VE1 will work up to say 50% throttle then it switch over to VE3. I havn't used autotune yet, not exactly sure on how it works. But is there a way to have my VE table set up for 100% tps and let autotune keep the fuel values down while cruising? I might be way off here, but please shoot me some ideas. thanks for any help

scott
Martijnus
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Re: ITB tuning questions

Post by Martijnus »

I went with Alpha-N...

viewtopic.php?f=31&t=33557

You also could try to use MAP/alpha-N blending instead of switching to a complete other table (because as far as I know, you can't switch to another table based on tps)
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Underdog51
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Re: ITB tuning questions

Post by Underdog51 »

Yeah thats what I have been thinking about, I am going to do some homework, try and figure it out. Its pretty simple I guess. Any major differences when switching over? Do you still use the TPS based accel enrichment? Are your maps pretty linear then as far as Idle to Full throttle? Do you have a screen shot of your VE maybe to could get a glance at to help me out with initialy setting up mine? Again I am mainly interested in how linear or unlinear the graph is. thanks

Scott
Martijnus
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Re: ITB tuning questions

Post by Martijnus »

Underdog51 wrote:Yeah thats what I have been thinking about, I am going to do some homework, try and figure it out. Its pretty simple I guess. Any major differences when switching over? Do you still use the TPS based accel enrichment? Are your maps pretty linear then as far as Idle to Full throttle? Do you have a screen shot of your VE maybe to could get a glance at to help me out with initialy setting up mine? Again I am mainly interested in how linear or unlinear the graph is. thanks

Scott
haven't got a screenshot at the moment. My car isn't tuned perfectly at the moment, but in theory your table should be just as linear as it would be with MAP.

I noticed that my VE values are the highest at my max torque with about 50% tps.. after that, they go down a bit... but there are no real 'spikes' in the table if that's what you mean.
Ignorance is bliss...
Underdog51
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Re: ITB tuning questions

Post by Underdog51 »

Well I spent a whole day trying to use alpha N, I couldn't get it do squat. I could start and idle, but any slight touch of the pedal would kill the engine. I am going to play with my MAP resolution. It idles at 38kpa, but cruise is just close high throttle. My main problem now is my MAP fluctuates from 100-92 a full throttle, and seems to fluctuate 8-10 kPa at all constant throttle points.

scott
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