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Discussion Starter #1
Below is a air/fuel vs RPM chart two pieces of information worth noting. The spikes going down are simply my tach pick up not being consistent, just smooth those over.

1. Air/fuel ratio. Notice it is very lean to a point then drops below 13. What is happening is the stock system with the stock O2 sensors manages fuel to a certain point thru what is called closed loop then it drops off and then fuel is done by a fuel map that has been manually programmed into the ECU. Point I am making is the stock system does not compensate for fuel after this point, it is what is called a narrow band system and will only change fuel in a very narrow range for cruising just like your car does and it will NOT compensate for some mod you do past this point and probably not under this point if it changes fuel much.

Note thepoint where it drops off is below 13 where I would run it at WOT so it appears we might be able to squeeze out a few more ponies by simply manipulating the fuel curve with a fuel controller and I have one coming, the Dobeck Gen 4. I will install it before I put the pipe on to see what good a fuel controller does.


2. RPM note how it ramps up toward 7900 then backs down then back up. This is NOT what we want to see, actually time test have proven this engine is quickest at 7650 in stock form so we are going to install the Dalton clutch kit to hold RPM at that point during the shifting phase then speed on up as shift out finishes. You can also notice between this graph and the HP graph how the rpm drop coincides with the HP drop off too.

 

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So in your #1 are you saying we will benefit from having an added fuel controller to correct the A/F ratio?
I know you prefer the dobeck gen 2 because of its adjustability, but the Digi-tune can correct this also correct?
 

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Discussion Starter #3
So in your #1 are you saying we will benefit from having an added fuel controller to correct the A/F ratio?
I know you prefer the dobeck gen 2 because of its adjustability, but the Digi-tune can correct this also correct?
Correction Dobeck Gen 4 and yes I am saying it might improve.

Can the digitune do that, I believe it is the Gen 3.5 that will take away and add fuel so if it is the Pro as Muzzy calls it then yes it will but you need a air/fuel ratio gauge to know how much fuel to pull out. Don't trust those lights etc on the digitune.
 

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Those RPM drops are most likely the throttle closing, not the pickup. Notice how the first one does it at around 8000rpms, where the rev limiter is.

The latter dip, may be the speed limiter kicking in, but maybe the axle saver kicking in, hard to tell.
 

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Discussion Starter #5
Those RPM drops are most likely the throttle closing, not the pickup. Notice how the first one does it at around 8000rpms, where the rev limiter is.

The latter dip, may be the speed limiter kicking in, but maybe the axle saver kicking in, hard to tell.
No it's the pick up, magnet is broken.
 

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No it's the pick up, magnet is broken.
Do you know for a fact that the throttle was held at WOT?

Bad pickups can cause the rpm signal to drop too, but even if the pickup is good, the power will stay up, since the dyno calculates power without knowing the rpm at all. So if power was dropping off, as you say in your first post, it wasn't because of the pickup being bad.
 

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Discussion Starter #7
Do you know for a fact that the throttle was held at WOT?

Bad pickups can cause the rpm signal to drop too, but even if the pickup is good, the power will stay up, since the dyno calculates power without knowing the rpm at all. So if power was dropping off, as you say in your first post, it wasn't because of the pickup being bad.
Never said the power was dropping off due to a bad pickup, I said the rpm was. I have had this bad pickup for a while, I deal with it because it really affects nothing.
 
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