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Strange: Lean after Fuel Pressure Change

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Old Aug 11, 2006 | 08:49 AM
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Strange: Lean after Fuel Pressure Change

Has anyone experienced a major Lean (160) after bumping up the fuel pressure ? I expected it to be richer ?
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Old Aug 11, 2006 | 08:30 PM
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From: Corona
Car: 92 Form, 91 Z28, 89 GTA, 86 Z28
Engine: BP383 vortech, BP383, 5.7 TPI, LG4
Transmission: 4L60e, 700R4, 700R4..
Axle/Gears: 3.27, 2.73
Are you sure you raised it? Tightening the screw into the FPR body raises it.

If your pump is old, you may have raised it enough to kill it. What pressure did you set it to?
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Old Aug 12, 2006 | 11:28 AM
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From: In reality
Car: An Ol Buick
Engine: Vsick
Transmission: Janis Tranny Yank Converter
Originally Posted by twadam
Has anyone experienced a major Lean (160) after bumping up the fuel pressure ? I expected it to be richer ?
Have you been having tuning issues?.

Are you sure your guage is good?.
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Old Aug 13, 2006 | 12:08 PM
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Well my father said he raised the pressure. He has a guage that hooks to the shraeder valve. But I don't think we were setting it correctly (we had the motor idleing). I wonder if we went too far ... we started at 39 and went to 46-47 at an idle. It took away the flat spot and popping at around 1700 RPM, high kpa. But now the BLM's seem unmanageable.

I know now we should have set the pressure with the engine off. Do you think we possibly just went too high on the pressure ?
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Old Aug 13, 2006 | 04:32 PM
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From: In reality
Car: An Ol Buick
Engine: Vsick
Transmission: Janis Tranny Yank Converter
Originally Posted by twadam
Do you think we possibly just went too high on the pressure ?
No thinking involved,
you did.

If you *have* to raise the FP, you're just covering up for other issues....

Now that you know what cured the problem, just adding fuel in the area should now fix it.
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Old Aug 14, 2006 | 02:42 PM
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Originally Posted by Grumpy
No thinking involved,
you did.

If you *have* to raise the FP, you're just covering up for other issues....

Now that you know what cured the problem, just adding fuel in the area should now fix it.
But does this make sense with the current LEAN condition ? More Pressure = LEANER than less pressure ?
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Old Aug 14, 2006 | 09:43 PM
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I figured it out !

I screwed up ... it had nothing to do with the fuel pressure. I was rushed the other night and the same evening we jacked up the pressure ... I modified the wrong .bin. I grabbed an old bin that had the fuel injector flow rate set to 27 lb/hr ... not the appropriate 24 lb/hr. That is what caused the LEAN condition.
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Old Aug 16, 2006 | 09:32 PM
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BLM 143 during open loop

Okay, after using the correct .bin and correct injector flow rate we were able to get the BLM's manageable within two runs. They are now between 123-131.
Here is the kicker. I first noticed this the other night and this symptom is still there. During open loop the BLMs are at 143 and stay there till it hits closed loop. It then returns to normal operating range.

Is there somewhere in TunerPro to modify the BLM during open loop ? I thought the BLM was supposed to be "hardcoded" at 128 while in open loop.

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Old Aug 16, 2006 | 11:51 PM
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From: Corona
Car: 92 Form, 91 Z28, 89 GTA, 86 Z28
Engine: BP383 vortech, BP383, 5.7 TPI, LG4
Transmission: 4L60e, 700R4, 700R4..
Axle/Gears: 3.27, 2.73
It will be limited to a low of 128 (some allow lower, like 118), but a high of 150 on reset. If your engine did not get warm enough to store the BLM (190 deg F), then it'll not store it. It's using old BLMs likely. It will use BLM from about 122F on up, but won't store it unless the engine is over 190F and less than 212F at powerdown.
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Old Aug 17, 2006 | 10:56 AM
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Open Loop BLM stored in ECM ?

When I started tuning the BLM was ALWAYS 128 during open loop. What does the system use for this, the AVG BLM during a given length of time ?
Or just the BLM at time of engine shut off ?

I guess I expect the BLMs to move in closed loop, but assumed the open loop value was hardcoded. Sounds to me now that the open loop value is 'learned' by the ECM ?
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Old Aug 17, 2006 | 11:43 AM
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From: Corona
Car: 92 Form, 91 Z28, 89 GTA, 86 Z28
Engine: BP383 vortech, BP383, 5.7 TPI, LG4
Transmission: 4L60e, 700R4, 700R4..
Axle/Gears: 3.27, 2.73
You can clear that by disconnecting the battery, or the ECU, or just the fuse for the ECU (driver's side of the radiator, actually, with a little flip cover).
BLM stores the last value for each cell, as long as the temperature is warm enough. The value is clamped by the limits. If you reset the BLM, it'll stay at 128 during open loop, until it's had a chance to learn.
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Old Aug 17, 2006 | 12:55 PM
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Always learning something new

Thanks RedNGold86Z ! I will try this tonight. That is awesome to know.
Although this motor is in a 1933 *****'s (pro Streeted) ... I'll just disconnect the battery for a bit.
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