voltran

A couple of days ago I was adjusting the TPS voltage. Then I decided to drive around to see what happens without the TPS. Of course Check Engine light came out right away. But even though the throttle response was slower, it started pulling harder and reved up faster. How is that possible ? ( Yes I am sure it was pulling harder, and my TPS is fine...) Since then I did not connect the TPS. Does it hurt the engine driving without the TPS ? And also I was wondering if anybody tried this before and how they felt..

JP84Z430HP

Plug that puppy back in! With it unplugged, the computer is in limp-in mode. It goes to preset values to determine how much fuel to deliver, and it is prolly too much. This causes higher emissions (If you're even worried about that) and if you have a cat on there still, it will most likely plug up from the extra fuel causing it to work harder. It may also be rich enough at times to dilute the oil, and that would cause major problems.

Vader could be more specific on the limp-in mode info, and probably how much too rich it would be.



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Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Awaiting results from all 8 ASE tests.

Starting to look like the Kicker poster child!

Vader

Voltran,

JP is right on. The fuel map in the base lookup tables ("limp-home" mode) is about 12:1, when the ideal ratio averages about 14.7:1 and down to 13.7:1 for maximum power output.

Disconnecting the TPS, MAP/MAF, oxygen, or other crucial sensors will drop you into this operational mode. The extra-rich mixture will probably give you better accelleration, but will eventually foul and carbon everything so that you'll be doing some serious cleaning in the chambers soon. Don't drive that way for more than diagnostics if you can avoid it.

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Later,
Vader
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voltran

Thanks both to JP84Z430HP and Vader. I'm plugging that in right away..

Red Devil

Voltran, the fact that the car pulled harder with it disconnected may signify a leaning out in the upper RPM band. You may want to bump up your fuel pressure a tad.

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