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Discussion Starter · #1 ·
I just re-installed my Accufab TB and I was adjusting the TPS. My reading was .998 volts and the idle is still low. Has anyone had their TPS reading higher than this?

Thanks
 
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I've had 1.04 and the idle was way way high.....these 03 Cobra's change like the wind when it comes to mods and tps readings...and then other days you can put the same mod back on and everything is fine...stock tps...reading right on .98.......

Harry
 
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TPS has 3 positions:
Closed Throttle
Partial Throttle
Wide Open Throttle

Below 1.05V is Closed Throttle.

When the TPS reads 1.05V it goes to Partial Throttle.

This is why you should set your TPS to:
between .97v-.99v

And remember the idle is controlled by the IAC.

Hope this helps
 

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Discussion Starter · #5 ·
BilletFlow said:
TPS has 3 positions:
Closed Throttle
Partial Throttle
Wide Open Throttle

Below 1.05V is Closed Throttle.

When the TPS reads 1.05V it goes to Partial Throttle.

This is why you should set your TPS to:
between .97v-.99v

And remember the idle is controlled by the IAC.
Doug,

So what should I do after I drop the TPS because the car idles to low and shuts off when I am driving and push the clutch in?
 

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jfclague said:
Doug,

So what should I do after I drop the TPS because the car idles to low and shuts off when I am driving and push the clutch in?
what has Accufab had to say about this? Doug is right on the money with those TPS settings

did it ever stall before the TB install? a lot of stock Cobras have that problem........
 

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You didn't say what rpm you are idleing at. From what I have been told, the EEC tries to make the engine idle at 649-699 rpm. If you are in that range, you are actually at factory spec. That's not to say that it works best at that rpm, it just means that the factory(for some strange reason) wants the engine to idle there.

Your problem should be easy to fix.....turn the idle adjustment screw to a higher setting. Then, after resetting the ECU, check the TPS again & adjust accordingly. This is assuming that you don't have any other issues going on like defective IAC, or vacuum leak, ect.
 

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Discussion Starter · #8 ·
I talked to Accufab and they said to adjust the TPS to around .98 and do not, do not adjust the set screw that would adjust the base idle.

They said the computer would eventually adjust the idle to where it should be (after driving the car for about 4 hours).
 

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The computer will try to keep the idle at about 650 rpm. For me, that was too low. My car has a tendency to stall when it idles that low. The ONLY way to make the engine idle faster is to either adjust the idle screw OR have the computer tweaked to "call" for a higher rpm at idle. Of the 2 choices, I opted for the easiest. I have had no stalls since raising the idle to 750-800 rpm. One downside of a higher idle is that the EEC MIGHT see the increased idle speed as a problem with the IAC circuit. If it does, then the EEC will trigger you Service Engine Soon light. I'm pretty sure that 750-800 rpm is below the "trigger" point. Of course, the tach is not 100% accurate. So, the visible reading might be slightly different than the actual rpm.
Finally, what have you got to loose? Just keep an accurate log of the amount that you change the stop screw from the factory setting. You can always put it back if you decide that you don't like the higher idle speed. And yes, the EEC will adapt to the new setting also. However, the IAC will not be called upon to bypass as much air around the throttle blade, but it will still bump the idle up to compensate for cold start & air conditioning operation.
 
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