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Idle Dips In Reverse Only

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Old 12-01-2019, 06:01 PM
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Something else to keep in mind. Line pressure in reverse is slightly higher than line pressure in first so it can put more load on the engine at idle. My son in-laws Nova runs a 4l80e and it rarely died unless you backed up and suddenly let off the throttle. The idle ramped down to fast and it was enough to stall the engine. He runs Holley efi so the fix was to program the iac to resume idle control at a higher rpm and slow the drop back to idle.
Old 12-01-2019, 06:59 PM
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Originally Posted by LT1DG
Well you came off like a**hole man how the hell I'm supposed to explain my situation with somebody like that. Regardless what you say, your in the wrong.
I was misled by false impressions. You didn't lay out all the facts to begin with, so I got off on the wrong foot. Had you fully explained it none of this would have happened.
So I'M in the wrong? If you say so. All you would have had to do was look up how to do it. I have never had to do the relearn, so therefore don't know how. If I had to, I would look it up. It's out there. Internet (forum) wisdom can be misleading too... ask the experts.
Old 12-01-2019, 09:56 PM
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Originally Posted by JakeFusion
Why would you need to do a TPS relearn? Are you at 4% with the throttle closed or something?

If it's dying when you are backing up, either fuel is off or your IAC is off. If you have an aftermarket TB, the IAC counts are all wrong I'm sure, and the IAC motor is not stepping correctly to keep the engine RPM stable.

Of course, it's a bit of balancing act to get the throttle blade open enough and then tuning the IAC transfer table correctly.

If however, you have a stock TB, then it's simply the fueling is off in idle. And you may need some more airflow in your follower table to offset the cam.

Btw, these are all shots in the dark. I have no idea what your combo is. And just because it idles rock solid doesn't mean anything. It's the return to idle, maintaining idle when you turn the steering wheel, etc. that determine if your idle tuning is any good.
On the scanner my iac it reads 28 In idle, 41-50 while cruising. The tps reads 75 at idle and 91 at cruising. I have 52mm BBK throttle body. The guy who tuned my pcm told to close my throttle blades as far as I can since he set my idle at 750. He also mentioned i may need to drill a hole in my throttle body since it's aftermarket. So I can get better flow.
Old 12-01-2019, 10:03 PM
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Originally Posted by LLLosingit
Something else to keep in mind. Line pressure in reverse is slightly higher than line pressure in first so it can put more load on the engine at idle. My son in-laws Nova runs a 4l80e and it rarely died unless you backed up and suddenly let off the throttle. The idle ramped down to fast and it was enough to stall the engine. He runs Holley efi so the fix was to program the iac to resume idle control at a higher rpm and slow the drop back to idle.
That's exactly what Mines does, I thought the tune would help but it still drops and it only stalled once. Sometimes I go into reverse and it would idle good, sometimes tho.



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