Idle Dips In Reverse Only
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.
TECH Senior Member
Joined: Jun 2016
Posts: 22,285
Likes: 3,613
From: Central Cal.
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.
Launching!
Joined: Apr 2019
Posts: 206
Likes: 11
From: Bay area
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.
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.
Launching!
Joined: Apr 2019
Posts: 206
Likes: 11
From: Bay area
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.
