[Solved] Lean Stumble off Idle or Coasting
Hello all,
I just installed my Fitech EFI GO 4 with Power Adder on a 67 Pontiac Lemans with a 400. I struggled at first with the most annoying RPM Noise fault - it still randomly shows up once in a while but for the most part (and in these logs) it is not seem to be an issue. Now I am having a lean condition off idle and off coasting where when I get on the gas again the car just seems starved for fuel and it almost dies.
I have adjusted my IAC steps several time to get them between 0-5 but each time I turn it off and restart the car it seems like it they end up much higher when I am driving around.
I have Accel pump set to 20 and lowered my AFR at Idle to 13.2 to see if that would help. I also put my idle loop up to 33 thinking that may help.
Logs can be found at the drop box link below you can see the condition around line 165.
https://www.dropbox.com/s/zskt4wrl0maygeq/Basic%20Sensor%208.3.20.csv?dl=0
One more question - is it recommended to run the blue tach wire basically directly from the Throttle body to the tach port on the distributor? Mine was installed with the blue wire going from the distributor to one of the wiring harnesses then from the wiring harness back up to the Throttle body wiring harness. It seems like I could just skip the first wiring harness and splice the wire that runs from the Tach port directly to the tach wire that runs into the throttle body wiring harness. It would make the distance much much shorter and I would assume eliminate any and all noise, but I wasn't sure if this would create an issue.
Thanks for your help!
Nick
I would isolate the wire that goes to your distributor now in the wiring harness to make sure it's not going somewhere else. Maybe it's needed elsewhere. If you can get that wire out and it only goes to the fitech wiring harness, than I would say you are ok removing it from the harness. I covered my tach wire in shielding that is grounded at one end.
The only time you need to really look at the IAC steps is at idle, because it will move all over while driving, that's normal. Looks like your IAC steps are at about 76 when it stabilizes at idle, might want to bring that down. Car needs to be at operating temperature (170 F) and standing still at idle. Wait until it settles for several minutes, then adjust.
What you are experiencing is what they call lean tip-in. Goes lean first, then rich after applying throttle. It will need more fuel in your accelerator pump settings. Do a little at a time until it fixes it.
Uploaded files:
- You need to login to have access to uploads.
Thanks for responding this is extremely helpful.
I had a follow up on your shielding. Did you shield your tach wire from the source to the wiring harness and then from the wiring harness to the ecu. It seems the tach wire that goes to the ECU is "prebundled" with the other main wires as it is a permanent connection.
Nick
I ran the fitech blue wire out of their harness through shielding directly to my HEI distributor tack input terminal and didn't have any trouble.
I got the issue sorted out. It seems there is a known issue related to the gasket on the ECU to the MAP sensor. Once I trimed the gasket as per instructions the car ran great.
https://fitechefituning.com/fitech-efi-tuning-forum-2/topic/bad-map-sensor/?part=2