Adjusted IAC Numbers and the idle speed is above 1900 RPMs
Hello, I am running a 3002 EFI4 600hp model on a stock 1965 Corvette 327/350hp. I installed a Tanks Inc tank with internal pump. Running stock distributor with Pretronics and selected "TACH" on the setup. On the first day of install the engine ran pretty good, but once I drove it, it would bog out about 2000-2500 RPMs. I contacted FiTech and they told me to make sure my IAC #s were between 1 &10. I finally got it to read between 0 and 4, any adjustment beyond that it goes to 44. Now the engine is running above 1900 RPMs. I have the warm idle speed set at 850. Any guidance would be appreciated. I am just a "righty tighty" mechanic, so any feedback is welcomed.
Welcome, see if you can create a log file, post it on dropbox and provide link here.
Thank you for trying to help. https://www.dropbox.com/l/scl/AACAvRJ1Hg5KP7Doc74gWLGN_KH8dhXnw9o
Ok, couple of things. Your battery is going below 10 volts during cranking, which will cause the unit to not initialize correctly I've found. I would make sure your battery is fully charged and that the fitech voltage comes directly from the battery and not down at the starter or other areas. I put in a voltage gauge in the cab of my '66 of the voltage at the fitech red wire input to check the voltage while cranking. Actually had to put in a Odyssey 850 CCA battery to keep the voltage from going below 11 volts while cranking. Like you mentioned, IAC steps got to zero, which you definitely don't want to ever happen. Bring that up.
After you get these things fixed, create another log, and we'll see what else needs looked at.
Thanks again for trying to help. I purchased a new battery 850 CCA battery. I tried to adjust the IAC steps up but could not without increasing the idle RPM even more. Below is a link to my data log, basically trying to keep it running. It will idle way up then come down and stall.
https://www.dropbox.com/l/scl/AACrviV-UPKnwN88_UM8QnP4SMF7Vx1cmyI
I would go back to basics. On first start up I had high revs, adjusted primary 1 turn in and secondary 1/2 turn in, I clamped a short strip of cardboard to each throttle arm on the linkage side with a small clip to accurately gauge when the adjustment screw touched the shaft, then only adjust primary unless secondary moves [there is heaps of play in the linkage between the two shafts].
Went good initially, then could not get IAC above 0-3, ran super rich. A squirt of starter fluid did nothing, made a smoker out of resistance wire wrapped around a short piece of exhaust wrap into a bottle with paraffin oil, hooked up 12v and used a 12v tyre pump for pressure, found I had blown a TB base gasket. Replaced and used fuel resistant sealer, now able to adjust IAC correctly, still have a bit of tuning to go, getting close - I have had to replace temperature sender, O2 sensor and fuel pressure sensor with genuine Bosch units as all were creating different problems.
If you have a vacuum leak, it negates [over rides] the function of the IAC, causes a supply of extra fuel to compensate for the extra air sucked in, the A/F reading will still be close to correct. With a exhaust leak, usually you can adjust IAC but will run rich.
Mine still find it has a mind of its own, seems to be a little different every time I go for a drive.
You are screwing the primary idle adjustment out to increase the IAC?
Thanks Ajax for the info. I am going clockwise to drop it down and counter clockwise to raise it up. I believe I am all the way out.
I'll put my money [not all of it] on a vacuum leak somewhere then.
Voltage looks a lot better, you can check that off the list. I've never seen the AFR so constant at 14.7 before, which is higher than your target AFR. Makes me think there is something wrong with the O2 sensor or the fitech reading it. That looks very strange.
https://fitechefituning.com/fitech-efi-tuning-forum-2/topic/afr-freezing/