Daily "rich bog" thread...
Like everyone else, it seems, I am having a rich bog issue. Here are the basics:
Go EFI 4 running fuel only (no spark, no fan, not even using the fuel pump relay trigger).
MSD 6A ignition system with MSD mechanical advance distributor has been running great with my Holley 650 for the last 2 years so I don't really think ignition or timing is a contributing factor.
Walbro 255 with return line (gauge at throttle body reads 56 psi w/o vacuum, approx 48 psi with vacuum).
302 with medium roller cam (pulls 11-12 inches at 650 rpm idle). Cam #2 selected.
IAC = 13-17 maintaining 650 RPM idle @ 197 degrees F.
New delco coolant temp sensor in manifold (not thermostat housing) and 180F thermostat. Autometer and FiTech agree on temperature at nearly 200F(!) during normal backroads driving.
Here is a thirty second idle log (with throttle blip at the end because it sounds great) https://www.dropbox.com/s/saan8zdaw5uizdg/ThirtySecondIdleWithBlip.csv?dl=0
Does my idle log look good? Is there anything that needs to be addressed before tackling this bog issue?
Steve
I have made a few changes to try to eliminate the lean/rich/rich/rich/rich bog. I changed the Accel Pump 170 from 0 to 30, changed the Fast Accel Pump 170 from 0 to 60, and increased my dTPS Acc Gain from 109 to 119. I have not yet changed the default value of DTPS Acc Max (153.1). The Accel and Fast Accel changes were made in increments.
The bog is much better than it was... should I continue tweaking the settings that I've already changed or should I try some other settings as well?
Attached is a screenshot of a short log file showing the bog in a 4th gear pull from 2700 RPM. Like I said, this bog is better than it was this morning but there's still room for improvement.
Here's the kicker: when I was running the bad CTS and had a 160F thermostat in the car FiTech would NOT see temperatures above 164... and the car ran like a scalded dog!!!!
Steve
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Can you confirm you are not loosing fuel pressure when you first throttle. The data goes lean for 1 second, then it over compensates, causing the rich bog.
If fuel pressure is steady, I would only adjust Fast Accel and look for improvements.
Idle log looks good btw.
Sorry, I don't currently have a way to monitor fuel pressure from inside the car... maybe I could:
1) Install a go-pro and a flashlight under the hood pointing at the gauge.
2) Remove hood and install a go-pro pointing at the gauge.
3) Remove hood and install a 90 degree fitting on the fuel pressure gauge.
4) Install a Holley Sniper system and look at fuel pressure in a data log (what a novel idea!)
5) Install a QuickFuel 750 CFM carburetor with annular boosters and electric choke, re-install my firewall fuel pressure regulator, and never worry about fuel pressure again! LOL. Sorry, I got a little carried away... maybe.
In all seriousness, though. Do the non-oil-filled FiTech 0-100 psi fuel pressure gauges normally bounce rapidly when the engine is running? It's rock solid with just the pump on. Maybe I should get a quick video at idle.
Quote from Austin DeHaas on April 24, 2019, 3:20 pmIdle log looks good btw.
Thanks!
Yep, got a little carried away. 😂
First try flogging the throttle while in the driveway and watch the fuel pressure.
I have pleaded with Fitech to add fuel pressure to the system. They said they had considered it initially, but it was going to add $100 to the price per unit. I use their small mechanical gauge. It is steady. I drilled and tapped one of the plugs on the front. Best solution I have found is Speedhut. For around $180 they will custom make you an electric gauge. I have one with the website printed on it. Pretty cool. Check out Hi-Way Dreams (hiwaydreams) on Instagram. I did a video on the gauge awhile back.