First start, 7060 to 7427 Conversion - Crazy rich at idle

**Daveo91** · 06-17-2021

Originally Posted by tayto

what pressure

Good question. I should have checked since I have a gauge at the TB. I will check next time I run it, but it usually runs around 13 psi. Too much?

Thank you.

**stew86MCSS396** · 06-17-2021

13 psi should be fine. That xdf regarding lbs/hr gms/sec, you change 1 and they all change respectively based on "fuel injection system."

**Daveo91** · 06-20-2021

Originally Posted by stew86MCSS396

13 psi should be fine. That xdf regarding lbs/hr gms/sec, you change 1 and they all change respectively based on "fuel injection system."

Thanks!

I changed the 70 lbs/sec to 74. Ran it again after that and it seems to have helped, but still very rich. Actually was able to drive it this time. After a long warm up it will rev and accelerate without bogging, at least enough to drive. I got it to go into closed loop and much more driveable in that scenario, but most BLMs are 110 or below, some pegging low at 90. It seems rich across the range.

My question is what to adjust? Should I adjust VE table as I know how to do? (Dave W's averaging spreadsheet) Or should I adjust more globally, since it's rich everywhere? If globally, how do I do that? Change the injector flow rate?

One other thing: the mask I'm using shows manifold air temp as -40 deg C. I noticed there is a flag for MAT that is NOT check marked so I think it shouldn't matter? But I just want to ensure that there's not a problem with the computer thinking the air coming in is freezing cold. Engine Temp and coolant temp values appear to be correct.

**dave w** · 06-20-2021

I would try injector flow of 78, with the expatiation that all BLM averages will increase from rich (less than 128) to a number much closer to 128. An injector flow rate that has some VE cells with BLM averages rich and some VE cells with BLM averages lean is a good setting.

The Manifold Air Temperature settings are correct, and -40 temperature is correct too.

dave w

**Daveo91** · 06-22-2021

Originally Posted by dave w

I would try injector flow of 78, with the expatiation that all BLM averages will increase from rich (less than 128) to a number much closer to 128. An injector flow rate that has some VE cells with BLM averages rich and some VE cells with BLM averages lean is a good setting.

The Manifold Air Temperature settings are correct, and -40 temperature is correct too.

dave w

Thank you, Dave. I've gone up to 78 on injector flow rate - it improved things, but still very rich. No BLMs are above 128, most are in 110s or lower. Should I just keep increasing flow rate in 4 lbs/hr increments until I see some BLM values over 128?

One other thing: at warmed up idle, closed loop, spark advance is jumping around a ton, all between 15 and 25, mostly between 15 and 20. Something to be concerned about?

**dave w** · 06-22-2021

Verify the O2 sensor is working correctly by looking at the voltage swings in the "Monitors" screen of TunerPro RT. If the O2 sensor is working correctly, then increase the injector flow another 4 lbs. It seems unlikely the injector flow would be greater than 86 lbs.

The idle SA is somewhat concerning, swings of a few degrees is normal. Idle SA swings of 10 or more degrees is concerning.

dave w

**Daveo91** · 06-23-2021

Originally Posted by dave w

Verify the O2 sensor is working correctly by looking at the voltage swings in the "Monitors" screen of TunerPro RT. If the O2 sensor is working correctly, then increase the injector flow another 4 lbs. It seems unlikely the injector flow would be greater than 86 lbs.

The idle SA is somewhat concerning, swings of a few degrees is normal. Idle SA swings of 10 or more degrees is concerning.

dave w

Thank you, Dave. From what I know about the NBO2, it looks like it's working normally by watching the monitor. Pretty regular swings from 100 to 900 mV. It does plateau low or high for a few seconds at times, but then starts swinging again. I'm going to bump up flow rate to 82 lbs and see what happens.

As for SA, I also plotted that on the monitor and it looks more normal there. Previously I was just watching it on the analog gauge in TP dashboard. At the end of the drive I let it idle for several minutes in closed loop and the SA stayed pretty close to 17-18, with swings of a degree or two either way, but very consistent. It did bounce around quite a bit more if I rev'd it, but I think that's expected. I also noticed that SA was very large (40-41) on cold start up and linearly decreased as engine warmed. Weird?

**Daveo91** · 07-07-2021

Originally Posted by dave w

The idle SA is somewhat concerning, swings of a few degrees is normal. Idle SA swings of 10 or more degrees is concerning.

dave w

Finally got back to tuning today and noticed that today's log and the most recent one before that Code 43, Knock Sensor Circuit is being set. I haven't had a chance to look underneath yet, but I'm wondering if my knock sensor circuit is open or broken. I've had problems with wiring down there by the exhaust before - maybe it melted. Could an open on that wire cause fluctuating advance at idle?

Haven't ruled out traditional ignition problems, either, e.g. plug wires, distributor, coil, etc. At hot idle I can hear slight fluctuations in the exhaust note that seem to correspond to fluctuations in spark advance.