Rich at idle and stumbles while accelerating

[p901]

Here are my specs:

1973 240z

l24 engine

N47 head

MS2 2.88 (DIY Autotune)

Relay Board

NB O2 sensor (GM)

Bosch High imp. red top 30lb injectors (Ford)

Custom Intake manifold (Similar to Lonewolf)

T3 turbo (Borg Warner) Compressor A/R? Turbine A/R 50 stage 1)

Type 6 BOV

65mm throttle body (Ford)

Crane xr700 (Megasquirt controlled)

 

Just converted my 240z to FI and turbocharged. This is the second time that I tried tuning and have a few issues.

Engine runs rich at idle and cannot bring the idle rpm down. The fuel pump pressure is set at 42lbs. The narrow band GM O2 sensor reads above .80v most of the time and occasionally drops to .2v

Stumbles while accelerating. Would this be because of the acceleration bins

not set correctly? Data log file shows small increases in acceleration shots that seems to have odd correlations with RPM ramps.

240z turbo.zip

[jeffer949]

i just set up my megasquirt with in the last month and half.. and if i can make a suggestion it would be to invest in a wideband O2 meter. i had no experiance tuning fuel injection systems. and a month later along with my wideband ive got a pretty good tuned map. but i couldnt imagine where i would be with out my wide band.. sorry i cant be much help with the tunning but it would make your life alot easier if you got a wideband. you can get a lc-1 for like 200bucks and it will help you out tons!!

[dexter72]

I may be mistaken but I see a couple of issues with your spark table.

 

Your KPa scale on the left column only goes to 100. Most spark tables I have seen go to atleast 200. I hit 140 and 160 on my scale so it looks like yours should be increased.

 

Your timing at idle should be lower 35 seems to be a bit much. 17 to 20 should be good for you. Your timing at the higher rpms looks a little high also. Timing should be decreasing after 4000 rpms. 35 seems high to me especially if you don't have a wideband 02 sensor.

 

Also if it stumbles at idle, Your required fuel setting may be too low. As an example if I set my required fuel to what it is supposed to be calculated too ( 10 ). My engine stumbles and almost dies when I try to accelerate it when in gear. Now if I adjust required fuel up to 12 or higher it has plenty of power and no stumbles or dieing.

 

If your engine is running rich at idle try lowering your ve table entries. If it's running rich while in boost don't adjust it until you get the wideband. Or adjust it lower so you can atleast drive the car and not get run over by anyone.

 

The map sharing sticky at the top of the page has a few maps so you can see what I am talking about. Also one of those maps might be close to what your setup is and will make your engine run better.