Smallblock Chevy tuning help

[drz712]

I have a 396 smallblock chevy with a 4 injector throttle body on it. They are 85lb injectors high impedance. The motor does have a long duration cam in it. To get it to run i had to adjust the throttle blades open quite a bit. Now when it idles the map is right around 70 kPa. My pulsewidth is not steady at all at idle. my ve table is rich in most spots trying to drive but from a stop if i try to get it moving the afr leans way out. When it is lean the bins it sits in are very close to my idle bins. Accel enrichment does not come on. Im not sure if it is supposed to for easy acceleration. If anyone could help me out with some ideas id appreciate it. Im not too good at some of the stuff and i know my tables arent that close. I just wondered if it is something im not seeing and if the pulsewidth surging could be part of the issue. I will try and attach a datalog.

[kjones6039]

I am running a very similar setup, except that I run Extra code.......

383 sbc
4-85# lo-z injectors
900 cfm 4 Bbl tb
fairly big cam etc.
400+ hp

IMO your log doesn't look too bad at this point. A couple of things do jump out at me when I look at your msq, however!

10.8 ReqFuel seems to be quite high. The calculated value for your combination is ~6.1 Mine is just about half of yours. That may well account for a lot of your richness....
Why 4 squirts? I have run everything for 1 to 8 and find that 2 squirts works very well....
What are you using for ignition?
Last but not least, what wb are you using for ego control?

Just one old guys observation though.........

Ken

[drz712]

I never changed the required fuel from the last motor. That high of a required fuel is the only way i could get my ve numbers to be reasonable on the last one. I am running a innovative lc1 wideband. would changing my required fuel change the pulsewidth jumping all over the place. what do i need to do from keeping it from leaning way out on me on low throttle accel.

[drz712]

The 4 squirts is also from the old motor it seemed to make it idle smoother by spreading out the fuel instead of just 2 pulses. But i am not that good so it may be causing more harm. I am willing to try anything and appreciate any advice

[drz712]

Could you be chance post your msq

[kjones6039]

Could you be chance post your msq

PM sent

[drz712]

i dont what to be stupid but what does that mean?

[kjones6039]

i dont what to be stupid but what does that mean?

Sorry!

PM=Private Message

Check your User Control Panel.

Ken

[drz712]

I changed my required fuel today and changed to two squirts. Got motor to idle again. Still leans way out on light acceleration at low rpms. Tried to make the cells in first two rpm columns alot higher and no help. Pulsewidth stills jumps all over and map sensor is still sitting right around 70 at idle. Anyone have any ideas on the pulsewidth or if my map at idle is crazy.

[kjones6039]

Post up a log & msq and we'll have a look.

Ken

[drz712]

Tried again to solve issue today. Read alot on the configuring and tuning pages in the last several days. They say with a throttle body you should run half the squirts as cylinders so I switched back to 4. Got a VE table with a good idle again and allowed me to give it throttle at a still. Went to go drive it. Did not seem to lean out quite as bad but then 2 blocks from my house the idle took off and started running at over 2000. Shut it off and started back up idle was at 1000 for a few seconds then just started racing. Got it home looked at the datalog and see nothing making it race. I had it idling in my driveway for a half hour before i took it out at a little over 900 and would open the throttle and stuff and it never raced. I reloaded an old msq and it does the same thing idles for a second then takes off. Looked at everything I can think off. Seem to be getting worse off trying to tune this motor. I had the same fuel and spark setup running on two different motors that were more stock. I am lost where to go now. I am posting a msl from when i took it out and it started to race. I shut it off several times during it. I will post my msq too.

[drz712]

I think the racing idle issue is fixed. When my warmup enrichment kicked off the motor was getting way too much air. I adjusted the throttle blades in a ton and now that is better. I also found that at idle my pulsewidth steady out if i turned xtau accel down to 5%. I had it much higher to compensate for the throttle body on the old motor. I have two more files with the idle now. Now that my pulsewidth doesnt jump i can get my idle much lower finally and stay steady like 700ish. But if i tap the throttle the rpms will go up and when they come back down itll hover at 1100 for quite awhile and then it normally comes back to idle. Sometimes it does not. Now that i can get the motor idling at 700 my map is even higher than before. Still not sure if this is the cam causing my map to be so crazy. The duration at .05 is 260 with lobe seperation of 110. can someone let me know if this map is ok or am i running in circles trying to tune some issue not fixable. Because my map is so high at idle is why im getting the leaning out on easy acceleration. Is there a parameter I can change to add some fuel on the easy accleration. the files are my new idle

[drz712]

Found the cause of the random high idle. There was 2 vac caps on the back of my throttle body and when I went driving the other day i had gotten a lean backfire and it must have blown those caps off but i didnt see it because it was on the back of the tb. So i put those back on and ended back to the same tune for idle but now my pulsewidth is stable with turning xtau off. Is it possible to have a good tune without the xtau accel? Talked to several people about tuning and they said that the high map doesnt matter because of the cam. Can anyone confirm this? Im getting a warmup tune pretty decent. Still having a few issues with easy acceleration. Any ideas to get more fuel with slight opening of the blades when map does not really come off idle bins? I will post my new msq