MSefi.com read only forum (Jan.15,2018)

Working on tuning the car now. I have a throttle response stumble when I open the throttle quick, kinda sounds like a bog and then the RPM's pick up. Looking at the data-log it looks like a delayed response. If I open the throttle slower and more gradual it just revs and roars like it should.

So, for tuning, where should I be looking? At the accel enrichment's?

Also of note, I have a LC-1 02 sensor, problem is it only ever reads like 12.1 or then it blips up to 14.6 and then goes back to 12.1 . I thought I read somewhere where it will do this if you are running too rich or too lean? Any advice? I'd like to be able to reference the AFR to help me tune!

I can post a datalog of a start-up, idle, throttle blip test and then about 10 minute drive to see if you can see what I am talking about and help.

Thanks,

Bryan

Think I figured out the slight hesitation/stumble. I worked the Accell bins and it fixed it. I will have to work on the VE bins and Accell bins more knowing what it is.

Also, seems my O2 sensor issue is due to not calibrating the sensor in megatune, I calibrated the LC-1......but didn't realize I had to do it in megatune also, so I'll try that and see.

More just posting in case anyone else has the same issues

Its very important that you tune your VE first and only tune it for steady state. Then when that is all done tune the accel parameters. You shouldn't have to touch VE. Otherwise you will be chasing your tail.

So, I have the car running well now, drives great, accelerates great. But one thing I did do was try turning the accel enrich off, and the car didn't even want to idle. How would accel affect idle if you aren't accelerating? I re-burned the working code after it did this and it idled great so I have not thought about this much since.

I just saw your response and it has me thinking, this is possibly when when I data-log and analyze the VE tables......I just seem to be adjusting the bins up and down depending on the driving (datalog)?

So your suggestion is, turn off accell enrich and tune the VE table, how should I go about this? In the garage dataloging as I move the throttle etc? Or drive around the neighborhood slowly?

Thanks,

Bryan

The only way accel should affect idle is if the tpsdot/ mapdot thresholds are set so low that just the normal small fluctuation in tps or map, which occurs even at idle, triggers accel enrichment. You should be able to see this on the datalog at idle. If the accel enrichment is > 0 ms it is acting on your fuel during idle, and shouldn't be. If the problem went away when you re-burned the code then don't worry about it, but if you still can't idle without AE being on, that is a problem.

In the absence of a dyno, the way I would tune is to warm up the car, drive around steady state in different gears at different rpms and jack the VE bin for that position up or down until the engine runs well/ highest map/ leanest without surge/ whatever you want to achieve. You can also use hills if there are any in your area to get different map values. You won't be able to safely get high rpm in final gear, but that is what a dyno/ track is for. Another way to tune is with your ego gauge, if you know what afr you want under different conditions - which no one really does know. However you do it, the main things are that when tuning VE the engine is warmed up and accel enrichments are OFF.

grippo wrote: [snip]
However you do it, the main things are that when tuning VE the engine is warmed up and accel enrichments are OFF.

Is there an easier way to achieve this than altering the TPS and MAP dot?

When you tune VE you should be in steady state, so AE should not be triggered. If it is getting triggered in steady state then it is best to fix the problem - you will have to eventually anyway. But if you don't/ can't do that, then AE should be disabled. There is no switch to turn it off - you either have to prevent it from triggering (which is just two variables: tps and map dot thresholds) or zero out the enrichment tables.