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

"We can't be the only 2 out there with this problem!!!!"
You are not! I have been working on this same problem for a few weeks too. Have you been datalogging? I noticed on my setup that when accel enrichment kicks in, O2 fuel correction stops. So if you are get 120% of the req fuel with the 02 corection and you hit the throttle that would go back 100% The accell enrichment would bring that up to 105% or something. Good reason to get the VE map dialed in. Another problem is that with a lot of manifold vac and a big butterfly valve throttle, that first few % that you open it make a much bigger diference than a much larger movement of the throttle at say 50%. Using MAP based Accel enrichment should help in that department. I have had sucess in dialing it in but still stalls once in a while It's odd because I didn't have this problem when I was using MSI. Are you guys using MSII to control spark as well? I'm pondering the posibility that the spark could be a factor as a missed ignition will make it look lean also.

One of the problems found with accel enrichment is that you need a lot of enrichment when starting your accel at at low rpm and not as much at high rpm. MS II v2.3 codes don't provide any way to enter rpm into the calculations, but v2.672 (on the beta list) provides up to 10 points of accel tuning as a function of rpm as well as a simple 2 point linear interpolated function. You might want to give this a try. We hope to release it as the base code in few weeks but there is nothing preventing you from trying it now.

On the datalog from your Saturn, line 11243 looks like what I have with my car. Look at the pulse width on that line and the lines leading up to it. It looks like it might be getting the fuel it needs. Do you guy have high compression? (I have 10.6/1) Weak spark?

Tanks for the input all. OK whatever I did I gave up and entered all the numbers pictured in the latest tuning manuel. This is much better than I could do on my own but not close enough for my liking. I guess I'm not seeing enough examples of what to do. So do any of the MS II pros have some examples of a good AE tune and the basic specifications of the engine? Maybe I can get a better idea of what to do from there. Seems like the new code will help in this department. My intake seems to GULP air at idle even with the slightest tap. The MAP AE has helped some in this area. I also turned my lag factor for my TPS to 100 shutting it off. This has helped much. My TPS is stable enough where I'm not seeing any noise even with the lag factor off. I know my VE is close I'd say no more off than 5% in the low RPM area.

Joffery: I'm running my stock ignition which operates just as good as it did with the stock setup. I think my engine is 9.5:1 CR.

The more I work with my MS the more I'm inclined to build a database that would be accessible online. Users would upload there best .msq tune. Attach datalogs. Then you could search for similar displacement and style motors and look through all the settings. Maybe even have a rating system like 5 stars if your tune is perfect and so on..... Sound like a good idea? I do have a server here with 120 GB mirrored RAID that isn't doing to much on a static business DSL connection. That at least could give me a good excuse to do more with this server. The key would be a flexible search function so you could find the tunes you want to look at. Like how google is so good but for engine specifications. Anyone wanna help?

Just a thought.

Off to think of what to tweak next,
A.J.

Also joffery,

Look at where the PW begine to increase...... it is after ay AFR is already dead lean. Seems to me like it is lagging behind. By the time the O2 sensor reads lean it is way too late to add fuel. The fuel should actually come in a little before you see any change in AFR. At least that would seem more correct to me......

A.J.

Thanks, it was the TPS and MAP lag factors. That explains why I could set my accel enrichment with MS 1 but couldnt get it right with MS II. No stalls yet - Better performance too. TPS signal is noisy with the lag at 100% but raising the threshold fixed that. even when the tps acel is not triggered it doenst go as lean because of less lag on the map input.
I think the documentation could be improved. There could be at least a paragraph on every feature in Megatune.

What did you set your MAP at? 100? Mine is a bit noisy there. Where did your TPS end up at? 90ish?

A.J.

I have TPS, MAP and RPM lag at 80 now. I havent spent time fine tuning yet (I may tweek further) but I see a big improvement. Now that it's getting there sooner, I reduced the amount of accel enrichment. Before, TPS lag may have been as low as 30 and MAP and RPM were 50. I have a light aluminum flywheel so rpm can change very quickly. I think I was having errors with the rpm lag factor at 50. It seems unlikely that I would have several datalog lines in a row with the exact same rpm while the engine was sputtering out. I could set the map lag higher, but I may need to put a restrictor or a bit o cotton in the MAP vac line to dampen the pulses.

Yeah I had my MAP at 100 and my AE indicator was blinking under WOT. Not good. hehe. I'll have to give 80 a go.

Much appreciated,
A.J.