Megasquirt idle issues

So i got my megasquirt ms3pro installed and setup all the basics with dual widebands. I calibrated throttle, adjusted timing so it was dead on as well. I also made sure to calibrate coolant temp. So the issue i'm having is i get crazy idle surge once i tap the throttle. also when its warm and once it dies it impossible to restart unless i give it throttle. I have been trying to mess around with PID controls but i just cant seem to get the idle stable. Anyone have some suggestions?

Have you done the sweep test yet? You also need to dial in the VE table before you start messing with the PIDs. On that note which PIDs are you messing with?

Check out Black Fox EFI Tuning page. He has a few videos that are really helpful for getting idle under control.

My main piece of advice is make sure the engine is completely warmed up before you start adjusting the timing and VE table. Otherwise you're fighting warm up enrichment and other things at the same time.

YouTube

Surge is bad fueling. Dial fuel in first then work on idle.

Surge can also be too much spark at idle. My car idles best with 10-12* FYI.

For the warm start problem, if you have to open the throttle a bit to start you may need either less fuel or more air at start up.

With SCT it took me a while to get cold / warm starts nailed down, along with a stable idle. Sounds like your having fun though.

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03cobra#2 said:

Surge can also be too much spark at idle. My car idles best with 10-12* FYI.

For the warm start problem, if you have to open the throttle a bit to start you may need either less fuel or more air at start up.

With SCT it took me a while to get cold / warm starts nailed down, along with a stable idle. Sounds like your having fun though.

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Yeah having fun for sure. Its been over 106* out here in west texas lately, so ive been taking baby steps and trying not to be out in the heat too much. I probly need to bring the spark down then in the idle cells. Its around 20* right now.

My idle spark is 16 degrees. And it idles steady at 750rpm. You'll just have to mess with. One of the nice things about the live tuning is being able to see when the change you make is good or bad right away.

Also, something I recently learned was to zero out the correction on the MAT/CLT table. I want it to only use MAT for spark control. Doing that also made it so my idle spark stays where I want it to.

Side note, I use the main VE table even for idle. I tried using idle VE but wasn't crazy about it. Just an FYI thing.

Sorry if you already know all this. Just things I've been learning.

01yellercobra said:

My idle spark is 16 degrees. And it idles steady at 750rpm. You'll just have to mess with. One of the nice things about the live tuning is being able to see when the change you make is good or bad right away.

Also, something I recently learned was to zero out the correction on the MAT/CLT table. I want it to only use MAT for spark control. Doing that also made it so my idle spark stays where I want it to.

Side note, I use the main VE table even for idle. I tried using idle VE but wasn't crazy about it. Just an FYI thing.

Sorry if you already know all this. Just things I've been learning.

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Okay good to know. Ive got it to cold start good and idles fairly well, but any throttle input and then it wants to die and surges like crazy. Hot starts are a pain and i always have to input throttle. When your talking about main ve table, are you talking about the fuel table or ignition table? So do you currently use pid controls? I noticed too that at WOT with the base map and running 14psi the timing is very low and it runs really rich lol. A lot of learning for me to do, ive manly tuned with sct and DSMlink/evoscan so this is a lot differt.

bmxr152 said:

Okay good to know. Ive got it to cold start good and idles fairly well, but any throttle input and then it wants to die and surges like crazy. Hot starts are a pain and i always have to input throttle. When your talking about main ve table, are you talking about the fuel table or ignition table? So do you currently use pid controls? I noticed too that at WOT with the base map and running 14psi the timing is very low and it runs really rich lol. A lot of learning for me to do, ive manly tuned with sct and DSMlink/evoscan so this is a lot differt.

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Under fuel settings you'll see VE1. That's where you're going to adjust your fueling. With SCT you're modeling the airflow. With Tunerstudio you're modeling the fuel flow. I had to get my head around that in the begining.

There's a couple tables for cranking you'll have to adjust. I don't remember them off the top of my head. They'll have an engine temp in one column and a percentage in the other. So if the hard start is at 80° then there's no need to touch the 60° bin. Plus you can change the temps. I think in the base tune it goes down to -40°F. Well, the coldest my car sees might be low 40's. So I adjusted my tables to only go down to 0°.

I do have the idle PID controls active, but you need to get a stable idle and tip in before messing with those. Get the idle fuel and advance dialed in then you can mess with the PIDs. Those are more for returning to idle anyway. Such as coasting to a stop (aka dashpot decay rate).

When I started driving mine I used the Autotune feature to start dialing in the A/F. Then I used the the VE Analyzer in the Megalog Viewer to final tweak.

Also, you did set up your A/F table right?

01yellercobra said:

Under fuel settings you'll see VE1. That's where you're going to adjust your fueling. With SCT you're modeling the airflow. With Tunerstudio you're modeling the fuel flow. I had to get my head around that in the begining.

There's a couple tables for cranking you'll have to adjust. I don't remember them off the top of my head. They'll have an engine temp in one column and a percentage in the other. So if the hard start is at 80° then there's no need to touch the 60° bin. Plus you can change the temps. I think in the base tune it goes down to -40°F. Well, the coldest my car sees might be low 40's. So I adjusted my tables to only go down to 0°.

I do have the idle PID controls active, but you need to get a stable idle and tip in before messing with those. Get the idle fuel and advance dialed in then you can mess with the PIDs. Those are more for returning to idle anyway. Such as coasting to a stop (aka dashpot decay rate).

When I started driving mine I used the Autotune feature to start dialing in the A/F. Then I used the the VE Analyzer in the Megalog Viewer to final tweak.

Also, you did set up your A/F table right?

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Air fuel table is setup correctly. I still need to link each wideband with its bank. As of right now im using 1 wideband to control all injectors even though both are hooked up. During install i didn't have each one marked so i will need to remove and test each bank to see which is which. Yeah coasting to a stop sometimes it dies. Tip in needs some work too lol.

bmxr152 said:

Air fuel table is setup correctly. I still need to link each wideband with its bank. As of right now im using 1 wideband to control all injectors even though both are hooked up. During install i didn't have each one marked so i will need to remove and test each bank to see which is which. Yeah coasting to a stop sometimes it dies. Tip in needs some work too lol.

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I would put the PIDs back to the default numbers or switch to the basic idle control for now until you get it tweaked.

What's your set up?

01yellercobra said:

I would put the PIDs back to the default numbers or switch to the basic idle control for now until you get it tweaked.

What's your set up?

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Okay, i need to figure out what the default numbers were as well. Setup as far as motor? Im running 9.8cr built bottom end with comp stage 3 cams, degreed to comps specs. Currently running stock blower with 2.76 and stock size lower, bbk long tubes, JLT high boost intake, 80lb ford racing injectors, dual 465 pumps, fore return fuel system, on3 thermostat relocation as far as bolt ons wise. Car was running e85 on a custom sct tune before and ran pretty well except for tip in and decel.

bmxr152 said:

Okay, i need to figure out what the default numbers were as well. Setup as far as motor? Im running 9.8cr built bottom end with comp stage 3 cams, degreed to comps specs. Currently running stock blower with 2.76 and stock size lower, bbk long tubes, JLT high boost intake, 80lb ford racing injectors, dual 465 pumps, fore return fuel system, on3 thermostat relocation as far as bolt ons wise. Car was running e85 on a custom sct tune before and ran pretty well except for tip in and decel.

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In the documents folder there should be a base file. It should start with an MS. It's pretty long. Open that up in a different project and you can get the base numbers. I did that a few times.

I was going to offer to send my tune to you to look over, but our set ups are way different. GodStang might have some advice for you since he's cammed and running E85.

The tip in will get better as you get the VE table dialed in. I would start autotune and drive it around. To be honest didn't even know I wasn't seeing accel enrichment for the first month or so. It wasn't until I started getting into the quick throttle movements I noticed the accel enrichment needed adjustment.

As for deceleration, I'm still working on that. Mine likes to go rich when I decel. So I have it set to go into overrun fuel cut shortly after I lift and coast.