New to Megasquirt on '90 5.0, having setup issues

Jaybal80

Member
Sep 16, 2019
5
1
13
41
Wintersville OH
Hey all, I skimmed through a bunch of threads here for help and I didn't find anything that made a difference for me - but it might also be that I don't exactly know what I'm looking for because this is all so new to me - so apologies for the newbie questions...

I should mention that prior to installation, my factory ECU was working and the car was starting and running. It would idle around 750-800 RPM and timing was set around 12-14*.

Where I am:
The new ECU is connected to my wire harness and Laptop successfully. The vacuum line for MS internal MAP sensor goes through my firewall and into an unused port on my vacuum tree. I removed my MAF.

On the initial setup I created a new project, set it to narrowband (my wideband sensor isn't here yet), input my injector and engine size, and changed the timing settings from 'table' to 'fixed' at 12 degrees. I removed my spout connector and tried to start the car to set timing as per the instructions. It started but only for a few seconds. Idled really rough at only 4-500 rpm and died out. I know the base map is for a stock-ish 5.0, here's what I have and I'm open to any suggestions, as I'm really new to tunerstudio and this whole process:

1990 Mustang LX 5.0
GT40P heads
Explorer/GT40 upper and lower intake
70MM Throttle body
1 5/8" Shorties into a Catless BBK Xpipe
24lb injectors
190LPH/255 Walbro fuel pump
mild cam (unknown model but close to stock HO cam)
SVE underdrive pulleys
All smog hardware deleted
Factory A/C and alternator
I also have an IAC adjuster plate, so my TB butterfly is closed at idle - not sure if or how that would impact this since it's allowing a constant flow of air, but thought I'd mention it nonetheless.

Any help of suggestions would be greatly appreciated - Thanks!
 
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96pushrod

I think they're a little easier to get off
May 15, 2018
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It’s going to be really tough to get any sort of meaningful tuning done without the wideband, so hopefully you got that by now.

As far as phasing the distributor, I’ve never pulled the spout out, set timing fixed to 20* and adjusted distributor to match, or use trigger offset when you get it in the ballpark. Done this with microsquirts and ms3x stuff. I always wondered why the mspnp says to remove the spout, you’d think they would want it to stay in for phasing. After that I return the timing setting to “use table” and make sure timing matches at the damper with commanded.

You also shouldn’t need any kind of adjustable iac plate. I like to open the throttle blade until I can get rpm where I like it, and keep iac duty cycle around 20% at idle rpm, at operating temp. This allows some room to command higher idle at cold temps and do it using iac only, plus a little timing if you like. I’ve also done cammed ls rpm manipulation for a/c and electric fans using only timing, and didn’t even have an iac. Iac is much easier though.

So anyways, leave the spout in, set timing to “fixed” and phase the distributor that way. You can also unplug the fuel pump relay, set timing to be fixed at 10* and have someone crank the car while you rotate the distributor to phase it. Then you can play the fuel pump relay back in and the car should have no problem starting.

I’d recommend waiting till you get the wideband hooked up though so you’re not tuning blind. Don’t be surprised if you have to hold the throttle open some until you get the car up to temp so you can adjust fueling at operating temp. Ve table adjustments should only be made at operating temp, although you can add some fuel at initial startup, just to get you going, then make adjustments when warmed up. After that, use the warm up fuel enrichment table to add fuel at cold temps, NOT the ve table.

Also, make sure your injector settings are correct as far as size and dead time go, and don’t forget to calibrate the tps after any adjustments in throttle blade.
 

Jaybal80

Member
Sep 16, 2019
5
1
13
41
Wintersville OH
Thanks so much! So, I did manage to get my wideband, hook it up, and I was able to get it to idle (albiet not super well). I set the timing at 12* fixed then changed it back to use tables. Does it matter if it's 12* vs 20*? I went 12 because that's what the instructions said.

So now it's idling rough and super rich, like 10-11 AFR and I can smell gas in the exhaust. I haven't had time to work with it further, but I now need to do more research on injector settings and how to best manipulate the fuel curve to lean out the idle. I appreciate the info about the VE table and operating temps - I didn't know that. I need to reduce fuel, not increase it at cold start - so that's next on my list I guess.
 

96pushrod

I think they're a little easier to get off
May 15, 2018
993
600
103
29
Savannah
Thanks so much! So, I did manage to get my wideband, hook it up, and I was able to get it to idle (albiet not super well). I set the timing at 12* fixed then changed it back to use tables. Does it matter if it's 12* vs 20*? I went 12 because that's what the instructions said.

So now it's idling rough and super rich, like 10-11 AFR and I can smell gas in the exhaust. I haven't had time to work with it further, but I now need to do more research on injector settings and how to best manipulate the fuel curve to lean out the idle. I appreciate the info about the VE table and operating temps - I didn't know that. I need to reduce fuel, not increase it at cold start - so that's next on my list I guess.
Doesn’t matter if it’s 12, 20, 15, etc for fixed timing. It’s all preference. I kind of like to set it close around where my timing normally at (17-18*) so 20* always just made sense to me. Pretty much a trivial number as long as it matches.

If it’s running rich, go to the ve table and select the cells where the tracker is hovering around and reduce the value. Higher number = more fuel, lower number = less fuel. It should take 30 seconds with a laptop to get it to idle at an acceptable a/f.

I also like to go to the timing table and make everything from 500 rpm - 1200 rpm for all the load cells the same. I like to start at around 18* as most engines run good there. Make all the columns here 18*. Also, I like to make every cell in the ve table where the car will idle pretty much the same value. This will usually smooth out the idle a good bit as big ve or spark changes can cause the car to surge.


Also, I’d set injector dead time at 1.1 for the style injector you currently have and just leave it there.
 

a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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Hillsborough county
The dead time for injectors matters much more in a sequential setup.

if you are idling that rich then you can highlight the idle area and the surrounding cells and multiply them by .8 this will remove 20% fuel and get you very close to where you need to be.
 

Jaybal80

Member
Sep 16, 2019
5
1
13
41
Wintersville OH
Doesn’t matter if it’s 12, 20, 15, etc for fixed timing. It’s all preference. I kind of like to set it close around where my timing normally at (17-18*) so 20* always just made sense to me. Pretty much a trivial number as long as it matches.

If it’s running rich, go to the ve table and select the cells where the tracker is hovering around and reduce the value. Higher number = more fuel, lower number = less fuel. It should take 30 seconds with a laptop to get it to idle at an acceptable a/f.

I also like to go to the timing table and make everything from 500 rpm - 1200 rpm for all the load cells the same. I like to start at around 18* as most engines run good there. Make all the columns here 18*. Also, I like to make every cell in the ve table where the car will idle pretty much the same value. This will usually smooth out the idle a good bit as big ve or spark changes can cause the car to surge.


Also, I’d set injector dead time at 1.1 for the style injector you currently have and just leave it there.

Super helpful, thanks! I'll try this tonight if I have time and if not this weekend for sure. I'll report back how it goes. Really appreciate the help.