5.0 microsquirt help

86_Capri

Member
May 13, 2019
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new jersey
Hi guys, I am in need of some help here. 5.0L, gt-40p heads, cobra intake 24lb inj, and 35-302-8 comp cams cam. The car will start and idle but not the greatest. When it's cold it shoots up to a little over 2k rpm and then slowly comes down to approx. 800-750 rpm sometimes lower. The idle isn't very consistent, it surges a bit. When I go to shift from park to reverse the engine will stall unless I give it some gas to keep it alive. I've been messing with the settings from the stock tune hoping to try and figure things out myself before asking for help but I seem to be chasing my tail instead of making any real progress. Hopefully you guys can point me in the right direction.

Thanks, Brad
 

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90sickfox

I didn't really have an issue with the stink...
SN Certified Technician
Mar 2, 2015
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Hey Brad...I'm one of the Scotts here. Welcome to the forum !

First, what chip or system are you using ?

Are you using a Mass Air Flow meter or is it speed density ?

I'm nowhere near a guru here...been on my own tuning quest with megasquirt MSPNP2.

A91what or one of the other guys will jump in soon.
 

86_Capri

Member
May 13, 2019
14
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new jersey
Hi Scott. I’m using a Microsquirt that I bought from EFISource.com, The one that plugs into the factory harness. I’m using speed density.

Thanks, Brad
 

stanglx2002

Mod Dude
Jul 7, 2005
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Welcome to :SN:

There is a lot of help here for the Megasquirt system as I personally use the MS2PNP as well. To best help you can you post your current tune and a datalog to see the issues you are talking about?
 

86_Capri

Member
May 13, 2019
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new jersey
Here is the tune for open loop idle along with the datalogs for idling and then idling and shifting into gear. Hopefully this is enough info.
I'm sure once anyone who knows what they are looking at opens this will quickly realize I am lost. Any help is greatly appreciated.
Thanks, Brad
 

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a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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So what kind of help are you looking for?? you just want some advice on how to try and get things into line? or do you need more than that? I am only asking because i do classes to get guys like yourself up to speed on the software and help you get things working like they should
 

86_Capri

Member
May 13, 2019
14
2
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28
new jersey
I guess at first I’d like a push in the right direction and see if I can get it working on my own. If that doesn’t work out for me what do your classes involve and how do they work? I watched a few of you YouTube vids and you seem to have a pretty good handle on this system.
 

a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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If you look around on the other MS threads on here i tune alot of cars. For more than just a mention about the services we need to chat in a private message or you can email me at [email protected]

The first thing i would do in your position is get the car to idle around 1100 RPM with the timing locked at 20* and an AFR of 13.8 then first sweep the timing up and down from 14* to 28* [you may need to alter the fuel to keep the 13.8 AFR] do this while taking a datalog and count to 20 between each timing change
once this is done I will show you how to disect that information to obtain your optimal idle timing. [or darn close to it]

lets start there first.
 

86_Capri

Member
May 13, 2019
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new jersey
Sorry for the delayed reply. I didn't have time to mess with the car yesterday. So today I came home got the car up to operating temp and did a datalog of the steps in your previous post. The rpm and afr fluctuated a little bit, hopefully it was steady enough to work.

Thanks, Brad
 

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a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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Ok well lets look at the data pulled from your log file...
Snip for review.PNG


Timing value on the Y and RPM on the X... Z axis is the MAP signal.

looking at what we have the MAP is very stable between 48KPA and 50KPA from 20-28* of timing. but as the timing drops below 20* we can see the MAP signal weaken quickly.

on this engine i would likely set the idle timing around 19-20* and use Idle advance timing to stabilize the RPM.
I show you how to set this up in Closed loop idle part 4
 

86_Capri

Member
May 13, 2019
14
2
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new jersey
I really appreciate the help :nice:.So does this mean that my idle will be set at around 1100 rpm? That seems kind of high to me ( I'm not doubting you, just asking)
Since approx. 50% on the iac valve netted me 1100 rpm at idle does this mean that I should set my idle warm up duty to 50 at my warmest temp and then gradually increase that number for the cooler engine temps.
 

a91what

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Mod Dude
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you could [although lowering the value should lower the idle] , or you can go into the idle settings and change it over to CL idle [closed loop]

the intent of the 4 part video series i made is to show you how to run the tests needed to setup closed loop idle.
warm up = set valve duty based on engine temp

closed loop = live feedback loop based on a number of parameters to control Idle speed actively [like the oem do]

on the MS2PNP the idle valve must be set to inverted in the idle settings or the PWM% duty of the idle valve will be reversed.
 

86_Capri

Member
May 13, 2019
14
2
13
28
new jersey
Ok so I changed over to closed loop idle and it is a little bit smoother. It still surges a little but not as bad as before. I'm still having an issue when going from P to R and then from N to D. The rpms drop really low and will stall if i dont give it a little bit of throttle. Then when going from D to N or R to P the rpms will shoot to like 1500 and then settle back to around 900. Any insight on this issue?

Thanks, Brad
 

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