Chuggish cold start idle, Dying when coming to a stop/revving, Etc (OpenSource SD)

[prestonztt]

Car is a 2006 WRX.

Mods are:
Built Motor
Rotated Kit w/ Precision 6262 Turbo
Crower 272 Cams
BC Springs and Retainers
Five-0 Motorsports 1400cc Injectors
Twin In-Intake Fuel Pumps
AEM AFPR
'07 2.5i Intake Manifold
GM IAT
Omni 4-Bar Map Sensor
E85

No mechanical problems whatsoever, no boost leaks, etc.

Car is currently tuned on OpenSource using Merp's SD Patch.

Anyways, the idling and drivability issues are getting pretty frustrating. When I cold start it, it seems to act like its struggling/chugging for a bit to get up to around 1500rpm's for the cold start. After about 20 seconds, it clears up and goes up to 1500rpm's like it should and it sounds a lot cleaner. Then the real problem is the regular idling. After its gets to operating temp, I go to start it and it just dies. I can do this about 3-4 times then it finally starts to catch itself and it finally starts to idle right. Also, if I rev it or if im coming to a stop, the car will just die. I really don't like that, as sometimes I have my children in the car and that can just be real dangerous.

I just want my car to have good street manners. I would love for the car to idle how its suppose to and not die when coming to a stop or revving it up.

Here is my current map: https://docs.google.com/file/d/0B2Ra7rEXATQqZXo2U1liejBqUXM/edit

And here is a log of the car starting and dying: https://docs.google.com/file/d/0B2Ra7rEXATQqZWxfUFhsbmlwS2s/edit

 

[Td_d]

Hey Preston, glad you posted it up in a thread, I'd like to get some other views here as well.

To summarise my discussion so far:

Sounds to me like a couple of issues here.

If you're struggling to start up, that's likely warm up enrichment that needs to be tweaked.

Then, you're struggling to start it once the engine it's warm correct? You running E85? In any case, there are hot restart parameters that have a habit of providing too much fuel, especially once you shift to a different fuel or change injectors.

The third issue, in terms of dying in coming to a stop would be the overrun fueling RPM threshold - with a 1400cc injector, the stock values switch the injectors back on too late.

And lastly, the engine load filtering, which is no good for SD.

Having checked the map out:

Engine load filter - done
Warm up, hot restart and overrun fueling values have been tweaked already. Hot restart is basically disabled, and warm up pulse width have been reduced markedly. I'm thinking that they may have been tweaked too much.

Looking at the log, I'm wondering whether it's not too lean cranking now. I would move the warm up fueling enrichment closer to the stock values in increments, and see whether that helps.

George - what's your view?

 

[HolyCrapItsFast]

I have to take a look. I have to install the xml's first :tup:

 

[HolyCrapItsFast]

Can someone post the xml somewhere for me? :lol:

 

[Td_d]

https://dl.dropboxusercontent.com/u/3099895/A8DH202X.MeRpMoD.Gratis.Testing.v13.4.27.1823.xml

 

[HolyCrapItsFast]

Got it! Thank you...

I agree with much of what TD suggests. Looking further into it I see a bunch of hot start parameters set to zero and some of the crank and warm up table look a little funky as well.

I will have a much better explanation when I have had a chance to really go through this with a fine toothed comb but I have to get there first :tup:

 

[Td_d]

You'll see that the cranking warm up enrichment pulse width are quite significantly lower - 3.15ms if I recall correctly, versus 5ms stock.

 

[Td_d]

Got it! Thank you...

I agree with much of what TD suggests. Looking further into it I see a bunch of hot start parameters set to zero and some of the crank and warm up table look a little funky as well.

I will have a much better explanation when I have had a chance to really go through this with a fine toothed comb but I have to get there first :tup:

Overrun, hot restart and warm up enrichment are all quite significantly different from stock - there could be others. I think the attempt to compensate for the larger injectors overshot the mark.

 

[fuji_production]

Should they be in the playground area of 4ms?

 

[Td_d]

That would probably be a good start - I would start raising them incrementally, and see whether it improves. The tuner removed ~40% pulse width - granted, these are 1400cc versus 550cc stocks - but that's a lot. E85 is a bigger issue with cranking than larger injectors.

 

[HolyCrapItsFast]

I agree that these parameters should be adjusted for larger injectors but the amount is in question. I'm still working my magic but I suspect we will be discovering much of it as TD suggests.

TD I have a question... When I look at the main VE table, the largest value I see in there is 1. I am assuming this is a multiplier like value and that 1 = 100%... Is this correct? I ask because the other SD roms I ever got from merp were 100 = 100

 

[Td_d]

I'll have a look, but yes - it can go higher than 1 (e.g in some areas where you're dealing with resonance), but that's the general idea 1 = 100%.

 

[HolyCrapItsFast]

https://docs.google.com/file/d/0B-3NCbhq0QiqcWs4R3hZbTVmTnc/edit?usp=sharing

So here's what I did... I located a recent tune of a car with similar mods and copied over the tables. I verified the values against yet another car with similar mods and they coincide. Give this a try and see if things improve. I fear that we will need to use trial and error to fix your issues totally. If this doesn't work then I feel other areas of the tune are in question. For instance... I feel that the injector scale is very wrong for your 1400cc injectors running e85. Scaling should be somewhere around 1000cc. Yours is set for 800. Is there a reason for this that I am not aware? It is important to get the injector scale near perfect because it will through everything else out.

This should be easy to fix and all you have to do is multiply your injector scale by 1.27 to bring the scaling closer to normal. Then add the fuel back by applying the same 1.27 multiplier to the entire VE table. I didn't want to do this unless I spoke to you guys first in the event I am missing something. :tup: Or maybe I'm just :tard:.

 

[Td_d]

I didn't look extensively at other areas of the map - it is surprising that the scalar is set so low, as you say, I would expect it to be closer to 1000 / upper 900's with a 30% reduction for E85. I guess it comes out in the wash if the entire VE table is shifted up.

I'll have a look at the rom when I get home tonight.