2G DSM Link Will Not Idle in closed loop

[lilboy529]

Overview- I have a (relatively) stock 1g 4g63 motor in my 2g gst. With PT 1200s, Walbro 255, Upgraded FPR, FMIC, 16G and e85, Everything is used via DSM link. I have scaled down the injectors to -41.7% (assuming my math is correct, I would be more than happy to share the exact numbers if someone was interested) as well as messing with the MAF scaling a tad.

ISSUE:- The car runs fine in open loop mode. Idle, WOT pull ect. But the minute the ECU goes into closed loop mode the car runs rich and will die if left to do so. For example if you're doing a WOT pull it runs fine, leave it in gear and slowly coast down to 1500 RPM it will be fine and not die. But if you kick in the clutch after the pull it will die.

DATA- I have attached a log of it so you can see it. If you skip to 1651.271 seconds you can see the open loop activate and the Rpm drops as it tries to die but I save it by giving it gas.

I am 100% a newbie at DSM link and Tunning cars. But I have experience with Tunning snowmobiles. Any help is appreciated!

 

[A Sharp]

A couple things:

1. A wideband is a must if you're going to run big injectors and e85. Maybe you're not logging it to the ECU, but my gut is telling me that you don't have one.
   
2. Your front o2 sensor is screaming lean. It almost never goes over 0.5 V. BTW an engine that wants to die coming off of throttle typically indicates lean. Your mafcomp settings probably are the issue here: you're taking a lot of fuel away at low MAF frequencies.
   
3. You have a DTC for the knock sensor. You'll want to get that figured out.
   
4. You'll want to adjust your TPS so that the offset is zero. If GSTwithPSI sees that, he'll get testy on you . I've made that mistake before.
5. Next time, make sure to log LTFTMid and LTFTLo.
6. I think you may have uploaded the wrong log. It is only 867 seconds long.

It would also help if you could fill out a profile for your car. The biggest takeaway here is to get a working wideband setup with ECMlink. It is an indispensable tool when dialing in a car with extensive fuel mods.

 

[lilboy529]

Thank you so much for your help ill be doing some more work tomorrow night. I think the Tpms sensor is is messed up because I have tried that process you're talking about and it continues to still not work so im going to replace it.

I do have a wide band I just dont know how to hook it up to the ECM link if thats possible. I tried using AFR est. but its different than the actual gauge on the car


I get about .4 degrees knock at cruise periodically but heard thats a common "phantom knock" from crappy 1g sensors if the car isnt in boost.

I can do LTFTmid and LTFTlo but honestly I dont understand what the values mean.

Also dont know what profile you're talking about

My bad on the log time. I meant at around 800 seconds you can see what im talking about

 

[doubleclutch]

Try starting here: https://www.ecmtuning.com/wiki/ecmlink101
and watch these: http://www.ecmtuning.com/demos.php

Make sure you follow this for ECMlink help: http://www.dsmtuners.com/threads/su...for-ecmlink-log-advice.511062/#post-153639384

Now to the fun stuff.

LTFTLo is your fuel trim for low MAF frequency values
LTFtMid is your fuel trim for mid range frequency values

From ECMlink Wiki:

LTFT Select
In the direct access tab, you'll see an item called “LTFTSelect”. That table defines which of the 3 long term fuel trim variables (lo, mid, or hi) are selected for use/update at any given time. The selection is done based on MAF sensor frequency (after user compensation is applied).

You'll notice the stock values on a 2G DSM are:

Mid on/off: 88/75 High on/off: 1594/1594

Meaning the mid will be selected above 88hz and continue to be selected until the MAF sensor frequency drops below 75hz.



Hooking up the wideband is fairly straight forward:
https://www.ecmtuning.com/wiki/lc2install?s[]=wideband
Pretty much just connect the 0-5V signal wire to your selected input on the ECU and then tell the ECU it is there.


AFRest will not match if you settings are way off.

The profile is a "DSM profile" go to your page on this site and add a profile of your vehicle so we can see what you are running.


Some comments on your log:
- Rev limit 6k? Lame. Sounds sooo good above 6K
- If your TPS is crap, then probably shouldn't use it to simulate idle switch
- MAF comps at low end look quite low. zero them out and start over watching your LTFTlo and LTFTmid
- Drop your knock CEL to around 3 degrees. At ten you will be picking up pieces of your pistons before you CEL goes on.
-Your ISC looks out of adjustment. That should be covered int he videos i linked above.

You got some work to do, but it is fun. You feel like a real 90's cool dude sitting in you 20yr old car on a laptop tuning stuff.

Good Luck!

 

[lilboy529]

You guys are awesome I wasn't expecting this much help. I plan on doing these all this weekend. This is just a fun side project for me as I got very lucky and am about $1800 into this build. Instead of getting it tuned I wanted to do it myself even if it takes a while.

-Rev limit is 6k because I don't want it blowing up if something goes wrong and the throttle gets stuck for now as we just got it running.
-I just checked and the wide band IS hooked up to the ECU already. So im assuming the AFR est value is the correct one?
-TPS will be fixed this weekend.
-By idle switch do you mean the IAC valve? or whatever the dsm name for it is?
-What is an ISC

I know a lot of these questions are dumb but Im just going to suck up my pride and ask rather than act like I know the answers

 

[doubleclutch]

I can't see how the throttle would get stuck, but you know your car better than i do.
The wideband may be wired in but you aren't telling dsmlink that it is there. you have to tell dsmlink where it is on the inputs tab for it to be useful. AFRest is a guess by dsmlink based on the MAF and fuel settings.

I believe there is a switch that notices throttle plate closed, but i could be wrong

IAC=ISC

Don't worry about sounding dumb, worry about being dumb. Keep asking questions and people will help. Think you know everything or don't listen and the help dries up fast. So far you are doing well!

 

[91talonts1]

http://www.ecmtuning.com/wiki/installnewsensor This explains the how to log an aftermarket sensor in detail. Like doubleclutch said if it's wired to an input already you just need to set which one in the inputs tab.

The idle switch is integrated into the 2g tps. The TPS has to be close in physical adjustment in order for the idle switch to work on its own without simulation.