troubleshooting with dsmlink

[91-gsx]

I started my car today after putting on the fuel pressure solenoid and it idled a bit better when I turned it on and when I let it idle until it was fully warmed up, dsmlink showed 190* as the coolant temp. When The temp got to 190* and I let it idle some more it would not go up, so I knew the 190* stock coolant thermostat was working. The thing that caught my eye was the fact that the o2 voltage was still not cycling when I let it just idle there. Then I decided to drive it and see if it would cycle and it did. But when it did, it would only go up to .61v tops and drop. The dsmlink a/f ratio estimate showed 12-12.5:1 a/f ratio, which is very rich while idling after a small drive. I think the o2 sensor might be shot, what do you guys think?
thanks for the help

 

[DSM90AWD]

DSMLinks AFR est does not recieve feedback from the O2 sensor, instead on it's an estimate based on calculations of the fuel injector size "Props" you entered (under AFR not global injector size) and compensated airflow.

What does your fuel trims look like? Trims are directly related to the Oxygen Sensor feedback. If they are off, it's likely you need to tweek global fuel.

Once you get fuel sorted out, you can mess with the AFR Parmater's Props to fine tune the AFR est. Then again as I mention above it is only an estimate and a true wideband (LC-1s are only $199) are extremely helpful for tuning

 

[steve]

Also remember that the estimate needs correct data entered. You must enter the effective injector size at your base fuel pressure (36 psi) not the rated size at 43.5 psi. So for example you would enter the stock injectors as 411-415cc not 450cc.

Steve

 

[91-gsx]

When I ordered the dsmlink they asked me what injector size I had so that it would work when I first put it on my car. I have 750cc RC injectors, the deadtime is set at 315. How much fuel should I take out with a base fuel pressure of 36psi and 750cc injectors? I will try to find out right now as well, that could be a major mistake in the base settings. But I don't understand why they would send it to me with the wrong settings, oh well, easily reversible.
thanks for the help guys

edit: I just checked the dsmlink user guide and it shows FIC 750cc injectors at 315 deadtime and -40% with the global fuel. I was working on the car earlier, but I know it was in the 30's range when it came to the global settings. So that might be why it is running to rich? Or do I have something reversed here?

 

[DSM90AWD]

When I ordered the dsmlink they asked me what injector size I had so that it would work when I first put it on my car. I have 750cc RC injectors, the deadtime is set at 315. How much fuel should I take out with a base fuel pressure of 36psi and 750cc injectors?

Note that the the initial injector sizes referenced in the DSMLink manual / your intial setup is what a 750cc injector should be compensated for if it flowed 750cc / min @ 43psi and your car is running 38psi base fuel pressure (1G) or 42psi fuel pressure (2G).

All injectors I've seen do not flow exactly what it says on the box, so you will always need to fine tune the global fuel +/- the recommeded settings if you want to be exact. Nice thing is the DSM ECUs have what is called Fuel Trims that can adjust fuel in closed loop operation -4.7% to +10% (1G) based on your O2 Sensor feedback, so make sure you read the part in the manual of fine tuning adjusting Global Fuel / Deadtime based on fuel trim feedback.

BTW, I see you found the DSMLink forums

 

[steve]

I'm talking strictly about what you do for the AFR estimates. The actual parameters for global already take the base pressure into consideration unless you change it from stock.

The DSMLink software doesn't automaticly take the parameters you used for injector correction and put them into the AFR calculations. You have to enter that and you need to tell it the effective size of the injector based on your fuel pressure. Since 2Gs run 43.5 there is no difference but 1G's run 36 psi stock the effective size is smaller than the rated value. The formula for calculating the effective size is:

New-Flow-Rate = (SQRT(New-Pressure/Old-Pressure) * Old-Flow-Rate)

Effective-Size = (SQRT(36/43.5) * 450)
Effective-Size = (SQRT(0.828) * 450)
Effective-Size = (0.910 * 450)
Effective-Size = 410

Just changing the injector value entered in the AFR calculation could bring the AFR estimate back in line to something close to stoch during closed loop since that what the O2 feedback targets. If it's still way off you have have problems with your sensor.

Steve

Registered DSMLink customers can access the DSMLink forum thread on this at:
http://www.dsmlink.com/forums/showthread.php?t=6734

 

[oldman]

DSMLinks AFR est does not recieve feedback from the O2 sensor, instead on it's an estimate based on calculations of the fuel injector size "Props" you entered (under AFR not global injector size) and compensated airflow.

What does your fuel trims look like? Trims are directly related to the Oxygen Sensor feedback. If they are off, it's likely you need to tweek global fuel.

Once you get fuel sorted out, you can mess with the AFR Parmater's Props to fine tune the AFR est. Then again as I mention above it is only an estimate and a true wideband (LC-1s are only $199) are extremely helpful for tuning

You must be a Link expert!

 

[91-gsx]

I went out for another drive yesterday and let it idle for a while ofcourse while I watched the readings on dsmlink. The car reaches full operating temperature(over 190*) and then does not cycle until I drive it. When I do drive the car it cycles the o2v, but goes to .61v tops. Then when I stop driving and let it idle some more, the o2v just goes to .04v or .06, not cycling, just showing one or the other sometimes. I am missing 1 bolt on the o2 housing because it got stuck and stripped, so I have it on there with only 3 bolts. There might be an exhaust leak that is causing this stuff? The thing is I have all of this new stuff to put on the car, but smog just got around and I put it back to stock all for the injectors, fuel pump and afpr. I slapped the whole setup back to stock in 1 day, but I just left the intercooler out, as in no smic or fmic. But that should not affect smog or the check sense he wont hit boost revving it and checking the smog. Awd means no rollers.
thanks for the help and input

 

[steve]

Not cycling at idle is a bad sign. The O2 voltage dropping to basicly 0v is also bad. I guess I don't have to say anything about the likely exhaust leak in the O2 housing.

You'll need to fix the leak and get the O2 to cycle at idle or I really doubt you pass the smog tests.

Steve

 

[91-gsx]

I am going to fix the leak, and I know how exhaust leaks make the car run rich and all at idle. But even if it was leaking, if the o2 sensor was functioning normally, it would still cycle, right? The only reason I ask this is because if I take o2 housing off to seal it(with exhaust rtv), I might as well throw on a new o2 sensor if the current one seems to not be working.
thanks for the help

 

[steve]

The idea is that a leak allows air to be pulled into the exhaust causing the O2 sensor to read lean. That causes the ECU to richen the AFR trying to hit the stoch target and if it's too far out the ECU drops out of closed loop.

I can't decide if your having a problem with a leak or a bad heater on your sensor but your O2 voltage is dropping to nothing at idle then it should be cycling in closed loop maintaining an average AFR of 14.7:1.

It's also possible that you have your DSMLink fuel settings off. There is a big difference between the delphi/rochester injectors FIC sells and the lucas style injectors RC usually uses. You need to figure out your deadtime and global values for those injectors. running the wrong values can also cause this type of problem.

What are the fuel trims doing?

Steve

 

[91-gsx]

I went out and let it idle for awhile, and then I drove it for about 10 minutes just like the dsmlink userguide tells you to. Well the only 2 values that I saw for selectedLTFT were 128 and 179. As far as which one is idle and which one is cruise, I don't know. It would show either of them sometimes. I will post all 3 logs that I took, they are long and stuff, so sorry ahead of time, I'm still learning. If you could take a look at them and see what you could derive from the logs. I will try to fix the leak next week because it looks like rain is coming. Worse comes to the worse, I will fix the leak and zero everything out for the stock 450's, pass smog and start were I left off, hopefully eliminating some variables like leaks and such.
thanks for the help

 

[Boosted98gsx]

Better question is why aren't you posting this in the dsmlink forums? Or at the very least in the tuning forum?

 

[91-gsx]

Better question is why aren't you posting this in the dsmlink forums? Or at the very least in the tuning forum?

, I just don't get this sometimes. I got every answer in this thread from either a wiseman or a moderator. So, why are you asking me this question?

As for the the moderators, if you want to move this thread, by all means. I already have gotten answers from the only people that stayed tuned to this thread.
later

 

[Boosted98gsx]

Because us that have PURCHASED dsmlink want to keep those that have STOLEN copies from getting answers.

 

[DSM90AWD]

Because us that have PURCHASED dsmlink want to keep those that have STOLEN copies from getting answers.

As an FYI, Thomas recently endorsed our helping with DSMLink support questions on this forum giving us Wisemen/Moderators some solace that doing such would be appropriate.

Obviously we would not help those whom are obvious thieves / seeing techincal help to pirate (have deleted such threads when found in the past). Also in this case (91-gsx) owns a non-copyable 1G version and is a member of the DSMLink forms and did post his initial question there.

To 91-gsx, although there is some DSMLink expertise here, DSMLink Forums is infinitely better for specific troubleshooting questions since it is product-specific, all it's members own licensed copies of DSMLink and Thomas/Dave (the programmers) are avail to field many of the questions

 

[robertseber]

So did you ever get this worked out. I have rc 750 injectors also and dont know what starting point for global deadtime. I have this posted in ecmlink forums also my link is legit there is just more traffic here then on ecmlink forums. my post and log is in this forum ECMTuning User Support Forums thanks in advance for the help i hope your issue is dealt with and im not threadjacking.

 

[91-gsx]

So did you ever get this worked out. I have rc 750 injectors also and dont know what starting point for global deadtime. I have this posted in ecmlink forums also my link is legit there is just more traffic here then on ecmlink forums. my post and log is in this forum ECMTuning User Support Forums thanks in advance for the help i hope your issue is dealt with and im not threadjacking.

Your not thread-jacking at all.

I started with the global deadtime set at 315, and then adjusted it accordingly. The Ecmlink user guide describes the process perfectly, and can be found on the Ecmlink website.

Let us know if you need any additional information. Good luck.