DSM Link: car doesn't idle very well

[99redgst]

I just got my car running a little over a week ago after being in my garage for eight months. The problem I'm having is that the car doesn't idle very well. When it is first started it idles ok for about thirty seconds then the rpms drop and it starts to surge from 500 to 1300rpm. I did the calculation for the global adjustment that looks like this:

450/880-1.0= -0.488 = -48% correct?

It seems as though the car still runs rich at idle. Is this formula just to get in the ballpark or is it right on? I changed my entire setup over winter(old:B16g, greddy fmic, ect. new: 60 trim,slowboy fmic, maft, ect) so I'm wondering if something else I put on is causing this. I don't have any vacuum leaks, any other ideas. Braking and feathering the gas is getting a little annoying.

 

[Pizzy]

Wait...maybe I don't understand...you have 880cc injectors?

I was told by a very knowledgeablt guy on DSMTalk to try to supply the ECU with as close to the correct airflow values with an AFC as possible. With larger injectors, move the entire fuel curve down via an adjustable fuel pressure regulator. On the logger the fuel trims should near 0% (100% for the 1g guys) if the fuel curve is adjusted well. After that, fine tune with the AFC as normal.

Now I realize you don't use an AFC, but DSMLink should be fairly similar. Rather than pulling the global setting down to -48%, perhaps you should just move the fuel curve? I've never worked with DSMLink but I suppose a -17% global setting would be the same as using -17% across the board on an AFC...so perhaps moving your fuel curve instead of the global setting would help?

Also, doesn't DSMLink take into account the injector size?

 

[KPWSerpiente]

48% is correct. What are your dead time settings?

-T

 

[sjwelna]

Straight from the dsmlink online manual:

Size (cc/min) Global (%) Dead time (ƒÝs)
RC 550 -18 180
Hahn 625 -18% 180
Denso 660 -31% 180
Denso 720 -38% 450
FIC 850 -47% 315
FIC 950 -53% 315


Sounds like you need to adjust the deadtime.

-Steve

 

[talonted_one]

After you set you dead time for you injectors you should log your learned idle adjust and your ISCposition. I believe they should be at 130/40.

 

[hostile]

Yeah if the car has been down for an extended period of time, the ecu is probably chasing the idle position.

Turn the idle up until it will stay running then give it a few minutes to warm up and find the idle postion.

Also make sure all the coolant lines that go to the throttle body are still hooked up. If they arent the idle will not be as stable.

 

[99redgst]

Coolant lines are hooked up. I realize that the ecu has a relearn time but the car has been run for several hours and still has the same problem, so I'm ruling that one out. Matbe the tps isn't adjusted correctly? I haven't ran the car in the past couple days because the rear main is leaking, taking care of that on Saturday.

 

[99redgst]

Oh yeah, my dead time is 330. And yes I have 880cc injectors from extreme motorsports.

 

[kpt4321]

What version of the MAFT is it? You need to be sure to set it to the default for a 2g and 450's, which is NOT all zeros with the newest version.

 

[kpt4321]

I was told by a very knowledgeablt guy on DSMTalk

I'll follow tuning advice on DSMTalk, right after I stick my hand in my compresor inlet at WOT.

to try to supply the ECU with as close to the correct airflow values with an AFC as possible. With larger injectors, move the entire fuel curve down via an adjustable fuel pressure regulator. On the logger the fuel trims should near 0% (100% for the 1g guys) if the fuel curve is adjusted well. After that, fine tune with the AFC as normal.

Well, whoever gave you that advice is wrong, sorry.

Sure, adjusting the fuel pressure and not adjusting the SAFC will do a great job of making the ECU behave correctly because the airflow number is accurate. However, this is because you're making the injectors flow less than they otherwise would! Why buy bigger injectors if you're just going to turn the fuel pressure down and make them flow less in the end?

An adjustable FPR is good for allowing the user to make small tweaks to the AFR and/or timing (due to the combination of SAFC corrections and FP changes) at mid to high throttle. However, even as such, you don't want to be too absurd, because your working range for fuel pressure is not that large.

Now I realize you don't use an AFC, but DSMLink should be fairly similar. Rather than pulling the global setting down to -48%, perhaps you should just move the fuel curve? I've never worked with DSMLink but I suppose a -17% global setting would be the same as using -17% across the board on an AFC...so perhaps moving your fuel curve instead of the global setting would help?

DSMLink doesn't work the same way that a SAFC does AT ALL. DSMLink sclaes the injector pulsewidth without scaling the airflow or timing or anything funky like that. SAFC is the suck, DSMLink is not.

Also, doesn't DSMLink take into account the injector size?

Yes, which is exactly what he is trying to do right now.

 

[Pizzy]

I'll follow tuning advice on DSMTalk, right after I stick my hand in my compresor inlet at WOT.

No offense intended but that's exactly what they say about Tuners too. I've tried your method and it all seems very intuitive but my car ran horribly. I tried a method from a guy on DSMTalk and I gotta say, the car ran a lot better with his advice. Not knocking you or your skill, you're much more capable than I.

And uh, easy there big fella, no need to flame me, I was just throwin out suggestions to think about that's all.

 

[kpt4321]

No offense intended but that's exactly what they say about Tuners too.

Last time I got into a technical arguement on Talk, I stopped posting there. That's all I have to say on that subject.

The level of "technical" tuning information there makes me sad.

I've tried your method and it all seems very intuitive but my car ran horribly. I tried a method from a guy on DSMTalk and I gotta say, the car ran a lot better with his advice.

This give us no information whatsoever. What was his method? What was mine? What settings did you end up with?

If you install a set of 550's and then adjust the fuel pressure so that the fuel trims all line up and don't use the SAFC to get them right, then the car will run just like stock. Do you know why? Because your 550's are now flowing the same rate as the stock injectors! Might as well just have left the 450's in there...

The deviation of ECU input airflow to true airflow in order to maintain a stock AFR on a ECU with no injector compensation is dependant ONLY on the injector size difference. The more fuel you are flowing through the injectors, the further off the ture airflow will be. There is NO way around this. If you get the AFR close while also keeping the airflow close, you don't have a lot of injector flow. End of story.

Not to mention, if your car ran like crap with the SAFC and a set of decently sized injectors, you were doing something wrong. I know plenty of people running SAFC/VPC's with 550's and 660's whose cars run well (as well as you could expect for ANY system without injector compensation).

And uh, easy there big fella, no need to flame me, I was just throwin out suggestions to think about that's all.

1. Don' try to tell me that DSMTalk tuning advice is better than mine, especially if you're just going to somewhat quote someone else. That's going to cause big messy problems. If you want to compare tuning methods, put me in touch with the person you are talking about, or at least get a direct quote so that there is no misconception.

2. Don't give advice on something you're not familiar with. You were proposing that DSMLink worked like a SAFC in that it altered the airflow signal entering the ECU; this is not true one bit, and as such your tuning methodology with the Link is entirely different than it is with a SAFC.

 

[99redgst]

Thanks for getting in on this kpt4321, it is good to see a wiseman getting involved. As far as the maft it is the latest version. I never even opened it up, I didn't realize that I had to make any adjustments since I'm not tuning with it. What do I need to adjust? This is most likely the problem I would guess as everything in DSM link is set up correctly.

 

[MaineDSM]

It looks like you have your Global fuel adjustment and dead time pretty close to where they should be.

The next step is fine tuning those settings using LTFT. This is described in detail in the DSMLink manual.

However, I suspect your problem has absolutly nothing to do with your injectors or DSMLink. Unplug the MAFT and reinstall the stock MAS, and I bet your problems will end. If that is impossible, then reinstall the stock injectors and zero out DSMLink, and I bet your problems will remain. You need to make sure your not on a fool's mission.

Good luck. It's nice to be able to install a bunch of stuff at once, but it sucks because you don't know what is causing the problems and have to uninstall it again anyway.

 

[Pizzy]

Last time I got into a technical arguement on Talk, I stopped posting there. That's all I have to say on that subject.

The level of "technical" tuning information there makes me sad.



This give us no information whatsoever. What was his method? What was mine? What settings did you end up with?

If you install a set of 550's and then adjust the fuel pressure so that the fuel trims all line up and don't use the SAFC to get them right, then the car will run just like stock. Do you know why? Because your 550's are now flowing the same rate as the stock injectors! Might as well just have left the 450's in there...

The deviation of ECU input airflow to true airflow in order to maintain a stock AFR on a ECU with no injector compensation is dependant ONLY on the injector size difference. The more fuel you are flowing through the injectors, the further off the ture airflow will be. There is NO way around this. If you get the AFR close while also keeping the airflow close, you don't have a lot of injector flow. End of story.

Not to mention, if your car ran like crap with the SAFC and a set of decently sized injectors, you were doing something wrong. I know plenty of people running SAFC/VPC's with 550's and 660's whose cars run well (as well as you could expect for ANY system without injector compensation).



1. Don' try to tell me that DSMTalk tuning advice is better than mine, especially if you're just going to somewhat quote someone else. That's going to cause big messy problems. If you want to compare tuning methods, put me in touch with the person you are talking about, or at least get a direct quote so that there is no misconception.

2. Don't give advice on something you're not familiar with. You were proposing that DSMLink worked like a SAFC in that it altered the airflow signal entering the ECU; this is not true one bit, and as such your tuning methodology with the Link is entirely different than it is with a SAFC.

Oh for the love of god...

Ok, first off I'd be shocked if ANYONE doesn't have a friggin printout of YOUR method. It's all over the internet and can be found in about 5min MAX. And I never said the other method of tuning was any BETTER than yours, I said it worked better FOR ME. If you have a problem with that then I don't know what to tell you...take it up with my car if you'd like, but the fact remains, it worked better FOR ME. And I followed your guide to the letter.

Secondly, I'm more just giving suggestions that might trigger something in his mind. I never said your method was wrong and to be honest I was fairly polite. I'm sorry that my knowledge of DSMLink is shit...I don't have it and have never used it. I actually stated that already. I never PROPOSED that DSMLink and SAFC tuning are alike in that they both alter airflow signals. My exact words were "Now I realize you don't use an AFC, but DSMLink should be fairly similar." Don't put words in my mouth.

And I KNOW that by lowering the fuel pressure with 550s it brought me back to the flow of a 450 injector. When I upgraded the fuel system, I did it with the intent of upgrading the turbo soon thereafter, but that never happened. So I was trying to compensate for the 550s and again, when I used your method, the car ran horribly. I would have put the 450s back in but my friend's garage is an abyss...they will be missed.

HERE: http://www.racingknowledge.org/topic.asp?TOPIC_ID=1011 That's Kyle's SAFC tuning method for those who don't know what it is...not like it matters to 99redgst though I suppose.

AGAIN! NOT KNOCKING YOU OR YOUR SKILL, BUT THE CAR RAN LIKE CRAP.

Regardless, SAFC tuning isn't what he's asking for...I'm not about to post someone else's SAFC method...apparently it's not at all applicable, and anyway I fear that I might get one word wrong and be flamed... ...but 99redgst, if you'd like me to get you in contact with the guy at DSMTalk, maybe it might help or he might find someone else that could help. I'm sure the advice you've received here and from Kyle is very good...sometimes it just helps to hear it from someone else.

Sorry that this thread has turned into Kyle vs. DSMTalk. That's never what I intended. I'm just offerring to put you in touch with more help.

 

[Pizzy]

Actually Kyle, do you have anything aside from the DSMLink manual that might explain DSMLink tuning any better? I've never seen the manual so I don't know how adequate it is or not. I'm sure they do a really good job though.

 

[sjwelna]

You can choose your viewing pleasure in either .pdf or .doc here:

http://www.dsmlink.com/downloads.html

It does a pretty good job of explaining things for the n00b Link user like myself.

-Steve

 

[kpt4321]

Thanks for getting in on this kpt4321, it is good to see a wiseman getting involved. As far as the maft it is the latest version. I never even opened it up, I didn't realize that I had to make any adjustments since I'm not tuning with it. What do I need to adjust? This is most likely the problem I would guess as everything in DSM link is set up correctly.

I guarantee that is the problem. When did you buy the unit?

Pull the cover off and check which version it is. If it is version 2.0+, set the aux knob to 4 and the base knob to 2, and if you have anything but a 3" MAF you also need to set the dip switches properly.

You're likely getting a 1g airflow signal, which is much higher than a 2g.

 

[kpt4321]

Secondly, I'm more just giving suggestions that might trigger something in his mind. I never said your method was wrong and to be honest I was fairly polite. I'm sorry that my knowledge of DSMLink is shit...I don't have it and have never used it. I actually stated that already. I never PROPOSED that DSMLink and SAFC tuning are alike in that they both alter airflow signals. My exact words were "Now I realize you don't use an AFC, but DSMLink should be fairly similar." Don't put words in my mouth.

You said that they should be fairly similar. That's wrong, period. They're way different.

From the site rules:

"No Guesses - if you don't know, don't reply - don't spread misinformation (no "I think" or "I guess" or "I've heard")."

And I KNOW that by lowering the fuel pressure with 550s it brought me back to the flow of a 450 injector. When I upgraded the fuel system, I did it with the intent of upgrading the turbo soon thereafter, but that never happened. So I was trying to compensate for the 550s and again, when I used your method, the car ran horribly. I would have put the 450s back in but my friend's garage is an abyss...they will be missed.

Are you are suggesting that everyone install larger injectors, and then turn the fuel pressure down so that they flow like 450's? Yes, everyone should certainly waste their money on big injectors and then turn them back into 450's with fuel pressure.

 

[Pizzy]

Are you are suggesting that everyone install larger injectors, and then turn the fuel pressure down so that they flow like 450's? Yes, everyone should certainly waste their money on big injectors and then turn them back into 450's with fuel pressure.

I'm suggesting that if you upgrade your injectors and find out later that you don't have the time or money to upgrade the turbo, AND don't have/want to put the stock 450's in, then you COULD turn the pressure down.

Stop being such a pompous ass. If you read you know why I did it.

 

[99redgst]

The maft was one of the last things I needed to get the car running so I got it about two months ago max. Its version 2.01. Its sounds like your sure this is my problem and I don't question your knowledge so I'll try this first. I am running a 3in blowthru setup. As far as putting in the stock maf or injectors, that is pretty much impossable the maft is hardwired and I don't have any of the stock parts. Wouldn't want to go through all the trouble to put it back in to take it back out. I'll try adjusting the maft tonight or tommorrow when I replace the rear main seal. I'll let you know how it works out, thanks for all of your help.

 

[99redgst]

Well I made the adjustments on the maft. I let it idle for about 30 seconds, it idled smoothly at 1000 rpms. I have DSM link set for 750 rpms but the car didn't get to operating temp, I think after it warms up the idle will come down. I need to go pick up some oil, then I'll take it for a drive. Could this explain why it was flooding itself when I hit boost, it would stumble then go. I pulled fuel out and it helped but it still likes to stumble in 1st gear. I guess I'll find out on the test drive. I'll let you know what happened when I get back.

 

[kpt4321]

I'm suggesting that if you upgrade your injectors and find out later that you don't have the time or money to upgrade the turbo, AND don't have/want to put the stock 450's in, then you COULD turn the pressure down.

You are? Then why did you say this:

I was told by a very knowledgeablt guy on DSMTalk to try to supply the ECU with as close to the correct airflow values with an AFC as possible. With larger injectors, move the entire fuel curve down via an adjustable fuel pressure regulator. On the logger the fuel trims should near 0% (100% for the 1g guys) if the fuel curve is adjusted well. After that, fine tune with the AFC as normal.

I don't see anything in there that says "if you upgrade your injectors and find out later that you don't have the time or money to upgrade the turbo, AND don't have/want to put the stock 450's in, follow these directions."

You were using it as a general tuning principle, and then when I proved it incorrect (and I probably know who came up with that shit ass idea, due to the totally craptastic ideas behind it) you acted like you said something you didn't.

Seriously man, it's not your fault! It's captain stupid on DSMTalk's fault for posting it without any technical basis, to people who aren't at the level to see why it might not work. Don't worry about it anymore.

It'll definately work if you just want to dial your big injectors back down to 450's if you don't need the added flow. However, it does NOT work as a general tuning idea.

 

[99redgst]

All right, just got back from an hour long test drive. The car idles much better although not completly consistant(900-1100rpm) it doesn't stall when coming to a stop, good enough for me. As far as part throttle, it is way smoother. Before it would jerk and hesitate, now it as smooth as can be. As far as WOT it used to be smooth and strong, now it has the kind of hesitation it did at part throttle. I zeroed out all of my settings on DSM link and started over. I am usally seeing 5 degrees of knock at some point during the pull and my timing peaks at a whopping 10 degrees. Why is my timing so low? It also seems to stay at a 10:1 fuel ratio even after pulling about 10% fuel from 4k-up. The ratio never really changed much from zero to 10%. Is it that small of a change and I need to pull more? Also in a third gear pull by the time I hit 6k the EGTs are going over 900c so I shut it down, I'm yet to make it to redline with out the EGTs climing higher than I feel comfortable with. I am no newbie to DSMs however I am a newbie to the tunning thing, any help would be greartly appriciated. I would like the advice from someone running or familier with it and no "I guess" or "it should" Thanks alot guys.

 

[Chargedawd]

You are knocking for a reason, this is retarding your timing and also makes your egt's go through the roof. You should check your knock sensor to make sure it is functioning properly. If you are knocking a 5 knock sum you are losing 10 degree's of timing.

If your fuel and timing is at all 0's you should not be knocking unless your running like 27 psi

What kind of CAS are you using and where is your base timing set at?