Who needs help with LNF's

[Tom Waldner]

the dal table is in kpa right? what I don't understand is why, on tuned cobalts do people put it to like 350 at 100% throttle? that like 50 psi. that's what I'm confused about.

[MikeM173]

I actually tune all of my cars in KPA, and do not convert them to PSI in all honesty. Keep in mind you need to subtract barometric pressure from the equation as well, which means 350 in a log, would really be roughly 250 kpa. I'll explain more on my write-up.

[MikeM173]

I'll try to do the write-up tomorrow. I went to start it, and realized that it will take me a long time to screen shot, and discuss a ton of stuff with it, and I have to be up early, so I am opting to take tonight off from this write-up. Post any other specific questions you have, and I will give some answers if need be, or I will include it in my write-up.

[cobaltssoverbooster]

the dal table is in kpa right? what I don't understand is why, on tuned cobalts do people put it to like 350 at 100% throttle? that like 50 psi. that's what I'm confused about.

because they dont understand what the table does

[gmtech16450yz]

Thought I'd pass this along guys...

DI has some very different aspects when it comes to tuning. I've been telling the Gen 5 guys that if they want to learn more about tuning the Direct Injected V/8's, read through some of the old threads in the 4cyl/ LNF sections. LNF's had DI, a turbo, factory wideband AND variable intake and exhaust cam timing. They used the Bosch E69 ECM that was pretty advanced in what it was capable of. There was A LOT of learning going on there, and amazingly enough, it looks like a few smart guys are continuing to pass along vital information to anyone on here that wants it. (Something that makes me HELLA PROUD to have been a part of BTW.) Discoveries made on the LNF years ago definitely carry over to the Gen 5 V/8's.

I posted that reply in another thread here. You guys DO make me proud! I can't believe you guys are still striving to "learn and share" as much as you are. It's pretty freakin cool and like I said, it makes me proud to have been a tiny little part of the LNF thing. GOOD JOB GUYS!!! Keep up the good work!

[GHuggins]

I've got one right now that I'm going in behind another tuner on and something I've noticed that I've personally been having problems with is that the idle timing is extremely low. It will cold start idling at -8 and hot idle at 3 to 5 degrees. I've tried changing the DAL in the lower torque and rpm areas by raising it very slightly - was this the wrong way? Haven't had a chance yet to try lowering it. I've been able to fix some of the fueling problems and dips in the power band, but I'm not 100% on the idle on this thing... This is the first lnf I've tuned. It's a 10ss - appears to have turbo, blow off valve, straight pipe, 4 inch intercooler and maf on inlet side of turbo (not sure if it was originally blow through before tb as it appears to have an extension hooked up and maf hole plugged before tb?)

Thank You for any input or insight into this...

[MikeM173]

GHuggins

http://www.hptuners.com/forum/showth...55951-LNF-Idle

I already did a write-up for Idle.

[powermizer]

Mike thanks for your help as usual. I would like to understand injector constant. I would like to start tuning for e47. I only understand that starting with raising injector constant about 30%. I would really like to understand what injector constant does. I would guess it raises injector millisecond per cycle? Thanks for any info. Injector stuff really slows me down! Lol

[MikeM173]

After people read your question, you will get some generic answers. I think this is a great question that has multiple answers.

I will do a write-up on my preferred method for tuning fuel, and if it isn't too long, I may add in some info on 5th injector tuning. We will see. It may need to be a separate write-up.

[powermizer]

After people read your question, you will get some generic answers. I think this is a great question that has multiple answers.

I will do a write-up on my preferred method for tuning fuel, and if it isn't too long, I may add in some info on 5th injector tuning. We will see. It may need to be a separate write-up.

You must be reading my mind! Lol I am in the process of building a engine right now. I have a fifth injector bung already welded in. I will obviously be starting from scratch on learning what needs to be done for running the fifth injector. Thanks Mike

[MikeM173]

Size of injector is VERY important for the setup you have. I will just do a separate write-up for running them.

[powermizer]

Ya I fought the injector size in my head for a month. I figured I needed the smallest one I could get by with. Just trying to figure that out is painful. Lol Thanks Mike

[GHuggins]

Mike do you mind taking a look at this? If you do mind, just let me know... I've just out of the blue starting having problems with this thing pulling timing for one, but also dropping up to 1700psi of fuel pressure at the same time. I've got a HPFP on it's way, since before even starting to tune this thing I could smell fuel in the engine oil - changed oil and informed customer who originally wanted to wait. I got the idle timing back up in the teens by taking away from the air load. I also went ahead and replaced the air fuel sensor and installed new plugs gapped to .030". Basically right at 3000 rpms now it actually loses engine speed - drops 200rpms then gains back slowly, sometimes loses boost and sometimes pulls considerable timing. I unfortunately lost my logs, but I've got the tunes. I tried adjusting the op spark tables as you describe, but wound up with hitting really negative ignition timing before I ever hit the rev limiter and the throttle became overly sensitive, so I put those back close to stock - this was before problem showed up... If I'm doing something really wrong, just let me have it I'll post a stock tune from the repository, the tune the car showed up with and current... Been fighting lean out problems since the beginning when turbo is first spooling up - was going into the 16's air fuel when first arrived with it's original tune - got it into the 14's now (was apparently tuned twice prior - on road and on dyno?)... I've been able to make some decent gains down low, got rid of a lot of weird hp and tq dips and been able to make the hp and tq graphs much more linear - it's putting down 318hp and 418tq right now to the tire or at least it was - not sure how far I want to push things...

AND like I said it was just like you flipped a switch, one pull OK - next motor dieing out.... Did the same thing with original tune back in it... Hoping I'll have it back on the dyno with a new pump by the end of the day? Compression checked out withen specs - 158,150,150,142 - still not where I would like to see it, but in specs and definitely not the worst I've seen on these motors with them running OK...

Thanks for any and all input on this.

[MikeM173]

Unfortunately today I am swamped. I can for sure look at it tomorrow, and I'll even try to look at it in the morning so you don't have to wait any longer. A log is ideal, but I'll see what I can come up with.

If you had negative timing in spots, you probably didn't have enough timing in your Spark Tables. This is just a guess without looking at anything and basing it off of what you said, but that is honestly most likely it.

[Tom Waldner]

Do u have to change anything in tune for 4.05 trans? Cause my cruise control is acting weird now

[codename Bil Doe]

Because of something personal that happened I've sold my coupe and my Solstice racecar is up for sale. Endurance racing now.

Because so many LNF questions have already been answered with other threads, I suggest posting links to other threads to answer people's questions when possible.

Because I don't need to keep it a secret any more I will be posting my tune and explaining the differences between what I do versus others and why.

I won't likely be on here much for answers, though I will try.

As for throttle hang, there are two causes. The first cause of throttle when on THROTTLE LIFT is in the integral gain table:

http://www.hptuners.com/forum/showth...LNF-PID-Tables


The integral gain controls how long the tb stays open. Stock settings cause it to hang open after lifting. You can adjust it tightly enough that the tb closes 1:1 with the pedal. Too high the tb will flutter fighting to close when wot. See thread.

The second cause of throttle hang is your OS table in the LOW LOAD/HIGH RPM area. Values too high there will cause throttle hang when shifting or in neutral.

My race tunes run very high OS values. My entire table is 25. A single value provides for linear pedal response regardless of rpm. A high value gives me instant throttle response everywhere. Very important to remove all lag for racing. But, if you try revving the engine in idle it will cause throttle hang. You shouldn't do that in the first place. I DD this race tune, so it's no issue unless you clutch in and idle at high rpm or rev the engine.

[Scott07GZP]

MikeM and Codename Bill, First of all, I can't say enough how much I've learned and benefited from your contribution to the LNF forum. I am a relative nube and just started tuning last fall on a LNF Solstice with large turbo. I have made... what i think... is great progress by reading your post and trying things as I learn... I not someone that post a lot, but I feel I have to ask something before we all loose your expertise....... BTW I hope your next project is as enjoyable as LNF hot rodding has been!!!

That said, I have not seen much on Lambda Efficiency. The description says it is used by the ECM torque efficiency calculation based on Lambda. So I have been experimenting with using this to improve engine response. When I lowered the value (ie told it to assume a lower efficiency for a given lambda - see below) the engine got more lively. I also had to re tune the WG table because my boost went way up.. from 25 psi to 30 psi.... Luckily I corrected this before doing any damage to the internals. I haven't gone back and experimented a lot with this and am a little worried before i do because of the effect. So I'd like to know if you have looked at this before and could shed some light on how this works. Again, thanks again for all of your input to this forum.

Labels 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20Efficiency 92.001 92.001 92.001 92.001 92.001 92.001 92.001 92.001 85.089 75.815

[MikeM173]

Sorry to all, I have been extremely busy, and have not had time to post. I know I still owe some write-ups for everyone.

Scott,

I will be 100% honest here. That table,and a couple other tables, I have not personally even tried to mess with. I never found the need to attempt anything with it. I moved onto groups of tables and tested them thoroughly to see what each did. If I was still in the game I would go test it out for you in every way possible, but unfortunately I do not even own an LNF anymore. Hopefully one of the other guys on the forum can help answer your question on this. Sorry.

[codename Bil Doe]

I played with lambda efficiency and had a couple runaway throttle scenarios on startup. I leave it completely stock because it is used for calcs over which we have no control.

You really have no need to touch the lambda efficiency table. All responsiveness is in the PID tables (specifically prop gain) and the OS table.

Modifying the prop gain table can max out the spooling of the stock KO4 at .458sec from 0-20psi. This is uncontrollable and not good for anything but drags. I keep 0-20psi spool to around .7-.8sec for road racing.

The biggest controller of responsiveness is the OS table. Read up on how to mod the OS and PID tables.

As a ref, don't go above 25 for OS. I've tested it up to 50. I run my entire OS table at 25 for racing for the quickest throttl response. I also used this on my DD. It will cause some throttle hang if you rev it in neutral. Don't rev it in neutral. The transition point is 22-23% pedal. We don't have access to any table that controls this. You just have to develop a feel for it or tune your OS down with a linear slope below 100-120% load. Play with it to get the feel you like.

This is NOT the reason people get throttle hang in gear when lifting at high rpm and the engine keeps the tb open. That's caused by the integral gain table.

[califcarm]

Two questions:
1st question: I would like to increase the response time of the turbo a little under fast transient situations (ie: just after shift and getting back on the throttle). I have read this:http://www.hptuners.com/forum/showth...+gain+prop+max, but still am not sure if I should be adjusting the prop gain, or prop max to help achieve this. Prop gain is a gain number like I am used to AC drives for electric motors, and prop max is a percentage number up to 327%. Not sure how to relate these two, or to try to increase boost response as I mention by adjusting them properly? I would assume higher gain numbers in the prop gain table, especially as I am at a small delta psi (at the risk of overshoot), but not sure on this.

2nd question: Under Torque management-> general, there is Tip-in limiting. Load Damping can be enable or disable (which then has charts if it is enabled). I have seen at least 3 tunes by "tuners" where it is disabled. What does this feature do and what benefit is there to enabling or disabling, or enabling and modifying the tables?

TIA

edit: I am completely stock and on a stock clutch, so I want to error towards "softening" the hit as to not overpower the stock clutch, but increase responsiveness where possible.