Speed density questions..misfire and low /high octane table

[Chris@HPTuners]

sorry i deleted my post, i didn't realize this was LS1

After checking the LS1 code (previously i had only checked the later code).

Here's everything that disables the misfire test:
RPM thresholds
ECT thresholds
IGNV thresholds
Throttle faults
IAT fault
MAF fault
MAP fault
VSS fault
ECT fault
Cam Sensor fault
Crank Sensor Fault
If Misfires are detected while the TCC is locked (and susequently unlocked)
If crank position is not learned
very cold startup
PTO is engaged

The list is very similar to the later vehicles, they just have more requirements!

Chris...

[ALB]

Ok so it dont work since you fail maf. So one more time.I have to do a write entire to put a 1bar non sd maf tune back in and then write entire to put the 3 bar sd back in if want to check misfire normally at any speed not just idle?

Has anyone drove car with maf not disabled by accident with the 2 or 3 bar map in there and what effects did it have ? Afr at wot especially?

[Frost]

Even if they were enabled, they are often times completely unreliable. The mix of cam and converter will have you increasing the factory tables quite a bit until they quit showing up. At that point, can you rely on that system? Using your ear in conjunction with the narrowbands works though, if the vehicle's physical setup supports it. I saw misfires in a race car that was full time OL when using a wideband on each bank as well in the past. Honestly, I have never seen it viewed as a problem before, though I don't remember ever putting put trust in it on anything other than a stock cammed and stalled car.

It's like a 3 minute thing to test. Make an OL file and set the OLFA to 1.047 everywhere over 140ish. Get the car fully warm with it's current CL file. Load the OL file. Log misfire by cylinder. Get someone to unhook a bank 1 injector. Have them return it and unhook a bank 2 injector. The NBs will certainly show them. Review the log, see if you see them, and flash your CL file back.

Chris,
Is this just disabling the DTC or does it do the counts/cyl also? That's that part I always use IF I actually look at it.

[slow67]

X2, i KNOW I have seen misfires is SD, I havent had a MAF in 2 years and I swapped to a 4L80e this Feb. and misfires stopped my converter from locking up.

[ALB]

I was more talking looking at each cylinder on the scanner to pinpoint bad cylinder.
My cam is very mellow and don't throw much if any misfires when they are working.
I guess was just spoiled with it in the past. Its not the end of the world as you said you have other indicators and that built in power balance test might find really bad ones although it didn't help me find my misfire problem at wot under load from several burnt thru plugs.

[Chris@HPTuners]

it disables everything

You can run most of the later (2000+) LS1 enhanced OS's like 3bar SD with the MAF, just that you aren't in SD mode anymore. Keep in mind the PCM is measuring the crank position after the cylinder firing angle to determine misfires, basically any mods that change the "smoothness" of the engine will require recalibration of the misfire delay threshold tables to be truly accurate otherwise you'll see false detection.

[ALB]

Hm so could run the car to test things at high speed with newer 0S no scary effects on afr at wot?? That would be handy sometimes.

So maybe one reason to use a newer OS on my 99 since curent OS is not compatible anyway with 4l80 blending.

[Chris@HPTuners]

you'll be running on the MAF at high speeds, if it pegs you will lean out.

[LSX378]

Huh you are the owner of hptuners .I would think you would have definitive answer for us.

Came across this post searching for something else. ROFL! It is 12 mths plus old but I still got a laugh.

GM designs and manufactures your controller. Where is their support forum? People forget that HPT gives us a view into a GM controller and enables changes to it. The dont make the PCM or "sell" it to users and make a big $ margin.

Kudos to Chris for taking the time to run through a stack of code and come up with the answers in another post. Thats a bonus IMHO.

At the end of the day misfire is an EPA based requirement for emissions controls to prevent the cats from suffering an early death. As Chris points out if anything is changed misfire needs retuning. Even the same motor in a Vette and a G8 have different misfire specs.

Yes pros do guard their "secrets". They make their living out of tuning, work long and hard and spend money to gain expertise and I dont know why any reasonable person would expect them to give away their livelyhood for free.

Sorry its a dredge but I couldnt resist.

[ALB]

Not on here much . Car is down for winter with a engine problem.
gm makes the ecu. They don't want you to tune your car so of course they don't offer any support for tuning it. Hptuners is a pretty good tuning program. And yes understand pro tuners want to guard their secrets. Now if they all guard the secrets what is the point of buying hptuners then for non pro tuners?
I have learned to tune and mostly its not rocket science at least the basic stuff. But yes pros help when you want the last bit of gas mileage,when you want to tame a wild cam down, they can help when you go get dyno tuning. I live in a pretty big city nearest chassis dyno is few hundred miles away. Most pro tuners are 500 miles away.
So we have to be a bit independent in my city. And not everyone can run back and forth to pro tuner every time they make changes in their car.

I also tune my own talons. I put in 1150 injectors in the talon this summer. Thats 115 pounders. I went on the talon board, took about 5 minutes to get the right numbers and the car ran perfect.

I had 60s in my 99Twin turbo. I bought Gregs dvd to get the 60s to work perfect and they did with his numbers. But needed 80s. Put in 80s and Gregs numbers don't work for 80s. Big huge off idle surging, not great idle. I surged and asked for help and mostly heard that 80s are not easy to tune or even tuneable. I pretty much found my own solution but did get some help from some pro tuners as well mostly on the other boards.

I like hptuners overall just saying that if you are not a pro tuner you may be on your own and the board really don't answer your questions a lot of the time. The talon tuning programs are not pro tuner but user oriented so that is a pretty major difference.

I paid money for my hptuners so I could tune my own cars. So just figure since the board is here it should help me do that. Pro tuners can have their own board.

Anyway after few years of reading posts and playing around would consider myself semi pro..pun intended.

So understand what you are saying and hope you understand what I am trying to say.

[ALB]

Oh and got a workaround on the misfire thing. I put maf back on and can run it with the version of speed density 2002 or whatever to test things out. I have had big misfire problems in the past and it was very handy to pinpoint which cylinder was the culprit.
I don't think my old 99 speed density version would let me do that.

[LSX378]

Yah I'm with ya no problemo ! Though sometimes I get the impression there are less pros here than one might imagine or hope for. Though there are some pretty generous people who know what they are doing and or collaborate until they find the answers.

[Physics]

Ok its one thing to not want to post your tuning secrets, and I wouldn't expect any volunteers here to answer such questions if they don't want to. But this type of question about misfires on the OS is a functional question of the program that is being used. That has nothing to do with tuning and it is the type of question I would expect answered from technical support. Laugh all you want but to think that doesn't deserve a definitive answer? You're insane.

[LSX378]

".....program.." ?

[Physics]

Yes program, it is a software program used to adjust parameters in a vehicle. If it isn't a program then what is it?

[LSX378]

Yes program, it is a software program used to adjust parameters in a vehicle. If it isn't a program then what is it?

Well there is the HPT software program and there is the GM program in the ECM. Clarified!

HPT does give access to misfire parameters so they can be tuned or turned off if required but never have seen any claims made that misfire operation is a function of HPT software.

Personally IMHO its a bonus that Chris @ HPT has dug deep enough into the code to understand it and or GM doc and can advise on some aspects of misfire.

[sheikss]

I have to agree with the op on the not getting answers. I thought forums were here for help and support. I fully understand that some people do this for a living. Coming on here and not helping seems counter productive to me. Just my opinion on the subject.

[LSX378]

Coming on here and not helping seems counter productive to me. Just my opinion on the subject.

Good point!

[Frost]

....
I like hptuners overall just saying that if you are not a pro tuner you may be on your own and the board really don't answer your questions a lot of the time. ....

Being a professional doesn't make me privy to anything that you don't get though. I still have had to figure most all of it out on my own by doing it. But as you pointed out by comparing it to your Talon and it's board, most people here want to be spoon fed. They don't want to actually learn to tune the car, they just want some magical drop in numbers that do the work for them (even when they don't exist or would be unique to their setup). That's actually not even really directed at you, it's more the user base on a whole here. Guys buy this because they can't or don't want to spend the money on pro tuning but they don't respect the learning curve or the process of experimentation. Getting the software IS the easy part, then you have to learn how to use it for your application.

[keith42]

I have a question regarding misfires and the O2's spiking downward. Is it considered normal for a cammed car 224/230 581/581 to have some misfires? Or is it a ignition issue?

My car see's a few of those types of events and I haven't worried about it but I want to verify that it's normal.