Scaled MAF 25%--Still Lean

[JerryH]

Careful to not start mixing and matching answers here... there are now 2 people with different situations and possibly different issues.

In the future, it is a good idea to start a different thread to discuss an issue.

[coachcrow56]

Yes---I started this thread, but I don't mind if someone else has the same problem. Spent all morning looking for vacuum leaks--exhaust leaks--found nothing. Did my first VE tune---LTFT's started out way rich -14 to -19. Worked on it all day and got LTFT's to 0, -1, -2. Car started out running like crap, TCC would not lock, etc. Got it to run smooth. Hooked up MAF, and yes it runs like crap. LTFT's at idle are +16.4 and just as bad everywhere else. I know its not the MAF sensor because I swapped MAF's from my son's 2002 TA----nothing changed. Going to start MAF tune tonight---MAF from ZZP for this Northstar is way off.

[coachcrow56]

Here is a short scan from this afternoon---this is after I hooked up MAF.

1-19-08

http://www.scandepot.net/viewscan.php?pk=4711

[GTPNoga]

Thanks guys for the answers. And sorry for the hijack. I just wanted to make it known the ZZP Maf file is not correct.

[devildog9999]

PM Sent.

[98gtp]

Here is a short scan from this afternoon---this is after I hooked up MAF.

1-19-08

http://www.scandepot.net/viewscan.php?pk=4711

do you have it in .hpl format?

[coachcrow56]

Here it is in .hpl

[Russ K]

You do realize that your Maf table is lower than stock up to 6250 HZ? Unless you posted a different tune than what was flashed for the scan log.
Plus your IFR table is 1.5% too high, and your Skew vs. cyl is another 3% leaner than stock except for #3 & #4 cylinders.

Russ Kemp

[JerryH]

You do realize that your Maf table is lower than stock...

Plus your IFR table is 1.5% too high, and your Skew vs. cyl is another 3% leaner than stock except for #3 & #4 cylinders.

In practice, any MAF file that permits the car to start and run enough to do a scan is ok, becuase it will be modified during the several MAF tunes needed to make any base MAF file work well with his car/mods/conditions. A closer start is preferable, of course, but not mandatory.

There are 2 comments that let me think that at some point the file was modified by a PT user or someone who used PT tuning methodologies. The IFR and cylinder skews.

There they take the stock IFR and scale it down to 87.4% instead of multiplying it by 1.18055. The results are close... but a touch richer than if this exercise is done in the HPT. I've tested and seen this. Just another minor difference that in this case adds to the issue.

The cylinder skewing... popular belief in the PT world used to be that the center cylinders run hotter/leaner becuase they are flanked by hot cylinders on either side of them. Increasing fueling to those cylinders by 1-3% decreases chances of KR popping up or chunking a piston. In the tune, one would increase the IFR by a set percentage and then lower the cylinder skew in the outside pistons. This in effect raises the center cylinder fueling and still lets the PCM meter fueling properly.

In real life, the ONLY way to know if skewing is good for you or not is if you check the colour of your spark plugs. I went through this exercise and found that my center plugs were running richer than the outside ones. By using a 0% skew across all cylinders, all my plugs were the same colour, a nice light brown. This is not to say that it will be the same on anyone else's car... it means each owner needs to look for themselves and see what is best for their conditions.

If this was my car, I would not have any reservations starting over from a 100% stock calibration file with the only exceptions being changes to accomodate my larger injectors and different MAF. I've done this MANY times in the past just as an exercise. Results always seem to be better when someone starts out with a stock file and goes through each table and carefully takes the time to modify the tune based on scan results.

My coming new Tuning Notebook (that is HPT specific) covers this in pretty good detail with the exception that we look at modifying all tables that try to control speed limiters and the very wrong attitude of using leaning out an engine as a limiter or torque management instead of spark cut-offs (which is WAY MORE engine friendly!).

[coachcrow56]

Russ K---The bin file that I posted on 1-16-08 had the MAF table that ZZP sent to me----I had not touched it at that point. For my IFR table--I took the stock IFR table and multiplied by 1.18----should have used 1.18055. Injector skewing I borrowed from a DHP 1.0 bin. I think I will take JerryH's advice and start back with a stock bin and work from there.

[JerryH]

As always, be 100% sure that mechanical hardware is good before starting to tune (no exhaust leaks and all basic maintenance is done).

I am glad you are starting over from a known good file. Your base file should start off with the following:

- table modification for 42.5# injectors

- LQ4 MAF table

- settings to support a 180 T-stat

- You want to go through the bin and remove all references to torque management where it disables injectors and where it leans the engine out as a form of TM.

- You want to zero out the Spark vs AFR table for a start, add later when you are in the timing tune phase

- you want to import a 2005 GTP spark tables for a start

- You want to set the spark to 0 degrees advance at 6000 RPM while you are tuning and once you are comfortable, raise that limiter slowly up to 6100-6200, but not above 6200. Though the cam may be able to handle a little more, even factory bearings have a limitations we don't want to push.

If you have issues finding the 05 GTP spark table files, let me know and I'll post them here.

[coachcrow56]

I downloaded a 2005 GTP bin file from the repository, but I can't open it. Trying to get the Spark Tables as you advised.

And pardon my lack of knowledge on tuning, but how do you tune for a 180 thermostat??--I am running a 195 right now so the heater works better---switch to 180 in spring.

[JerryH]

If you are running a 195 now, leave the 180 till springtime. I'll pass you that info when you need it.

As for the spark tables, they're attached to this post:

[coachcrow56]

There are some big differences in those tables over the 2000 GTP tables. Do you run those tables in your 99? Is that one of the reasons you get such great mileage? Just curious. Thanks for the help.

[JerryH]

My MPG increases are becuase I've done years of tuning specific to that, and spark is just one part of the puzzle. Your MPG will increase a little... but these tables (believe it or not) are just a good startng point.

Do not forget to zero out your AFR SPARK table when using these tables. Most stock tunes cannot accomodate a +4 degree increase at WOT without tuning for it.

[coachcrow56]

(Do not forget to zero out your AFR SPARK table when using these tables.)

JerryH--you lost me on this one---do you mean IAT Spark or ECT Spark??

[BlackGS]

(Do not forget to zero out your AFR SPARK table when using these tables.)

JerryH--you lost me on this one---do you mean IAT Spark or ECT Spark??

The table is AFR Correction. It is a new table added to version 2.2. The table was designed to add timing during decel, but also adds timing during WOT, which gets confusing if you are trying to set timing in the High Octane table.

[JerryH]

Right.

Spark Control > Spark Advance > Spark Correction > AFR Correction

Thats the table commonly known as AFR Spark. Meaning that when your car hits a richer AFR, add 3 or more degrees of spark. Dumb table if you ask me. This table is the cause of a lot of flask KR in many cars. Zero it out. The 05 GTP tables add as much as 4 degrees over the 99 tables... thats why I say to zero this one out.

[coachcrow56]

http://www.scandepot.net/viewscan.php?pk=4727

I have done several VE and MAF tunes--used lots of JerryH's recommendations---did first run to 100 today----it didn't blow!!! Need more recommendations from you guys--will try to post my bin file too.

[coachcrow56]

Here is my current bin file---please recommend any changes you feel are necessary.