1999 LQ4 - Suggestions

[Cougar281]

My friend is buying a 99 Silverado with the LQ4 6.0L. Does anyone have any suggestions what we can do with it, tune wise, to improve mileage and maybe some responsiveness? Not looking for anything crazy (and I know tuning alone can't really net a ton in a gasser). I know a little about tuning diesels, but I know zip about gas motors.

We haven't gone to pick it up yet, but does anyone know what PCM is in it? Is it the 0411 or something else?

[ScarabEpic22]

If you want to learn a little bit, get a wideband installed in it, upgrade the to the 02 operating system then upgrade to COS. Setup lean cruise and lean it out under cruise conditions. Have to setup AutoVE before then get some logs on the hwy at light load to lean those cells out.

Its a regular 99-03 512kb LS1 PCM. (Same thing as the 0411 from what Ive heard, might be a different service number but you can run the same OS)

[1FastBrick]

The service number in the 99 and 00 silverado should be 9354896.... The 12200411 was released in the 01 models in the silverados....

[Cougar281]

This may be a dumb question, but if we did want a little more "oomph" out of it, could I just load up a 2002 GMC Sierra Denali's cal? The pickups are rated at 300/360, the Sierra Denali is rated at 325/370, both with the LQ4.

[GAMEOVER]

Post up the tune and we'll help you modify it...:D

[Cougar281]

Thanks GameOver; I've got the VIN, so I'll see if my Tech2 will flash it's calibration to my 0411 PCM (was out of a 2001 4.3L Blazer); If it will, I'll get it up tonight. If it won't, it probably won't be until next weekend (We're planning on picking it up on the 5th).

[Cougar281]

Well, the 0411 PCM took it, but my Tech2 erased the serial number and whacked the Seed & Key (set the seed to $FFFF). :rolleyes: Is there any way to fix the seed & key?

Attached SHOULD be the stock tune.

[Sid447]

My friend is buying a 99 Silverado with the LQ4 6.0L. Does anyone have any suggestions what we can do with it, tune wise, to improve mileage and maybe some responsiveness? Not looking for anything crazy (and I know tuning alone can't really net a ton in a gasser). I know a little about tuning diesels, but I know zip about gas motors.
We haven't gone to pick it up yet, but does anyone know what PCM is in it? Is it the 0411 or something else?

Does it have the iron or alloy heads?

[Cougar281]

Does it have the iron or alloy heads?

Pretty sure Iron heads.

[Sid447]

Pretty sure Iron heads.

Well worth it if you can get the alloy heads!

[Cougar281]

Just out of curiosity, why are those castings in the "Stay away" category? I don't think we'll do any kind of headswap on it; Any tuning we may or may not do on it will likely be relatively short term, as our "tentative" plan is to swap a Duramax into it at some point. Not sure which cone yet, but I'm hoping to find a good LBZ doaner truck to convert the whole truck over to newer stuff.

[Sid447]

"Stay away,"

......Is aimed at the people who want to get the best out of them.

Easy thing for you to do as a suggestion, is flash in a later LQ4/LQ9 stock tune file from holdencrazy.com (stock tunes) I would think. :)

[Cougar281]

"Stay away,"

......Is aimed at the people who want to get the best out of them.

Easy thing for you to do as a suggestion, is flash in a later LQ4/LQ9 stock tune file from holdencrazy.com (stock tunes) I would think. :)

That had gone through my mind, as well as copying tables from a Sierra Denali's tune to get the 325/370 that it puts out. Wouldn't an LQ9 tune not work too well as it has flat top pistons, thus higher compression?

[Sid447]

That had gone through my mind, as well as copying tables from a Sierra Denali's tune to get the 325/370 that it puts out. Wouldn't an LQ9 tune not work too well as it has flat top pistons, thus higher compression?

As long as you use a pre '04 tune for the IFR reference table and the rest from a LQ9 file, I don't see why it won't work. It even has the same Maf Sensor Calibration as yours. The later VE tables look a lot better than the early ones too.

The ignition timing table actually moderated somewhat from around 2002 and stayed un-changed for quite a few years. So it must be pretty bullet- proof.

Have a look at some of the tune files offered on Holdencrazy.com
(Just remember to use a pre-2004 set of Injector Tables).

[Cougar281]

What are the benefits of the 2002 OS over the 99 OS, and would I be able to use my Tech2 and TIS to flash in a cal from a similar 2002 vehicle?

[joecar]

My understanding is the 2002 OS has some "corrections" in it, but I'm not sure what exactly...

Also, the 2002 OS allows you easily jump to COS5 if required.

[Cougar281]

I've been doing some reading, and I see posts where people say to copy all the tables from teh 99 OS into the 2002 OS... Why is this if you're going from a 99 LQ4 OS to a 2002 LQ4 OS (for example)? As long as you're using a new OS from the same "model" motor, shouldn't the new tables work just fine, if not better?

[joecar]

If the same model motor has the same calibration values then it should copying tables is not required.

In the day, the typical 2002 F-car file upgrades were:
1999/2000 F-car file: required copying of some tables.
2001 F-car file: did not require copying.

[Steve Bryant]

I have a 2000 Yukon XL (K2500 4X4) and the 1999 and 2000 trucks had cast iron heads. I've ported mine, but the 317 and 035 aluminum heads are better flowing in stock form versus the cast iron originals. Essentially, the 317 and 035 aluminum heads are the 243 LS6 heads with 72 cc combustion chambers. One big difference in between the 1999/2000 trucks versus 2001 and after is the cam. The cast iron head LQ4s had a reverse split 191/190 cam like the 4.8 and 5.3 L engines. The aluminum head LQ4/LQ9 had a 196/207 cam like the F body cars. All can be improved with a good tune. These trucks did not have power enrichment enabled. I think conservatively, you could get 20 to 25 more HP with a good tune and no other change. I've run a 212/218 cam that I recently had reground (too much intake duration, torque band too high for a heavy truck) to a 206/212 with a 112 ICL that I'm going to install in my stroker engine that I'm finally ready to finish.

I do recommend doing a full flash to a 2001 or later OS. I'm currently running OS 12208322 because I could download it from http://www.holdencrazy.com/EFILive/stockTunes.php. I uploaded my 2000 stock tune a few years ago and it is on the same web page, but you really want to get away from the back up VE table. BTW, I was running COS 3 for about three years, but I think that running full closed loop is better for a daily driver that is operated in a place like Wichita where we have 10 degrees F in the winter and 110 F in the summer and I go from 800 feet above sea level to the Rockies at 10,000 feet MSL.

On another point, how could I find out what OS is in like a 2002 K2500 Suburban or Yukon XL and how could I get a .tun file to use as a starting point. I'm reworking my tune now, but I'd just as soon have the latest and greatest version for a 512 k PCM. I've looked on used car lots for a couple of years now, to no avail.

Cougar281, I'll be glad to help you in any way that I can.

All my best,

Steve

[Hyper99]

Yeah, I played around with the 02 OS I bit and what I can remember was that it was not a cut and paste deal across the whole tune. You have to go thru the whole tune completely. There were a couple of tables that the values were inverted from the 99 to the 02. (might just have been my stock OS )

I spent most of my time working with the stock OS and tune just modifying it as I go based on the mods that I've done. It really seems to breathe well with the cam and the blower now. Adding the cam seemed to piss off the computer in regards to KR.....I had to turn the sensitivity of the knock sensors way down....I have read that the 02 OS did a better job of controlling this....One other reason to update if this is actually fact....

I am pretty happy with the tune in OL, but have been playing around with the MAF to get good drivability to pull my trailer in CL (and to pass emmisions) The 02 tune does not have the backup VE and two spark tables, less work when setting up the autove tune for SD. I'm considering going back thru the tune again and starting with the 02 OS because I eventually wanted to go to COS5 for the blower, but I was not really done messing around with the MAF yet to see if I can get the fueling table and the trims to agree....

The truck seemed to really benefit from some trans tuning as well.....it was a bit lazy stock IMHO- pulling up the shift points, among other things, made for stronger shifts and felt better based on the seat of the pants dyno.....Joecar put together some really good info on trans tuning....Very helpful...:rockon:

Just my .02 - let me know if I can help.:grin:

[Cougar281]

We got the truck all back together (had an oil pressure issue that turned out to be a bad O-ring on the oil pickup) and I flashed in a 2002 LQ4 OS from holdencrazy. Changed the Vehicle platform options to remove the "F" terminal and disabled the associated DTC's, as well as fix the tire size (was calibrated for stock 245's but has 285's) and the truck is running like a champ. Seems to run better than with the original tune. Now I just need to look into safely adding some power... I don't want to blow his motor up :).

[Steve Bryant]

I'm glad that you've got the truck running again and all seems well. Do you have a wide band oxygen sensor that will interface with EFILive? I have some suggestions on setting up your tune that I'll be glad to share with you.

Steve

[GAMEOVER]

Post up the current tune Cougar....

[Cougar281]

Post up the current tune Cougar....

Here are the original (Jon Stock.tun) and current (2002 Chev......)

And no, I don't have a WBO2 :frown:. I do need to get one for my car eventually so MAYBE I can learn how to tune it...

Not looking to do anything crazy with it. Primatily some "refinement". The end goal is to drop a Duramax/Allison in the truck, but until then...

[Steve Bryant]

Since you don't have a WB, you could work some on your VE Table and try to verify the accuracy of the MAF at Stoic, but I don't think that it's worth your time right now. After all, your running the stock cam and heads and in closed loop most of the time, so I wouldn't worry about tweaking the VE & MAF. What I would do is set the PE Time Delay from 60 seconds to 0 seconds. Then, I'd set up the Power Modifier Based on RPM {B3618} to an EQ of about 1.14 (theoretically a little less than 13.0:1 AFR), but you can't check it without a wideband. Right now, it's set up for pig rich in the upper RPM range.

Then I'd bump up the high octane spark table about 3 degrees across the board and see what happens regarding knock retard. One important point on timing is to not over do it and verify under towing loads (light, medium and heavy throttle). When the truck isn't towing, you can zip right through an RPM range that you might get a lot of KR when towing a heavy load. This is a big difference from a car or a truck that's never used for towing (especially heavy loads). Also, if like me, you always run 87 Octane, you can't bump up the timing a lot.

Steve