LQ4 50 Degrees Timing Too Much??

[LowKeyIdiots]

Hey guys! I have a 2002 gmc sierra 1500 Denali with the 6.0, cruising down the highway with the cruise set on 70 rpms at 1800 (4.10 rear end) i noticed on my scanner that my timing advance is staying at 50 degrees +- 1 or 2, is it just me that thinks thats too high for a stock truck? Saw on some forums people say dont go higher than 30 ish at wot? The truck is horribly slow and i read a bad MAF could cause high timing and poor performance? Thanks in advance!

[CamGTP]

Cruise timing and wide open throttle timing will be two completely different things.

 

Many calibrations will have high timing at cruising speeds to help with fuel mileage and because they use the EGR, seeing 40-50 degrees is not out of the question depending on engine rpm and cylinder airmass.

 

Timing at full throttle is usually around 18-28 degrees with variables. Things like commanded air fuel ratio, intake temps, coolant temps and knockretard can all alter how much timing advanced there will be.

 

A bad MAF sensor in itself will not cause high timing, it will just hurt performance.

 

Here is a stock 2001 GMC Sierra 6.0 file. If you look at the numbers it's roughly 38-40 degrees of timing at 1,800rpm and low cylinder airmass, then add in the 7-9 degrees that the EGR adds in you are near 50 degrees.

 

 

[LowKeyIdiots]

2 hours ago, CamGTP said:

Cruise timing and wide open throttle timing will be two completely different things.

 

Many calibrations will have high timing at cruising speeds to help with fuel mileage and because they use the EGR, seeing 40-50 degrees is not out of the question depending on engine rpm and cylinder airmass.

 

Timing at full throttle is usually around 18-28 degrees with variables. Things like commanded air fuel ratio, intake temps, coolant temps and knockretard can all alter how much timing advanced there will be.

 

A bad MAF sensor in itself will not cause high timing, it will just hurt performance.

 

Here is a stock 2001 GMC Sierra 6.0 file. If you look at the numbers it's roughly 38-40 degrees of timing at 1,800rpm and low cylinder airmass, then add in the 7-9 degrees that the EGR adds in you are near 50 degrees.

 

 

Ok i didnt know it would be different from wot to cruising, i will do a data log with my scanner tmr of some wot pulls and see what happens, the thing is a dog i calculated the 0-60 to be roughly 11 seconds and it has a 4.10 rear end. I saw someone said they took the tune from an 06 escalade and popped it on one of these trucks and it turned into a totally different animal, is this even do-able? wouldnt the different compression ratio from the lq4 to the lq9 cause issues in the tune? bare with me ive never tuned anything and dont own HP Tuners lmao im just trying to figure out why this thing is so slow and why with a 3000 lb trailer it wont go past 50 ish mph at 4000 rpm, wanna figure this because im considering dumping it for a duramax.

[CamGTP]

You'd need to do some digging to figure things out.

 

Like a compression test to make sure all cylinders are even. Check fuel pressure at idle and under heavy load, make sure everything is within spec.

 

It's possible there is a restriction in the exhaust that is not letting it breath, thus making it slower. That truck should do 0-60 is far less than 11 seconds.

[LowKeyIdiots]

1 minute ago, CamGTP said:

You'd need to do some digging to figure things out.

 

Like a compression test to make sure all cylinders are even. Check fuel pressure at idle and under heavy load, make sure everything is within spec.

 

It's possible there is a restriction in the exhaust that is not letting it breath, thus making it slower. That truck should do 0-60 is far less than 11 seconds.

Just replaced the fuel pump and regulator due to it stalling sometimes after starting and now fuel pressure is 60 koeo and 50 give or take 1 or 2 with engine running revving it stay at 50 ish, i lopped the stock muffler off and put on a dynomax cat back which helped a little, is there a way i can check if my cats are clogged besides looking to see if they are cherry red at night? But yeah the awd doesnt work due to a bad encoder motor (i believe) and it wont do a burnout it just revs to like 3 grand and nothing. Buggin me because even dragging my jet ski around (1500 lbs on trailer) it screams like 4500 rpms up hill at highway speed and accelerating from a stop will go to 5 grand before it shifts.

[CamGTP]

It has buttons for the 4WD or it's an AWD truck??

 

If it's AWD then it's always in AWD, so it can't do a burnout when the transfer case is always driving the front wheels.

 

You can test back pressure in the exhaust by removing the front o2 sensor and threading the gauge into the o2 sensor bung. It should be minimal back pressure, like less than 1 psi.

 

There are no engine codes still active right? No pending or current codes. One that can pull power away is a knock sensor code.

[LowKeyIdiots]

4 minutes ago, CamGTP said:

It has buttons for the 4WD or it's an AWD truck??

 

If it's AWD then it's always in AWD, so it can't do a burnout when the transfer case is always driving the front wheels.

 

You can test back pressure in the exhaust by removing the front o2 sensor and threading the gauge into the o2 sensor bung. It should be minimal back pressure, like less than 1 psi.

 

There are no engine codes still active right? No pending or current codes. One that can pull power away is a knock sensor code.

Yes its the awd quadrasteer truck however something with it is not right, jacked it up and both front and rear wheels turn but i got stuck the other day in snow and my buddy jumped out and noticed neither of the front wheels are turning, and if i get into even a dusting of snow then it will sit there and the speedo will read like 50 even though the truck isnt physically moving, so something with that isnt right. Nope there are no codes ive owned the truck for 8 months and at first it wouldnt even downshift when i put it to the wood, pulled the ecm fuse and did a relearn on the trans while driving aggresively and now it downshifts instantly and quick but still doesnt have the power to go anywhere. What kind of tester would i need for the 02 bung? or can i pull the upstream sensors and drive it to see if it makes a difference? thanks for the help!

[Grumpy Bear]

Things are really sophisticated now. Encoding and ECU controlled everything. Let's them tune to the very edge of the cliff. 

 

This post is for fun and for reference. I ramble sometimes.  Grab a drink. it's late, right?

 

Around 1980 I bough this 67 Mustang with a 200 I6. They gave one timing spec in the FORD shop manual for the cars with the C4 three speed automatic. 12* BTDC at curb idle which was 550 rpm. These cars were dogs and loved fuel to the tune of 12-14 mpg. I had access to a SUN distributor machine a machine shop and a regional NAPA rep living next door that knew the entire Belden line by memory.  We put the distributor in the SUN and gave it spin to find that it had roughly 10 distributor degrees of mechanical advance, so 20 on the motor plus 12 gave 32 degrees of total advance at 2500 SUN rpm or 5000 motor rpm. Well those motors had cams like a lawnmower and get them to rev to 4500-4800 was about the limit with the factory tune. 

 

RJ, my neighbor and I started with a set of Mallory wires and matching coil, condenser and points (standard tension) and with a few dozen plugs and a freshened distributor set out to find the motors 'liking' for timing at WOT and found it to be 36* once the carb was jetted and in step. Vacuum advance was at this time locked out and can removed. Once that was in the bag I vacuum tuned the idle advance to find it was loving 8*. That were vacuum peaked. So I need more mechanical advance than I have. Noted. Now we need to find the earlies spot in the rpm at WOT it would eat 36* without complaint. Yea, you can read timing in a plug as well as mixture. 

 

Anyway it turns out it will take and like it at 2,000 rpm. So okay I also need a quicker curve and reworked stops. 4* more and 3000 rpm earlier. Well the factory weights and springs wouldn't get there and neither would aftermarket springs but close. I needed heavier weights as well. I love Mallory Metal and a box of new weights. I also relocated the pins (stops) and made them adjustable. What a device does on the bench and what it does at speed don't always match and the SUN machine really helps there. Some fretting out and bingo. Okay all good and fine. I can dial in 8 at 550 rpm and hit 36 degrees by 2K and did that ever wake it up. However it's now guzzling 10-12 mpg. 4:10 gear 27" tire FYI. 

 

I need some vacuum advance and the thing about vacuum advance is that the higher the vacuum the more timing it will chew on. Low density mixtures that are also lean burn really really slow. I needed an adjustable and RJ came up with a replacement unit from something like an Edsel. (Kid you not). Took some experimentation and a few more plugs but down the road at 55 mph (was the speed limit then) I had 50 degrees dialed in when at max vacuum and tapered to zero by WOT 3" vacuum or there about. Yea, I had to pull a few degrees of total from it so glad I made the stops adjustable. 

 

End result was a motor that ran much cooler and got 25 mpg at 55 mph. Started just looking at it. What took weeks and allot of resources is now done by guys like Cameron in a few minutes with the ECU and his lap top/software.

 

So yea 50 degrees is possible. 

 

 

[CamGTP]

I would really look into that transfer case issue if the front wheels aren't even spinning. I'm not exactly sure how those operated compared to the 4WD units but that could be a big loss of power if it's a problem there.

 

This is the tool for a back pressure tester. You can find them at most auto parts store and online. It's possible some places may even have them for rent so you don't have to buy one.

 

https://www.autozone.com/test-scan-and-specialty-tools/exhaust-pressure-tester/oemtools-exhaust-back-pressure-tester-and-gauge/347232_0_0

[LowKeyIdiots]

46 minutes ago, CamGTP said:

I would really look into that transfer case issue if the front wheels aren't even spinning. I'm not exactly sure how those operated compared to the 4WD units but that could be a big loss of power if it's a problem there.

 

This is the tool for a back pressure tester. You can find them at most auto parts store and online. It's possible some places may even have them for rent so you don't have to buy one.

 

https://www.autozone.com/test-scan-and-specialty-tools/exhaust-pressure-tester/oemtools-exhaust-back-pressure-tester-and-gauge/347232_0_0

Thanks for the link! From what ive read having the awd disabled should help mpg and performace because its not sending power to the front wheels so the motor doesnt have to work as hard to turn the rears.... thats the theory anyway! i should also note i only get 12.8 mpg and when its cold it idles smoothly but after a few minutes it will develop a missfire, randomly on every cylinder and start shaking, no code but scanner shows that every cylinder missfires at some point, has new plugs and wires 2000 miles ago.

[LowKeyIdiots]

57 minutes ago, Grumpy Bear said:

Things are really sophisticated now. Encoding and ECU controlled everything. Let's them tune to the very edge of the cliff. 

 

This post is for fun and for reference. I ramble sometimes.  Grab a drink. it's late, right?

 

Around 1980 I bough this 67 Mustang with a 200 I6. They gave one timing spec in the FORD shop manual for the cars with the C4 three speed automatic. 12* BTDC at curb idle which was 550 rpm. These cars were dogs and loved fuel to the tune of 12-14 mpg. I had access to a SUN distributor machine a machine shop and a regional NAPA rep living next door that knew the entire Belden line by memory.  We put the distributor in the SUN and gave it spin to find that it had roughly 10 distributor degrees of mechanical advance, so 20 on the motor plus 12 gave 32 degrees of total advance at 2500 SUN rpm or 5000 motor rpm. Well those motors had cams like a lawnmower and get them to rev to 4500-4800 was about the limit with the factory tune. 

 

RJ, my neighbor and I started with a set of Mallory wires and matching coil, condenser and points (standard tension) and with a few dozen plugs and a freshened distributor set out to find the motors 'liking' for timing at WOT and found it to be 36* once the carb was jetted and in step. Vacuum advance was at this time locked out and can removed. Once that was in the bag I vacuum tuned the idle advance to find it was loving 8*. That were vacuum peaked. So I need more mechanical advance than I have. Noted. Now we need to find the earlies spot in the rpm at WOT it would eat 36* without complaint. Yea, you can read timing in a plug as well as mixture. 

 

Anyway it turns out it will take and like it at 2,000 rpm. So okay I also need a quicker curve and reworked stops. 4* more and 3000 rpm earlier. Well the factory weights and springs wouldn't get there and neither would aftermarket springs but close. I needed heavier weights as well. I love Mallory Metal and a box of new weights. I also relocated the pins (stops) and made them adjustable. What a device does on the bench and what it does at speed don't always match and the SUN machine really helps there. Some fretting out and bingo. Okay all good and fine. I can dial in 8 at 550 rpm and hit 36 degrees by 2K and did that ever wake it up. However it's now guzzling 10-12 mpg. 4:10 gear 27" tire FYI. 

 

I need some vacuum advance and the thing about vacuum advance is that the higher the vacuum the more timing it will chew on. Low density mixtures that are also lean burn really really slow. I needed an adjustable and RJ came up with a replacement unit from something like an Edsel. (Kid you not). Took some experimentation and a few more plugs but down the road at 55 mph (was the speed limit then) I had 50 degrees dialed in when at max vacuum and tapered to zero by WOT 3" vacuum or there about. Yea, I had to pull a few degrees of total from it so glad I made the stops adjustable. 

 

End result was a motor that ran much cooler and got 25 mpg at 55 mph. Started just looking at it. What took weeks and allot of resources is now done by guys like Cameron in a few minutes with the ECU and his lap top/software.

 

So yea 50 degrees is possible. 

 

 

wow pretty sure i had a stroke reading this lmao, i understood a sentence or two then i was lost then i new what you were saying again and so forth lmao, i dont really know much about tuning im trying to learn it all, so what your saying it more timing = more mpg's while cruising and less is more power? jeez im confused lmao, i have horrendous mpg as it is! lmao what i know so far about tuning (which isnt much) i learned from Jeremy Formato at Fasterproms i guess he is some type of tuning wizard or something 

[CamGTP]

This thread has all the information on that transfer case. It seems that only under extreme situations is it okay for 100% of the torque to be applied to the rear wheels. If it's doing that all the time it's not working correctly at all.

 

 

[Grumpy Bear]

1 hour ago, LowKeyIdiots said:

wow pretty sure i had a stroke reading this lmao, i understood a sentence or two then i was lost then i new what you were saying again and so forth lmao, i dont really know much about tuning im trying to learn it all, so what your saying it more timing = more mpg's while cruising and less is more power? jeez im confused lmao, i have horrendous mpg as it is! lmao what i know so far about tuning (which isnt much) i learned from Jeremy Formato at Fasterproms i guess he is some type of tuning wizard or something 

Glad you enjoyed it  

 

Perfect timing peaks cylinder pressure around 17 degrees ATDC. In a running motor 'time' is measured in degrees of crank rotation. Call it "Time per degree". Flame speed is dependent on a bunch of things but the point is those things slow down or speed up the flame front thus the the point of peak pressure. WOT creates a dense rich mix that burns fast and low  throttle angles create a less dense leaner slower burning mixture. So when you light the mix depend on rpm which is how much time per degree, throttle angle which combine with rpm and fuel mapping vary flame speed thus cylinder pressure. It will hurt your head but not your ECU. 

 

Point is, if you get all these things in sync then you get the most work out of the fuel. It gets powerful and economical too. 

 

In the 60's economy was not a big deal. Gas was under 25 cents a gallon so little attention was paid to part throttle spark mapping. Today economy is King. Detroit is all over those spark and fuel tables with a good dose of clean air tossed in. 

 

Tuners take the 'safety net' out that the OEM put in to get either power or the illusion of it. 

 

Gasoline does not know what year it is and obeys the laws of thermodynamics. Looking back on the simpler tuning methods used then helps one get his head around what is happening now. IMHO of course. It's like seeing it in slow motion. 

 

Anyway....looks like Cameron has you covered like a blanket. I'm just the entertainment. 

 

[LowKeyIdiots]

9 hours ago, CamGTP said:

This thread has all the information on that transfer case. It seems that only under extreme situations is it okay for 100% of the torque to be applied to the rear wheels. If it's doing that all the time it's not working correctly at all.

 

 

So it seems as if it should always be in 4wd, now there is a fuse labelled (automatic transfer case) and another one labelled (4wd) i was told that the atc fuse will cut power to the trans case so it cant shift and the 4wd does the same thing only to the diff. I think im gonna jack it up later and see if i have a broken axle, im starting to wonder if the axle splines are sheered off and thats why when in the air the wheels spin but on the ground they dont. I was told it had a brand new T case when i bought it cause an old man owned it in florida. Thanks for you help!

[LowKeyIdiots]

8 hours ago, Grumpy Bear said:

Glad you enjoyed it  

 

Perfect timing peaks cylinder pressure around 17 degrees ATDC. In a running motor 'time' is measured in degrees of crank rotation. Call it "Time per degree". Flame speed is dependent on a bunch of things but the point is those things slow down or speed up the flame front thus the the point of peak pressure. WOT creates a dense rich mix that burns fast and low  throttle angles create a less dense leaner slower burning mixture. So when you light the mix depend on rpm which is how much time per degree, throttle angle which combine with rpm and fuel mapping vary flame speed thus cylinder pressure. It will hurt your head but not your ECU. 

 

Point is, if you get all these things in sync then you get the most work out of the fuel. It gets powerful and economical too. 

 

In the 60's economy was not a big deal. Gas was under 25 cents a gallon so little attention was paid to part throttle spark mapping. Today economy is King. Detroit is all over those spark and fuel tables with a good dose of clean air tossed in. 

 

Tuners take the 'safety net' out that the OEM put in to get either power or the illusion of it. 

 

Gasoline does not know what year it is and obeys the laws of thermodynamics. Looking back on the simpler tuning methods used then helps one get his head around what is happening now. IMHO of course. It's like seeing it in slow motion. 

 

Anyway....looks like Cameron has you covered like a blanket. I'm just the entertainment. 

 

Entertainment? GOT THAT RIGHT!! haha what you said here makes more sense to me, i still have a headache now (as you said lol) but i read it like 5 times and i think i kinda get it, ill have to do some more reading on the subject to really grasp it, but thanks for the info!