lq4 boosted w/ gt45 questions
03-24-2019, 08:11 PM
#1
lq4 boosted w/ gt45 questions Recently finished my build, well getting it in the truck and moving around. 2002 LQ4, 706 heads w/ 2.0 in valves 1.55 ex, TR6 spark plugs, stock cam, LS7 lifters, 7.35" pushrods, GM 12499224 blue valve springs, HVHP oil pump, 80lb injectors, ebay GT45 turbo, 60mm wastegate w/ 12psi spring, 50mm blow off valve, front mount intercooler (2.5" piping). Using HPTuners to tune.
Hot side piping - flipped truck manifolds with 2.5" crossover to turbo, EGT after Cyl 7 on crossover pipe, 3.5" downpipe, WB02 is 18" from turbo.
Wastegate is set to 12psi, and I checked all vacuum lines, everything is sourced to a vacuum block coming off the intake manifold. BOV, Wastegate (fitting on side, top is atmospheric vented), fuel pressure regulator, boost gauge.
On a test drive the max boost I could get was 4psi at 3800rpms.
From my logs it looks like it starts spooling up around 3000rpms, at 3800rpms and 4psi its showing knock so I backed off, WB02 shows 12.37 cmd is 12.05. It started to pull timing but tune is set to 13 degrees. Also, cylinder airmass shows 1.35 which is higher then in the spark tables. Max Airmass is 1.20 in the spark tables.
Another log shows 100% throttle, 4400rpms, wb 12.06 cmd 12.05, no knock, max 3psi. EGT were around 900 cruising to 1100 WOT.
Should it be commanding richer then that at 80% throttle ? I am no expert in tuning but understand and want to give it a shot.
Also - I read that a single GT45 spools up quickly on a LQ4, 3k seems a bit laggy. I can hear the turbo around 2k rpms but doesn't build boost till 3-3200. Anything I should check for the laggy boost or is it normal? I checked pre-turbo exhaust pipe and no leaks. I will check the intake side tomorrow with a boost leak tester. I attached log just for reference if anyone has suggestions. Thanks !
Hot side piping - flipped truck manifolds with 2.5" crossover to turbo, EGT after Cyl 7 on crossover pipe, 3.5" downpipe, WB02 is 18" from turbo.
Wastegate is set to 12psi, and I checked all vacuum lines, everything is sourced to a vacuum block coming off the intake manifold. BOV, Wastegate (fitting on side, top is atmospheric vented), fuel pressure regulator, boost gauge.
On a test drive the max boost I could get was 4psi at 3800rpms.
From my logs it looks like it starts spooling up around 3000rpms, at 3800rpms and 4psi its showing knock so I backed off, WB02 shows 12.37 cmd is 12.05. It started to pull timing but tune is set to 13 degrees. Also, cylinder airmass shows 1.35 which is higher then in the spark tables. Max Airmass is 1.20 in the spark tables.
Another log shows 100% throttle, 4400rpms, wb 12.06 cmd 12.05, no knock, max 3psi. EGT were around 900 cruising to 1100 WOT.
Should it be commanding richer then that at 80% throttle ? I am no expert in tuning but understand and want to give it a shot.
Also - I read that a single GT45 spools up quickly on a LQ4, 3k seems a bit laggy. I can hear the turbo around 2k rpms but doesn't build boost till 3-3200. Anything I should check for the laggy boost or is it normal? I checked pre-turbo exhaust pipe and no leaks. I will check the intake side tomorrow with a boost leak tester. I attached log just for reference if anyone has suggestions. Thanks !
03-24-2019, 09:47 PM
#2
i cannot view logs on this computer,
1) but i'd put some more timing in it until your at 4-5psi (see #3)
2) I usually set my PE table to kick in at 50% throttle, but big heavy rigs you may push it back to 60-70% TPS---ive actually had really good luck using BE with heavier vehicles
3) yep airmass maxes out at 1.2, so basically it's just the last (bottom) two rows that are used in spark calculations past that airmass number.
4) with tr6's, pump gas only and a 12.0 afr on the gas scale you can start having problems. consider a br7ef, observed afr down around 11.5 and maybe some water meth spray as you turn it up
you are on the right track. make small changes, read the plugs, rinse and repeat
1) but i'd put some more timing in it until your at 4-5psi (see #3)
2) I usually set my PE table to kick in at 50% throttle, but big heavy rigs you may push it back to 60-70% TPS---ive actually had really good luck using BE with heavier vehicles
3) yep airmass maxes out at 1.2, so basically it's just the last (bottom) two rows that are used in spark calculations past that airmass number.
4) with tr6's, pump gas only and a 12.0 afr on the gas scale you can start having problems. consider a br7ef, observed afr down around 11.5 and maybe some water meth spray as you turn it up
you are on the right track. make small changes, read the plugs, rinse and repeat
03-25-2019, 11:10 AM
#3
i cannot view logs on this computer,
1) but i'd put some more timing in it until your at 4-5psi (see #3)
2) I usually set my PE table to kick in at 50% throttle, but big heavy rigs you may push it back to 60-70% TPS---ive actually had really good luck using BE with heavier vehicles
3) yep airmass maxes out at 1.2, so basically it's just the last (bottom) two rows that are used in spark calculations past that airmass number.
4) with tr6's, pump gas only and a 12.0 afr on the gas scale you can start having problems. consider a br7ef, observed afr down around 11.5 and maybe some water meth spray as you turn it up
you are on the right track. make small changes, read the plugs, rinse and repeat
1) but i'd put some more timing in it until your at 4-5psi (see #3)
2) I usually set my PE table to kick in at 50% throttle, but big heavy rigs you may push it back to 60-70% TPS---ive actually had really good luck using BE with heavier vehicles
3) yep airmass maxes out at 1.2, so basically it's just the last (bottom) two rows that are used in spark calculations past that airmass number.
4) with tr6's, pump gas only and a 12.0 afr on the gas scale you can start having problems. consider a br7ef, observed afr down around 11.5 and maybe some water meth spray as you turn it up
you are on the right track. make small changes, read the plugs, rinse and repeat
I am gonna check the intake piping today and see if there's any leaks. I read the 80lb Injectors are known for leaking around the orings under boost.
On a side note, I am running 5w30 oil and cold my pressures are great. 50 idle, 60 cruise, 70 WOT. Once warm it sits at 40psi, and doesnt change regardless of idle/cruise up to 3500rpms. Now once it cools down it's back to 50-60-70 again. I read a lot of people use 15w40 when boosted. Is it good idea to change it from 5w30 ?
03-25-2019, 12:56 PM
#5
br7 is a colder plug. ime less chance of detonation when the cylinder pressure gets really high. no real downside, lots of upside
I couldnt tell you what for about the oil pressure or oil weight. i use 5w30 and as long as it's not zero psi I'm happy.
I couldnt tell you what for about the oil pressure or oil weight. i use 5w30 and as long as it's not zero psi I'm happy.
03-25-2019, 06:01 PM
#6
Good to know about the br7. I'll keep that in the back of my mind. If I have issues with the tr6. I did find some leaks when I did the test. Some small ones that I fixed. I found the injectors are leaking on intake side, only air no fuel leaks. I will pull them and see about different orings to seal them better.
03-27-2019, 09:19 AM
#10
What is commonly called a gt45 will be able to brake boost several lbs on a stock torque converter with an lq4. If you do not see boost until 3krpm, something is dramatically wrong. If, however, you have an actual gt45, we are talking a completely different scenario. What is commonly called a gt45 is a garret clone 67mm t4 turbo. Is this what you have?
03-27-2019, 10:53 AM
#11
What is commonly called a gt45 will be able to brake boost several lbs on a stock torque converter with an lq4. If you do not see boost until 3krpm, something is dramatically wrong. If, however, you have an actual gt45, we are talking a completely different scenario. What is commonly called a gt45 is a garret clone 67mm t4 turbo. Is this what you have?
I did have leaks so I fixed those, one major one was a broken clamp. Did a leak test and able to build pressure a lot quicker then before. Leaks around injector orings but that should be fixed tomorrow when orings get here.
03-28-2019, 08:33 AM
#12
04-02-2019, 11:44 AM
#13
So took it for a drive yesterday. It is building boost much better. I also re-piped the PCV hoses into a catch can and have it vented with a filter. I have new AC Delco knock sensors and harness which they are throwing DTCs. Also around 3000rpms the truck is misfiring, sounds like a machine gun. My AFR are good, rich in some spots. Go as low as 9.0. When it the sensors pick up knock my AFR don't seem bad. Any suggestions moving forward ?
I am running TR6 plugs gapped at 0.030, is that too big of a gap for 12psi and could be why its misfiring? highest boost it built on this run was around 10psi, but it was misfiring bad. Well I call it misfiring, it sounded like a machine gun and truck was jerking back and forth a bit.
I have attached log and tune. Thanks !
I am running TR6 plugs gapped at 0.030, is that too big of a gap for 12psi and could be why its misfiring? highest boost it built on this run was around 10psi, but it was misfiring bad. Well I call it misfiring, it sounded like a machine gun and truck was jerking back and forth a bit.
I have attached log and tune. Thanks !
04-02-2019, 12:56 PM
#14
i couldnt really look at your tune, you must be using 4.0 or newer
but from the log it looks like you're building boost much earlier than your PE is set to begin adding fuel or removing spark. Your WB doesnt show up for me as I dont have your config loaded.
i'd be inclined to lower your TPS PE threshold to 50% and pull timing down to 12* in the bottom two columns of the g/cyl vs rpm main spark table. be sure and unify both high and low octane tables
do you know how to set up an AFR error % histogram?
here's a vid I made about it. there are some errors but overall the process is good ( I say add to, when I meant multiply by)
but from the log it looks like you're building boost much earlier than your PE is set to begin adding fuel or removing spark. Your WB doesnt show up for me as I dont have your config loaded.
i'd be inclined to lower your TPS PE threshold to 50% and pull timing down to 12* in the bottom two columns of the g/cyl vs rpm main spark table. be sure and unify both high and low octane tables
do you know how to set up an AFR error % histogram?
here's a vid I made about it. there are some errors but overall the process is good ( I say add to, when I meant multiply by)
05-03-2019, 06:05 PM
#15
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So took it for a drive yesterday. It is building boost much better. I also re-piped the PCV hoses into a catch can and have it vented with a filter. I have new AC Delco knock sensors and harness which they are throwing DTCs. Also around 3000rpms the truck is misfiring, sounds like a machine gun. My AFR are good, rich in some spots. Go as low as 9.0. When it the sensors pick up knock my AFR don't seem bad. Any suggestions moving forward ?
I am running TR6 plugs gapped at 0.030, is that too big of a gap for 12psi and could be why its misfiring? highest boost it built on this run was around 10psi, but it was misfiring bad. Well I call it misfiring, it sounded like a machine gun and truck was jerking back and forth a bit.
I have attached log and tune. Thanks !
I am running TR6 plugs gapped at 0.030, is that too big of a gap for 12psi and could be why its misfiring? highest boost it built on this run was around 10psi, but it was misfiring bad. Well I call it misfiring, it sounded like a machine gun and truck was jerking back and forth a bit.
I have attached log and tune. Thanks !