Replacement turbo

[OregonHorseTug]

Mike

You are running a stock pcm, right? What TDC number are you running?

TDCO set at -1.85. Set by optical bump, best I can do with this vintage and my equipment.

And since I am not from Portland is the top of the Terwillerger curves a steep hill?

Measuring the distance and elevation on Google maps, I get 3 miles climbing 430 ft. Averages almost 3% with some steep parts at maybe 4%.

What was your injection pulse width at 2900 rpm and those 2700 lb injectors? I would be interested in that, did the truck run smooth.

I'd be interested, too. The ScanGauge won't tell me that (at least that I have been able to figure out). I'm going to have to rig up my OBD-2 on my laptop and make another run with the data logger running. The truck runs smooth although I get an occcasional hickup. After a year of running these it is sounding like I have one going soft. I'm planning on going back to 2300# with marine nozzles when I get around to it. I'm still trying to figure the best injector combo for my horse-puller. I've got my old injectors that I want to build my own pop tester and "fiddle with".

This is intersting stuff and looking forward to some data since you are running the high pressure injectors. Very Very interesting, another person pressing the envelope, what was fuel mileage or do you know yet?

No mileage data yet with a load. I'm hoping for a long trip loaded in the next month so I can see what it does.

Mike

 

[Ratman]

Yep, I go up that hill every day on the way in to work, -and it is a steep one, I can vouch for that.

Isn't defuel supposed to happen at something like 280F?

 

[Slim Shady]

Yep, I go up that hill every day on the way in to work, -and it is a steep one, I can vouch for that.

Isn't defuel supposed to happen at something like 280F?

de-fueling happens at 210 intake air temp and goes up the higher the intake air temp. This is according to a Standyne fuel injection repair manual from GM. It relates how the fuel system limits fuel so the engine will not overheat. Quote "The PCm uses the IAT sensor signal to adjust fuel delivery according to incoming air Temp" The sensor reaches its lowest reading 177ohms at 212 F. that is the max the pcm will use as normal values.
Above that it defueles. The manual number is 16015.15-2 STG Service Technology Group.

 

[Matt Bachand]

de-fueling happens at 210 intake air temp and goes up the higher the intake air temp. This is according to a Standyne fuel injection repair manual from GM. It relates how the fuel system limits fuel so the engine will not overheat. Quote "The PCm uses the IAT sensor signal to adjust fuel delivery according to incoming air Temp" The sensor reaches its lowest reading 177ohms at 212 F. that is the max the pcm will use as normal values.
Above that it defueles. The manual number is 16015.15-2 STG Service Technology Group.

Yet they put the red on the Temp guage at 260, and a fan clutch that barely kicks in by 212...

What does heath do with his programming around this area?

 

[OregonHorseTug]

Actually my ScanGauge2 will show IAT up to 299 (and I've seen that with the GM-8). Of course by that time I'm down to about 8 mph with a load on a 6% grade and thinking about dropping it into 4x-low to see if it will help (doesn't). I'm guessing that after 212 the PCM starts scaling back the fuel? I've played with it right at the 200-210 zone and managed to learn to keep the fuel on but I'm just feathering the throttle and crawling.

It sure is tough trying to keep the engine coolant temp at 200 when you're feeding it 300* air. ATT to the rescue

 

[Acesneights1]

well the heath chip must do something cause mine hits 260+ and no de fuel.

 

[Slim Shady]

well the heath chip must do something cause mine hits 260+ and no de fuel.

The de-fuel does not change the requested fuel it changes the IP spill chamber timing to limit the injected amount of fuel without setting a code. The Gm series turbos were not designed to flow more than 6 to 8 psi max for extended periods, hence theh waste gate and lower boost at 2220 plus rpm.

 

[OregonHorseTug]

well the heath chip must do something cause mine hits 260+ and no de fuel.

IAT or ECT?. See the connection? The factory program is set to keep the customers from overheating the engine since GM is on the hook for the warranty, :nono:. I read in my owners manual that if the engine coolant reaches a certain temp it will shut down to protect itself. Few customers are cognizant of what they're doing to the engine. We buy re-programmed chips with these limits removed so we can get the power we want and to go with it is "enough-rope-to-hang-ourselves-with" . It is assumed we are watching the engine temps so we control them with our right foot.

• If the factory had installed intercoolers these limits wouldn't have been a problem
• If the factory had used a turbo like the ATT these limits wouldn't have been a problem
• GM targeted a very light duty market and we got stuck with soccer mom's turbo diesel .. :rolleyes5:
• ..and we know how to fix it ..:thumbsup:

You want more power? ..sure! Next bottleneck is cooling. Fix that? Tranny's getting hot! Fix that? Oops, there went the transfer case; shoulda dropped that New Process for the Borg Warner :mad2: ..so that's what the book meant by 8000# towing limit...:mad2:

Mike
..keeping my ear to the ground for a BW Xfer case...

 

[buddy]

well the heath chip must do something cause mine hits 260+ and no de fuel.

I think you were defueling. your foot was requesting 73mm3 fuel rate and IP was only giving you 60mm3. And the max you ever hit was 70mm3 before defueling.

Youve done the cooling upgrades, something just isnt clicking.

 

[Acesneights1]

I think you were defueling. your foot was requesting 73mm3 fuel rate and IP was only giving you 60mm3. And the max you ever hit was 70mm3 before defueling.

Youve done the cooling upgrades, something just isnt clicking.

IATs are the only thing left or the rad isn't getting rid of enough heat but I'm leaning on IATs. Gonna put a borrowed GM8 on to see if it helps at all. That will push me to ATT. I'm just wondering if the ATT would experience turbo lag with a top mount I/C(and sporty hood scoop... :devil: )

 

[96 OILBURNER]

Adding piping will increase the lag some. I believe the consensus is that the ATT has more lag than the GM-* turbos.

 

[Turbine Doc]

Adding piping will increase the lag some. I believe the consensus is that the ATT has more lag than the GM-* turbos.

negligible lag, some I was experiencing I'm not so sure was not attributable to transmission issues I was having, because after last Friday picking up my trans from overhaul, I really don't seem to have the same lag as I first felt I was having. That said I did notice an improvement going IC less

 

[Turbine Doc]

. I'm just wondering if the ATT would experience turbo lag with a top mount I/C(and sporty hood scoop... :devil: )

The lag is there but not enough to write home about, do this Kenny, get the ATT, and WMI save a lot of install issues and some $$$, if that still doesn't fit the bill sell the WMI and then go with an IC.

 

[NVW]

I can't say I notice any turbo lag, it may not build psi as quickly but you get the same bang with less psi. Punching the throttle you get a puff of black smoke just as the GM turbos did and that's all.

Leo

 

[NVW]

Tim, no IC just ATT. IIRC The longest hill was about 1 mile at I'm guessing 2% +/-?, I wasn't pushing it hard, didn't downshift out of OD, EGT at 1050 F, I never let it get higher than that and thus the drop to 55 mph. If I were to get rid of the K&N air filter or make a box for it I think I could push it a lot harder. The TCC also remained locked without the TCC mod.

Leo

Using Google Earth the climb in that mile was 210 feet so unless my calculations are wrong that would be closer to a 4% slope.

Leo

 

[Matt Bachand]

IAT or ECT?. See the connection? The factory program is set to keep the customers from overheating the engine since GM is on the hook for the warranty, :nono:. I read in my owners manual that if the engine coolant reaches a certain temp it will shut down to protect itself. Few customers are cognizant of what they're doing to the engine. We buy re-programmed chips with these limits removed so we can get the power we want and to go with it is "enough-rope-to-hang-ourselves-with" . It is assumed we are watching the engine temps so we control them with our right foot.

• If the factory had installed intercoolers these limits wouldn't have been a problem
• If the factory had used a turbo like the ATT these limits wouldn't have been a problem
• GM targeted a very light duty market and we got stuck with soccer mom's turbo diesel .. :rolleyes5:
• ..and we know how to fix it ..:thumbsup:

You want more power? ..sure! Next bottleneck is cooling. Fix that? Tranny's getting hot! Fix that? Oops, there went the transfer case; shoulda dropped that New Process for the Borg Warner :mad2: ..so that's what the book meant by 8000# towing limit...:mad2:

Mike
..keeping my ear to the ground for a BW Xfer case...

My truck has a BW xfer fwiw.

 

[preachermic]

Mine is a GM4 turbo. I run max of 15psi boost normally which goes to about 18psi when towing 10+k. In 85-90 degree outside temps with AC on I have never seen coolant temps pass 200 degree F. My IAT's go to about 220 max with no defueling. Temps and Boost recorded GMTD ScanTech. EGT's have not passed 1000deg. F. accxording to Autometer pre and post gauges. All of this with Heath 2.0 tune. Will have to see what the GL4 will produce. Steady cruising at 55-60mph on average day w/truck at 8K gross my EGT's run between 400 and 500 deg F.

 

[Slim Shady]

Mine is a GM4 turbo. I run max of 15psi boost normally which goes to about 18psi when towing 10+k. In 85-90 degree outside temps with AC on I have never seen coolant temps pass 200 degree F. My IAT's go to about 220 max with no defueling. Temps and Boost recorded GMTD ScanTech. EGT's have not passed 1000deg. F. accxording to Autometer pre and post gauges. All of this with Heath 2.0 tune. Will have to see what the GL4 will produce. Steady cruising at 55-60mph on average day w/truck at 8K gross my EGT's run between 400 and 500 deg F.

I hauled a little over 20000 lbs trailer and load, not including the truck passengers and extra fuel along with gear and never saw over 1050 degree F on the exhaust temp pre turbo. Pre and post turbo make a difference in egt temps. I would beg to differ with you that you are getting some defueling at 220, 212 is the max the IAT sensor will register and at that temp the pcm is already defueling.

 

[OregonHorseTug]

My truck has a BW xfer fwiw.

Aaah-haa! Well, yer lucky I'm on the left coast...

As I understand it the K3500 had the BW. Mine is the K2500HD and I haven't actually looked it over to make sure it's a NP but I understand that it does. That thought just makes me nervous when I have the tires pulling 19k

..OOPS..thread hijack!
..and now back to your regularly scheduled program...........

 

[1999gmc]

212 isn't the max. I hooked up my snap-on scanner and was reading IAT's pulling 9000 lbs up 6-7% grades going over the Sierra Nevada Mtns. and I saw 303 degrees and didn't have defueling with stock ECM. That was why I did the charge air cooler.