6.7 Cummins Suburban Build

[grampsbutler]

Maiden Voyage!

I got the drive shaft in this weekend and put the fuel pump into the tank. I got it all plumbed and took it for its maiden voyage.

It ran great while cold, but then it died on me repeatedly as soon as it got close to operating temperature. It started to loose power, and then at a certain point straight up died on me, and would not restart until it had had time to cool off. I spent the best part of Sunday trying to figure out what was going on, it felt like I wasn't getting any fuel pressure. I had read on another board that loose fuel cross over tubes can cause a loss of fuel pressure, so I pulled the fuel rail, and retorqued the cross over tube nuts. They only took about an 1/8 of a turn I used 2 different torque wrenches just to be sure that I didn't have an out of spec wrench.

Sure enough this solved the problem. Now it runs great. I drove it back to my house, with zero issues. It feels like it should have more power, but it also does not have exhaust sensors hooked up yet, so the ecu is probably limiting the amount of fuel.

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[Big Ray]

Out-freaking-standing job!

 

[grampsbutler]

Its Alive!

This past weekend was a big milestone. I took the maiden voyage...

I put the fuel pump into the tank. I was worried about this because the tank was almost full of diesel.....and 40 gallons is too much to handle. So I decided to cut an access hole in the cargo area above the fuel sending unit. I used a small reciprocating saw to cut a circle the correct size around where the old sending unit used to be. Then using a steel ring that I made, and some 1/8 closed cell urethane sheet cut into a circle as a gasket, I mounted to dodge lift pump. Before putting the pump into the tank I swept the bottom with a magnet to catch the debris from cutting the hole. It is not the best way to do these things, and I will definitely need to change the fuel filter after the first tank, but I think I got almost all the metal out of the tank. I wired it up to the ignition on circuit, and plumbed the fuel lines.

With this done, I threw the wheels on and fired her up. I have omitted an important item....the clutch. I will do a whole write up on the clutch because it is hand operated. This was a big reason for doing the build.

Any how.....The first drive was AMAZING.....but short lived. I got about 3 miles up the road and the engine lost all power and died.....It was not over heated it just died when it got to temperature. After it cooled off it fired up and I made it back to the shop. I figured it had to be fuel related, and after reading the internet for hours researching, I decided the most likely culprit was the fuel cross over tubes. I removed the fuel rail and used two different torque wrenches, and sure enough, they all took 1/8 of a turn to get to the specified 41 ft lbs. Put it back together, and the problem was cured!

The next day I was able to drive it the 30 miles back to my house.

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[grampsbutler]

Teething issues! Need advice!

Power Steering:
I have several teething issues. The first is the power steering is not working well. I have the dodge pump hooked up to the GM Hydroboost, and GM steering box. It feels like I am not getting enough pressure from the Dodge pump. Its okay when im moving, but I cant dry steer at all. I am really surprised, because the Dodge also had hydroboost and ps.

I have read that you can remove shims from the pressure regulator in the pump to increase the pressure.... has anyone got experience with this? The only other option would be to get a GM saginaw pump, but that would involve a custom bracket, and pulley to fit the dodge serpentine belt.

Tuning and emissions:
The truck ran great, when I first fired it up, but it has recently gone into limp mode, which means I have very little power.....It will run, but thats about it.

The problem is that it is not getting the inputs from the exhaust temperature sensors. The dodge had 4 sensors, monitoring temps at various points to tell the ECU when to run a regen cycle for the Diesel Particulate Filter. Obviously the chevy does not have this....infact it doesn't have an exhaust pipe of any sort yet.

I have 2 options: I could do an EGR delete which would eliminate the need for the sensors in the exhaust. Or I could install sensors in the tail pipe, which would provide a signal to the ECU hopefully making it run more like stock....

I really didn't want to do an EGR delete, but I am coming around to the fact that to get it to run well in the chevy it might be necessary. Im not about to go out and get a DPF etc, because the truck never had one on when it was new!

I am considering EFI Live for the tune and delete. Does anyone have any experience with them?

I have started gathering the parts for the exhaust. That is going to be the next part of the project.

 

[Itali83]

There is no way you are going to get the sensors, just plug them in and the ecm will be happy and run fine. You either need the WHOLE aftertreatment system, or nothing at all and tune the ecm. No in between. You should have pulled all the egr plumbing off the motor before installing it. It’s useless unless you put a complete dpf system on it. I have no experience with efi live and its ability to tune/delete diesel engines. Can’t help you there.

Not trying to be a dink but I can’t believe a build of this caliber and the excellent fabrication has such a major oversight with the emissions system. You’ll know for the next one I guess.

Ben

 

[Buck69]

EFI live is/was very popular in these parts. Not sure if they are still around though due to the epa crackdowns. What most did was just the turbo/back exhaust. The tune looked after the rest.

 

[89Suburban]

This build is awesome, sub'd.

 

[grampsbutler]

I am with you.....I knew it was going to be a challenge. This is my first build with electronic controls so I am learning as I go. The bottom line here is that I'll need to get a full emissions delete or find the full dpf system. I am talking to a couple of tuning shops about it and it seems like the delete its a pretty common thing to do. The first thing I will have to wire in an OBD2 port so that I can verify what codes are being thrown, and if that is what I decide, it will be necessary to load up the new tune.

I already had the security skim removed from the ECU so it runs without a security abort. I'll post back once I have decided on a direction.

 

[CountKrunk]

Posting to follow along. Super sick so far. Hard to know all the steps for a dance you've never done before.

 

[grampsbutler]

Update: I am wiring the OBD2 into the wiring harness and am having a hard time finding the wiring diagrams to splice into the engine harness. Does anyone know the pinout for the OBD2 port on 2010-2011? Here is what I have so far.

Ground: pin 4 and 5
12v: pin 16
CAN c(+): ???
CAN c(-): ???
CAN J1939(+): ???
CAN J1939(-): ????

I need to be able pull any codes load a new tune if required.

 

[akchevrolet]

Nice Square would love to get me a suburban. 4x4 3/4 or 1 ton

 

[HotWheelsBurban]

Nice Square would love to get me a suburban. 4x4 3/4 or 1 ton

Burbs were never available from the factory as one tons, 3/4 or 1/2 ton only. But they could be had with big blocks, full floaters and heavy duty suspension and transmission (400 or 4L80) in square body trucks and the OBS trucks.
And of course nowadays anything can be built, with enough time, money, and workspace....

 

[akchevrolet]

3/4 will be fine. ya know unless i get the time money and space to swap to a 1 ton haha.

 

[grampsbutler]

Chipping away at it: I am back at it! The controls issues are now solved..............I won't divulge all of the gory details in this forum but for those that are curious please feel free to PM me. There were actually several issues, one of which was no connection to the ASD circuit which sends power to the mass airflow sensor and the turbo actuator. This was a total oversight on my part.......did I mention this was my first build with an electronically controlled engine? The way that I figured it out was that I could hear the turbo whine only at very high power levels. With VGT Turbos, they are supposed to adjust the size of the turbo to accommodate a larger engine speed range. This helps it to spool faster and at lower RPMs.....which I noticed was not happening. The actuator is also supposed to cycle at key on - which it was not.

To make a long story short.....the difference is INCREDIBLE. I took the truck up the local mountains this past weekend for a ~100 mile drive up to 4000feet. Lots of climbing and it had no problem holding 75mph, and if I had asked I am know there was significantly more to give. As a comparison, with the 6.2l Detroit motor, I was down to <55 and needed to shift down to third on the same climb. With the Cummins I was able to hold 6th gear no problem at all. I was also very happy that my temperatures never started to climb, and the noise level in the cab was a great improvement, because I could hold top gear, and kept the RPM is a more ideal range (I don't have a tach, but based on feel and calculation I was would have been holding 1750 RPMs)

I don't know what type of fuel economy I am getting. I have not yet driven far enough to need to visit the petrol station. Stay tuned for more on economy.

 

[grampsbutler]

Exhaust system: This post is a couple of weeks late.....but better late than never.

I fabricated a custom exhaust. The fab work was pretty straight forward but took a lot of fitting and fiddling. I started with a universal 4" stainless steel kit, which contained enough pipe and bends to go all the way back (with some spare). I also used some v-clamps and a repair flange for the down pipe. Details below

- $260 Universal 4" Stainless kit
- $48 vband weldments coupling clamps
- $69 Down pipe repair flange PN GRD00187
- $7.00 exhaust u clamp

I started at the front and marked, cut, fit and adjusted each piece, tacked it, then on to the next section. After the whole pipe was fitted in a way that I was happy with clearances, I took the whole thing off and completed the welds. I did not use a resonator, and went with a straight pipe. It actually sounds relatively civilized, but I reserve the right to change my mind after taking it on a long trip. See below for pictures.

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