LQ4 Build

[RockChucker]

Still plugging away on this thing...I’ve been told that the OEM LQ4 injectors were going to be at the very edge of their capability to fuel this motor. They are somewhere in the range of 24 lb/hr injectors. It just so happens that the gen IV intake I picked up had the fuel rail and injectors with it for the sweet price of $75. I took a peek at the injectors and they are a 50 lb/hr based on specs I can find on the interwebz...we all know those are super accurate 100% of the time. They are an EV6 style connector. The OEM gen III injectors are a multec style connector. $30 later and I have some wiring harness adapters on the way. I may wire them into the harness, but the gen IV intake seems taller and I may need some extra length. Have to see.




Turns out a removable floor makes it pretty easy to install a 150 lb tcase solo...

 

[RockChucker]

Got the radiator mount 90% done this weekend. I need to build a support link for the top of the radiator. Didn’t get a finished pic, but here’s a big radiator sitting in its home for the first time in a year and a half.


the new mount is supported under the center of the radiator and floats between the frame rails. The previous iteration was a plate spanning between the rails and the minor frame flex destroyed one radiator. That’s an expensive mistake. Wasn’t going to let that happen again.



if you look above the steering cylinder mount you can see the radiator mount cantilevered off the front bumper.

 

[RockChucker]

Radiator mount is complete. Accessories mounted. I have modified a cheap weed sprayer (put a schrader valve in it) to pressurize to 25 psi with my air compressor to pre oil my engine. There’s an m16x1.5 plug on the driver side of the block right by the oil pump. I’ll pick up a barbed fitting at pirtek tomorrow when I go get my last steering line crimped. Then pressurize the oil in the weed sprayer and fill the engine that way while slowly turning the crank. Hoping this will a) prime the oil pump and prevent a dry start and b) pump up my new hydraulic lifters fully. There is still assembly lube in the engine, but since I finished assembling it over a year ago, I want to be sure everything has a nice film of oil.

 

[RockChucker]

Got the fittings needed to complete the weed sprayer oil primer. I pressurized it to about 30 psi and seems like it will work well! Not bad for a $17 investment. Way cheaper than the melling deal that does the same thing for $213 from summit racing.


the fitting on the end of the hose will thread into the place where the Allen head plug pictured goes for those wondering.

 

[Greg]

Are you going to pull a valve cover and look for oil flowing to the top end? Or do you have a gauge to check for oil pressure?

I primed my oil pump when I installed it, soaked my lifters in oil, etc.

 

[RockChucker]

Are you going to pull a valve cover and look for oil flowing to the top end? Or do you have a gauge to check for oil pressure?

I primed my oil pump when I installed it, soaked my lifters in oil, etc.

If I was smart I would have done this while it was still on the engine stand but I’m not. I have my Jeep oil pressure sending unit hooked up and I’ll just turn the key on and watch the pressure that way. I don’t have a specific gauge. I also soaked my lifters and filled the pump with oil, but I’ve got a lot of time and money (relatively speaking) tied up in this motor and I don’t want to risk a dry start.

 

[RockChucker]

All the fluids but engine oil and the gas tank are filled. The engine harness is mostly hooked up but I need to spend some time securing it. Getting closer. It was a very productive week off work.

 

[RockChucker]

@dbriml on Instagram: "Major milestone this evening. And anxiety relief. First time I’ve ever built a motor from the ground up. So happy it fired up and had great oil pressure at idle. Waiting for a few more things to arrive so I can button it up and

413 likes, 31 comments - dbriml on May 17, 2021: "Major milestone this evening. And anxiety relief. First time I’ve ever built a motor from the ground up. So happy it fired up and had great oil pressure at idle. Waiting for a few more things to arrive so I can button it up and get it to the...

www.instagram.com

 

[RockChucker]

The end of the road is drawing nigh. I should have my tcase back on Friday. As long as fedex freight is accurate. Heck it might even show up tomorrow as it is already in SLC. The tcase put the brakes on the whole project. I love the 3 speed but it has not been without issue. The biggest issue I’ve had should finally be put to bed though. When I was installing my driveshafts a few weeks ago, I found the fresh rebuild was still able to have the front and rear outputs in opposite ranges. Something in the detent block was right. TWF wanted it back to take a look again, as they couldn’t get it to do that at all when they rebuilt it a year ago. They were super helpful and shipped it back on their dime. Which I was glad for because they wouldn’t provide any exploded parts diagrams or specs for the detent block. Wasn’t thrilled about pulling it again and the wait that would ensue though. Oh well.

They found that there was a tolerance stackup where the middle shift rail (toggles between different low range ratios) was on the long side of spec, the detent pill was small and the detent pocket was big. All in spec but the stackup caused issues. So they have resolved it, and will be implementing the fix on new cases and any cases coming in for service. Time to get this Jeep done and go wheelin!

 

[RockChucker]

Washed this old thing today. The paint is getting pretty bad. Planning on a cheap-ish paint job probably early fall. The engine still has the safe base tune in it to get it running. I’ll be taking it in sometime next week (hopefully) to get the trans and engine tuned. With no power to the trans controller yet, I got lucky and get 1 forward gear. I’m going to guess it is 3rd gear based on the fact that I can go about 35 at about 2500 rpm. I drove it over to the gas station and put fuel in it and drove around for 15 miles or so. I’ll drive it around a bit everyday this week to get the engine started to break in.

 

[Bart]

Good to see it out and about.

 

[RockChucker]

With the pending tap shift capability, I decided it would be nice to have a gear indicator. PCS has one that integrates with the CAN bus of the trans controller, so I bought one. Drew up a mount and hit the print button. Still need to route/tie down the wiring.

 

[RockChucker]

Tuning day is finally here! Dropping it off after work. Should have it back early next week.

 

[Greg]

Who is doing the tuning? Using a dyno or road tests?

 

[RockChucker]

Who is doing the tuning? Using a dyno or road tests?

Matt Snell is tuning it. We went back and forth and decided to ultimately use a dyno. The dyno will be slightly more expensive, but he'll get to the ideal tune faster. So more $ for the dyno, but less $ for his time. Gonna see how tricky we can get with the trans too. My ideal state:
1. Grampa driving to church tune.
2. Performance (tow/haul tune)
3. Full manual sequential gear box via tap shift (I command the gear and it can't leave it unless a mechanical over rev on the engine would happen)
4. 4 low tune. Apparently because the 6Lxx trans are always learning, they can do some funny things and don't necessarily do well with a 2wd tune like my 4L80 did.

 

[Greg]

Matt Snell is tuning it. We went back and forth and decided to ultimately use a dyno. The dyno will be slightly more expensive, but he'll get to the ideal tune faster. So more $ for the dyno, but less $ for his time. Gonna see how tricky we can get with the trans too. My ideal state:
1. Grampa driving to church tune.
2. Performance (tow/haul tune)
3. Full manual sequential gear box via tap shift (I command the gear and it can't leave it unless a mechanical over rev on the engine would happen)
4. 4 low tune. Apparently because the 6Lxx trans are always learning, they can do some funny things and don't necessarily do well with a 2wd tune like my 4L80 did.

Sounds like the right way to do it! I'm very interested to hear how you end up liking that 6LxxE overtime, they work well in a standard, stock truck.

 

[glockman]

Matt Snell is tuning it. We went back and forth and decided to ultimately use a dyno. The dyno will be slightly more expensive, but he'll get to the ideal tune faster. So more $ for the dyno, but less $ for his time. Gonna see how tricky we can get with the trans too. My ideal state:
1. Grampa driving to church tune.
2. Performance (tow/haul tune)
3. Full manual sequential gear box via tap shift (I command the gear and it can't leave it unless a mechanical over rev on the engine would happen)
4. 4 low tune. Apparently because the 6Lxx trans are always learning, they can do some funny things and don't necessarily do well with a 2wd tune like my 4L80 did.

This is awesome.
I'm interested in the 4WD tune. I have played around with HP Tuners and adjusting throttle response tables and they seem to make a difference. I'd like to have a dumbed down throttle table when the T case is in low to avoid the throttle bounce you get with V8 power in low range.

 

[RockChucker]

Due to a terrible stack up of circumstances and "custom" work getting somewhat sidelined, my Jeep has been at the tuner's for almost 2 months. He started working on it a little over a week ago and has been getting his butt kicked due some communication issues between the 6L90 TCM and PCS controller. He finally got all the issues resolved and the trans is shifting like it should, and tapshift is happy. There were 2 main issues...First the harness I got with the controller had some pins that were not fully seated in the connector at the trans. Amazing it was able to communicate at all. One of the bad wires was a direct com line (there are 2) and the other was for the tap shift. After he seated those, tap shift was working and he could communicate with the trans much more reliably, but the TCM was still throwing a U0100 code for bad communication. That brings us to the second issue...the trans cal file was corrupted. He flashed in a fresh one and voila, everything is happy. He drove it around a bit last night and ran it through all six gears, both auto and tap shift.


Next up is wiring in the toggle switches that will allow me to tell the trans what to do. First is for tow/haul mode (performance shifting) and second will be to tell the trans the tcase is in low range. After that, time to strap it to the rollers and tune the engine. Hopefully I'll have it back in my possession by the end of the week!

 

[ivantalk]

Looks like everything is falling in the right place. I am excited to see the result of this build.

 

[RockChucker]

Just realized I never updated this. I’m very pleased with this motor. It put just over 250 hp down through that big gear driven tcase and 40” tires. The calcs with air and fuel equate to about 500 hp at the crank. It is very torquey, making 450+ lb-ft at the tire 1200 rpm and beyond. Peak torque is close to 550. After driving it, i believe it. Quite the ripper. Sand dunes are much smaller than they used to be.

The shift points were a little wonky when I was in sand hollow a couple weeks ago. It shifted super early and refused to down shift, even with my foot on the floor. I went back to the tuner’s last Saturday to rectify the issues. I drove while he data logged. We’d pull over and he’d make changes. The shift points were way off because the final drive ratio was way off. Once we got that corrected it was shifting much better and when expected while driving normally. Not holding the gears too long or too short. After that it was time to dial in shifting at WOT. The first few passes resulted in bouncing off the rev limiter. It wouldn’t shift until I lifted. Slowly dialed each gear in with each pass. By the end of our session, it shifts right before the rev limiter and barks the tires at each shift all they way into 4th gear. 😳😍 It’s safe to say that we exceeded the Q speed rating on tires.