1987 R20 Suburban LQ4 4L80E swap

[COS399]

Looks great. Good Job.

[MTCK]

Nice work that looks awesome. What are those codes?

[Nodnarb76]

Originally Posted by MTCK

Nice work that looks awesome. What are those codes?

Keep getting p0171 & p0174, too lean on banks 1 & 2.

Thanks for the kind words!

[Marshy]

Nice work. What are you getting for fuel mileage now? Did you move your filter and get the codes figured out?

[Nodnarb76]

Originally Posted by Marshy

Nice work. What are you getting for fuel mileage now? Did you move your filter and get the codes figured out?

Thank you, I'm getting around 14mpg (mostly highway driving). I have clocked about 2000 miles on my tuck since the swap and everything seems to be going fine with no problems. I moved the fuel filter/Regulator down a little bit on my firewall with no issues. I did get the CK engine light figured out, turns out the people that did my exhaust left the bolts loose that connect the exhaust to the manifolds and that allowed air to get into the exhaust and past the o2 sensors creating a lean code.

Here is a recent pic of the motor after everything was done.

[Marshy]

Very nice. I want to build a 6L myself even though I don't have anything to put it into besides my K10 right now.

How is the power?

[OutlawDrifter]

Just read through your thread. Very nice setup! I would live to have an LS swapped 3/4t burb. Lice the two tone combo also!

[Nodnarb76]

Originally Posted by OutlawDrifter

Just read through your thread. Very nice setup! I would live to have an LS swapped 3/4t burb. Lice the two tone combo also!

Thank you for the kind words!
it was a lot of work and a lot of money, but in the end it was definitely worth it.

[l92powered77]

Wow really nice burb.who tuned the ecm? I have the p0171 ans p0174 and cant get rid of them either. Bolts are tight. I need a serious retune i only have a stock tune from psi conversion. Who did your tuning? You have hgen 3 you can send it quick anywhere to want without having to take out tcm like ua hen 4 guys. Sounds good i have same mufflers on a 6.2. Did you end up shaving tabs off tranny for manifolds? I had to switch to ls3 manifolds. nice build! Do you tow anything?

[Nodnarb76]

I found an exhaust leak at the manifolds where they meet the exhaust. Got that taken care of and codes haven't come back. I would recommend running some seafoam through your motor, and see if you see any smoke/leaks.
My ECU came already tuned with my harness/motor from LSX4U.com. Good people to work with.
I did have to cut the tabs off the transmission with a sawsall for the exhaust to clear.
I don't tow anything but if I wanted to, I feel I could with no problem.
Good luck on your build, I hope you get those codes figured out.

[dwntwn]

Originally Posted by Nodnarb76

Got a lot more done today.
Got the TBI harness out.

Nodnarb, Awesome build! I've read this thread through a couple of times, had a couple of questions

How much of your stock wiring harness did you retain/reuse with the new harness?

Removing the TBI harness—that includes the ECM, right? Did you go off of a GM shop manual or did LSX4U give you the instructions on what to delete/what to keep on your '87?

[Nodnarb76]

Originally Posted by dwntwn

Nodnarb, Awesome build! I've read this thread through a couple of times, had a couple of questions

How much of your stock wiring harness did you retain/reuse with the new harness?

Removing the TBI harness—that includes the ECM, right? Did you go off of a GM shop manual or did LSX4U give you the instructions on what to delete/what to keep on your '87?

Thank you for the kind words!

when I did my swap I un-plugged the factory TBI harness from the motor. then found where the wires went into the firewall on the driver's side. I was very nervous but I cut the wires where they go into the firewall and left the TBI harness plugged into the stock connector with the cut wires coming off the connector. I did leave enough wire at the stock connector in case I had to re connect a wire I removed. I took the TBI harness home and took an entire Sunday afternoon and traced every wire on the factory harness and probed them with my multi-meter to make sure I knew what each wire did. I realized the majority of the wires were 12v switched on power for the various sensors on the motor, and of course some wires going to gauges, etc. I did remove the TBI ECU. After I removed the stock engine harness I had moment of truth, I reconnected the battery and wanted to make sure I didn't remove anything that needed to remain. I checked and all of my lights, wipers, turn signals, horn, blower motor, radio, windows etc all still worked. Thank goodness everything still worked, and I had not removed anything that I didn't need to.

The LSX4U harness was great to work with, just follow the instructions they send you, the hardest part was wiring the torque converter lockup relay.

I also made my own harness for the fuel pump/gauge sending unit and ran it back to the tank, and other end to the LSX harness and my new fuel gauge.
I figured I might as well have new wiring for everything at that point lol.

Good luck with your swap, let me know if you need anything else.

[Nodnarb76]

While I'm posting also wanted to show off my intake I painted.

[MTCK]

Truck looks great. Have you been driving the wheels off of it? How's the performance and economy been?

[Nodnarb76]

Originally Posted by MTCK

Truck looks great. Have you been driving the wheels off of it? How's the performance and economy been?

I have put about 7500 miles on it so far and it runs great.
I love this truck!

[aggie91]

This suburban would make a great tow pig for my son's '84 SWB. It has the same color combo!

[Dads79GMC]

How did I miss this one? Great stuff!

[Dads79GMC]

I could be totally wrong, but could you have used the "Upper Radiator Mounting Panel" below to mount your radiator? It steps down a couple inches or so vs the SB mounting panel???? My radiator did the same thing and I put a 1"x 1" x 3" square tubing on the bottom of the radiator core support and put the mounting cushion on the tubing.

Just thinking out-loud.

Mike