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LS4 swap begins


carkhz316
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A grinder and paint make the welder I ain't. 

 

I could have done better, but my cheap Hobart is clapped out and well, I'm not a fabricator. Also, I did some rattle bomb to touch up the transmission as well, in addition to some black paint on the underhood to clean up the strut tower. I'm going to be hopefully nestling the engine back in the engine bay for the last time this week so I can continue on plumbing and wiring.

I did find that I can just crimp new fittings on AC lines as the hydraulic hose maker at the local parts store can do AC line crimps (basically same operation). I just need to get the appropriate fittings is all. But if I can procure some, then I I can keep the AC system native to the Monte (easier in the long term, in my opinion) and only have to be concerned with the suction/ discharge hose assembly being custom.

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Edited by carkhz316
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And it's in............. hopefully for the last time................for awhile... or at least until it runs. The cradle is bolted solidly to the car at this point, and the motor mounts are loosely attached (gotta get more bolts and nuts). Everything fits so far, so now its on to wiring and plumbing. I also did a little trimming on the PCM box to tuck it farther into the fenderwell. My goal was to keep it in the stock location, and I think it'll work.

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Edited by carkhz316
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This is actually after I've consolidated all the LS4 and Z34 wiring. There are no extra wires left in this picture.

 

It really looks worse than it is.

 

Theres really only a few main bundles to sort through, otherwise the rest are categorized based on component/ sensor, etc. with labels at the PCM end so I can keep track of everything. The foreground bundle is the original Z34 front end harness that has the battery cable, ground cable(s), fan wiring, and any accessories on the drivers side of the engine bay, so it'll be returned back to the bottom of the radiator support. I had to take it apart to rid it of the old 4T65 wiring and some other bits.

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Edited by carkhz316
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A little more clean up has been done. I need to order another round of terminals to crimp one of the fan plugs, and some others for the right electrical buss (fuse box), as well as the PCM terminals. I also need to either modify the throttle and cruise cables or get different ones, as they are overall too long (not a big deal), but more importantly, the throttle end is too short to attach properly.

Also also, I'm debating retaining the EVAP function. I know I don't have to, but it doesn't hurt to have and helps to avoid having transient gas fumes venting all the time. Thoughts?

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Edited by carkhz316
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  • 2 weeks later...

I received my PCM pins and a few others I needed to continue pinning and terminating my wiring harness. I have power steering and coolant lines connected. Suspension/ drivetrain is reassembled, though something happened with my clutch hydraulics during the course of engine R&R as they no-worky. No matter, I have a spare new Master, and ordered a new slave from RockAuto. I thought of nabbing the used ones off my parts car Lumina in the meantime to try out. The PCM pinout will follow 99-02 F-body, since they're the closest match to the Monte I feel. They both run dual electronic fans, 3-wire pressure transducer AC control, and have built in manual trans calibrations in the OS. They only hiccups I've found so MIGHT be with the charge indicator ("VOLTS" light in the Monte), fuel guage control and the knock sensors (I'm running the LS4 2-wire knock sensors). Regarding the fuel and KS: supposedly HP tuners has been updated in recent years to where LS1-style PCMs toggle the settings to run the PWM fuel guage like the Monte has, as well as run 2-wire knock sensors. I guess I'll see how that goes.

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Edited by carkhz316
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  • 3 weeks later...

It's almost done, I think, haha. I realize this is like the umpteenth engine bay shot, but its a little more progress with every picture. I've forgone some final detail work temporarily (such as A/C connections) in favor of getting it running under its own power this year. Anyway, all I have remaining is:

 

Cobble together an intake so I can slap the truck MAF and a cone filter on it for the time being. Later I intend to build a proper cold air intake utilizing an LS7-style MAF.

 

Load an F-body tune to the PCM and tweak some settings for the Monte.

 

Fill with fluids and double check for leaks and any connections/ fasteners, including figure out where/ how to mount a coolant overflow reservoir. The LS4 version is just sitting there as I don't know how I want to proceed with it.

 

 

Besides that, I've: 

- made a bracket for the oil filter mount to attach it to the rear motor mount. Connected to the engine using -10 PTFE hose and AN-type swivel elbow fittings.

- mounted a catch can to a modified (shortened) Monte upper engine mount. The catch can actually made routing the PCV hoses a little easier.

- shortened cruise and throttle cables, and reattached.

- replaced clutch hydraulics. The master cylinder somehow rolled the inner piston seal since it's been home. I don't know how thst happened, but it explains why it wasn't working upon reassembly. I'm going to try to rebuild the blown master because the appear to be unobtainium nowadays.

 

I'm sure I'm forgetting something, but it's getting so close to turn-key that I can taste it. Thanks for looking!

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This is amazing! Great job!!!!  

 

I am curious why you are using an LS1 style wiring/PCM diagram etc, vs just running the LS4 PCM ?  Maybe I'm mis-understanding.    Looking forward to this moving under it's own power!!

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So the reason I went with a Gen 3 controller is because I felt it would be the best option to integrate with the Monte. It has analog inputs and outputs that are compatible with the car, as its a similar electrical architecture to the 99-02 F-body. A/C, fans, fuel pump, and instrumentation are all very similar and since my main goal has been to "make it look like it belongs", it made sense for me. Plus, the Gen 3 PCMs are physically the same as this era of W-body, so I could keep it in the stock location if I wanted (mostly). Theres some other reasons, but that was my main motivation.

 

Also, Gen 3 engine wiring is nearly identical to Gen 4 (even the wire colors) with the exception of the Gen 4 engines adding 2-wire knock sensors, DBW throttle control, and DOD. So most of the wiring is the orignal LS4 that I reused.

Edited by carkhz316
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I absolutely have to tune it some more, but I was just too anxious to wait. I'll have to continue tomorrow and through the weekend to hopefully get to take it for a test drive. Anyway, here's a sneak peak

 

 

Edited by carkhz316
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On 11/1/2022 at 8:47 AM, carkhz316 said:

So the reason I went with a Gen 3 controller is because I felt it would be the best option to integrate with the Monte. It has analog inputs and outputs that are compatible with the car, as its a similar electrical architecture to the 99-02 F-body. A/C, fans, fuel pump, and instrumentation are all very similar and since my main goal has been to "make it look like it belongs", it made sense for me. Plus, the Gen 3 PCMs are physically the same as this era of W-body, so I could keep it in the stock location if I wanted (mostly). Theres some other reasons, but that was my main motivation.

 

Also, Gen 3 engine wiring is nearly identical to Gen 4 (even the wire colors) with the exception of the Gen 4 engines adding 2-wire knock sensors, DBW throttle control, and DOD. So most of the wiring is the orignal LS4 that I reused.

Ah yes. the Gen 3 vs gen 4 LS.  Makes sense to use Gen 3 and keep it DBC! 

 

 

The engine sounds and looks really good!!!  Great work!!   Going to be a blast once it's tuned and on the road!!  

 

 

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I did technically get to drive it, and its pretty awesome, though I need to really work on the tuning. The good news is that everything seems to work and theres no extra noises, or warning lights. Unfortunately, the videos are pretty basic and it was really late on Sunday when I took it into town to get gas and run it through the car wash. I was in a hurry finishing other things so only a crappy cell video for proof of concept.

 

 

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So sweet!!  great job!!  Glad the clutch is working properly as I know you had to do some custom measuring etc!  This is awesome!    Hopefuly tuning will go smooth for you!

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  • 3 months later...

I just read the entire thread and I think it's an AWSOME undertaking! I bet she'll be fun to drive and show off this summer! My question is what you do with your old setup? You mentioned there was nothing wrong with but you just wanted the V8 noises (LOVE IT). I have a 93 Lumina Z34 and am planning on doing the L36 swap. Yours is already done, tested and true- any chance on you selling it if you already haven't? 

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Hey thanks for the kind words. My top-swapped SC3800 is just sitting on the engine stand in my garage collecting dust. I've considered selling it but the truth is that 3800s in general are plentiful and getting on in age. As such, they don't seem to be worth as much as they used to. However, I'm not against the idea of it living on in another vehicle. I do have the engine harness and PCM(s) for it as well. Where are you located at?

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Sorry, I'm just seeing this. I'm in Michigan not too far from Detroit. I was inspired by your build too so now I'm going back and forth between the 2. Everyone is warning me about the LS4's transmission issues but I also read somewhere that with some mods, there is another trans that'll for and hold up.

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So yeah, I've been looking around. The trans I mentioned was the 4t80e. I've seen comforting numbers, but by all accounts, it's a stronger tranny.  On another note, hopefully you documented your wiring changes to make it easier for us who will follow your lead😁

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Do all of your gauges work? This is pretty cool. I’ve been deciding wether to do my 95 . Figured the obd1 differences would be greater challenge than my current van 

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On 11/1/2022 at 7:47 AM, carkhz316 said:

So the reason I went with a Gen 3 controller is because I felt it would be the best option to integrate with the Monte. It has analog inputs and outputs that are compatible with the car, as its a similar electrical architecture to the 99-02 F-body. A/C, fans, fuel pump, and instrumentation are all very similar and since my main goal has been to "make it look like it belongs", it made sense for me. Plus, the Gen 3 PCMs are physically the same as this era of W-body, so I could keep it in the stock location if I wanted (mostly). Theres some other reasons, but that was my main motivation.

 

Also, Gen 3 engine wiring is nearly identical to Gen 4 (even the wire colors) with the exception of the Gen 4 engines adding 2-wire knock sensors, DBW throttle control, and DOD. So most of the wiring is the orignal LS4 that I reused.

Did you use fbody ls1 ecu? Just making sure. I’ve been considering doing this to my 95 but felt the computer issues would be too great. 

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On 3/17/2023 at 8:28 AM, project 92z said:

So yeah, I've been looking around. The trans I mentioned was the 4t80e. I've seen comforting numbers, but by all accounts, it's a stronger tranny.  On another note, hopefully you documented your wiring changes to make it easier for us who will follow your lead😁

So in regards to the wiring, its basically wired like a 99-02 F-body with a manual transmission. Where this is interesting is that the chassis electronics are near identical to the Monte Carlo, including fans, A/C, cruise control, and some other items. The only wiring changes were the "LS-swap" aspect, which would be applicable to any vehicle. Thats where the vast majority of the custom work was done as it was merely wiring up the PCM to the engine harness along with the PCM controlled chassis items (fans, A/C, etc).

On 3/19/2023 at 7:24 AM, ManV8n said:

Do all of your gauges work? This is pretty cool. I’ve been deciding wether to do my 95 . Figured the obd1 differences would be greater challenge than my current van 

All the gauges work with the exception of the fuel guage. I have to calibrate the PWM signal in HP tuners yet. There is no set table since the values for an F-body differ from a W-body. So, when the tank is at 1/3, it reads half; half reads full, etc. Also, F-bodies are screwy as only 98 models relied on a PWM signal sent directly to the cluster from the PCM (which is what the Monte needs to register). 99+ F-body relies on serial data to control the fuel gauge, which isn't compatible with the Monte.

You can certainly use any Gen III, P59, P01, or 0411 PCM for a swap. They'll all blend in with the car just as I've done. The chassis electronics in your 95 don't really differ from my 98, so the changes you'd make would be the same as I did. Most of the wiring changes are simply adding the V8 to the car, and running the wiring to the PCM.

The only OBD-related aspect would be swapping your DLC connector basically. All the OBD2 info is going to be contained within the PCM, which will still communicate to the DLC connector via a single serial data wire already present.

On 3/19/2023 at 7:51 AM, pshojo said:

Did you use fbody ls1 ecu? Just making sure. I’ve been considering doing this to my 95 but felt the computer issues would be too great. 

No, I started with a random 0411 PCM from a 2001 Avalanche. I then "found" a stock VIN from a 2001 Camaro manual transmission to reference for an OS. Then I used my VXdiag and Techline Connect to reprogram my donor PCM with the above Camaro OS (basically what you'd do if you brought your car to a Chevy dealer to replace a PCM). Then, modified the bin with HP tuners.

On 3/19/2023 at 7:52 AM, pshojo said:

Appears you also had to pound the strut tower in a little bit? 

Yes, I had to modify the strut tower. I cut and folded the inboard edge of the top of the tower down, re-welded it and did a little bit of body work to cover up my changes. It looks mostly factory and still has plenty of room between the sheetmetal and the coil spring.

Edited by carkhz316
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  • 1 month later...

Wow!  I've been gone for ages and I missed this!  Looking good!  That's a crazy amount of work you did but it turned out really well!

Edited by Dark Ride
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