1997 E36 M3 Sedan LS1/T56 Swap

**BigL350** · 10-22-2018, 10:45 PM

Tried to start the LS3 for the first time today but only got it to crank and no start. The fuel pump will prime with the first turn of the key but not afterwards. I’m getting the following codes after clearing that keep coming back after turning them off in HP Tuners:

P0122 Throttle/Pedal Position Sensor Circuit A Low

P0223 Throttle/Pedal Position Sensor/Switch B Circuit High

P0449 Evaporative Emissions System Vent Control Circuit Intermittent

P0807 Clutch Position Sensor Circuit Low

I can see the throttle position moving normally in HP Tuners when I move the gas pedal and the throttle body is moving accordingly. I guess I’ll double check my wiring for the DBW pedal anyway.

It still doesn’t make sense that these DTC’s keep coming back after I’ve shut them off.

Any advice would be appreciated. I’m super newb with HP Tuners.

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**JimLev** · 10-22-2018, 11:54 PM

What are you using for an ECU, the one from GM for the LS3? If so there is a pink wire that needs to be connected to 12 volts when the key is in crank and run position, otherwise the engine won't start.

**BigL350** · 10-23-2018, 07:45 AM

It’s the e38 PCM from the LS3. It’s getting Batt, Ignition, and ground where it’s supposed to. I was able to connect with HP Tuners but had a communication error at first so I checked all that.

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**JimLev** · 10-23-2018, 10:38 AM

Did you have the security things from the PCM programmed out?

**BigL350** · 10-23-2018, 12:18 PM

Just figured out that I didn’t have VATS turned off correctly. I needed to be in “advanced” view in order to see this in the OS tab. Going to load the file and give it another try after work.

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**BigL350** · 10-23-2018, 07:24 PM

VATS deleted and still no start. Next day I can get in the garage I’ll double check the pedal wiring.

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**RulyLSX** · 10-23-2018, 11:38 PM

even with vats on it would still start than just die slowly after, at least on ls1's it does. Is there a way to bypass the pedal just to get it started somehow? Feel like that would be the only thing preventing it.

On my car I had a similar issue of crank but no spark and it ended up being the temp sensor that wasn't plugged in

**BigL350** · 10-24-2018, 10:02 AM

I have a GM pedal I can wire up if needed. I put a six pin weather pack connector in between the main engine harness and the pedal harness going into the car. I’m going to check the pins from the PCM to that connector and then to the pedal connector. Maybe I just screwed someone up there. Odd that the throttle body follows the pedal movement perfectly though....

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**JimLev** · 10-24-2018, 11:47 AM

A few years ago I helped a friend put a GTO LS into his E38. I did the wiring and have been looking for the info on my computer, just can't seem to find it. It did start up and run.
Schitzo did give me a few pointers.

**BigL350** · 11-07-2018, 06:27 PM

It’s running! The e46 DBW pedal works perfectly. I learned the hard way that to make changes in HP Tuners to things like VATS, you have to select “Write Entire”. I was doing “Write Calibration” and didn’t realize that nothing was changing. Total newb/inattentive mistake.

Anyways, here it is. Please excuse the wiring mess:

Whole jam:

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**BigL350** · 11-07-2018, 06:36 PM

Forgot to mention that I found my battery dying problem. While I was poking around in HP Tuners with the ignition on but the engine off, the HVAC blower turned on with the HVAC controls off. Later I put a clamp- on ammeter on the negative battery cable and saw an 0.9A draw with the car off. Pulling the blower fuse got me back 0.5A then pulling the cigarette lighter fuse got me another 0.2A. That’s because some knucklehead (me) wired the gauge pod to battery, not ignition. Gotta change that. Once those draws were eliminated, amperage varied between 0.2 and 0.0. I wonder if the FSR itself was still pulling some intermittently. Anyways, that’s a hell of a lot better than where I started.

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**BigL350** · 11-25-2018, 07:13 PM

Just want to pass on this link that is a guide for idle tuning on the GM E38 ECM. With the factory settings it was all over the place and my cam is VERY mild. Before finding this thread I just increased the idle RPM settings to get the car to stay running. I followed this guide exactly and was able to get my car idling smoothly.

https://forum.hptuners.com/showthrea...e-tuning-guide

**Tim Mc** · 11-25-2018, 08:23 PM

That idle tuning looks very complex!

The finished product is super clean.

How does it run compared to the previous combination? Worth the effort??

**BigL350** · 11-25-2018, 10:02 PM

Originally Posted by Tim Mc

That idle tuning looks very complex!

The finished product is super clean.

How does it run compared to the previous combination? Worth the effort??

Thankfully the person who did the write-up was really detailed. I don’t think I really grasped what was going on until after it was done. It’s basically having you disable anything that influences idle spark, airflow, and RPM, then has you find the setting that make it idle best, and then has you enter those settings in the appropriate places and re-enable all the other factors with a few tweaks. Probably 1000x easier with a stand-alone.

It’s a significant increase in power from the LS1. It feels like there’s a lot more mid-range power. Where the LS1 needed to be pushed a little more for it to feel fast, now you feel it as soon as you move the pedal. I’m really happy with it and I think it was worth all the effort. Hopefully I’ll have the mechanical side of things wrapped up by the end of the year so I can get moving with the restoration work.

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**BigL350** · 12-10-2018, 10:16 PM

Small update: I’ve been putting some mikes on the car and evaluating my likes and dislikes. One of my dislikes was all the gear noise from the transmission.

I tried putting some sound deadening foam sheets in the center console but that didn’t make any noticeable difference. I did a little research and found that the Hurst Billet Plus shifter I was using is notorious for transmitting noise into the cabin.

Some companies are selling strips of rubber to put between the shifter and transmission case and between the handle and shifter. Neither is going to do much because there’s still metal to metal contact through the bolts. No guarantee from the seller that it will do anything either.

I decided to try the OEM Hurst shifter that came as an option on the 4th gen F-bodies. I figured an OEM wouldn’t tolerate that much noise in the cabin. Another difference is that the OEM handle has a rubber isolator built in. So, I bought a used shifter off eBay and made my own isolated handle with some pipe and flexible marine sealer from Home Depot.

I’m happy to report that the gear noise is almost totally gone when everything is cold and completely gone after a bit of driving.

Next on the list is the exhaust. I’m going to do dual 3” out of the headers, through cats, into a pulse termination box, dual 2.5” out of the box, then resonators and the Borla muffler I already have. The other trick is that I’m putting in a vacuum actuated butterfly valve in one side after the box to keep things quieter at idle and low load. Hopefully I can make it happen before the end of the year.

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**Tim Mc** · 12-11-2018, 05:36 PM

Glad to hear the bump in power is significant. Certainly always welcome and cubic inches is typically understood as the best way (and LS3 heads).

Is the trans a bit long in tooth? Our T56 Magnum is nearly silent...a bit of sound on gear spin up, but cruise is unnoticed.

Unfortunate on the shifter as the Tremec offering with ours is the best in the house...very short stick, but works like one would hope. Makes my other shifters quite disappointing!

Will be interesting to see the exhaust combination.

**BigL350** · 12-11-2018, 10:46 PM

Eh, I’d say it’s middle aged. If I didn’t find so many threads about that particular shifter transmitting noise I would have suspected the trans. One thread had a guy who rebuilt his trans only to find that the noise was still there.

If I had to do it all over I’d go with a CTS-V T56 or TR6060 and adapt the BMW shifter and linkage. For now I’m pretty happy with it.

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**BigL350** · 08-14-2019, 08:04 PM

Long overdue update: The car sat in the exhaust shop for about six months. It was pretty frustrating but I’m pretty happy with the outcome. I wound up doing 3” pipe from the headers through cats into a pulse termination box. Then dual 2.5” out through resonators into the existing Borla dual in/dual out muffler. I had them put a vacuum actuated butterfly valve in one tailpipe that is held closed by vacuum. The vacuum line still needs to be connected.

The shop said that they’d lose the gas pedal response once in a while but putting a jumper pack on the battery would keep it from happening. I experienced the same thing when I picked the car up. Codes were p0138 and p0122. I though that maybe it was due to the battery having been dead a few times but after I installed a new battery the pedal was lost permanently. I did some troubleshooting and determined that it was the PCM. I installed a new one and pushed in my last tune and now all is well. Hopefully it stays that way.

The exhaust sounds incredible under load, like an exotic. There’s a slight resonance I think because I didn’t reinforce the termination box enough. The exhaust is going to come back off soon for reinforcement, to have flanges installed between the mid-section and muffler, and for ceramic coating. Just want to put some more shakedown miles on before going any further.

I will try to get a video soon so you guys can hear the exhaust. That alone was worth all the headache.

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**Lantz** · 08-15-2019, 12:04 PM

6 months in the exhaust shop? Holy crap, what happened.

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**BigL350** · 08-15-2019, 12:20 PM

Originally Posted by Lantz

6 months in the exhaust shop? Holy crap, what happened.

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I don’t know but it’s probably because they know my job has me out of town most of the time and it’s not my DD. They’re willing to experiment with things like a termination box and butterfly valves and don’t charge me much because they’re into it. They’ve done more routine stuff for me and got it right in and out.

Also, forgot to mention that I finally found some LM reps:

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**RulyLSX** · 08-16-2019, 05:39 PM

6 months, holy shit. exhaust work looks nice and tucked though

**motorV8ed** · 08-17-2019, 10:23 AM

Topside and underneath both looking really nice!

**mrallande5020** · 08-17-2019, 07:06 PM

Damn, just read this whole thread and you'r bringing that thing close to oem specs man. From cabin noise to the fit and finish of you'r engine bay and interior. Incredible! And the rims fit the build perfectly.

**Michaeldip** · 08-17-2019, 07:56 PM

yep, replaced the starter. car starts like a gem again minus a/c issues lol. the top bolt for the bracket and starter location is a b to get to. haha

**Tim Mc** · 08-18-2019, 02:19 PM

Agreed - must have much time traveling to plan your next moves!

Really impressed with your new wheels...how do the weight against the DS2's?

Car looks brand new...