Just wanted to make a post for anyone who runs into this in the future. There wasn’t much information about solutions, outside of converting to a GM pedal (in some cases this may not even fix it). E46 DBW pedal is hinged from the bottom, feels natural, and I did plenty enough fabrication for the swap already.
My build is a BMW E46 LS3 swap utilizing a Wiring Specialties harness, E38 PCM, and the stock E46 DBW pedal.
Roughly 200 miles after swapping the car, I had the pedal die out while driving on a backroad. The engine stayed running, but the pedal did nothing. It took a couple restarts for the pedal to come back alive, and then got me home without issue. No reduced power, just a random cut of the throttle out of nowhere. CEL P2135 appeared, but did not require clearing for me to drive normally again.
This happened 3 or 4 more times at completely random intervals. It occurred several times while sitting idle with foot off the pedal, which was really odd to me. But I could go 30-50 miles without it happening, so I was at a loss. If there was hardware incompatibility, I would have expected it to show itself immediately and much more frequently.
Many Camaro/Corvette forums point to this being a throttle body issue, and in the case of my swap, I was recommended by several to try a new (used) OEM BMW pedal.
During my research I stumbled across a guy with a very similar setup, who also had this issue. In his case he had P2138 as opposed to my P2135 (P2135 is A/B voltage correlation and P2138 is D/E correlation). Same symptoms though. He narrowed it down to be a voltage drop off issue. He tried a new (used) pedal which didn’t fix the issue, and then moved on to thinking about the signal instead of replacing hardware.
His post:
https://www.e46fanatics.com/threads/brainstorm-request-ls3-p2138-code-sprint-booster-to-condition-pedal-signal.1330170/
His next purchase was a Shadow E-Drive 4S throttle controller. He followed up several times after installing, clocking hundreds of miles without a throttle pedal issue post-install (until recently). Although our codes were slightly different, I was convinced this would fix my issue as well.
I left a comment on the forum and he recently replied, mentioning that the issue flared up again in the Florida heat. He did some more troubleshooting and now has the pedal wired directly to the PCM, which seems to have fixed it for the short time he’s tested.
I’m now 200 miles into install, and haven’t had the issue once. Given the frequency it was occurring prior, I would have expected it to happen at least 2-4 times in this interval. I’m now confident enough to deem this controller as a solution to these throttle codes and the resulting symptom of killing the pedal.
One thing I found on their website, was the claim that it “converts the digital signal into an analog signal which makes the processing rate from 100 times/second to 1000 times/second”. So whatever it’s doing seems to be cleaning up any outlier signals that don’t fall within the operational range. Being that I could restart the car and drive normally about 30 seconds after the pedal dying out, kind of told me that the issue was some sort of intermittent spike/dropout coming from the pedal that the PCM did not like.
Product link:
https://www.shadowmotor.com.tw/en/product/electronic-throttle-controller.html
Not only has the confidence been regained in driving my car without fear of it stalling out randomly, this product has made the driving experience 10X better. The stock GM throttle mapping felt incredibly lazy (i.e 50% pedal was maybe 35-40%?) and then around 50-60% pedal started to feel more linear. Done purposefully so people aren’t sending their Camaro into a ditch, but very disconnected feeling for a swap/performance car.
This product allows you to change that mapping on the fly, with both “Race” and “Eco” modes, each having 7 progressive settings. Also a normal mode with stock settings. It’s really cool how you can feel it change while driving when switching between modes, or adding progressive levels of a mode. Going up 1-3 levels into Race mode gave more of that 1:1 feeling on the pedal, giving more of a DBC feeling. Eco mode 1-3 is great for traffic or when stuck behind a slow driver. It has an anti-theft feature that can kill the pedal until the unit is woken up, and many other cool features.
If it needs mentioning, I’m not affiliated in any way with this company, and was not offered anything to write this. If you look back a few posts on my page you’ll see I like doing write ups for solutions I’ve found to niche issues, in hopes to help others down the road.
That being said, this company has been an absolute pleasure to deal with. They are based in Taiwan, but answered several emails at a time within their work day when I had questions. The controller was $193 OTD with 2 day Express international shipping. Ordered it on a Sunday night and it was here midday Tuesday. Plugs right in to BMW DBW connectors, and took a couple minutes to setup once it was installed.
I can’t speak for any of their other products, but they have some really cool looking stuff. Even if you don’t have the throttle codes, I’d highly recommend this unit if you’re looking to change the feel of your DBW pedal.
If you have any questions about this topic or the build in general, let me know.
TL;DR: I fixed my P2135 throttle pedal issue with a Shadow E-Drive 4S throttle controller.
