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It finally cooled down below 100 and got to drive the car for a bit tonight. Immediately had an issue with the throttle and hopefully someone can help me figure this out.
While driving, about every 30-60 seconds the throttle would stop working (oem camaro drive by wire). Car acted as if the throttle input was just gone. To get it to work again I had to turn the battery off, give it about 15 second to reset, and then start it back up and start driving again. This has only happened to me once before and I had hp tuners hooked up and logging. Couldn't find anything of interest that would explain this in the logs. The one thing different about tonight was that I had the headlights on. I'm going to do another drive tomorrow with no headlights, but the only thing I can think of is that somehow the power draw from the headlights is causing issues with the drive by wire throttle, but that sounds a little crazy.
The battery was fully charged before the drive and the car had no issue starting back up immediately every time I turned it off.
I checked all the connectors and everything is nice and snug on the ecu and throttle.
Could a voltage dip cause the throttle to drop out? I am running the oem alternator and it does have the known issue of not reaching the ideal charging voltage. Maybe the headlights were too much to keep up? I never drive the car at night with headlights, so this is a new issue. Curious to see if it does it tomorrow with no headlights.
OEM alt is capable enough, and despite being 13.8 setpoint, should output that reliably. I suspect it'd gone into limp mode possibly from the throttle pedal - they tend to fail safe so you're not barrelling into a family on their Sunday walk by the freeway. Ours did something similar - though somewhat random at times, and despite recrimping the pedal, I finally had to give in and solder the crimps. No reoccurance since then.
OEM alt is capable enough, and despite being 13.8 setpoint, should output that reliably. I suspect it'd gone into limp mode possibly from the throttle pedal - they tend to fail safe so you're not barrelling into a family on their Sunday walk by the freeway. Ours did something similar - though somewhat random at times, and despite recrimping the pedal, I finally had to give in and solder the crimps. No reoccurance since then.
Interesting.... so soldering the crimps on the connector at the gas pedal fixed this for you? I'll do it today and see what happens. Thanks!
I was going to suggest the throttle wire just like gooflophaze. I’ve been told by a buddy who has done multiple ls3 swaps that the throttle wiring is very finicky. Im guessing he had a bunch of issues with it, it was one of the few things he seemed very adamant about. Good luck! Hopefully quick fix & cools down a little more and you get to drive her!
I was going to suggest the throttle wire just like gooflophaze. I’ve been told by a buddy who has done multiple ls3 swaps that the throttle wiring is very finicky. Im guessing he had a bunch of issues with it, it was one of the few things he seemed very adamant about. Good luck! Hopefully quick fix & cools down a little more and you get to drive her!
I'm am 99.9% certain that this issue is caused by a DBW calibration that we are unable to run in HPT and can only be done in the GM SPS software when they install a new throttle body.....similar to the "case learn" process that recalibrates the ECU to the crank and cam sensors.
Like Goof mentioned, the whole system is a failsafe to make sure you dont have a stuck throttle body. The basic version of how it works is that there is a 5v refrence signal to and from the ECU that manages the change in position of the throttle pedal to the TB and then there is a pair of circuits that verify the current position of both. If the resistance difference between those two circuits is exceeded, you go into limp.
I think there are a few things that can cause it, but he most common instance I have seen of this issue, and I have been investing at least a dozen around the world, is when the TB gets hot and impedance climbs, the tightly calibrated threshold between the two throttle position sensors is exceeded and throws the ECU into limp. I think the issue is compounded by the fact we are normally mating a TB and ECU that were never calibrated together so some swaps have almost no tolerance at all to them and others only see the problem on the hottest of days and on the track. I think if it was a harness/connector issue, we would have seen a recall on almost every vehicle the 3.6 was installed in if they were really that intolerant of wiring variables from the factory.
As others have mentioned, the connector at the throttle is a finicky one and if those pins are not perfect they will cause a similar issue between the pedal and the ECU.
So I have been trying to figure out how to weight the exocet. No weigh stations within 15 miles of me and I'd like to be able to do this in my garage. I also didn't want to spend $1k+ for scales. Just came across this video which looks awesome. Btw, already tried cheap bathroom scales and that didn't work for ****.
So I have been trying to figure out how to weight the exocet. No weigh stations within 15 miles of me and I'd like to be able to do this in my garage. I also didn't want to spend $1k+ for scales. Just came across this video which looks awesome. Btw, already tried cheap bathroom scales and that didn't work for ****.
I soldered all the pins and put the connector back together. Matched the wires exactly as they were when I took them out. Now the car has no throttle control. Just idles. No error codes in the ecu either. I triple checked to make sure the connector was seating all the way and the pins weren't moving or out of alignment. Everything looks great. Wtf?
Ordered a new accelerator pedal just to start eliminating things. Since this is now getting worse I'm wondering if the pedal sensor is on its way out. Mine only had 14k miles on it though, so that would be odd.
Griff just happened to be in town and stopped by to look at the car. Couple things, wires are in the correct order and throttle pedal works just fine. He had me clear the error codes and the throttle immediately started working even though there was no throttle code being thrown. I'll let him go into more detail on this if he wants, but it seems as though this is a common issue on these swaps and he is working on a solution.
Edit: He also brought his scales and we got a weight. She's a fat pig... 1,805 pounds with 10 gallons of gas. Trying to figure out where I might be able to lose some weight on the car, but I'll save that for another day.
Griff was reviewing my most recent log and saw that my Bank 1 (passenger) O2 sensor was flat lining, and has been for a while now. New one ordered and hopefully this fixes the issues I have been having.
Couple big updates and fingers crossed I think all of my issues have been resolved. Thanks as always to Griff for helping me through this. He has become my moral support buddy as I go back and try to fix my mistakes and all the random parts in this build.
1. My passenger side O2 sensor was unplugged just enough that it wasn't visible from looking at it. It sits up against the hose off my radium expansion tank and it looks like it may have been just the right angle to come undone, or it was just never properly plugged in. Stupid mistake on my part, but huge issue when the ecu sees one bank of the engine flatlining. Weird part is that it never threw a code. Tugged on the wires and the plug pulled right out. Plugged it back in and the engine is running the best it ever has. Woohoo!!!
2. On the Keisler harness there is a molex connector between the accelerator pedal connector and the main engine harness big connectors. This little bastard had a lot of play in it and I decided to remove it and hardwire the wires in place of the connector. Accelerator pedal drama immediately went away and has yet to return. Code being thrown was a P2138 for future reference.
Taking the car for a drive this weekend and hopefully can start the E85 tuning.
Car is running absolutely amazing. Need to go get another dyno run as I am very curious where it is at. It is WAY faster now that nearly all of the issues have been resolved. The misfires on cylinder 2+5 are still persisting. It is a small amount and not even noticeable while driving, but I want this car mechanically perfect and I can't rest with the misfires. Was talking to Griff and walking through it and we are both a bit skeptical of the Corvette fpr/filter I'm using. These seem to be the common go to for this swap, but everything else that could possibly be causing a misfire has been tested or replaced. The fuel system seems like the last culprit and the pump is nearly new and very capable of supplying this motor. I have no idea what pressure the fuel system is running at and I also don't think that fpr/filter combo is capable of handling E85.
Ordering a new fuel pressure regulator, gauge and 6 micron fuel filter, both ethanol friendly. Not cheap, but should add some flair points to my fuel system. Once those go in, the E85 tuning starts and then I'll get some dyno runs in on 93 and E85 for a comparo. I've never seen a direct comparison dyno for this motor on 93 and E85, so I'm curious how much of a power gain there is.
09-05-2020, 10:49 PM
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