C6 Z06 ECM options

I have a 2008 Corvette Z06 time trial car with a Samsonas transmission and xineering flat shift module. This week at Watkins Glen the factory ECM failed. P0606code. Car was shutting off at 5000 rpm and 50% throttle on the second day of the event. Ran 5 sessions the first day flawlessly. Car still has factory ECM, BCM, but I'm running a Mk 60e1 ABS swap. I'm trying to evaulate ECM options to simplify and ruggedize the wiring of the car. The options I'm thinking of right now are as follows, but I'm open to considering other solutions.

1. New factory ECM, code to vin, keep everything as is other than adding extra ground from ECM to engine block. Keep xineering module. cheapest solution. Does not simplify wiring or future fault resolutions. ECM in factory position behind passenger front fender.

2. "connect and cruise" style factory ecm. Delete BCM and all factory wiring. Keep xineering module. need to rewire door openers, windows, wipers. can mount ecm in cabin for ease of wiring and future trouble shooting.

3. Motec M150 with custom harness. Delete BCM, factory wiring, Delete xineering module, still need some chassis rewiring. most expensive.

4. Haltech nexus R5 with harness. Delete BCM, reroute necessary factory wiring through R5 PDM, seems like the R5 can handle the flat shift functionality like the Motec. Middle of the cost spectrum.

Anything else I should consider? I'm a bit intimidated by the Motec from friends that run those systems. I'm comfortable with the factory ECM and HP tuners. The Haltech is intriguing, but I'm not certain about support in northeast USA.

I would at least try another ECM first. Never hurts to have a spare. If that doesn't cure it, they I would look for someone with good diagnostic skills / tools to find the actual fault in the wiring. Once you know the fault (and wiring harness weakness), then rebuild / replace that with a more rugged solution.

Steve,

That's a pretty common setup and I end up using Link or Motec, including having it handle traction control and sequential box without external units. On a dedicated race car all the safety features, better logging, etc. just make sense.

They can be used with or without replacing body wiring.

FWIW P0606 doesn't necessarily mean the PCM failed, and once that code is thrown the engine will be limited like you mentioned. Calibration settings which cause the PCM to determine an implausible condition is present will cause that code, most frequently this is related to the drive by wire system, but can be caused by other things. You generally won't get other codes and have to narrow things down yourself. I've seen people replace PCMs, think they fixed it, then next track day have the same issue because it was their tune not the PCM actually physically failing.

Another example of a P0606 cause on your car that I've seen is getting the throttle body hot and it starts sticking because someone didn't specifically request the high temp shaft seals when they got their big throttle body. Most of the 100-105mm ones commonly used on your car aren't up to the task of road course use in off the shelf form.

Mike, I suspect the problem is the wiring not really the PCM - but that got me thinking that it is probably time to simplify and eliminate all the unused factory wiring, get rid of the body control module, key fobs and everything else a time trial car doesn't need. All the factory wire is 16 years old now. I think the problem started at Watkins because of the extended amount of full throttle around that track, and thus more extreme heat soak. I have a full GSpeed cooling package on the car, and temps were decent, but after the second session on day 1 the car did not want to restart while it was still hot. That had never happened before.

Thanks for the advice about the throttle body, I had not heard of that issue before. I am running a Katech TB, but I forget the exact size at the moment.

I am picking up a spare factory vin coded pcm because they are $200, just to help diagnose the issue while I decide on a long term solution. Everything seems to be pointing to Motec. I'll work my way through the HPA Motec course.

Steve,

I totally agree with your thoughts, just wanted you to know the stock PCM likely isn't the root cause in case that helps you make a more informed decision. Like I said, I'd go standalone too. I think you're on the right track and glad you're taking advantage of the HPA course!

Keep in mind if you have the super common heat soaked big LS throttle body sticking on track issue, Motec will fail the DBW system as well when the throttle body gets sticky and isn't behaving. In general this isn't the easiest thing to replicate because sometimes you can't replicate it without sufficient track time. Like you said the Glen has way more time on power than some other tracks, especially if you are comfy enough there to be flat from T1 apex to the bus stop. A track day lost is usually far more costly than a throttle body, so I talk to Nick Williams and get one with the upgrade applied up front for my folks. He's very aware of the situation and what to do about it. Katech also does a good bit of road course work so since you already have one, I think it's worth asking if they have any insight or if they have some higher temp seals and other components that they use on race cars which might help your situation.

In terms of the cooling package you have, what removes more heat from the engine and places it in the engine bay, can make the throttle body more likely to act up. Hood venting will help fluid cooling work even better, and also help engine bay temps, as long as the vents are put in just the right place, properly constructed. If you haven't gone down that road yet, it's something I'd look into.

Mike,

I have a vented world challenge hood on the car to help with heat evacuation, but I do know that hood design was dictated by the series rules, so it is better than stock, but not optimal. I'll do some homework on my throttle body - I should probably carry a spare with me anyway.

Thanks,

Steve

Sounds good Steve!

Got the car operational for the last TT of the season for us in New England. New ECM worked, but I think Mike is right that at least part of the problem is my throttle body - since I got some engine hiccups during practice sessions, and on lap 3 of my time trial. I'll be talking to Katech today about a new throttle body, and hope to test that in a week and a half.

Well done!