AT Check light flashing...car won't start
 

Background on the car.

03 G35 coupe
88,xxx miles
5AT
Vortech SC
TurboXS UTEC
supporting mods (walbro, 440s, exhaust, etc...)
Car has been street tuned, still ran a bit rich under medium throttle

Took it to get dyno tuned today. The car was strapped down and a quick run was done w/o any measurements just to make sure the straps were secure. Car was shut down to cool down a bit. Car then wouldn't start. It cranks over real strong, but it doesn't fire up.

The cars "AT Check" light flashes 16 times. According to tech specs its something about the speed sensor. We tried to hook up an OBD reader and we're getting a read error. When the key is in the "on" position, the fans automatically kick on and stay on.

I spoke w/ a few tuners, including Mark over at SGP who was frickin awesome. He said there was a bus read error or something to that effect. Something is throwing off the electrical communication within the system. We checked all fuses and everything seems to be just fine. No blown fuses. We reset the ECU by the pedal method, disconnecting the battery, and attempting to clear w/ the OBD diagnostic tool. The "AT Check" light is still blinking. Tomorrow we will try to get a hold of a Consult to read the code.

Does anybody have ANY experience in something like this?

Good luck William, keep us posted on the outcome.

Did you check the wires near the blower to make sure nothing was cut from a stray belt like what happened to Firefox? It's definitely sounds like something electrical and hopefully nothing more than that...

Have you tried just starting with the stock ECU without the UTEC?

I'm no tuning or electrical expert, but that's what popped into my mind too, the UTEC/ECU interface. Do you have a remote map selector? My first one went bad, got stuck on one map and wouldn't change. I wonder if it's stuck on map 7 (security mode) - don't know if that would throw an error though.

i would disconnect the utec and see if the car will fire up.

I will try disconnecting the UTEC. Maybe as the tuner was plugging in his cable, the UTEC map switch got toggled.

A new ECU from the dealer is $840 list price. =\

It may be worth it to see if this harness plug is rubbing against the belt (see attached). You said you checked the fuses. Is that the fuses under the driver side kick panel or the ones under the hood near the battery?

Will! You are owning this section of the forum buddy. No help, just wanted to say good luck :/

The car is fixed!!!

We had almost given up hope. I was calling around to get towed to the dealership, when a 350Z with UTEC came in to get tuned the next day. The SAME EXACT thing happened to this auto 350Z. So with some deductive reasoning the shop was finally able to determine the common link between the two cars. The USB cable used to connect to the UTEC was slightly damaged/crushed. This caused a short when connected to the UTEC, which blew a fuse in the box behind the battery. This threw off the electrical communication within the vehicle. A call to TurboXS helped determine which fuse it was. The fuse wasn't visibliy blown, but replacing it corrected the issue.

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Special thanks to Mark @ SGP who actually called me yesterday morning to see if I had figured it out. He then said he was going out of town for thanksgiving and would take my contact info with me to check in, and he'd call me again on Monday if nothing had been resolved. I have never had my car worked on by SGP, but had been referred to them by several friends who have had their G35s tuned there. He was extremely helpful in lending advice and suggestions on how we could diagnose the problem. Thank you again Mark.

Nice! Funny how the little things can cause such nasty problems.

Wow that's great to hear. I was not ready to hear about a Vortech going bad and causing serious damage!

Keep us updated once you get the final tune!

Wow, similiar thing happened to my car and took nearly 2 months to finally find out it was a stupid broken grommet in the fuel tank that was the culprit!

good it workout for you, did you get any final dyno numbers?

I have a boost leak and I'm only hitting 5lbs right now. It put down 300whp @ 5lbs. I think once I get that leak taken care of it should be hitting 8-9. Belt is tight, but I might do the GTM mod just for kicks.

Good to hear that it was a minor but pita problem.

Congrats on getting the problem fixed. Have you figured out where the boost leak is coming from? Its really time to get retuned for me..