370z Ignition cut at Full Throttle

robertkroll

I need some help here folks. I have a tuner working on the car, but for whatever reason, we cannot get it sorted. Everything works fine, except when you plant your foot after 2-3 laps (once everything is warm), the ignition completely cuts out. If you leave your foot planted, the engine pops and doesn't regain ignition until you ease off the throttle slightly. If you don't plant your foot and let the car rev, it WILL hit redline on its own, but for obvious reasons, while racing, we kinda need max throttle.

Here is the lineage of the vehicle:
-Full race trim, not street legal
-Stock VQ37VHR motor
-Stillen cold air intakes w/air sensors
-UpRev software
-Stock fuel tank removed (Custom Fuel Cell)
-Return line fuel system set at 70psi
-High pressure fuel pump in surge box
-Fuel temp sensor delete (switched off in UpRev)
-Flat foot shifting switched off in UpRev
-All unused wiring harnesses removed, cut back and made safe (Capped)
-Completely rewired signal lighting and headlights (not part of factory bus)
-A/C Delete
-TCS Delete
-ABS Delete
-Dyno tuned to 354RWHP stock

I think that's the most pertinent information. We noticed on the Dyno there were some unusual oscillations in the horsepower curve, not sure if that is pertinent to the situation at hand or not. The VVEL was damaged in a racing incident, but was replaced (not sure if this is pertinent either).

We have one of the best tuners around (Vinny Ten Racing), and we have been working with UpRev on zeroing in on the problem, but as yet, we have not nailed it down. I figured I would throw it out in the open forum to see if anybody else has seen any issues similar to this.

I have a video of the cutout happening, but it is particularly large, not sure how I can cut it up and upload it. Maybe I can put it on youtube and link it to here?

BGTV8

What revs does it happen at (or any RPM)

Sounds like the ECU thinks you have hit rev-limit for some reason

If you have hacked the canbus and are still using the OEM ECU, you are into test-pilot territory

robertkroll

The car ran fine last year. All we did was install a fuel cell, require the lighting and tune the car. Tried to find a stand-alone ECU, but there doesn’t seem to be anybody out there that says “Yes, we have the solution”. Seems with VVEL, there is no way to ditch the factory electronics. The problem happens after about 5-7 minutes after starting from cold, and it happens at any RPM. It’s definitely not a limiter, it’s a complete CUT. If you plant your foot, she shuts right off.

It’s a shame, this car is so capable on track. It routinely eats E-46’s, many mustangs and some vettes, but right now, we are on a ledge ready to jump off.

jchammond

Have you disconnected & ohm’d the tps?
Being a race car & hard on the throttle pedal may have got something loosened up in there,
Wouldn’t hurt if you had a spare to try.

__________________
MazWorx built long block | FI-TT-100 Stage 2.75 | IPT built 7A/T

http://www.the370z.com/members-370z-...s-musings.html

robertkroll

We took it out and disassembelled, cleaned and re installed. Looks good, and there’s nothing really complex going on in there. Just a small board and brushes. And, the issue doesn’t happen cold. I think there is something to that. Not sure where to look though.

SG4247

Sure sounds like a bad TPS....

Ive had a couple that would not work at certain specific throttle angles. Worked fine every where else.

robertkroll

I'm ok with changing it, but did you have the problem intermittently? Did it happen when the car warmed up? It's not that expensive if the consensus is TPS, I'll give it a go.

jchammond

Though other sensors do different things during wot, the tps was the first thing that popped in my head & then thought about a possible short to ground in the disconnected A/C circuit or a failing o2,A/F sensor.....I know they don't like leaded fuels.
After engine is warmed up, seems like a good Lab-Scope would pick this up.

__________________
MazWorx built long block | FI-TT-100 Stage 2.75 | IPT built 7A/T

http://www.the370z.com/members-370z-...s-musings.html

SG4247

Yes it was intermittent, mostly when the engine bay was really hot.

If you can data log the engine parameters, that might help.

jchammond

Spoke with one of my tech's from work & he asked if you installed a one-way check valve vent for the fuel tank?.....he then added to try & run it with fuel cap off-say's it sounds like it's pulling a vacuum on fuel system; though i emphasized that it's like turning ignition off when WOT is achieved.
Don't Jump...it's not worth it....i'm sure you'll find it soon.

__________________
MazWorx built long block | FI-TT-100 Stage 2.75 | IPT built 7A/T

http://www.the370z.com/members-370z-...s-musings.html

Spooler

Check your brake switches at the brake pedal. If the ECU see's that it is mashed, it will kill the throttle. Ecutek can cut that off with Throttle Highjack feature. Not sure about UpRev.

lj909

If your really looking a stand alone there is a solution now. Contact VitViper. He has a Motec set up for our platform.

__________________
PW 07 HR350Z R.I.P. Totaled by 82yr old woman
2010 40th Anniversary 370Z

robertkroll

The car has a fuel cell with all of the requisite ATL lines.

robertkroll

I believe the tuner defeated that in UpRev.

BGTV8

What he said ........

I have an M150 Motec running my OEM VQ37VHR engine using the VitViper package.

I can provide a patch harness to connect the M150 into the OEM harness for an M150 running Vitaly's package if you require.