B2BigAl

So I decided to take my 03' Track to the Dyno yesterday to get a baseline before I start modding the car. This is my second Z, I bought this one used with about 25k miles on it, and the previous owner had put on a grounding kit and an injen CAI. Otherwise, the car appears to be stock.

We did the first pull and I only made a measly 219hp/219tq SAE Corrected. I was a little disappointed, but I just figured it was because of the heat. So we let it cool down for about half an hour before the second run. On the second run, the TCS starts acting up, showing the slip light, but I figured no big deal. Until I looked at the Dyno readout! The hp curve had a huge momentary drop, and the tq curve had a massive spike. The car only ended up making 214hp/229tq (only because of the weird spike). Now I'm wondering what the hell is going on with my car, but we decided to go ahead and do a 3rd pull while it was still running. This is where it really got strange. The car was pulling fine, then at ~5500 rpms the car just completely cut the throttle response. The VDC off light, SLIP light, and service engine light all came on and we had to restart the car to get throttle response back. Then the VDC wouldn't turn back on and the lights all stayed on until I took it for a drive around the block. SES light is still on and won't go off.

We checked all the fuses, they're all okay. All 3 pulls were made with VDC turned off (well as off as you can get just pushing the button), and the temps outside were in the low 90's. This was at my cousins performance shop, and they're stricly an F-Body/Vette shop, so he didn't know too much about the Z. He said if he were to guess, I either had an ignition/electrical problem (possibly the aftermarket grounding system?) or there was a problem with the VDC. Thought I'd see if any of the experts on here had any clues. Do you think the car is safe to drive? Any input would be appreciated, thanks.

kcobean

iTrader: (2)

What you experienced was the ECU entering limp-mode. Restarting the car clears this condition, as you saw. The VDC/Slip lights come on because the system is never really off, per se (as you know) and driving the car for a few minutes does clear the condition.

As for the weirdness on the dyno, I'm not sure what to say, other than that 219 WHP isn't too terribly far off the mark, and since every car and every dyno is different, it's not an unreasonable number given the high temps at the time.

Fletch69z

iTrader: (50)

I've experienced similar things with my popcharger, but not while at WOT. Sometimes, the popcharger confuses the ECU when I run it hard and then take it out of gear to slow down. The lights on the dash all come on and the throttle gets cut. I have to restart the car when this happens to clear it. It's really weird.

Alang

iTrader: (1)

The VDC and Slip lights will always come on when you dyno. This is due the the fact that the front wheels arn't spinning. The system views this as a bad wheel sensor, and thus the lights come on. This does not put the car into limp mode and will clear up after a few minutes of normal driving.

The check engine light however is not typical. Pull the code and that should give you an idea where to start looking. Tell us what the code is and maybe we can give you a few ideas where to start looking.

B2BigAl

Thanks for the input guys. I figured the VDC/slip would go off since the front wheels weren't moving, so should I pull the VDC fuse when I'm on the dyno? I'm going to run the car by Autozone after work and have them pull the code it's giving. Hopefully that will give me some idea what's going on, I'll post back when I find out what it is. Fletch, I know what you're talking about. I had a popcharger on my 03' Touring. It used to do the same thing when I'd pull it out of gear at high RPM. Like you said though, it darn sure never happened at WOT. This whole deal has me scratching my head.

elms350Z

How often does that happen? I was planning on getting one soon.

ElmZ

35ounces

iTrader: (5)

what kind of DYNO?

B2BigAl

Well, took the car to Nissan today and they pulled the code. They said the computer recorded that the rear wheels were going 95mph and the front ones weren't moving and detected it as a major error and shut down the engine. They said there appeared to be nothing wrong with the car and reset the SES light, though they had no idea why it went off in the first place.

This leaves me to wonder, how the heck am I going to dyno my car after I put the turbo on it? I know there are numerous threads on whether the VDC actually stays off when you push the button, but I think I can safely say MINE DOES NOT. Guy up at the performance shop has a Supra and says he has to pull the fuse for the TCS before he can dyno his car, so should I just pull VDC fuse next time I go to the Dyno? Is there a better way to do it?

@35ounces: it was just a standard dynojet. Other than it wasn't a Mustang Dyno, that's about all I know. Is there something in particular I should be looking for?
@elms350z: that only happened to me twice in the 8 months I had the car.