cwigg66

Hey guys. Quick question. I took the car to the track this weekend and it ran amazingly, especially for a car that is almost stock. I was hanging with Vettes, new 350Z's, and some pretty heavily modded racers. Anyways, I have the car back home now and today I decided to turn the boost up a bit since it ran so strong all day at the track. I have no idea how high I set it but the Reliaboost tops out at 21 psi. I would guess I was 18-19 psi max. The car pulled well in 5 th gear for a long time today just driving around, until one time I gunned it in 5th and it pulled and then absolutely went dead. The power just vanished. I clutched and came to a stop to find the engine still idling. I pushed the accelerator and the engine died. At this point I am thinking very bad thoughts. I take a very close look under the hood to find nothing wrong. WTF happened. The car cranked right back up and ran fine. Did I run out of injector or air flow meter range or what? It was very weird. Anyone with any ideas? Thanks alot
Chris

rhesus

you increased the boost, but did you do anything to increase the fuel? if not, you most likely fried the HG or something similarly bad...

cwigg66

The head gasket is fine. I checked it visually and the car runs great. Honestly, it felt just like blowing off an intercooler pipe, except without the stall out. Any other ideas?

Gary Gaukler

How did you check the head gasket visually? Did you take the head off??

I'd do a compression check or leakdown test very soon. Cranking up the boost without adding fuel doesn't go over well with headgaskets.

Maybe you just hit fuel cutoff. The computer will cut off fuel if it senses an overboost condition if I remember correctly. If that's what happened, it may have just prevented you from grenading the headgasket.

Best,

Gary.

v944god

I was thinking the same about the fuel cutoff. The original computer would shut off after a certain boost amount just incase you were overboosting but since you have a chipset i dont know what to tell you.

cwigg66

OKay. The fuel cutoff thing sounds like what it felt like. There were no strange noises, no bang, no hiss, just dead. I checked the head gasket visually by searching for the death foam around the head/block interface as well as listening/feeling for leaks. While doing this and revving the engine, I noticed a strange sound, sort of like high pressure gas hissing out from somewhere. The gas is coming from a small metal tube that is located near the passenger side firewall. The tube is vertical and dives down past the header. The tube was hot and has what smelled to be exhaust gas blowing out of it. There was a smal rubber cap on the top of it with a hole in the cap, but no tube attached and no evidence that there ever was a tube. The cap is rubber and held on with a hose clamp. Both are njow whitish in appearance and cracking from the heat. Anyone know what this is and what it does. Thanks guys
C

Sami951

That sounds like the emission test tube, it comes from the crossover pipe (I think, in any case from somewhere before the cat), should be used when adjusting fuel mixtures and stuff like that. I wouldn't worry about exhaust gas coming out of it (it probably should be capped though)

Gary Gaukler

The majority of blown headgaskets are not that easy to track down. Unless you've completely destroyed the gasket, you won't find foaming or hissing at the head. Many times the headgasket will leak internally. You cannot find out for sure by just looking at the outside.

My advice still: do a compression check!

Gary.

roadrunner

It sounds sort of like a blown off intercooler hose. The engine idles, but dies when the throttle is opened, and no obvious smoke/steam from the exhaust nor contaminated oil/coolant.

If your Stage 2 chips aren't designed for 18-19 psi, then maybe the overboost protection did indeed cut in.