Fuel Cut without Boost Controller - Toyota Nation Forum : Toyota Car and Truck Forums

HKS1991 · 09-05-2005, 01:49 AM

I have quite a bit done to my MKIII, but it seems as though I am over boosting from stock levels. At full boost the stock gauge pins past 8 lbs. Then the wonderful lung forward of hitting the breaks happens. I have a port and polished head with a competition valve job, larger FMIC, 80% hard piped, HKS blow off intake, and mild exhaust. What exactly is happening? And is it fuel cut? Would injectors, fuel pump, and MAF make the difference with a boost controller?

Jeeves · 09-06-2005, 06:44 PM

That's fuel cut. The only way to remove it is to upgrade fuel and then use a device that gets rid of it. Aftermarket/piggyback ecu stuff can sometimes remove it, FCD (Fuel Cut Defenser's) can remove it, etc. However, if you don't upgrade injectors, pump and regulator first, you're asking to pop something.

HKS1991 · 09-07-2005, 07:40 AM

Why would this be happenning if i should be running a stock map?

***bgrieger*** · 09-07-2005, 11:13 AM

The stock map is designed with fuel cut as a failsafe. In a nutshell, the system thinks you are running too much boost by accident, and stops the fuel to prevent you from grenading the engine.

Jeeves · 09-07-2005, 12:00 PM

On the stock fuel setup, you shouldn't ever exceed 12PSI. With the factory boost gauge pinned (See: Worthless Pile of Crap) it's impossible to know how much you're really running. I'm betting you're running into FCO (Fuel Cut Off). Do yourself a favor and buy a actual boost gauge.

HKS1991 · 09-07-2005, 10:53 PM

What is interesting is that my knock sensor had failed and the sup was lagging hard and getting horrible mileage most likely cause of the richness of the mixture. It got it rewired and I noticed an incredible difference (probably cause it ran an leaner mixture due to no code being thrown). Besides the fact, does the Walbro bolt right in along with 550 injectors? what boost controller is best too?

Jeeves · 09-08-2005, 01:12 AM

The Walbro has to be strapped to the factory mount, and you'll have to drop the tank to install it. The 550's will be required to get proper fuel for more than 12psi. You'll also need a way to flow more air or a way to turn down those injectors before they flow TOO much fuel and cause cylinder wash.

As for the Knock sensors, if you've got one broken the car almost doesn't run, it'll pull timing like a bitch, run WAY rich, and IIRC it has a rev. limit at like 3,000.