I wouldn't encourage anyone to hit fuel cut, but usually hitting fuel cut is preferable to overboosting or overreving

 

^That is the take home message in this thread.



This makes me wonder if the fuel cut could be modified rather than eliminated. At least raise the fuel cut by a specific amount, say from 8psi to 10 psi. Doesn't the fuel cut work by modifying the output from the pressure sensor to the ecm? Could that mod be measured and controlled ?


Great thread.

 

Im pretty scared to run the stock turbo more then 14 psi at most lol.
Running a Rtek 1.8 just simply removes the Fuel cut.
I run 12 psi all the time with stock ported wastegate but it rarely goes past that. But once in a while I see it going there in 4th gear pulls sometimes.

I dont know anybody having blown an engine from overboosting anf fuel cut activated. The only way I can see it happening is if their injectors are leaking gas into the rear rotor while fuel cut is activated. Detonation occurs and bye bye engine.

As far as I know if other FCD can modify the output signal from the Pressure sensor, you can modify it to a range of psi you want to make the fuel cut activate.

 

I don't believe so, I just picked up the ecu a couple days ago. Before I would hit 10 psi on the n/a ecu but leaned out bad around 5200rpm-5500 (14.6 afr)

Once I found and switched over to the N370, I've hit 10psi and around the rpm I lean out, i'm actually rich now, 10's. I don't have any struggle or problems. I thought the factory fuel cut was at 8 psi, but wasn't to sure.

I guess I won't question why my ecu lets me boost 10 pounds and no fuel cuts... But I have blown a motor from setting a boost controller on backwards... 26 psi ftw.

 

When I bought my 7, it had a straight pipe to the stock catback, hybrid turbo, and notes from the shop that tried to modify it back in 1987. They didn't know about factory fuel cut, so I'm sure they continually bounced off the fuel cut dozens of times. I'm sure the second owner did the same. So with 50+ fuel cuts on hard acceleration, the engine still runs strong.

ReTed's site says he's had motors blow due to the factory overboost.

As for retaining the system, it could be integrated into the FCD since I'm assuming it uses an unmodified ECU. Below the cut setting, the FCD would act normally as a voltage clamp. Once the sensor output reaches your desired setting, it would bypass the FCD circuit and send it directly to the ECU triggering the fuel cut. I hated my electrical engineering classes, so maybe someone can chime if such a circuit exists.
Maybe this could be integrated with an RTec reflash, but it probably wouldn't be adjustable.

 

Power FC ftw. fully adjustable fuel cut. mine is set to 17psi, I run 16psi +/- 0.3 psi depending on weather

On the factory ECU's it's probably coded into the chip. I'm not sure if there is a reflashable EPROM on the 2nd gen ECU's but I don't think there is. The FD ECU is reflashable though, it's similar to the OBD I Honda ECU's.

but if you're a gambling man, odds are you're going to pop it from overboosting and NOT fuel cutting

 

Sorry, I quoted FC3Spro wrong. He points to fuel cut as the reason for the failed engine. http://www.fc3spro.com/TECH/FAQ/fuelcut.html

But fuel cut is the reason my car is on the road instead of in a junkyard from a blown engine. So I'm a believer. I was just thinking of some way to integrate this feature using the stock ecu since many standalones/ modified ones remove or have their own overboost feature. The stock boost sensor would limit any setting to 14.7 psi, but that would probably be fine for any setup that is still controlled with a stock ecu.

 

i think what ted is saying is that if you just keep driving on fuel cut, something bad might happen.

i'll ask ted

 

nobody in their right mind, Ted included, is encouraging anyone to

1) repeatedly hit fuel cut. it can't be GOOD for the engine.

2) disable the fuel cut and then detonate due to poor tuning or improper modification

 

+2 ^^ I wouldn't keep hitting the fuel cuts.