Fuel Cut Defender and Speed Cut Defender for R33

[Speedy Gonzalis]

I have just installed a boost controller and when I run about 14 pounds boost and floor it I experience stuttering like the fuel is being cut or the spark is being retarded. Can any-one tell me what this is. You can buy a HKS Fuel Cut Defender and you can buy a 180km Speed Cut defender for the R33. Has any-one experienced the same problem. I have also been told that it could be because the vehicle is producing to much pwer for the fuel pump/spark etc.

[Lazy-Bastard]

Between 5 - 6000 rpm?

I think the general consensus for solving this problem is normally reducing the spark plug gap.

I had the same problem after fitting a front/dump pipe, which in turn, raised the boost a little.

At the moment I have standard copper plugs gapped at .6mm and the missing/stuttering has disappeared.

Worth a shot and cost = free

[Speedy Gonzalis]

Ok, thanks for the advice, I will try increasing the plug gap. I am still curious about the Fuel Cut Defender and the 180km Speed Cut Defender and how and when they work. If HKS make these 2 products then it means that the R33 will cut the fuel and cut the speed. I would love to know when and what makes the R33 cut fuel and when and what makes the Speed cut.

Questions???????,

1. What triggers the fuel cut?

2. What does the speed cut do?, ie: cut fuel?, retard spark etc.

3. Can the fuel cut be triggered by overboosting?

I have also been told by a couple of people who have had the same problem on a WRX and a Pulsar GTR that all you need to do is get a one way bleeder valve from an Aqaurium and put it in the map sensor line. Apparently this blleeds out enough presseure at high boost to stop it triggering any fuel cut or spark retardation.

[strutto]

Ok, thanks for the advice, I will try increasing the plug gap.

Decreasing, not increasing...

1. What triggers the fuel cut?

Excessive airflow...

2. What does the speed cut do?, ie: cut fuel?, retard spark etc.

Good question, I'm not sure...

3. Can the fuel cut be triggered by overboosting?

Most definately...

I have also been told by a couple of people who have had the same problem on a WRX and a Pulsar GTR that all you need to do is get a one way bleeder valve from an Aqaurium and put it in the map sensor line. Apparently this blleeds out enough presseure at high boost to stop it triggering any fuel cut or spark retardation.

This might work for a car that uses a MAP sensor for management, but the 33 GTS25t does not. It uses an AFM...

[superspit]

Stock @ 14 pounds?? ......Kookey.

[FATGTS-R]

I would try gapping down the plugs first before the fuel cut defender.

I dont have an R33 but an RB20 in an R31 and I have problems with the fuel cut out, it doesnt happen gradually and start stuttering as you describe, its more like driving into a brick wall.

The cut out is sudden and abrupt, like you nearly headbutt the steering wheel.

[Speedy Gonzalis]

Ok, sounds as though I need to DECREASE the plug gap before I spend my cash on the HKS Fuel Cut Defender and the HKS 180km Speed Cut Defender.

My confusion about the 2 HKS is as follows. Every-one I have spoken to about the Speed Cut on an R33 says, " yeh at 180 the fuel cuts", but how can this be if HKS are producing the 2 proucts specifically for the R33. Ultimately I am not to bothered about going past 180 as this is where death awaits us. I am more interested in how quickly I get to 180km.

I would love to hear from some-one who has fitted either of the HKS Defenders to there R33.

Thanks for the help so far, if we were in Japan we would have have all the answers so easily.

[geno8r]

Ultimately I am not to bothered about going past 180 as this is where death awaits us. I am more interested in how quickly I get to 180km..

Lol, i agree with ya there... 180 is enough to be doing on Aussie roads... Until ya get on the drag or race track & need more.

By The Way...I think Series 2 Ecu's do allow 14 psi.. just not series 1.

[fresh]

i had this problem last night at the drags hit max speed about 30-40m from the finish and the car wouldn't go any faster, my understanding is that it cuts fuel when there is either to much boost, or when u hit the speed limiter it cuts fuel then aswell, not sure, grab an aftermarket ecu and that should fix it all

[Speedy Gonzalis]

Problem Solved, it is the fuel cut defender, had it checked out by Mercury Motor Sports and found out why HKS produce a "fuel cut defender" and a "speed cut defender". The 95 model ECU allows about 14 boost and if you go over the fuel cuts intermittantly when when it senses to much pressure. The speed cut also cuts the fuel but it is a speed signal which is sent back to the ECU which kicks in the pressure sensor and cuts the fuel. The 95 ECU seems to cut the fuel at about 220 km and not 180. This makes sense becuase it cuts the fuel at a higher boost and as both cuts are ultimately based on excess pressure then the speed would cut higher.

I also found out that Caltex fuel is only a 95 octane and not 98 like Shell and BP. The Skyline is actually designed to run on 100 octane as this is what they use in Japan. So if you want to run the optimum fuel then use Shell or BP 98 Octane with 1/4 of a can of Octane Boost. This is the perfect fuel mix for our cars. If you use to much Octane Boost it will clog up the plugs, make them go an orange colour.

Not sure what the problem is that some of you were having when you suggested decreasing the plug gap to .06mm.

Later

[Speedy Gonzalis]

Update on stuttering and spluttering, Mercury Motor Sports got it wrong, it wasn't the caltex 95 Octane fuel that caused the problem. I told them about reducing the plug gap and they said "oh yeh, its blowing out the spark". I will now reduce the plug gap and hopefully that will fix it. Mercury had had the same problem on another R33 which they put a large intercooler on but ended up taking it of because they couldn't fix it.

I should have listened to you guys in the beginning and just reduced the spark before handing over $120 clams to Mercury for not fixing the problem.

Later

[NismoGirl]

I was having a "spluttering" episode in my car a few weeks back and it was the gap in the plugs that was wrong. They were at 1.1 which is what they come standard and had to be gapped down. Plus my coil packs were on their way out so I had to get some new splitfire ones.

[wizard79]

I have just installed a boost controller and when I run about 14 pounds boost and floor it I experience stuttering like the fuel is being cut or the spark is being retarded. Can any-one tell me what this is. You can buy a HKS Fuel Cut Defender and you can buy a 180km Speed Cut defender for the R33. Has any-one experienced the same problem. I have also been told that it could be because the vehicle is producing to much pwer for the fuel pump/spark etc.

I had the sAME problem , it was the gaps in the plugs that needed resizing....

After that it seemed to drive o.k under boost....... :headspin: