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Discussion Starter #1
Ok.. so this may or may not have been covered before.

How many of you recognise this... driving along in your GTR... minding your own business... straight line... around 60-ish... and your rear end deicides to dance... scary stuff... when it first happens.

Similar sensation happens if i turn my stero up... but can happen at any speed.

Just want to know how many of you get this... and if you fitted an amp in the boot, do you get any problems.

:mad: :confused:
 
E

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Yeh its been covered loads on every skyline web site in the world probably. Its the amp messing about with the Hicas. Dont know quite how it works but at certain volumes it all gets a bit confused.
 

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Discussion Starter #5
OK.... so the general story for the hicas interferance is put up or shut up... call me an old git.. but that aint good enough

ive spoke to ian about this at hiteq... we agree that although the symptoms are similar... the cause is quiet different... the straight line shudders is probably a software error in the hicas that nissan never debugged.. gotta live with it us R33 owners.

But as for amp interference... anyone tried shileding all thier amp wires??? if its allready been done then i wont steam ahead.. also anyone got wiring diagrams for the hicas??? perhaps some supression chokes on the wheel speed sensors might sort it.. or improved decoupling (just engineering rambling)

i dont believe that every R33 skyline in the world just puts up with this.
 

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If it is the amp causing the problem rather than the speakers then it's probably due to the power fluctuations - if so then fitting one of those huge capacitors in the power supply for the amp would probably smooth it out enough.

If it's the magnetic field from the speakers then shielding is your only hope.
 

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Discussion Starter #7
Well i got a yellow top optimax in the boot... so that should count out power supply fluctuations (around 1100 CCAs just 10 inches from my amp terminal)

Im still running standard rears.. so why dont people get it when they crank up the volume on a standard head unit.

The hicas is sheilded... and the rack its in should do enough to take the induced currnet to ground.

I think its more likely that the wires are generating e.m.c and thats getting on the hicas inputs/outputs/supply.

grrrrrrrr!
 

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Hmm... Hicas control unit is on the parcel shelf in mine, not sure of the R33...

Anyway, it does look wel shielded etc etc, but then again, it all runs off the same electrical circuit.

To be honest, I woulda thought that a decent sized cap would take car of HICAS wobble issues, if they were caused by the AMP.

Could try relocating the amp I guess....

Never heard of there being a 'software issue' with HICAS before, one would think Nissan tested the cars enough to iron out what after all is a MAJOR cock up if thats the case.

Ok, this may not help, but runnoing on 'train of thought' right now.
 

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Discussion Starter #9
train of thought.. thats probably why i started the thread!

Yeah HICAS us under the parcel shelf, and looks sheilded.. but yes wires going into could be a source of induced noise.. thats where a supression ferrite clamp could be used... and I could change to sheilded wires on all my 8 speaker runs... no real use running on RCA's cus their low current and wont generate much field.

How else you gonna explain the straight line one.. other than software... what Ian (Hiteq) seams to think os that if your cruising on the threshold of the HICAS switching on and off. it gets in a pickle and well 'shuders' you only get it on R33.. cus R32 is mechanical.. and R34 gets un upgraded computer.

chug chug chug went thomas... ahha.
 

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One more thought for you - do you have a non-standard steering wheel and boss ? if the boss is the wrong one it can confuse the hicas system, though the hicas warning light should come on when that happens. The hicas light should also light when you turn on the ignition.
 

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Discussion Starter #11
What..... ??? explain that one.. you saying that their are electronics within the steering wheel, other than my airbag? (if tahts electronically actuated).

Nope anyway.. standard boss and bus driving wheel (why did nissan give us such a big wheel).. No hicas warning light either!
 

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I was always under the impression that it was down to the amount of power used by your ICE. That's what I read on the GTR forum anyway.

Matt
 

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Ada,

Not sure exactly how it works but there is some kind of sensor in the standard boss so that the hicas knows when you turn the steering wheel and by how much. Most non-standard bosses confuse it.

When that happens the hicas light will come on and stay on and the hicas locks itself straight - it'll stay like this until you next turn the ignition off.

Doesn't sound like this is your problem though, so I guess it must be interference of some kind. Could you maybe try moving the amp temporarily into the boot and see if the problem is still there ?

If it is then it's gotta be power fluctuations or the speakers.
 

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Discussion Starter #14
im going with interference in the boot area.. whos intersted if i sort it... ill get an oscilloscope from work.. i was hoping someone could come up trumps with a hicas wiring diagram.. oh well.... guess i can diagnose it myself.
 

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I had this problem a while back too. I had (at the time) a LOAD of ICE in the boot running a lot of power.

My battery ran completley flat when it was off the road and knackered the battery so I decided to upgrade it. As you know the factory cell is a small sized one, and i went for an Optima deep cycle jobbie, with somthing like 900A capacity. However being a solid gel type, it's fairly small, I had to modify the battery securing brace but it did fit on the small battery tray in the R33.

Have had no more problems since fitting this.
 

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Discussion Starter #16
Yeah... ive got a optima yellow top deep cycle in thier... running parrallel with my nissan battery (y do nissan have thier own terminal size)... just running a diode at the mo.. so may build myself a decent split charger... so i dont get a voltage drop!
 

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I've got a Mac absolute 250 10" sub mounted vertically in an MDF panel that's just inches from the HICAS computer. The amp to drive it is on the same panel in front of the battery. I've never had so much as a twitch from the HICAS even when it's really shaking the car.

I don't suppose one amp & sub will draw too much power but I guess it kind of rules out the magnitic field.

 

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Discussion Starter #18
Yeah.. im gonna borrow a oscilloscope form work and do some power supply measurements over time... do you think that would be classed as driving without due care and attention if i got pulled by the rozerrs for wathing my scope output!
 
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