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HKS FCD running lean?


downimpact

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i haved double cheked my wirring, and it is mountet as the link above... normalley on Coldstarts the air/fuel reads 10.5 to 10.8, after hks fcd it is only 11.8 - 12.0 on the air/fuel gauge, so something is wrong...

 

the fcd stand on 9 on the adjustment..

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I have a j-spec supra 2jzgte, and i have mountet the hks fcd, i also have the problem with the car running lean, i have mountet is after this guide:

 

http://www.mkivsupra.net/vbb/showthread.php?251053-HKS-FCD-Installation-Instructions

 

under idle the air/fuel gauge reads 14.8 to 15.2 witch is pretty normal..

 

under load the car leans total out. 17 to 18 on the air/fuel gauge...

 

does the hks FDC not Work on a map based car, or what am i doing wrong

 

Have you read that whole thread? And in particular my reply and link?

Not saying it's wrong but the next owner of that car had to re-wire the HKS FCD.

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Have you read that whole thread? And in particular my reply and link?

Not saying it's wrong but the next owner of that car had to re-wire the HKS FCD.

 

what do you mean?? i can see he is talking about some wires was wrong on the fcd , but he dident mentioned what wires it was :(

Edited by jza800 (see edit history)
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now i am confused, it is the exactly same wire both, on the link i added, and the link on the mkiv.com, and it is that wire i have connectet the fcd to??? the same sayes the hks manual.. so what is wrong???

 

I'm not following what you've put there but:

 

Red is power

Black is earth

Yellow to the ecu side of the pressure wire

White to the loom side of the same pressure wire

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i've really not a fan of any FCD on a map sensor equiped car, just don't like how its tuned.

 

But saying that jurgen fitted a HKS unit to my supra before i bought it and its running 1.2bar and seems ok. although you can feel the map isn't quite perfect with slight heseration on cold start driving, little judders if you come off the throttle slowly etc etc.

 

Because of this i've bought a power fc for the soup and tune it properly. We have the same issues when tuning starlets but there fuel cut is only 0.75bar and i'm again running 1.2bar on that so again i managed to find a power fc and had that setup properly.

 

FCD's on map sensor equipped cars that are used for air/fuel calibration is really a bodge way of tuning :( But its a damn sight cheaper than the alternative so i can see why people do it.

 

 

Tim

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i've really not a fan of any FCD on a map sensor equiped car, just don't like how its tuned.

 

But saying that jurgen fitted a HKS unit to my supra before i bought it and its running 1.2bar and seems ok. although you can feel the map isn't quite perfect with slight heseration on cold start driving, little judders if you come off the throttle slowly etc etc.

 

Because of this i've bought a power fc for the soup and tune it properly. We have the same issues when tuning starlets but there fuel cut is only 0.75bar and i'm again running 1.2bar on that so again i managed to find a power fc and had that setup properly.

 

FCD's on map sensor equipped cars that are used for air/fuel calibration is really a bodge way of tuning :( But its a damn sight cheaper than the alternative so i can see why people do it.

 

 

Tim

 

Can you explain that Tim? I can't see how clamping the voltage just below the cut point has any affect on the map at all. The map remains exactly the same up to that point. Only when the voltage is clamped do you then start to change things from stock. It shouldn't affect cold start at all.

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the HKS isn't a clamping FCD its one that is basically a variable resistor so throws out the entire map. if i'm running 1.2bar it must be lowering the map reading by atleast 0.25bar of boost to compensate. So not only is it not injecting enough fuel for the boost but its also going to be using more ignition advance because of the position in the loadcells. Its just allowing for the overfueling nature of the stock to allow enough fuel not to blow up.

 

But like i've said i'm not a fan of trickery to the ecu in anymore. The clamping type is the lesser or 2 evils. But still not ideal.

 

Tim

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If it behaves normally without the FCD then it's either wired up wrongly or faulty. Slight chance the pre set rotary switch within is set wrong if you have fiddled with it. Have you?

 

now i what to be sure off WHO it is fittet correctly..

 

red = 12v input

Black = ground

yellow = to the ecu side off the turbo pressure sensor (pin 62)

White = to the turbo pressure sensor at the wirringloom.

 

adjust it to 9 on the fcd..

 

 

thats it how i connectet it to the ecu..

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i think i found the problem, as i have a j-spec car, all fuel depends on the map sensor, so my input voltage should not exeed 5v, so the red wire is connectet to a 5 volt source.. now the fcd is set on 9, red and White wire connectet to 5v power source, the output voltage is now 1.5 volt on setting 9.. does that sound right?? should the output voltage not be 4.1 volt?

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the HKS isn't a clamping FCD its one that is basically a variable resistor so throws out the entire map. if i'm running 1.2bar it must be lowering the map reading by atleast 0.25bar of boost to compensate. So not only is it not injecting enough fuel for the boost but its also going to be using more ignition advance because of the position in the loadcells. Its just allowing for the overfueling nature of the stock to allow enough fuel not to blow up.

 

But like i've said i'm not a fan of trickery to the ecu in anymore. The clamping type is the lesser or 2 evils. But still not ideal.

 

Tim

 

 

I see.

 

Well Ian suggested the HKS device scaled the signal as you suggest and that this was naff in the second post of this thread 2 years ago, and then others seemed to think it didn't and was ok.

 

If they do work like that then they are a very poor design and should be avoided at all cost imo. I cant see the point in fitting something that is going to change the whole map and all of the time when a simple voltage clamp will only affect things from 1 bar and over. Other than the clamp removes the fuel cut point completely rather than moving it and some wouldn't like the idea of this.

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i think i found the problem, as i have a j-spec car, all fuel depends on the map sensor, so my input voltage should not exeed 5v, so the red wire is connectet to a 5 volt source.. now the fcd is set on 9, red and White wire connectet to 5v power source, the output voltage is now 1.5 volt on setting 9.. does that sound right?? should the output voltage not be 4.1 volt?

 

Fella, St3ven posted you the complete info you needed to fit it. The majority of the cars on here are Jspecs. If you have fitted it and still have problems,, then the chances are that it is faulty or set up incorrectly. I cant remember the exact voltage that the fuel cut comes in at, but yes it's 4. something. Imo, if the HKS one provides a scaled output, then bin it and just by a cheap 3 wire type that wires straight across your MAP sensor and lets you set a clamp voltage so your ecu never sees a voltage above the clamp level, but until that point everything remains the same as stock. There was a guy called Nathan Munns known as Pocket rocket or something flogging these on Ebay for about £25 and they worked fine.

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year, an thats how it is fittet, but haved just heard the insted off 12v power suppaly, it should only get 5v power suppaly to the fcd, because the j-spec run a different ecu, and only use the map to give the correck amount off fuel and air, where the eu/uk 2jzgte uses both the map and maf sensor to give the correct amount og fuel/air.

 

so thats way i am i Little confused now..

 

can i somehow check the fcd is in working ordre or not??

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