The vc-2 does a hard clamp, versus the vc1 which does a soft clamp. And its ajustable too (so you can get as close as possible to the ecu's 4.79volts limit).

I'm going to be ordering it next week to replace my hrc fcd (seems to be acting up). Also will allow me to gain as much voltage from the MAP sensor as possible without hitting fuel cut.

as far as i know the vc-2 is not out yet? correct me if im wrong? i plan to order the vc-1 soon since my hrc is acting up again..
Michael 99gs-hrc stage 2

I called and talked to them about 2-3 months ago...and back then they said in about a month from then it would be out...so i'd call in to check..

What's the difference between a hard and soft clamp?



Eric Madden

The soft clamp will allow some variation in the voltage clamp point (ex. 4.70-4.80...sometimes more like the HRC clamp ~4.3-4.75).

The hard clamp will not allow any variation. The VC-2 will also have an adjustable voltage point.

hey guys, the vc-2 will be ready early next week . also the vc-2 is alot better then vc-1 correct? also i know everyone says it has to be 4.7v but when i talked to bill at hahn he said 4.7v could causes a cel? also he said 4.5-4.6v is good ? so when i order my vc-2 or vc-1? should i ask it to be at 4.7v? also he said i can adjust it 2.5-5.5 only is the range! the vc-2 cost $86.13
i need some input i plan to buy it soon since my hrc mapper is again giving me a low voltage.
also will my car running better and stronger with the higher voltage output? that is what i heard
thanks
Michael 99gs-hrc stage 2

Unless the service manual is incorrect, it will not trigger a CEL and other nasty behaviors unless the map sensor sends more than 4.79volts. Anything below should be OK.

If you can ajust the hard clamp on the VC2 (which i believe you can), i would set it to 4.7 or as close as you can to 4.79 without hitting 4.79. You'll known when you hit 4.79 or too much voltage when your car fuel cuts at 4k rpm =) Dont ask me how i came to find this - A bad map sensor does wonders!

That's great news to hear its coming out just in time when i need it.

Well that must be the problem with the VC1. It works great except it causes the check engine light to come on (well at least 2 96up star turbo's I know of check engine light came on immediately after installing). If it stops that I guess its worth it, if it doesn't then whats the point, they both keep the PCM from acting crazy.

I think the key attribute that I'd be interested in getting with the VC-2 is the adjustability and the non-variance of the voltage clamp. I can see a discernible variation in my A/F ratio when my HRC mapper clamps at 4.4 as opposed to 4.7.

Max fuel under boost is what I want, and if I'm able to clamp at 4.79 volts every single time, check engine light or not, I know that's one fuel component that's no longer going to be an unknown or unpredictable variable. I'm sick of having my S-AFC on the check sensor screen everytime I turn the car, so I can play "voltage clamp roulette" wondering what type of EFI max output I get for that particular ride.

IC but is that a problem with the VC1 or is that a HRC fuel mapper problem?

How much fuel you get is directly proportional to the voltage out of the MAP sensor. That's how the SAFC controls the gain/decrease in fuel delivery - by modifying the incoming MAP voltage. The ecu sees "so much air being seen by the MAP sensor, requires this much fuel delivery". The higher the voltage, the more fuel delivered. Of course there are other parameters, but the map sensor voltage is key.

Lets make sure we all understand this: If you get more than 4.79volts out of your map sensor, nasty things will happen. Its all in the service manual for your car (at least for OBD-2 cars). Check engine light (i believe code 34?), fuel cut at 4k rpm, rough and stalling idle, etc.

The VC-1 and HRC FCD both do a fairly good job in preventing you from going over the higher-than-allowed voltage limits, but one fault that they both share is that they are "soft" and "transient" voltage clamps. Meaning that when the voltage from the MAP sensor starts getting close to the 4.79 limit (lets say at 4.3), these "black boxes" will start holding and clamping the voltage. But because they are soft clamps, they dont stop the voltage at our example 4.3 volts. They will vary every single time what voltage the clamp stops at. So there are times that the clamp will stop your MAP sensor voltage from getting high enough to yield optimum fuel delivery (i.e. at a low 4.3 volts) or not stop it by the 4.79volts limit (i.e. at 4.89 or 5volts even) which will yield nasty stuff such as the check engine light or even fuel cuts.

In addition, by being a "soft clamp", the voltage "holding" or clamping action is variable or "transient" i.e. the clamp starts at 4.3volts, but will continue to clamp at an unknown and unpredictable rate until X voltage, where X could be 4.7, 4.5, 4.9, etc. Like said before, you play "voltage roulette" everytime you run your car and try to tune it with something such as a SAFC.

The advantage of the VC-2 like many others have mentioned above is that 1) its a hard clamp. If you set it to stop the MAP sensor voltage at 4.78volts, it will always and ONLY stop it at 4.78volts and 2) its ajustable! set it as close as you can to 4.79 to get the max voltage out of your MAP sensor.

Hope this helps. I'm hanging on to the last piece of reason for keeping my HRC FCD. At least until vc-2 comes out.

you guys are talking about the voltage reading off of the Corbin a/f gauge right???

So did anyone ever find out if it was available, my HRC FC messes up every now and then and stalls at stops, and I get code 34 and 43 when at other times I only get 21...

No.. they're talking MAP sensor voltages. You can see it with the sensor check screen on an SAFC, or with a voltmeter. The AF gauge only shows O2 sensor voltages..

top notch, man... :-)

i was wondering if i got a 4.7v from the vc-2, how that related to my fuel? would the higher voltage output effect me if i got bigger injec or fmu etc? i plan to get 440cc and s-fmu also a afc...
cool
Mike 99gs-hrc stage2

vc-2 is ready to order. i just placed my order a couple days ago. i asked them to clamp it at 4.7v! i was thinking i should have asked 4.6v and since its adjus to up it till my check engine light comes on? im not so sure if the adjus can go down?>
thanks
Michael 99gs- hrc stage 2

>i was wondering if i got a 4.7v from the vc-2, how that
>related to my fuel? would the higher voltage output effect
>me if i got bigger injec or fmu etc? i plan to get 440cc and
>s-fmu also a afc...

No. your AFC would never let the PCM see 4.7V with 440cc injectors if you have it set up to work right.

So how much is the VC2 i know the VC1 is like 70 right??

So if I have a stage I soon to be stage II (HRC)
and I have the Vortech S-FMU
I do need to get the VC 2 right..........It would benifit me??

so if i call to order one today what voltage do i tell them to set it at?...4.78?...4.70?

and how do you adjust this?

mark

you ask them to clamp it to whatever you want! if your turbo most people clamp it to 4.7v.
the rnage is 2.2-5.5 from what split told me.
cool
Michael 99gs-hrc stage 2

It is 86 bucks