# HOW TO: Make stock MK4 pedal work with FSI Swaps.



## dorkage (Jul 7, 2009)

*After driving my FSI swap for a while I learnt my way of attempting to make the MK4 pedal work isn't perfect. Still get a occasional EPC light.

Bought a MK7 Golf accelerator. It's can be easily mounted to a firewall. I'll keep you posted as I add on the miles, but no more EPC light!*



So one of the first things said to people when they ask about FSI swaps is that you need to use the MK/5/6 or B6 pedal and somehow mount the pedal in the car, usually involving drilling some holes in the floor.

I read that someone once used resistors to get the correct voltages out of the MK4 pedal. I spend a few hours to try to get the same voltages out of the MK4 pedal as the B6 pedal. They were slightly different to begin but after a few hours of work, I had the voltage bang on on the test bench.

Plugged it into the car and no dice. Total pissoff.

I check measuring block 062 expecting the accelerator values to be the same as the B6 pedal, but no they haven't changed, the values are exactly the same as with the pedal plugged into the ECU directly. 

Note: Values of accelerator position are a percentage of the 5volt input.

Plug it back on the test bench and it works perfect again.

I decided to try something different. It seems like an impedance mismatch, the MK4 pedal being high impedance (because it's passive) and the FSI pedal being low impedance (because it's active).
I decided to buffer the output of the MK4 pedal so that the ECU didn't pull down the voltage of the pedal by putting too much load on it.

I had bought an aftermarket cruise control since the MK4 and B6 cruise controls are no compatible. I figured it must buffer the accelerator output.








AP900c is the one I got. Pretty easy to wire in. 




*TADA!*






Bonus, cruise control for your swap is about 6 wires away!

-Andrew


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## Eric D (Feb 16, 1999)

Thanks for sharing.:beer:


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## MikkiJayne (Jan 1, 2007)

Well that's very handy to know about :thumbup: So the CC basically intercepts the signal from the pedal to the ECU and buffers it in the process?

Any idea if this would work with the mk3 sender as well?


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## dorkage (Jul 7, 2009)

MikkiJayne said:


> Well that's very handy to know about :thumbup: So the CC basically intercepts the signal from the pedal to the ECU and buffers it in the process?
> 
> Any idea if this would work with the mk3 sender as well?


Basically that's what happens. 

As long as the sender is within the limits of the accelerator sender, it should work.


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## GolfCL Smooth (Jul 9, 2006)

Somewhat off topic, but did your troubleshooting (well done might i add) gain you any insight into a mk5/6 floor mounted gas pedal swap into an mk4? 

Sent from my Nexus 5 using Tapatalk


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## dorkage (Jul 7, 2009)

GolfCL Smooth said:


> Somewhat off topic, but did your troubleshooting (well done might i add) gain you any insight into a mk5/6 floor mounted gas pedal swap into an mk4?
> 
> Sent from my Nexus 5 using Tapatalk


I never wanted to drill holes in my floor. That's what caused me to find a nice easy solution. I never found a nice way of mounting the floor mount pedal.


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## jaysvw (Oct 15, 2001)

Interesting. I bet this would work if you wanted to swap a MK5 non-FSI motor like the R32 3.2 into something that already had a MK4 pedal. I might look into this, it would vastly simplify a swap I'm working on. I want to swap a MKV R32 motor into my MK2. I already have the DBW setup installed from my 1.8t swap. Instead of messing around with converting the motor to MK4 spec, I could just run a MK5 ECU, use a universal CC module and call it a day. 

Nice work! :thumbup:


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## dorkage (Jul 7, 2009)

Small hiccup guys, I get an EPC light occasionally if I lightly press the accelerator. I am going to try a different MK4 / passive pedal as well as the stock B6 pedal to see if my issue goes away. Otherwise the pedal works and I've been driving it down the back lane a bunch.






Here you can see the issue with the pedal.






Once it's not -20C or +5 and my garage flooding I'll try the other pedals.


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## dorkage (Jul 7, 2009)

Updates in the first post.

Spoiler: Bought a MK7 pedal since the MK4 ones were causing issues still.


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