Calling HKS Guru(s) - HKS FCON Harness - and VPC Help!!!

[87witmoreboost]

Hey guys, I sourced a HKS FCON harness last winter and got one for the 87-88, and was told it was "the last one in HKS's computer system". Idk how true it is, but in any case, it sat in a box since February.

I just pulled it out to get ready to install my FCON and VPC and realize - it's not a TP-8 like most, its a TP-8U. WTF!? Never heard of it and even a google search has nothing. Who invited this letter "U" ? So, I realized something was up when I realized it has different wire colors than other TP-8's, AND it has no wires to connect the pressure sensor. See pics.

vs.

Does anyone have any idea why there is this "U' and why HKS would have made a harness without pressure sensor input? I am running a VPC, which also uses a pressure sensor. Is it possible that the FCON does not need a pressure sensor when the VPC has one? (did HKS really design this for people to have two identical sensors in their engine bay or expect us to cut wires and splice in?!)

I have an extra harness for the FCON and I guess I have to pull the pins out where the pressure sensor loom goes in (if I need that second pressure sensor).

Calling HKS_TRD, calling Crisp, HELLPPPP!!!

 

[JDMMA70]

If i remember correctly the HKS FCon ran off the AFM, i believe you can use it with the VPC no 100% sure.

 

[87witmoreboost]

If i remember correctly the HKS FCon ran off the AFM, i believe you can use it with the VPC no 100% sure.

Oh, I know I can do that. That's not so much the issue. My question regarding their workings is if the pressure sensor is still required for both. Since the original HKS package included these both, I think it would be strange for them to put two identical sensors in the engine bay, on the same port. Some people splice and use one sensor for both, but I feel like having two AND splicing are both things HKS wouldn't plan on a user doing.

 

[HKS_TRD]

I'm pretty sure you do run both sensors but can splice if you want to.

If the wires are missing in the connector, how else could the FCON get the sensor signal it needs, all seems rather odd.

Unless it was for a Turbo-A and use the factory MAP sensor, but the Turbo A was the later wiring harness not the early like yours

 

[87witmoreboost]

Yea, I really don't know. I had an extra FCON harness (hardwired from prev. owner), so I pulled the pressure sensor wires and pins out of the connector and put them in my tp-8u connector. It should work, but something is really weird about this.

 

[87witmoreboost]

Dan, Crisp - all VPC users.

I wired it all up. I used an old FCON harness to add the pressure sensor pins in the plug and i checked all wires to make sure they line up properly with respect to pin locations on both the ECU jumper and the FCON harness. It's installed and the car runs.

On top of my wastegate actuator being either bad or adjusted WAY wrong (20+psi on actuator), the throttle response while running VPC is really bad. Like, tap the gas, half-second later it responds. The car was VERY responsive on the stock setup and as soon as I do this, it's awful. I tried another pressure sensor to be sure the first one wasn't bad and I get the same thing. For kicks, I also tried unhooking the wiring from the pressure sensor to the FCON (giving pressure sensor signal to VPC only) - still bad response. Even if I play with the response knob, it's still really delayed, and not just off-idle. It does it going down the highway, etc.

I wondered if the nipple of the back of the intake manifold is too small to equalize the vac line quick enough to tell the pressure sensor what is going on, but 1.) my AEM boost gauge is on the line, way downstream and works fine, AND 2.) the pressure sensor has a tiny nipple so seems to like this size vac line.

Has anyone experienced this slow response? Any advice? It makes me want to go Lex/550's and sell the VPC/GCC/FCON, but it's such a cool combo with so much versatility if working right...

:1zhelp:


edit: No check engine light.

 

[dbsupra90]

i've never thought the vpc was all that great by itself. never played with one that has an f-con with it.

add an afc to the vpc and it will be magic. imo still one of the best setups outside of a standalone. you can pick up an afc2 for like $150 these days.

 

[87witmoreboost]

i've never thought the vpc was all that great by itself. never played with one that has an f-con with it.

add an afc to the vpc and it will be magic. imo still one of the best setups outside of a standalone. you can pick up an afc2 for like $150 these days.

GCC was made to work with this and is direct-plug-in. I don't think that's my culprit. If I didn't have this hesitation when I hit the gas, it'd be a great system.

 

[dbsupra90]

then its the mustang wheels. lol j/k

i didnt see you had a gcc as well. i know it was designed to work as a system but i dunno, like i said all the vpc system cars i've been in have driven like ass with anything but an afc. someone did some testing back in the day and said the signal coming from the vpc was really noisy and the afc helped clean it up.

do you have a wideband?

 

[87witmoreboost]

then its the mustang wheels. lol j/k

i didnt see you had a gcc as well. i know it was designed to work as a system but i dunno, like i said all the vpc system cars i've been in have driven like ass with anything but an afc. someone did some testing back in the day and said the signal coming from the vpc was really noisy and the afc helped clean it up.

do you have a wideband?

I sure do. It is pretty happy in AFR land. I adjusted the response to richen up the throttle responses and it helped a little, but there is still a serious response time. What boggles me is that everything else seems fine so there is nothing catastrophically wrong. I put 100 miles on it today. No issues. Just the response.

 

[JesseH]

have you checked your TPS calibration? that can lead to lagging throttle response.

 

[HKS_TRD]

have you checked your TPS calibration? that can lead to lagging throttle response.

This is a very good point

I can say when I ran my VPC the first time with stock cams for a trial, I used it barefoot and with the AFC and didnt really notice a difference but apparentlhy the AFC does clean up the signal. I had all the dials on 12 O'clock and it drove fine. It had a very slight hesitation just off idle if you jabbed the throttle but that was it, you never found it when driving no matter how hard you looked for it.

 

[87witmoreboost]

have you checked your TPS calibration? that can lead to lagging throttle response.

It is better when the engine is warm too...

As for TPS calibration, I can't imagine it's off because the response is flawless on the stock ECU.

 

[HKS_TRD]

You may find it is a little more touchy with the VPC so therefore whilst the TPS does not cause a problem on the AFM, the VPC exacerbates the problem to the point of being noticeable. Its definately worth checking so you can definately strike that off the list

I saw you are selling it all though anyway, what happened? Even the TEMS controller :-(

 

[87witmoreboost]

You may find it is a little more touchy with the VPC so therefore whilst the TPS does not cause a problem on the AFM, the VPC exacerbates the problem to the point of being noticeable. Its definately worth checking so you can definately strike that off the list

I saw you are selling it all though anyway, what happened? Even the TEMS controller :-(

I know, it makes me sad. Ugh.

The TEMS controller is so awesome, but those shocks are too soft and I've never been able to feel a difference with the TEMS adjusters. I have tokico illuminas. I think I want to get Koni's or something stiffer... For what the HKS controller is worth, i'd rather pick up an AFPR or something go-fast.

As for selling the others, i'm gonna go to Lex/550's/SAFC. The VPC setup is awesome in many ways, but I am very discouraged by this throttle response issue. It must be able to be tuned out, but idk. Maybe the temp sensor isn't working. I will test that for signal.

 

[LAYZORBEEMZ]

I got a hks vpc with my supra I just bought but it's for a 1GGTE and my car is a 7MGTE, it's such a let down

 

[87witmoreboost]

I got a hks vpc with my supra I just bought but it's for a 1GGTE and my car is a 7MGTE, it's such a let down

Hm. Click this.

http://www.supramania.com/forums/showthread.php?t=109423

Buy my VPC and sell yours. You'll break even and have the right one.

 

[LAYZORBEEMZ]

Hm. Click this.

http://www.supramania.com/forums/showthread.php?t=109423

Buy my VPC and sell yours. You'll break even and have the right one.

I don't think want a PFC f con anymore, I already have an apexi safc2 and if I'm gonna get a standalone it's gonna be microtech, sorry.

 

[87witmoreboost]

I don't think want a PFC f con anymore, I already have an apexi safc2 and if I'm gonna get a standalone it's gonna be microtech, sorry.

You don't "need" the FCON and this is NOT a standalone. It's a VERY tunable piggyback. The VPC just converts you to MAP. You can do VPC/SAFCII. Very common combo.

 

[LAYZORBEEMZ]

You don't "need" the FCON and this is NOT a standalone. It's a VERY tunable piggyback. The VPC just converts you to MAP. You can do VPC/SAFCII. Very common combo.

Ya I was gonna do that combination and ya I forgot to type in piggyback, I said standalone because I was thinkin / talking about microtech. Thank you for correcting me though.