VPC acts as a FCD - HOW?

[87witmoreboost]

Ok, so with 550's, I can see this working fine. It sounds like with a stock injector chip, it will cap the karman signal at the standard frequency of fuel cut. This being the case, someone with a stock injector chip really shouldn't run all that much more boost than stock or it will go lean. Correct?

It does sound like the FCON is a good solution for someone with stock injectors. Then again, the price of an FCON and chip, one could be well on the way to the price of 550's.

Crisp, how did your car run with the VPC and stock injectors? Did you run any high boost? If so, what kind of AFR's were you seeing?

 

[crisp]

Crisp, how did your car run with the VPC and stock injectors? Did you run any high boost? If so, what kind of AFR's were you seeing?

Okay, let's see... first off, THANK YOU ALL for this thread!!!:bowdown:


I'm an "arm-chair" tuner these days... and mine was a progression that goes back to 1996, when the car was procured WITH the PFC-FCON w/FCD, HKS IC/plumbing, HKS exhaust, EVC, TEMS, NOS (dual 10lbs. with heat/fogger nozzle) and a genuine HKS-BUILT!!! A/T, Art Carr converter and 4x4 truck-like 4.88 Precision Gears in the pig, making about 22% under-geared!!! (that's right... ZOINKS!!!:aigo

Okay, anyway... it was blowing through the stock CT, and years later, I went to a TEC H3 trim hybrid, and have always run 15-16psi, but the QUALITY of the PSI improved with the addition of:

VPC, GCC, 550cc HKS injectors, ROM upgrade, HKS SuperDrager, and a host of other progressions along the way.

AFR? What's that? DOH!!! Seriously, I've only ever had it monitoring EGR (HKS gage) and kept it at "controlled range" for where my probe is in the elbow, and other than a CRACK in the head (ex side leak) always "blowing/steaming" off coolant for a spell... (second "BHG", but more serious) with a fresh head, it's been running cool and a little rich, if anything since the 550's. (rich... presumed from my experience, plugs, exhaust "fart" behavior, EGR "creep" or lack thereof at varied PSI and loads... etc...) so I think I'm okay, but have an AFR (wideband) planned this next round.


...er... first question. YES, I ran the VPC with stock injectors (440cc) and "modified" rom in PFC-FCON, but NOT the 550cc rom. (Pretty sure there are at LEAST three ROM options for it...) My boost was kept at 15psi max, and it ran GREAT there for MANY miles. I even had NEAR 15psi (briefly, but would not hold boost anywhere NEAR to redline without fall-off) with the STOCK turbo with other HKS mods. Impressive even when I GOT it! The H3 works GREAT for what it is... and the A/T tranny was un-freakin' believable from a stop straight to pinned on the dial... all pull.

KOYO goes in it this spring, and maybe bigger turbo... thinking about the head/valve kit as well... and desperately need BBK. (WILWOOD! FTW!)

Oops! Got carried away...:biglaugh:

-crisp

 

[87witmoreboost]

This is making me think I can't safely run too far past stock fuel cut off with the stock injectors or else I will be quite lean - even with minor fuel tuning via GCC or SAFC.

Maybe someone in this situation needs the F-CON to have a fuel map after the normal stock cut off so that it is not capped.

 

[crisp]

I can tell you for a FACT that at about 12+psi this thing would fall FLAT on it's FACE when I had BOTH the stock turbo dialed up, AND when I ran the H3 trim at any setting above about 10psi... which would also STALL sometimes when you HIT it... which I discovered when the FCD GROUND wire was "broken" WITHIN the casing once during one of those tricky problems I had YEARS ago...

That was WITH FCON, EVC, 440cc's, HKSIC in "elevated" boost situations. Running "stock" (lowest boost I could with HKS exhaust, etc... and EVC "off" or "bypassed") the car still always posted nearly 9psi... which made it tricky in the wet if you weren't careful. (At 15psi, it's a gamble up through 4th if you aren't careful about your traction in the wet...)


Anyway... I've HIT fuel cut... and it is real, and not a "good thing"!


-crisp

 

[crisp]

On another point, I DID run 15psi for YEARS with the H3 spool and stock injectors using the EVC and FCON w/FCD... and later the VPC... then 550's most recently. It ran like a raped ape, with just a LITTLE SURGE at top in higher gears at 15-16psi... but NONE at 14psi. I think that's about the limit of the 440's safely... depending on HOW efficient your setup is.



-crisp

 

[87witmoreboost]

That loss of boost issue sounds like it would come from the stock turbo elbow, no? Was this before you did the exhaust?

My car went right on it's face with the stock elblow and DP and when I opened to a 3" elbow and downpipe, it was full power to redline.

 

[Poodles]

IIRC the article on the HSK tuned Supra back in the day had them running the VPC and the FCD (plus every other piggyback and accessory they made at the time).

Outside of that, can't tell you...

 

[crisp]

That loss of boost issue sounds like it would come from the stock turbo elbow, no? Was this before you did the exhaust?

My car went right on it's face with the stock elblow and DP and when I opened to a 3" elbow and downpipe, it was full power to redline.

That may be possible... with the stock turbo it could still peak at 15psi briefly... but with the H3, I always blew 15-16 even occasionally 17psi through the STOCK elbow, and held it at full-spool right until the shifts, no sweat. I'm pumped about what happens with the larger elbow/DP I'm planning. I already DID have the HKS DP/Sport Ex from early on. (Dual Tip aluminized one, with NO resonator (can, but hollow pipe through it) and no cat. It was elbow-back open, essentially... so I had good flow from the start. I'm sure the increased volume and reduced restriction of an elbow swap will help me, and the Super Drager is DEFINITELY an awesome exhaust!


-crisp

 

[crisp]

IIRC the article on the HSK tuned Supra back in the day had them running the VPC and the FCD (plus every other piggyback and accessory they made at the time).

Outside of that, can't tell you...

That's my recollection as well! I'm gonna dig up my handful of earlier catalogs...



-crisp

 

[87witmoreboost]

Hah, you still have the stock elbow!? Wow. Just wait and see what a difference it makes to go with a high flow elbow...

To keep it on topic, is there anyone here (or anywhere) that has facts about running VPC with stock injectors (and stock injector chip, of course) that ran boost beyond stock fuel cut off without running lean and without FCON?

 

[Bondango]

To cure my own Curiosity, could i ask anyone who is Running both VPC and SAFC (i know most do run these in tandam to help clean the vpc signal) to
Monitor the SAFC's Karman signal and see if the VPC is clamping it at all during high boost

Marty

 

[87witmoreboost]

To cure my own Curiosity, could i ask anyone who is Running both VPC and SAFC (i know most do run these in tandam to help clean the vpc signal) to
Monitor the SAFC's Karman signal and see if the VPC is clamping it at all during high boost

Marty

Good call. To make sure all members catch his drift, monitor the karman signal on the SAFC display to see if it reaches a value under fuel cut off and remains constant at high boost. This is the way to see if the VPC does cap the karman signal to avoid fuel cut.

Anyone know the magic fuel cut frequency? 1400hz rings a bell.

 

[Bondango]

To cure my own Curiosity, could i ask anyone who is Running both VPC and SAFC (i know most do run these in tandam to help clean the vpc signal) to
Monitor the SAFC's Karman signal and see if the VPC is clamping it at all during high boost

Marty

PS I know that fuel cut is dependant on other factors such as TPS, RPM, AIT, Coolant temp, but was wondering if these factors may be incoporated someway into the VPC's logic as it processes RPM and TPS and Knows the Stock ECU's AIT is locked at 32degrees?? (2.2K ohm resistor in pace)

Marty

 

[SupraDrew]

Hah, you still have the stock elbow!? Wow. Just wait and see what a difference it makes to go with a high flow elbow...

To keep it on topic, is there anyone here (or anywhere) that has facts about running VPC with stock injectors (and stock injector chip, of course) that ran boost beyond stock fuel cut off without running lean and without FCON?

I ran this setup for about 6 months using a EGT for how rich/lean i was running. VPC w/440 Chip, MKIV fuel pump, CT26/TO4B H3 wheel with a speaco intercooler, HKS DP, and HKS Dragger. I ran 16 to 18 PSI and Dynoed around 350-370hp at the wheels.

 

[crisp]

I ran this setup for about 6 months using a EGT for how rich/lean i was running. VPC w/440 Chip, MKIV fuel pump, CT26/TO4B H3 wheel with a speaco intercooler, HKS DP, and HKS Dragger. I ran 16 to 18 PSI and Dynoed around 350-370hp at the wheels.

Wow! That's... like... IT! Similar ratings and setup. I think I even pulled a 387HP rating with the early G-Tech once... and within 200lbs of proper weight input. Mine didn't creep over 15 by much, unless the conditions were just right, and I ran Blendzall additive in the fuel or high-tes stuff. The 550cc injectors gave me more headroom, but the H3 is at about it's limit.

Second H3 I've run... and the two housings were several years apart and milled a little differently. Always served well... and on the second one, it blew the seals and trailed off-throttle smoke. I put the original one in, and have been running it last. Still strong, at least 40k miles at 10-15psi range.


-crisp

 

[87witmoreboost]

Crisp, when did you hit fuel cut as you mentioned? I am considering getting a FCON to run with the VPC (both with stock injector chips). I am hoping that the extended fuel map will let me run safe boost after what would be stock fuel cut (12-13psi). Being chipped right, I would probably be able to tune with just the VPC and not need a GCC or SAFC.

 

[crisp]

Crisp, when did you hit fuel cut as you mentioned? I am considering getting a FCON to run with the VPC (both with stock injector chips). I am hoping that the extended fuel map will let me run safe boost after what would be stock fuel cut (12-13psi). Being chipped right, I would probably be able to tune with just the VPC and not need a GCC or SAFC.

My fuel cut was hit BEFORE I had the VPC only. If was at that time that I had the H3 spool pushing 15psi no problem, but then when it started to CUT all of a sudden... it was happening as SOON as the spool-up swung through the 12psi range or so. (happened so quick... and I really didn't experiment with EVC boost settings to see how high I COULD get without cut.) Initially, I pulled the FCON OUT of the series wiring, and went back to the STOCK ECU only at the 8psi range and car ran fine. Began to trouble shoot the HKS electronic wiring, and found the FCD had a GROUND LEAD (black) that had a break INSIDE the casing... form "flexing" when the glovebox was opened and closed all the time. Fixed the ground, put the FCON back in series, and VIOLA!

Don't think that helps you thought... since the VPC came LATER, and I haven't has any trouble since... but I'm SURE my FCD is STILL wired as per original arrangement.


-crisp

 

[87witmoreboost]

My fuel cut was hit BEFORE I had the VPC only. If was at that time that I had the H3 spool pushing 15psi no problem, but then when it started to CUT all of a sudden... it was happening as SOON as the spool-up swung through the 12psi range or so. (happened so quick... and I really didn't experiment with EVC boost settings to see how high I COULD get without cut.) Initially, I pulled the FCON OUT of the series wiring, and went back to the STOCK ECU only at the 8psi range and car ran fine. Began to trouble shoot the HKS electronic wiring, and found the FCD had a GROUND LEAD (black) that had a break INSIDE the casing... form "flexing" when the glovebox was opened and closed all the time. Fixed the ground, put the FCON back in series, and VIOLA!

Don't think that helps you thought... since the VPC came LATER, and I haven't has any trouble since... but I'm SURE my FCD is STILL wired as per original arrangement.


-crisp

Gotcha. I think I will be all set if I put an FCON in with my VPC.

My question is how an FCON will help me since it was previously discussed that the VPC likely caps the signal after stock fuel cut to prevent the cut when the VPC is installed. If this is the case and the FCON changes the ECU signal AFTER the stock ECU, how would an extended fuel map help? Does the FCON see the signal going into the stock ECU and change it, allowing the stock ECU to be bypassed for loads above stock fuel cut?

Simplified: Can anyone here tell me the path of an airflow signal for a VPC/FCON combo? i.e. pressure and temp as a function of voltage-->VPC converts voltage to frequency-->frequency goes to....

 

[HKS_TRD]

The Fcon has its own pressure sensor to read, so that whilst the airflow signal going to the ECU is capped, the FCON can still look at is own pressure sensor (which is the same as the one for the VPC) and engine rpm etc to make calculations on what adjustments to make to the injector signal.

Hope this makes sense

I had to figure out how all these worked to be able to tune it right back in the day when my Glovebox was crammed full of HKS much to my tuners dismay

I remember the last time we tuned it, my tuner said to me "I'll see you next time when you are ready to trade your glovebox in for a real ECU" lol

 

[87witmoreboost]

The Fcon has its own pressure sensor to read, so that whilst the airflow signal going to the ECU is capped, the FCON can still look at is own pressure sensor (which is the same as the one for the VPC) and engine rpm etc to make calculations on what adjustments to make to the injector signal.

Hope this makes sense

I had to figure out how all these worked to be able to tune it right back in the day when my Glovebox was crammed full of HKS much to my tuners dismay

I remember the last time we tuned it, my tuner said to me "I'll see you next time when you are ready to trade your glovebox in for a real ECU" lol

Haha. I know - Everyone seems to slowly gain piggybacks, then sell them all for standalone.

Your reasoning behind the FCON makes total sense - I gotcha.

Now - Could I share the pressure sensor for the VPC with the FCON? (avoid buying one for an FCON that I may get that doesn't have a sensor)