I'm sooooo frustrated right now, please help me solve this issue.

Setup
-TWM 50mm on LS/Vtec
-Tuned with Apexi Power FC (Alamo Autosports)

Problem
Anything below 38% TPS under load will cause the car to sound
like it has a miss to it. Anything above 38% TPS and it runs just
fine. For drag racing that would be fine... However, this is an
Auto-X/HSDE car where partial throttle is very much needed. I have
searched, and only found the thread with Whitfield's MAP issue.
My MAP is reading just fine.

Please only respond if you know something about this issue. Thanks!

 

my only thought is that the power fc canot deal with the sudden increases and decreases of vaccum,

look into crome for the best way to tune itbs for part throttle it uses a combo of tps and map .

can PFC do tps load ?

also was the car tunned with the power fc , sounds liek you might be runnign lean under load

 

I don't run TWM, but my ITB set up runs excellent on Power FC, Shaun Church had no problems with getting a good tune. Partial throttle is perfect, usually cruising on the freeway, I'm at about 15-20% throttle w/out any issues. Perhaps the tuner needs some more time with it? Did he tune with the commander, or lap top?

 

You need to throw a wideband on the car & determin what your street load a/f ratios are at partial throttle. It sounds like you need a street tune :-p

 

youll need a full standalone for itb aem ems would work but fc wont

 

there are alot more variables to the ITB than the power fc can compensate for really im not sure how youd tune it with the fc

 

The car is completely tuned (street & dyno). Under WOT it runs steady 12.8, and partial throttle jumps around anywhere from 11.7-14.1. I do have a wide-band in the car. The tuner was in the car with laptop (not commander) and we drove around to get the timing/AFR for street use. No matter what we did it still has that (missing/popping) noise under 38%TPS under load... The other interesting thing is that the timing does jump around a lot when it's doing it's crazy dance... It's a brand new distributor, and worked just fine with the previous IM/TB setup. I'm not a tuner so I can't answer the questions about what the FC can/can not do. I was hoping that someone had run into this before. I LOVE the response of the setup, but the partial throttle problem is hindering me when racing.

Could the placement of the MAP sensor be the problem? Maybe being too close to the cylinder is causing problems under too little vacuum.... I'm just throwing that out there.

 

FC will not work , and what the guy above siad is untrue you DO NOT need a standalone to tune itbs
but you will need somthing that will understand the lack of vaccume the car has at part throttles .

look into crome, many people are runny it , i ran it for a year and not one complaint

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by machine4321 &raquo;</TD></TR><TR><TD CLASS="quote">FC will not work </TD></TR></TABLE>

It works just fine. It may not be the best choice per se, only because it cannot use alpha-n tables. However, we have had great success running ITB's on the PowerFC.

I would guess rather, that the FC is having a hard time with the MAP signals at low throttle.

First thing I would do, is purchase a vacuum manifold and tap each runner on the TWM's to feed the vacuum manifold, then run your MAP sensor off of the vac. manifold rather than the integrated TWM manifold, which really stinks to begin with.

I tapped this set for a buddy, and he was using PowerFC tuned by us, runs perfect.

 

I had the same problem ... heres the link

https://honda-tech.com/zerothread?id=1548326

 

how was your car after the box we made ? the mid-range was much better

 

That's more like it. Thank you guys for giving some better information. Arghh... That means taking them back off the car. What a pain! Oh well, it will be worth it. Thanks again for the input!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tegfan16 &raquo;</TD></TR><TR><TD CLASS="quote">youll need a full standalone for itb aem ems would work but fc wont</TD></TR></TABLE>

It will work, I've been using it for over a year with 2 different ITB set ups.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92TypeR &raquo;</TD></TR><TR><TD CLASS="quote">I tapped this set for a buddy, and he was using PowerFC tuned by us, runs perfect.
</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tegfan16 &raquo;</TD></TR><TR><TD CLASS="quote">youll need a full standalone for itb aem ems would work but fc wont</TD></TR></TABLE>

Not to bust your bubble, but the power fc IS a full standalone... Do a little more research next time before just throwing something out there.

Time to get busy...

 

Amazing... Runs like a champ!! Drives just like a throttle body setup now. Thanks guys!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crxtc76 &raquo;</TD></TR><TR><TD CLASS="quote">Amazing... Runs like a champ!! Drives just like a throttle body setup now. Thanks guys! </TD></TR></TABLE>

do they stick at all?gtood to hear it worked out good

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crxtc76 &raquo;</TD></TR><TR><TD CLASS="quote">Amazing... Runs like a champ!! Drives just like a throttle body setup now. Thanks guys! </TD></TR></TABLE>

Did you create a separate vacuum manifold? If not, what did you do to remedy the problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sheepey &raquo;</TD></TR><TR><TD CLASS="quote">do they stick at all?gtood to hear it worked out good </TD></TR></TABLE>

Oh yeah... I have to blip the throttle all the time. I will work on adding a helper spring later to fix that too.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92TypeR &raquo;</TD></TR><TR><TD CLASS="quote">Did you create a separate vacuum manifold? If not, what did you do to remedy the problem.</TD></TR></TABLE>

Yes, it's going to sound ghetto but it looks good and functions great.

1) 6" piece of 1 1/2" pvc pipe painted flat black
2) 2 rubber end caps
3) GM brake bleeders (8 total) part# 1303 @ advance auto (cut the bottoms of just below the threads)
4) 7/16th vacuum hose
5) 8 small wire ties
6) block-off plate for the built-in vacuum log

Drill and tap the runners just beside the injector holes and thread in 4 of the brake bleeders. Then do the same on the pvc pipe. Use your map sensor as a template and drill the holes in the pvc and mount it as well. Run the lines, and your done... Took ~3 hours to take the ITB assembly back off and complete the project. Not bad at all. Now it runs like it's supposed to, and I am totally satisfied with my decision to go this route. Hope this helps someone else out.

Time to get ready for the race next weekend....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crxtc76 &raquo;</TD></TR><TR><TD CLASS="quote">The car is completely tuned (street & dyno). Under WOT it runs steady 12.8, and partial throttle jumps around anywhere from 11.7-14.1. </TD></TR></TABLE>

11.7 is pretty rich.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ATS*Mark &raquo;</TD></TR><TR><TD CLASS="quote">11.7 is pretty rich.</TD></TR></TABLE>

I agree, we have not done a street tune on it yet. Just dyno.