I have a heavily modified FC with a gold FCON Vpro, it has been retuned in Canada by a HKS certified tech. I remember on the Japanese tune the car was idling like stock even up to the period when it was fully warmed up, now ever since an engine rebuild and local tune it will idle surge and backfire slightly (AF ratio goes all over the place during this period) up until I start driving it. When It warms up and I get some revs going 3000-5000rpm it runs super smooth under all conditions. Seems like its building up too much carbon inside the engine ?

Relavent mod list:
street ported engine
T04E turbo with gold fcon vpro
Wideband hooked up to the FCON
denso race plugs
MSD coils with HKS ignition amplifier.
4x 1000cc injectors
340lph dw fuel pump

Another odd thing I noticed is that after I cool down the turbo before shutting off the car I will rev to 6000 RPM for about a second and then turn it off, the next morning when I will turn on the car the wideband will sometimes not communicate with the FCON (no AF reading) and the car runs like absolute **** worm or cold therefore undrivable, BUT if I don't do 1 second rev to 6000 rpm before shutting it off it will always communicate with the FCON and runs fine after wormup.

Seems like the wideband communicating with the FCON is a bad thing because if the wideband doesn't work then my car is undrivable.

Thoughts ?

Thanks!

 

Umm... don't rev the **** out of your car before turning it off. And if the car ran fine before getting retuned, but like **** after being tuned... chances are that map is the source of your problems. Other than having a rebuild, what else was changed to necessitate a remap?

Also, I dunno if your car makes the "heavily" modified list based on whats listed

 

Items that were changed before the final tune:
-type11 spark plugs to denso race 1 range different than factory plugs.
-changed 1 coil.
gtr fuel pump to DW 340 fuel pump
wideband hooked up the the fcon

why is my car not considered heavily modified ?


"Umm... don't rev the **** out of your car before turning it off. And if the car ran fine before getting retuned, but like **** after being tuned... chances are that map is the source of your problems. Other than having a rebuild, what else was changed to necessitate a remap?

Also, I dunno if your car makes the "heavily" modified list based on whats listed"

 

Do FCs run the same 7/9 factory plugs as the FD? "Race" plugs tend to foul more easily under normal driving conditions and you really wont get full use from them in a lower power application. Not to mention they are like $36/plug..

With a competent ignition system you can run 500whp+ using the stock 9 plugs in all holes.

Have you confirmed that your coils are working as they should?

Have you confirmed that your pump is flowing what it's supposed to?

Are you sure that your wideband was setup, and is working, correctly?

You've got a turbo in a car that's turbo from the factory, you changed out an ecu to something of limited usage due to the manufacturer restricting editing to only a few people here and there.. You've just got a couple minor changes that are, for the most part, very common.

What makes you believe that your car qualifies as being heavily modified??

 

'
I had stock plugs in right after the rebuild and 2 of them failed during dyno, that's why we ordered denso race. I have an HKS ignition amplifier.

The car runs perfect once it worms up and I get some revs going and under load all the way up to 7000rpm so I have no reason to think the coils are bad.

The wideband always works and reads AF ratio, except for the times that I rev the car up before shutting it off like mentioned earlier.

The car didnot have a wideband when it came from Japan, I'm thinking it has something to do with it being diretly hooked up the the computer (if the wideband doesn't read then my car is unlivable)

by most people's standards it's heavily modified ,here is the full list.

http://alberta.kijiji.ca/c-cars-vehi...AdIdZ497438050

 

I know you don't want to hear this, but sell the Vpro and buy an ECU that's more convenient to tune and diagnose. Haltech, AEM EMS, and even Power FC would be a better option.

 

There is nothing wrong with the fcon and I have an fcon tuner here in my city. Power fc is pretty shitty compared to the gold fcon also.

The shop that tuned my car tune most cars with all of these standalone ECUs, they recommend Haltec or fcon.

 

Ok... So you came in here asking what the problems with your car could be. You've had two members both give suggestions (that if you were to follow, would likely fix your issues) and you've essentially argued against the solutions given by both.

If you don't want to listen to what you're told than why even bother asking??


You're having idle issues and surging while cold. Fix/replace your ECU (and your tuner, since their map caused the issues to start with), get plugs that don't foul as easily, and upgrade your ignition (stock plugs + a Twin Power is "ok" but not competent considering what's available today). Do that and get a GOOD tune then enjoy your car.


Good luck.

 

replace tuner and recheck.

 

I'm not sure how you concluded that I don't want to listen. I'm not going to replace my fcon with another standalone because there is nothing wrong with it, but I will get the tune checked out again. The person who tuned my car tunes most fcons in my area and his own vehicle is fcon powered.

I have denso rance plugs + hks twin power amplifier - what is wrong with this setup ?

Will check back in when I have an update

Thanks!

 

You want your car to be tuned well, right? Would you not agree that, a good tune takes a lot of time, time which costs money?

And would you not agree that it's often beneficial to get a second opinion when you are purchasing a professional service?

You would agree that a tuner can't stand over your shoulder 24/7 to constantly make corrections for all driving conditions?

Wouldn't it be in your benefit to have a system that gives YOU access to the maps and datalogging, so at the very least you aren't relying on a very small network of people who charge for their time to help you with your car?

 

why rev to 6k and shut down? I know this is an old carb trick, but useless on a "modern" engine. Also, don't quote me, this is really bad for a turbo car as it kills the oil flow to the turbo when it's been spun up from 6k engine revs and immediately stopped.
PS
"ever since an engine rebuild"
Did everyone miss that?!

 

I had a similar problem go back to basics and check your all of your manifold gaskets and vacuum ports for leaks with some carb spray or brake cleaner.

 

Sooo I'm not sure what happen but it started idling steady without surging ever since I stopped revving up before shut down.

I was doing the rev up before shutdown to prevent flooding when I drove short distances... guess it's useless.

I had it tested for leaks with a smoke machine right after the rebuild.

 

Just wanted to mention that my wideband needed to be recalibrated, now it always communicated with the fcon and all is good.

 

another update...

the wideband was in a very bad spot (too close to the turbo) so it basically crapped out.