Since I had the engine built I have had a crappy up and down idle. The idle goes up to normal rpm and drops to below 300 rpms and sometimes dies till it is warm. It only does this with the initial start up when it is cold or turning on and off the A/C. My tuner adjusted it and made it significantly smoother with the A/C on or off but it still sucks Azz with the initially warm up. Has anyone with a fcon experienced this problem or is there an area that needs to be adjusted. I will have to send my fcon by mail to my tuner for him to adjust the "water temp parameters". If anyone knows a fix I can let him know so I won't have to send the fcon back and forth to the tuner. Thanks

 

That sounds normal to me.... Because initially the car is still warming up.. and then when you turn the ac on it takes more power to initially start the ac.. My Z has always done that also.. But it could also be that you need a reflash of the ecu idle set.. I had mine set at 900.. Although Im not sure if the fcon can actually control the cars idle...

BTW.. your only one hour away from UPREV.. they can flash the ecu for you with the quickness....

 

+1 you may just need to have your idle turned up.

 

Which brand of fuel injector are you using?

 

Mine is doing the same thing(built shortblock, tt, cams). I think my tuner is going to try to bump up the idle to resolve the issue.

 

Bump idle 900-1200. Should fix the issue. F-Con doesn't have the ability to control idle??? Didn't know that.

 

The cams and larger injectors will cause of the bumpy idle . You can raise idle , do the JWT fix , or drill a very small hole in the throttle plate . I drilled and it worked real well

 

If it only occurrs during start up as you have indicated, the ECU controls idle in "open loop" mode until engine is warmed up..thereafter it's controlled in "closed loop" where the O2 sensors and A/F ratio are controlling.

When in WOT it goes back to open loop mode..

 

He has Fcon so none of that applies.

Try drilling the small hole on the throttle plate, that helped me out tremendously in smoothing out the idle. I started by making a half circle hole at the bottom of the plate and making it bigger until it helped.

Although your dealer should have gotten this down before giving you the car back, the idle is one of the things that takes some time to get perfect with the Fcon but once done it should be rock solid with or without ac on.

Do you have air fuel feedback setup on the Fcon? If not that would go a long way to help the idle settle down over time.

 

I've seen this on a lot of domestic cars, but never really though about it with ours... Thanks for the tip

 

If the car is surging then it seems to be "searching" for that perfect A/F ratio at idle during warm up. Generally the car will warm up rich and lean out as it gets warm. This is called "start up fuel" in the Fcon.Most likely your tuner has no Start fuel added to stabilize the idle during the first 20-30 seconds of startup. All of the cars I have done with the Fcon, took a bit of playing to get the idle down rock solid. Also reccomend getting the Knock amp and enabling the A/F feedback in the "fuel Trim" map, which will add or subtract fuel no more than 10% on the map and resets each time the car is started. The idle should be rock solid, and definitely needs to be bumped up to about 800-900.Get the Cipher and bump the idle a bit and see if that helps.
Also, monitor your A/F when the car is surging,im betting its going from 15-16A/F to 13-14 while the idle is fluctuating, cause its searching for the proper A/F. Sounds like your Fcon tuner needed to spend a lil bit more time on perfecting the map.

 

+1....need more start up enrichement...and for a longer period of time.

One of the main reasons your car idles poorly, is you are running 650cc saturated injectors, and aftermarket camshafts. Since you are using the FCON, you should use peak and hold injectors. RC and HKS make them in 1000cc size, which is what I would use. Peak/Hold Injectors have a response that is 3-5 times faster than a saturated injectors, and will drastically improve your idle and cruise conditions, which the injector is operating at very low pulse widths.

But at the end of the day, with cams, you may need a small idle bump, in order to rid yourself of this issue completely.

I couldnt determine it from your post, but does the car idle perfectly when its completely warmed up?


Who did the tune? SGP is pretty close to you, so maybe they could take a look at it.

 

I have my idle aready bumped to 900rpms. It idles great when warmed up with an occasional idle dip. I am aware that the cams make the idle bumpy but not surge like it does. It was surging alittle while warm and my tuner fixed it but when it is cold it surges bad. I am about 3 hours from my tuner and he wants me to send in the fcon via mail to fix it. Can he stabilize the cold start surging without the car being there?

 

SGP never got my idle right with the FCON. They didn't even install the FCON properly.

 

Well, thats a good point. Maybe Jotech?

Based on what he just posted, it sounds like a start up enrichment issue, like Julian suggested.

 

That's strange because although I had alot of the same problems with my tune that you did, my idle was actually perfect. I would've had a hard time convincing anyone that I had cams and headwork done, haha.

 

My car doc fixed mine back when I was PE TT, there is little tricks they can do to fix it.

 

Shariff do you ever plan on doing a tuneapalooza in texas? Just rent out a dyno in central texas and make a killing tuning our cars! It's just a thought.

 

Tuneapalooza...nice word.
Honestly, doing a complete tune takes time, and I dont like to rush. I do fly around for tuning, but its pretty limited, to those that can't/don't have good tuners in their area. It's almost always a one or two car deal max....just not enough time to do more tunes...thoroughly.

 

This is the very reason I ditched the plan to buy sard 800cc and decided to go with the HKS 1000cc.