two problems with rb25det

[jrb92se]

hi i have an rb25det in my 240sx, i recently had the a/c hooked up and installed flexalite fans but now when i start the car it seems like it doesnt have enough elctrical power until i blip the throttle then the rpm at idle comes up and the fans seem to power up and run a little faster also some times when i am driving at night the headlights seem to vary in brightness, they get dimmer or brighter when i hit and release the accelerator the dash lights also sort of flicker like that too. ive checked the grounds and everything seems in order but i cant figure it out (i havent had my alterntor tested yet). since ive installed the fal fans the car seems to be running way to cold it rarely gets over 85 degrees celcius on the pfc controller read out..

also its been some what cold and rainy here in tampa the last few days and when i start the car in the morning (when it was below 50 f outside) it smokes something fierce for a few minutes then it stops my father says its condensation in the exhaust but im not positive. it stops after the cars warmed up a bit and really only happens on startup when its cold.

any imput will help thanks
Modified by jrb92se at 3:37 PM 12/6/2009

[Pchabz]

it most likely is condensation if it is cold outside, but you can woft yourself a wif of the exhaust and make sure you dont smell any oil or coolant to make sure.(or notice any funny color of smoke)

as for the flickering, check the amps coming out of the alternator while its running and of course also check the battery with a load on it.

but for a/c on a rb25

good luck!

[jrb92se]

thanks for the insight i got the a/c hooked up because its my daily driver since my sonata threw the timing belt, how many amps should the alternator be making? the smoke is white and smells like exhaust gases or like an outboard boat motor(it smells good but gave me a headache ) the car runs good its getting up there in mileage and im sure its got over 100000 on the engine by now, ive done alot of the preventative maintanence* (spelling) timing belt, tensioners ,water pump, ngk plugs, fresh turbo, o2 sensor etc.

[ItzGenX]

It could be your battery going down hill. It might not be holding enough charge to buffer some of your power spikes for fans etc, forcing your electrical system to rely more on the alternator. All my cars have done it before with an old battery with the same symptoms you explained. I've also noticed that old batteries usually show their ugly face when cold weather starts to come around. Replacing them fixed it right up. As for the smoke out the tail in cold weather, it is just condensation from the heating exhaust in cold air (much like a jet's vapor stream you see in the sky, their exhaust heat in the cold atmosphere makes clouds). As long as your exhaust doesn't smell sweet or plume out oil smoke (blueish in color), then you are good to go.

[Pchabz]

Im not 100 percent sure the stock amperage, i havent needed to do such a thing. But it should be somewhere 12-15 coming out (amps) i think (startup pull). I had the exact same problem, (dimming lights) on my bmw. After I replaced the alternator all was fine. Had the same problem also on my other bmw and its problem was a bad battery connection that moved on accelleration. (throttle= battery wiggle)

also if none of this solves the dimming problem, you can check the wiring to make sure sufficient power is traveling through the lines on each side. If not you could have a ground, damaged or opened wire, or just good ole 100k mileage dirty a** coroded bad connections.

(I cannot offer you a wiring rescource cause everyones got there rb25's wired in some wierd way or another lol.)

P.s. Some older cars draw a large amount of power when the a/c is turned on, Naturally dimming on accelleration due to stress on the belts on initial a/c startup (once your battery is worn in generally 11.5 volts or lower). newest one I know of is the pre 2000 z3 coupe models (2.5 litre and 2.8)

But good luck.And make sure your using a stock rb25det ac unit!

[RustspecS13]

It should out put 12-14.5v while the car is running, ideally it'll be in the high range. But a stock alt wont be. It'll probably be in the 11-12.5v Amp out put for a stock rb25 is 70 or 80 amps or in that range. But its over all output is not really enough for a modded car with eletric fans.

Look into upgrading to a quest alternator it'll out put a constant 14v and 120-125amps. Its a huge upgrade and will help your car run alot better since all your fuel and ignition systems will get the voltage they are designed for.

~Alex

[jrb92se]

ive heard of that mod but i couldnt find any threads about it, what year quest do i need to get the alt out of and wht mods to the alternator will need to be made for it to function properly im pretty sure you have to change the pulley correct. about the battery my pfc says that im running between 12.5 and 14.5 volts according to the voltage reading. btw thank you very much.

[Bluefire]

I totally agree with the above posts. E-fans sap a lot of juice. If your battery is in good condition, you may have to upgrade the alternator. Do you have any other aftermarket electronics that might be using a lot of power? Audio perhaps?

-Bluefire

[l0nestar]

JRB,

As others are have stated, as far as teh voltage goes, it immediately is sounding like an alternator issue. I have a stock 25 70A unit that was good when I pulled it out, or just pick up a new unit from a 93 Quest and call it a day.

If you haven't found any info on this, you haven't looked very hard.

I can't really comment about your smoking, but I would check your wideband and see if it is too rich at first, possibly take it to your trusted PFC tuner.

[TwoJayZee240]

hi i have an rb25det in my 240sx, i recently had the a/c hooked up and installed flexalite fans but now when i start the car it seems like it doesnt have enough elctrical power until i blip the throttle then the rpm at idle comes up and the fans seem to power up and run a little faster also some times when i am driving at night the headlights seem to vary in brightness, they get dimmer or brighter when i hit and release the accelerator the dash lights also sort of flicker like that too. ive checked the grounds and everything seems in order but i cant figure it out (i havent had my alterntor tested yet). since ive installed the fal fans the car seems to be running way to cold it rarely gets over 85 degrees celcius on the pfc controller read out..

Modified by jrb92se at 3:37 PM 12/6/2009

I have the same problem. When i start the car it relies on power from the battery untill i blip the throttle also.. then the alt takes over. But you guys are right. The alternator was not made to handle 2 or more e-fans and other electrical loads we put in. I also found that my Nistune consult disconnects when the alternator is charging. Giving me the feeling the quest alternator is the way to go. As for a battery mine is fresh. Its a mini battery also so i could keep it in stock location.

[craz4240]

The mini battery I had when I first did my swap took out my alternator due to not having enough reserve to keep the car running. I switched for an optima and new alternator I never had a bad alternator since however I am switching to quest.