Bump4life Posted December 22, 2015 Report Share Posted December 22, 2015 i never noticed it when i had caps but i ran caps only. my guess would be the caps loading down the system but to the point you cant see and regulator in alternator keeping up. Buyer/Seller Feedback Thread: http://www.stevemead...5015-bump4life/ MB C220 153 Trunk Car Build Log: http://www.stevemead...d/#entry1840136 MB C280 Ipad Dash SQ Build Log: http://www.stevemeadedesigns.com/board/topic/194484-bump4lifes-new-benz-tony-c-relay-kit-pictures-ce-electric-audison-front-stage-installed/ My SPL Log: http://www.stevemead...__fromsearch__1 BMW M340 xDrive Stock, for now. Corner Load 10" maybe soon. But does 10s in the 1/4... Best Scores out of a trunk 153.0 sealed legal full tilt clamped 5524 @ 42 hz 154+ windows down, 155+ kick Link to comment Share on other sites More sharing options...
SLYentist Posted January 16, 2016 Report Share Posted January 16, 2016 My car does something similar. It's intermittent and seems to happen depending on the charge of the batteries. With no load, the idle will bounce some. Under load, or recently under load, the idle is pretty solid right where it should me. I hypothesize that it has something to do with the load that the alt/s are put under. I have two HO alts, and they're set at different voltages, so that could also have an impact when voltage drops slightly at idle. Cables and wires almost never fail; the terminations do. Link to comment Share on other sites More sharing options...
Chubbza5 Posted January 16, 2016 Report Share Posted January 16, 2016 Find it if your vehicle has something like Bypass Air Control, or Idle Air Control. These are basically little valves that increase the engine rpm a tad to compensate for the added electrical load. They can get gummed up over time and need to be cleaned it even replaced. What your engine is doing is Idle Hunting it sounds like. It sees an increase in current draw to top the caps off so it raises the idle a hair, but then the caps fill and the demand disappears, causing the idle to drop again. Great suggestion. A weak idle would for sure be magnified by a loaded charging system. I'm betting what's heppening is your alternator charging cycle is hitting and slowing engine RPM, but some other reason is keeping the car from reacting properly. What year is the car? It could a dirty PCV valve (soak it in solvent overnight) or a bad EGR valve (might throw a CEL here) or even bad IACV (idle air control) Ford's are notorious for these. Do you still have lead cell batteries? If so it's probably the ALT charging cycle hitting and loading down the crank pulley. Try turning the A/C on and see if it's as noticable (usually car will compensate and raise idle RPM a little bit to account for the A/C compressor load.) If it's older try some seafoam through the vaccuum line then I'd make sure IACV was nice and clean as well as the PCV if it's a smaller engine. Link to comment Share on other sites More sharing options...
Chubbza5 Posted January 16, 2016 Report Share Posted January 16, 2016 If you ever listen to a microwave it's a similar situation. It's not constantly putting out power, it "pulses" more or less to keep itself from burning up. ALT's do the same thing to charge the battery (like a trickle charger) on a lot of vehicles. That's why you can see the RPM drop. Overdriving them might help if you could afford the amp loss. Link to comment Share on other sites More sharing options...
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