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Author Topic: electric fan causes stall at idle? anyone...? JoeT ¯ Member # 298 posted                                 I have a somewhat aggressive cam, 14-15" of vacuum at 800 rpms. I have a lincoln mark VIII electric fan that is just switched on manually. The alternator is a 3G. Well get this. At idle, the bitch stalls when I flip it on. It will surge once or twice real bad, and eventually die. Usually 10 seconds or so after I switch it on. 1 solution I have already found is to set the rpms to 1100 at idle Does it sound like maybe I just have a vacuum leak or something? Anyone else run a fairly big cam on a car with an electric fan? reason I say I may have a vacuum leak, is the machining of the threads/factory heli-coil on my 'made in china' intake leaves something to be desired. Basically I have a couple loose bolts on the upper intake (although the lower seals perfectly. I can't "feel" a vacuum leak where the upper meets the lower, but ya never know. also, it's not exactly a steady 15" of vacuum. It tends to swing from 13-15" but at times holds a steady 14-15" If not vacuum leak, what could it be? My ignition timing is at ~15-16 degrees BTDC. (I'm positive of that, yes I took out the SPOUT ) [ May 09, 2002, 02:24 PM: Message edited by: shade-tree ] -------------------- 1984 Ford Tempo AOD--- RIP Posts: 6785 | From: San Jose | Registered: Jun 2001  |  : Stimson _ Member # 51 posted                              Can you quickly put the battery back under the hood and see if that changes things? I have a feeling your trunk mount is to blame. Posts: 2373 | Registered: Jun 2000  |  : ScuEleanor ¯ Member # 785 posted                              The vacuum fluctuating is normal, don't worry about that, for it also sounds like you do have an agressive cam. It also shouldn't be a vacuum leak. Though it obviously sounds like the electric fan is instantly pulling heavy power from your system. You might want to try getting an Idle air adjustment plate if you don't already have one, bolts onto throttle body. Also, with an agressive cam, your mass air sensor might not be letting enough air flow to come in, try both of these issues, maybe getting a bigger air flow sensor also. You also might want to try backing off the timing 1 degree at a time to see if that might change the result, my guess is that you might be optimal at between 12 to 14 degrees. P.S. I am sure that you do but if you don't, once you advance the timing you absolutely need premium fuel. hope this helps Posts: 77 | From: Santa Clara | Registered: Jan 2002  |  : JoeT ¯ Member # 298 posted                                 Although the battery mount is in the car, I have the battery in the stock location for now. I'll try a little timing reduction. Perhaps the only true solution is a fan speed controller. I'm not 100% sure of the draw, but the 'startup' pull of a Mark VIII fan is supposed to be 75 amps. Sustained is something like 40 amps. I have a 75mm PRO-M and a 65mmTB with 30# injectors and the meter is calibrated for that. drives great. Just watch out for switching the fan on at idle I have the timing that far out as supposedly TFS aluminum heads can handle ~18 BTDC, so I assumed 15-16 was being conservative. I'll try 10 degrees tonight. [ May 09, 2002, 03:56 PM: Message edited by: shade-tree ] Posts: 6785 | From: San Jose | Registered: Jun 2001  |  : roseville5oh ¯ Member # 406 posted                              does your MAF sit in the engine compartment? If so, is it shielded from the majority of the engine compartment? Sometimes fan wash can throw off the reading at your MAF and cause your vehicle to run funny, or even stall. -------------------- '91 blue/gray GT -SOLD :( '03 DRZ-400S '76 GMC Truck - building '92 Chevy k2500 454 Posts: 369 | From: Roseville | Registered: Aug 2001  |  : JoeT ¯ Member # 298 posted                                 hey bingo. I think you found it. I was running the MAF *completely* open to the air. So yeah the fan wash was hitting it. I probably owe you a beer. Posts: 6785 | From: San Jose | Registered: Jun 2001  |  :

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