open loop vs closed loop throttle response
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open loop vs closed loop throttle response
My 95 351 w/mass OBD-1 Bronco has better throttle response at 1500 rpm and up when in the open loop condition. This truck is no slouch when in the closed loop condition , but I can notice a difference. I have installed a Bassani cat back and "Y" pipe, JBA headers, 56mm BBK TB, Edelbrock performer truck manifold, MSD coil & 8.5mm wires, Ford performance racing 19# injectors, K&N drop in filter W/ homemade cold air tube, and it has new IAC, TPS & WCT sensors, and EGR. The timing is set at 10 deg BTDC and I have no codes from the ECM. I disconnected the battery to reset the computor, and have put on over 250 miles since , so the computor should be adjusted. Now, what would be the next step in diagnostics or adjustment to improve it"s closed loop throttle response. BTW the TPS reads .996 volts in the idle position, with a steady increase to 4.57 WOT.
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Kemicalburns, I have Autolite sparkplugs (A24), your basic copper core, gapped at .044. Now at the risk of being redundant, are you suggesting that I time the engine at 12 deg BTDC with the spout connector off and then keep it off? Sometimes I've been known to get easily confused, but it's a simple case of no stupid questions. Also, I'm going to back probe the ACT sensor and see if it is operating in the correct parameters. If you have any other tips I would appreciate it.
Hotshot
Joined: Jul 2002
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From: Bend,OR
time to 12*btdc with spout removed, check then reconnect spout connector and your done. also i hight suggest you regap your current plugs to .55 or buy new plugs if others are old and cap to .55 . the msd coil requires at least that much gap.
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My MSD coil is the Blaster TFI #8227, and is rated at 48,000 volts , no bigger in dimensions than the stock unit it replaced. This weekend I'll pull the plugs and gap them at .055, they'er only a month old. According to the fordfuelinjection website ACT values chart, My ACT sensor resistance reading is a little low, and I'm going to replace it.
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Kemicalburns, I bumped the timing to 12 deg BTDC and regapped the plugs to .055, and now the engine is definitly more responsive. I bolted on a lot of performance parts and the fine tuning will bring the full potential out. Well now, down the road I'll be interested in getting some better flowing cast iron heads and I'll be once again be asking for some advice. BTW when I was installing the Eldebrock performer intake this Cali 95 351 bronco I see has a roller cam. Don't know how this will affect my choice on aftermarket cast iron heads.
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Hotshot
Joined: Jul 2002
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From: Bend,OR
shouldnt affect much really.what heads did you have in mind. you might just look into some E7's that have been worked over alot. it would be cheaper and a direct swap. wouldnt need to change anything tune wise.
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Hey Kemicalburns, you got me interested in finding out more on the E7 heads. Is there a company I can get a set from who has done all the porting, put in new valves, ect., and all I had to do is bolt them on? I got to be able to pass the Cali smog so I'll just put on better flowing heads and not replace my roller cam.
Hotshot
Joined: Jul 2002
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From: Bend,OR
I would ask around to some of the offroad shops or mustang shops in your area. our heads are the same as what the mustangs run so they are plentiful. might even check into corral.net or stangnet.com's classifids.
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