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Old 11-11-2009, 01:44 PM
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ExtrmZ
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Default retard curve?

What would cause the ignition timing to retard? as the RPMs get higher, the spark gets more retarded.

any ideas?
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Old 11-11-2009, 06:23 PM
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dreamer1uk
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Hola,

A Knock Sensor will cause ignition timing to retard. How do you know the ECU is retarding the spark? Scan tool?
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Old 11-12-2009, 03:06 PM
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the ecu is what controls how much advance/retard to give it. i unhooked the knock sensor and it did the same thing. When its unhooked it wouldnt sense a knock right?
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Old 11-12-2009, 08:23 PM
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Hi,

Yes, thats right on the KS. However, it may run in a fail safe mode or limp mode if the KS is unplugged. I know on some of the Import vehicles, people will disconect the KS for performance, but im not sure how that will work on an OBD1 system

You could test your current KS by using a DVOM on the A/C voltage scale and gently tap on the KS and look for a change in A/C voltage.

I would start by doing to voltage drop tests on your ECU, then onto your KS, MAP, ECT, TPS and so forth.

Hope this helps.

Last edited by dreamer1uk; 11-12-2009 at 08:48 PM.
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Old 11-16-2009, 09:03 PM
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I took it to a guy i know at the Ford dealership. He is a transmission specialist (doesnt know a whole lot about motors) he scanned it, and the only codes it threw were for the EGR (which is taken out) and one for the MAP sensor. He said on the older cars, the MAP sensors didnt influence much. He sent us home without anything. So i dropped it off at a "friend of my dad's" shop and have him check it out tomorrow.

the question i have, does the MAP sensor have anything to do with the advance curve? And since no other sensors threw codes, whats left?
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Old 11-16-2009, 11:42 PM
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Hi,

The MAP, TPS and ECT are the most important sensors for the ECU to determine injector pluse width on Speed Density vehicles.
You can test a MAP sensor pretty easily with a DVOM on the htz scale, while using a vacuum pump.
What the MAP sensor does, is measures manifold absolute pressure (as the name MAP implies). It effects the air/fuel ratio of the vehicle. So, yes, its a pretty big deal.

I cant see however, how this sensor would retard your timing. I can talk to one of my ASE professors at college on Wednesday (unless a Ford Tech. will chime in the thread before then) and ask him if he has seen any problems like your experiencing in the past. My shop manager is also an avid Mustang fan so i will poke him for some info too.
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Old 11-19-2009, 09:45 AM
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yeah thatd be great

im stuck here. nothing makes sense
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Old 11-19-2009, 11:30 AM
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dude your ****s retarded, get a new one.
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Old 11-19-2009, 11:56 AM
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i just bought a new truck for the winter (car's not the best on ice), '88 F-150. but i need to figure this out.
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