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Author
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Topic: Need some info confirmed
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-21-2003 07:52 PM
   
I finally took my truck in to a (semi retired)Ford technician/racecar driver. While I was talking to him about the problems my truck was having (he seems to think it is in the ignition with preliminary testing) I asked him to go ahead and time the thing while it was there, and that I had put a different cam in it. He told me that you can't (read: very frowned upon) put a different cam into the truck engine of that time frame (truck is a 90) becasue the computer doesn't like it. It messes with a lot of the signals and ends up dropping vacuum. Is this true? If it is true, is there any way to remedy this without changing cams?
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KULTULZ
Gearhead Posts: 384
From: Rockville, MD
Registered: Oct 2002
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posted 11-21-2003 08:26 PM
If the engine control system is speed density, there are few changes you can perform without changing the fuel/timing events in the PCM.You will need a FORD RACING mass air changeover to pump the engine up without having to recalibrtae the PCM with every change.
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-22-2003 08:49 PM
Since you are the only one to respond, I thank you KULTULZ.I figured that someone (here) would know for sure. So i want to go from speed density to mass air?
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KULTULZ
Gearhead Posts: 384
From: Rockville, MD
Registered: Oct 2002
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posted 11-22-2003 10:50 PM
quote:
I figured that someone (here) would know for sure.
Ouch!
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-22-2003 11:05 PM
No offense was meant, I just don't trust mechanics anymore. I trust the people on this site, and was hoping for help.
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KULTULZ
Gearhead Posts: 384
From: Rockville, MD
Registered: Oct 2002
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posted 11-23-2003 04:30 AM
Your engine control system is Speed Density. You can make very few changes to this system without modifying the PCM or changing a chip. Mass Air engine control allows you to make most any engine modification and the PCM will adapt to it.FORD Racing now makes a changeover kit for pickups. The mechanic was/is correct. You need a FORD RACING PARTS catalog to read the description. M 9000-T51 5.0/5.8L AOD The FORD RACING PARTS site is down (as usual). I don't see how they expect to sell anything.. 
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-23-2003 03:50 PM
I didn't change to a drastically different cam, do you think I might be OK? I wasn't doing anything radical to it, just wanted it to be able to tow better.
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SteveLaRiviere
Administrator Posts: 35449
From: Saco, Maine
Registered: May 99
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posted 11-23-2003 04:28 PM
What problems are you having? All I am aware of is your starter heat soak problem.------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-23-2003 09:21 PM
The hesitation or pre-ignition problems.
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KULTULZ
Gearhead Posts: 384
From: Rockville, MD
Registered: Oct 2002
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posted 11-24-2003 05:28 AM
You cannot change cam timing events (or fuel-say larger injectors) on a Speed Density engine without reprogramming the PCM (Powertrain Control Module) and not expect changed engine performance. That system is designed to see a very narrow set of engine pre-set parameters. If it sees something different, it cannot adapt and will not operate correctly.It's main feedback will be a Intake Charge Temperature Sensor and a Manifold Absolute Sensor. The cam has changed the engine vacuum so the EEC does not recognize the MAP signal. If you do not want to change to MAF, you will have to change the chip (or flash it). Have you had anyone put a scanner on it yet? [This message has been edited by KULTULZ (edited 11-24-2003).]
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-24-2003 04:30 PM
It's at the shop now. It has gone past my knowledge, and WAAAAAAAAAAAAAAY past my patience.It sounds like it isn't quite limited to these trucks then.
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SteveLaRiviere
Administrator Posts: 35449
From: Saco, Maine
Registered: May 99
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posted 11-24-2003 06:09 PM
I didn't think you put that radical of a cam in it. {?} What do you get for vacuum?------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-24-2003 09:04 PM
I could swear I didn't either. Give me enough time, and I can dig up the specs on the cam. (actually, I can walk out to shop to get it, but I am too lazy right now  )I can't tell you what it is pulling for vacuum right now. I really did take it to a mechanic. I'll find out in a day or two what's going on. But I chose the cam because it wasn't very radical. Didn't need radical, just a little boost while towing.
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F-150Moneypit
Journeyman Posts: 33
From: Oregon
Registered: Jul 2003
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posted 11-25-2003 03:30 PM
I found that the main problem with a cam swap is the LSA.If you have at least a 112 LSA (114 is better) and mild duration it should work fine. I have a 204/214 @.050 .448/.472 lift cam with my 302 SD and stock calibration, it works fine. I DID have to use Cranes adjustable valvetrain conversion though. With the added lift and pedestal mount rockers, the valves were being held open and not fully seating. (shorter pushrods would have worked too)
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F-150Moneypit
Journeyman Posts: 33
From: Oregon
Registered: Jul 2003
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posted 11-25-2003 03:45 PM
A few suggestions;How old is the ignition module? (mounted on the distributor) These are known to fail often. Also heat sensitive, when they start to go out it will start running bad after warm up. Have you tried cleaning out the IAC (mounted on the throttle body) These get carbon built up and restricts the air flow at idle and off idle speed.
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-27-2003 10:32 PM
I get my truck back tomorrow morning. I'll let you know what's up. (and if the mechanic will be seeing me again)
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67stang
Gearhead Posts: 1676
From: Lynn Haven FL
Registered: Jun 99
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posted 11-28-2003 09:55 PM
I got it back this morning and took it on a drive. No hesitating, jerking, or just plain out misbehaving. It ctually felt good being able to drive that gas guzzler without worrying if it's gonna make it. Took it up to 70 mph and
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nothing. Nothing at all, it ran smoothly, even shifted softer And downshifts when you stomp it  And it no longer runs hot! At least for now, we'll see when summer comes back.Kenny (the mechanic) replaced the ignition module, and the wires, and went and retimed it for me. He also said that the EGR gasket must have fallen out of place when I put it back on 'cuz only one bolt held it on, so he fixed that because it was causing a leak. Now...just gotta get that exhaust leak fixed and maybe I'll keep it and get rid of the Cherokee.
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KULTULZ
Gearhead Posts: 384
From: Rockville, MD
Registered: Oct 2002
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posted 11-29-2003 02:41 AM
Glad it was nothing major...
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SteveLaRiviere
Administrator Posts: 35449
From: Saco, Maine
Registered: May 99
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posted 11-29-2003 04:44 PM
That's good to hear.  ------------------
'70 Mustang Mach 1 351C 4V/FMX/3.25 Open
'70 Mustang Convertible 250 I6/3 speed/2.79 Open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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