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Discussion Starter · #1 ·
Hello. I'm new here (and new to turning wrenches). I have an 86 F150 302 fuel injected. I'll start by listing what I have replaced, then tell you guys my issues.
Replaced:
Fuel Pump (on rail) and filter
Fuel pressure regulator
Idle air control valve
Egr valve
Egr valve position sensor
Throttle position sensor
Oxygen sensor
Air charge temp sender
Coolant temp sender
Coolant temp sensor
Starter and solenoid
Vacuum lines from plenum to canister, fpr, evr solenoid, etc.
Plugs and wires (gapped to .040)

On to the problem.... It almost never starts on the first try. After it finally idles down, it seems to idle fine. When I start driving, it seems good until about 1500rpm then it feels like I hook to an extremely heavy trailer. Then from about 2100-3900rpm, it feels like it's missing. So, when I put a timing light on it (after warming engine and removing spout), the timing mark jumps around. I can get it close to 10 BTDC, but I'm not sure with the jumping around. I'm clearly not a mechanic and I understand that I have thrown a lot out there with this one, but any suggestions on where to look would be great. Thanks.
 

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2013 F-150 XLT 4WD with 5L
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First, welcome to the forum.

You have done a pretty decent amount of work but I need to start with the basics. Have you Verified the firing order and have the wires connected accordingly? Also, have you checked the condition of the cap and rotor and also made sure that the distributor is in the right spot (gear wise)?

Mac
 

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Discussion Starter · #3 ·
Mr. Mac.,
Thanks for the reply and welcome. I have triple checked the firing order (per the Haynes book) and made sure the wires were in the right spots. The person who had it before me said that the distributor, rotor, cap, and condensor is all new. I'm not sure what the condensor is, but I have pulled the cap and rotor. It all seems to look pretty good in there.
I have absolutely no idea how to check the distributor (gear wise).

On a different note, I read in the Haynes that the wires on the TPS should be facing away from the idle air control valve. A few weeks ago, I took the old one off and put the new one on and the wires were facing the IAC. Today, I took the throttle body off and replaced the new TPS with the wires facing the EGR valve. Here's the funny part... No difference at all. Is that normal?

Again thanks for all of the help.
 

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2013 F-150 XLT 4WD with 5L
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Shouldn't be the same with wires reversed. The wiring is all shared by the MAP, EGR position and the coolant temp sensor so everything might stop working if it were backwards. Without having the TPS in front of me to see the pin numbers it would be hard to tell what is correct.
 

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Discussion Starter · #5 ·
Sounds like I've got some pretty serious issues that are far beyond my skill level, huh? Do you know where the engine control computer is on this particular model? I'm starting to wonder if something might be burned in there. Again, thanks for the replies. I appreciate it.
 

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2013 F-150 XLT 4WD with 5L
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Normally the ECM is located behind the passenger kick panel. While you're in there, check all of the splice joints to make sure they're still connected.
 

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Discussion Starter · #7 ·
Here's an update. Today, I tested the MAP sensor (VREG is at 5.1V and rpm is at 311 with no vacuum and 212 with engine running.) I broke my mityvac so I had to cheat. Anyway, long story short, I plugged the MAP sensor back in and rechecked my TPS (.8V with closed throttle and 5.1V at wide open throttle). I then reset my timing, as best I could with the jumping, and the darn truck runs great now. The "trailer pulling" sensation is gone and the "missing" is much less noticeable. The only problem now, is it idles at about 1150RPM. I'm kind of scared to back the screw out on the throttle body. Should I just leave it like it is?
 

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2013 F-150 XLT 4WD with 5L
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I would experiment with the idle speed a bit. Who knows, you may just find that sweet spot it wants. Glad she's running better!

Mac
 

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Discussion Starter · #9 ·
Ok, so I played with the idle speed and as I pulled out of the driveway, it stumbled once and then idled fine. It may be a little low, but I'll keep working at it. At this point I guess the only things I need to address is the slight miss and my four-way flashers. Speaking of my four-ways... Is the "relay" the same one as the turn signal. When I turn the four-ways on, the just stay stuck on.

I can't thank you enough for all of your help.
 

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2013 F-150 XLT 4WD with 5L
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There is a separate hazard flasher and, you're welcome!

Mac
 

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Discussion Starter · #11 ·
Well, the problems are all back. I just don't get it. Anyway, I hooked up the fancy code reader and got 22(MAP or BARO sensor out of range) and 63(throttle position circuit fault, below minimum voltage).

So here's my questions....
1.)What does MAP sensor out of range mean?
2.)What the heck is a BARO?
3.)Can I adjust the "idle screw" to get the TPS voltage above minimum voltage?

Any help is extremely appreciated.
 

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2013 F-150 XLT 4WD with 5L
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The barometric sensor reads air pressure and deduce humidity by that reading when combined with an air temperature reading. It then adjusts the fuel injection system (spark and fuel) to compensate for the changes in both and certainly can affect your engine's performance.

Many newer cars and trucks have the BARO sensor built in to the MAP sensor but I don't think your truck has a BARO sensor, only a MAP (manifold absolute pressure) sensor.

Honestly, with as many issues as you seem to have it might be worth looking at the ECM and associated wiring if you haven't already. Worse case scenario is a new/re-manufactured ECM for about $100
 
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