94 F350 giving me fits

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#46

01-17-2015, 06:58 PM

Tranz zam

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Quote:

Originally Posted by timbersteel

Usually, if you replace one, do them all. These are 20+ year old caps, and they have been subjected to extremes. Good that now as RLA mentioned, you are passing KOEO.

Lean code can be vacuum leaks, leaking exhaust, gasket leaks. The bogging down and hard shifting could be result of code 172, because it its not able to enrich the fuel mixture, thus not having the power when loading it down.

Either case, I would be inclined to check resistance if the TPS circuit, and clean the contacts of the TPS connector. If it's a no name brand, then try to get a Motorcraft TPS sensor when possible.

Also, if you haven't found the O2 sensor harness, that's the next step. If you look on the passenger side fenderwell, near the battery and close to the fender mounted relay, there should be a weatherpack connector that is white. It is the beginning of the O2 sensor harness that runs down the passenger side wheel well and then to the separate O2 sensor pigtail.

Good to know about replacing all the caps. If I have to take it back out I'll replace them all

Its never thrown the 172 until I fixed that cap. I don't know if its a coincidence or not? I'll work on the tps tomorrow while its warm out. Could the lean code be from a faulty tps combined with no o2?

I'll have to look for that weatherpack. I don't remember seeing anything over there but I wasn't really looking for it. It would be nice if its there.

Thanks for the help!

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#47

01-18-2015, 12:53 PM

Tranz zam

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I think I might have found the answer.

Theres that bunch of vacuum lines that go into the top of the intake. There was 3 that were blocked, so I removed the caps and re-installed the lines. The truck started a little funny, but caught itself. Now the truck seems to run great! And theres no CEL on anymore. This doesn't explain the TPS or EGR codes (I don't think) but its working.

I also tested the TPS and it seems to be ok.

I found that white plug on the passenger side inner fender for the o2. It seems to be capped off from the factory? Heres a pic:

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#48

01-18-2015, 01:01 PM

rla2005

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I suspect one of those vacuum lines is for the EGR valve. No correlation to the TPS code. What was the closed throttle TPS value?

That truck left the factory with an O2 sensor.

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#49

01-18-2015, 01:27 PM

Tranz zam

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Quote:

Originally Posted by rla2005

I suspect one of those vacuum lines is for the EGR valve. No correlation to the TPS code. What was the closed throttle TPS value?

That truck left the factory with an O2 sensor.

I believe the closed value was 1v. Whatever changed helped tremendously.

I believe you about the o2, I just cant believe whoever got rid of it went through so much trouble to hide it.

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#50

01-19-2015, 11:00 AM

Tranz zam

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If that's the plug for the o2 harness, do they sell the harness that plugs into it? Theres very few of these trucks left in the junkyards around here.

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#51

01-19-2015, 11:18 AM

rla2005

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In my experience wiring harnesses/assemblies/sub-assemblies are no longer available for this vintage truck.

The connector in your photo appears to be the correct one, C103. It has 3 wires (Gray/Light Blues, Orange, Black).

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#52

01-19-2015, 05:04 PM

timbersteel

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I recall reading somewhere that the wiring assembly for the O2 may still be available. I would have called my parts guy if I had seen this post earlier, was asleep though, and didn't. But I would check eBay or call around to several well known junkyards, and ask them what's available. I have 2 huge junkyards within 50 miles, but they pull it, not you. But everytime I've called, they have the part.

Added.. I'll try tomorrow and see if he can locate it. If not, I'll let you know.

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#53

01-19-2015, 07:11 PM

Tranz zam

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Thanks for all the help guys! So far so good, the truck runs 100x better then before!

I'll dig around the yards around here and see if I can find a harness. Just to make sure, the F150s went to obd2 in 96 while the larger trucks stayed obd1 until the body style change? If I find an older F150 that's obd1 will the harness still work if the trucks a 5.0?

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#54

01-19-2015, 07:34 PM

timbersteel

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Yes, either 4.9, 5.0, or 5.8 harness will work.

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#55

01-20-2015, 04:37 AM

Spktyr

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Quote:

Originally Posted by rla2005

Even if they aren't, the connectors/pigtails still are so you can build your own as need be. Motorcraft® Wiring Sets for Ford and Lincoln Vehicles | The Official Ford Parts Site | FordParts.com

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#56

01-20-2015, 04:39 AM

Spktyr

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Quote:

Originally Posted by Tranz zam

If that's the plug for the o2 harness, do they sell the harness that plugs into it? Theres very few of these trucks left in the junkyards around here.

Tons and tons of them down in my area. Where's "here" that you don't have many?

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#57

01-20-2015, 01:08 PM

Tranz zam

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Quote:

Originally Posted by Spktyr

Tons and tons of them down in my area. Where's "here" that you don't have many?

Im in Northern MA on the coast. Most of these trucks rusted into the ground.

I drove the truck 24 miles today. For half the ride it was fine, but on the way back it reverted back to its old symptoms.
I got code 111 122 172 332 334

334 is a new one for me. I thought I read in a TPS write-up that sometime they can go a little crazy when they're bounced around. Maybe its a sign that its going bad?

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#58

01-22-2015, 11:02 AM

Tranz zam

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Just to give you guys an update....

I replaced the aftermarket TPS with a used Ford one. I then took the truck for a ride and hit some really choppy bumpy roads and the issue didn't come back. I wonder if the aftermarket one was right on the edge of what the computer is looking for, and when I hit rough roads it had an effect on the TPS?

Whatever the case may be the truck seems to be running nice now! I'll work on the o2 next.

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#59

01-22-2015, 11:22 AM

rla2005

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Thanks for the update. Aftermarket TPS and other sensors are really starting to get hit or miss on their quality control. I hope the used Ford TPS works out for you!

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