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Running rich


Alecs

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Hello everyone.
I'm having problems with my 97 ranger running rich. It has the 4.0 ohc engine with a 5 speed rwd.

It's throwing the following codes: p1132, p1152, p0135, p0141, and p0155. They indicate heater circuit malfunction on all three o2 sensors and that both banks are running rich.

Here's what I've already done: replaced all o2 sensors, new plugs and wires, new coolant temp sensor, pcv valve, seafoam engine cleaner. I'm wondering if anyone has had a similar problem and found a solution because me throwing money at it is making me want to trade my hair out.
Thank you all in advance.
 


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RonD

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Have you checked the fuse for the heated part of the sensors?
Try Fuse #20 in the engine compartment fuse box, 15amp I believe


In general a Rich condition means fuel is leaking into the intake.
1997 will still have Fuel Pressure Regulator(FPR) on the front of lower intake passenger side.
FPR has a vacuum hose attached, and the Return Fuel line.
Remove the vacuum hose and see if there is gasoline in it, if there is then you have a leaking FPR diaphragm, replace FPR.

Leaking fuel injector can also cause rich mix but harder to pin down.

I would fix the O2 issue and then clear the codes and see if you get "rich" codes after that
 

Alecs

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I did find a blown fuse on slot 20 and also was missing one in slot 27. Replaced both of those. I'll look into the FPR and let you know.
 

Alecs

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Checked my fpr and didn't find any fuel in the vacuume line starches to it. My fuses in the door jam are all good. If there another fuse under the hood possibly?
 

RonD

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When do you replace the fuses and have you reset the computer since then to see if codes come back?
 

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I replaced the fuses yesterday and reset the codes and they came right back on.
 

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Then you will need to test for power at any one of the O2 connector.

It will be the Light Blue/orange stripe wire for 12v

The Computer is the Ground for each O2 heater element that is how it monitors if "heater" is on.
So key must be on to test for Ground

This pin lay out should be correct for your year: http://easyautodiagnostics.com/ford/4.2L/oxygen-sensor-resistance-test-2

If there is 12volts but no ground then computer could be the problem, or one of it's grounds
 

Alecs

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I figured out it is my computer that sent bad. Just wondering if that's something that's pretty easy and straight forward to fix like plugging it in our if it's more comprehensive and I should just let a shop do it.
 

RonD

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As long as the replacement computer(PCM) is from(for) 1997 Ranger, 4.0l, manual transmission model it will be "plug and play".

I think all '97 4.0l would have EGR system not just Calif. models but not sure, computer must match EGR or no EGR.

2WD or 4WD shouldn't matter

Make SURE battery is disconnected when swapping out any electronics, PCM especially :)

PCM = Power control module
A.K.A.
EEC = electronic engine control
ECM = engine control module
 
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Alecs

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Got the PCM replaced and she definitely runs a lot better but still haveing a couple issues.
I'm now throwing codes p1443 and p0420. Are these things I need to fix asap?
Also how would I go about fixing them?

Sent from my XT1042 using Tapatalk
 


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