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2.9L & 3.0L V6 Tech General discussion of 2.9L and 3.0L V6 Ford Ranger engines.

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Old 12-21-2015
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Join Date: May 2015
Location: New Caney, TX
Posts: 1
Not Running Right

Hey I'm having some trouble locating the cause of my problems and I'm hoping y'all here can help.
I have a 2000 Ranger, 3.0l flex and it's got spark knock really bad. According to the Ford TSB it says to fill with 93 octane and if this doesn't fix the problem, follow normal spark knock diagnostic service procedures. I took it to a buddy with a super awesome Bosch diagnostic tool and pulled the following numbers this is a snapshot, they didn't vary much from this:

ABSLT TPS(%): 16.1
CALC LOAD(%): 25.1
COOLANT (F): 183
IAT (F): 93
IGN ADV (degrees): 25.0
LT FTRM1: 25.0
LT FTRM2: 24.2
MAF (LB/M): 0.68
O2S11 (V): 0.155
O2S12 (V): 0.085
O2S21 (V): 0.380
ST FTRM11 (%): 3.9
ST FTRM21 (%): -0.8
ST FTRM1 (%): 2.3
ST FTRM2 (%): -0.8

It feels like a misfire at idle but I just recently changed the plugs, wires, and the coil. I have a feeling that it's a fuel problem but I don't know where to go from here. I changed the fuel filter but I haven't checked the fuel pressure yet. Can someone please advise?

EDIT (12-21-2015, 2013): I don't think the RPM is correct there as this was at idle with no additional throttle.
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Old 12-22-2015
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Join Date: Jan 2014
Location: Vancouver, BC
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Was engine warmed up?

Engine temp should be higher that 183degF

O2 11 and 12 are the ones the computer uses to adjust fuel mix, they are showing extremely Lean burn, O2 sensors can only see Oxygen levels in exhaust, O2 sensors generate their own voltage, 0.1v to 0.9v
0.1v means too much oxygen is in the exhaust, so Lean burning of fuel, 0.9v means too little oxygen in exhaust so Rich burn.
O2s 11 is bank1(passenger side of engine) and showing 0.155
O2s 12 is bank2(drivers side of engine) and showing 0.085
These would mean alot of engine knock(pinging)

The problem I see is that computer should be adding more fuel to bring these O2 sensors voltage up to 0.45v, and it is not doing that.
O2 sensors can only working after they get above 600degF, so engine MUST be warmed up to get valid data from scanner/reader, which is why I asked if engine was warmed up

It also says MIL(check engine light) is off, which it shouldn't be if engine was warmed up and those 2 O2 sensors had those levels

having two O2s sensors fail at the same time would be extremely long odds
So problem needs to be something that effects BOTH banks of the engine.

But my problem with the data provided is that it shouldn't happen, the computer gives the O2 sensors final word on the fuel mix ratio.
MAF can fail, fuel pressure can drop, massive vacuum leak can happen, but computer would just add more fuel to keep O2 sensors at 0.45v, and then turn on CEL to let driver know about the problem.

Maybe in the "snapshot" you caught both O2 sensors at a low, which could happen.
And your Long Term Fuel Trims(LTFT) do show +24 and +25 which do indicate extra fuel is being added consistently.
Check fuel pressure would be a good step

Last edited by RonD; 12-22-2015 at 10:34 AM.
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