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1997 Ranger 3.0L No Throttle Response and O2 / Fuel Codes


WackoRanger

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Wisconsin
Vehicle Year
1997
Make / Model
Ford Ranger
Engine Type
3.0 V6
Transmission
Manual
Hello,

We've been having all sorts of troubles with this Ford Ranger we bought as a small project a few months ago. So far, we've replaced the engine after discovering the original had junk piston rings when we were trying to replace the heads and we've taken it to a mechanic who did nothing but sit on it for 2 months only replacing the O2 sensors. On the new engine, we also did an EGR delete and I don't think that matches all of the symptoms we're having.

Now, we've just got it back in the garage from the mechanic after forcing them to give it to us after a very long 2 mile drive. When we were on our way back, the truck seemed to stall as soon as any throttle was given to it. Sometimes, it could handle the smallest bit of throttle to get it above 10mph, but most of the time we were cursing at a solid 5mph. Every once and while, it would backfire, but it was never sustained for a long time. Before we took it to the mechanic, it had crossed spark plug wires and 3 separate misfires. I've just checked the error codes that it's spitting out and there's so many of them I'm not really quite sure where to start.

So far, we've got:

Active:
P1445: EVAP Purge Valve High Input
P0171: System too lean (Bank 1)
P0174: System too lean (Bank 2)

Pending (I don't really know what makes these different, but this is how my reader presents the codes):
P1130: Lack of Upstream Heated Oxygen Sensor Switch – Adaptive Fuel Limit – Bank No. 1
P1131: Lack of Upstream Heated Oxygen Sensor Switch – Sensor Indicates Lean – Bank No. 1
P1150: Lack of Upstream Heated Oxygen Sensor Switch – Adaptive Fuel Limit – Bank No. 2
P1151: Lack of Upstream Heated Oxygen Sensor Switch – Sensor Indicates Lean – Bank No. 2

Ordinarily, I would start at the O2 sensors, but seeing as they've just been replaced, I don't think that's the real suspect. One of the problems we've had was the Camshaft Position Sensor disintegrating and causing the synchronizer to fail. As far as I can tell, it's been installed properly and I would hope (although I don't know for certain) that the mechanic checked the installation of the synchronizer and camshaft position sensor. I should also mention that the engine was dropped due to the harbor freight stand failing (only about 3 feet) but there was no major damage to anything besides the camshaft position sensor and a transmission mounting point which was welded back together.

Anyways, if someone out there has any ideas, please let us know!!

--
WackoRanger
 


stmitch

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How was the EGR delete done? Was the PCM tuned afterwards? Was the vacuum line to the EGR valve plugged? Was the EGR port in the exhaust manifold capped?

The lack of misfire codes is interesting. That makes it seem like it could be in some sort of limp or protection mode because it thinks there's an issue with the O2s.

Since the engine was just swapped, and the O2s were just replaced, I'd go over wiring connections and vacuum lines very very closely. I had an issue after an engine swap once that boiled down to the connector for the PCM not being fully tightened down. So even if connections look good to your eye, I'd physically check to make sure everything is properly hooked up and tight.

Does the speedometer work? If the Vehicle Speed Sensor goes bad, you won't have a functioning speedo and vehicle speed will be capped pretty low. I think it was around 25mph when mine went out.
 

WackoRanger

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1997
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Ford Ranger
Engine Type
3.0 V6
Transmission
Manual
Thanks for your reply!

The EGR delete was done fully legit and the vacuum line to the valve was plugged completely. The only thing we didn't do was tune the PCM. From what I've read I don't believe an improperly tuned PCM in terms of EGR would cause this.

As for the Vehicle Speed Sensor, the Speedo worked correctly as far as I could tell when driving it. There seemed to be a sweet spot on the throttle where it could just barely be touched and the engine would slowly rev. This only happened sometimes, usually after an uphill stretch going into a flat stretch. I never got it past 2k rpms and if I went harder than just a small tap on the accelerator, the engine rpms would start to fall and the vehicle would stutter until the clutch was pressed. The speedo did reach and point to 25 when we were on a downhill stretch and the engine was running slightly better.

When I checked quickly last night, the connections seemed fine, but I'll check again later tonight after I get home from work.

One of the possibilities that we were thinking of was if this was caused by a bad ECU because the new engine came from a 5 speed A/C unit and the ECU is from the old engine that is a 5 speed non A/C. Could this be it?

--
WackoRanger
 

WackoRanger

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1997
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Ford Ranger
Engine Type
3.0 V6
Transmission
Manual
I'm back!

When I got back from work yesterday I was able to find that all of the connections were physically OK.

However, I was reading somewhere else that a guy unplugged his MAF sensor and the engine acted as normal for the first few minutes. When I did it yesterday, I was able to find that the engine fired right up and revved as high as i wanted it to go when I was applying the accelerator!

Now, what he did in his own quest was replace his MAF sensor, but there was also some talk about replacing the IAC Solenoid. I have the old MAF sensor from when I first started this project and I plan to stop by my shop after work to pick it up and swap it in. I originally replaced the MAF sensor because it was giving bad readings until the engine was "snubbed" out by the transmission. It would then give the proper readings.

So, my question now is, what do I replace? Do I replace both the MAF sensor and the IAC Solenoid or do I just do one of the two. This engine was dropped off the engine stand which leads me to think that it's the IAC but if it is, why is unplugging the MAF helping?

--
WackoRanger
 

WackoRanger

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Location
Wisconsin
Vehicle Year
1997
Make / Model
Ford Ranger
Engine Type
3.0 V6
Transmission
Manual
And now the final part to this epic saga!

I talked to a buddy of mine at work, he told me to try and throw the old MAF sensor back on and check to make sure there were no intake leaks.

After installing the old sensor back in and re-tightening everything down, I was able to not only turn the engine over, but the truck now revved with a MAF sensor plugged in and it even got up to highway speeds!

The only thing that really puzzled me about this whole episode was the fact that there were never any MAF sensor codes. Throughout the entire project, there has only ever been one MAF sensor code 6 months ago, which i got rid of thanks to the new (now defective) MAF sensor. But, oh well.

Thanks for all your help!

--
WackoRanger
 

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