Need help with my Ranger!

[GR8TSCT]

Hi I have a 1989 4X4 Ranger Extra Cab XLT. It has the 2.9L V6. The truck has 220,000 miles. The Engine was rebuilt at 198,000. It passed smog just fine. I am having trouble with the trucks run ability. The new engine ran fine for 20,000 miles. The problem started after I let it sit for two days. The truck has a very ruff idle, has no power (well less then it had before). Does not miss fire. running so rich the exhaust burns your eyes. Some guy before me put headers on it, but they are the legal ones with the O2 sensor in them. When you take off from a start feels like it is loading up and really doesn’t go anywhere. It does not pass smog. I have replaced the spark plugs, wires, distributor cap (and rotor), coil, throttle position sensor, map sensor, and a few others I don’t know the name of (as a mechanic helped me), O2 sensor, checked the timing (remembering to disconnect the spout connector). I have replaced the ECM (computer), and it still didn’t fix the problem. There are a few exhaust leaks but I don’t think it would cause it to run like this. Does anyone else have any ideas. I am fresh out. The tags are now out of date, because of the smog, so I really need to find out what is wrong. I have tried two different Ford dealerships, who told me they don’t work on trucks that old. There is one Ford dealer that said they would work on it, but I would rather fix it myself and save $100 an hour labor, and 300% markup on parts. PLEASE HELP!

 

[MountaineerGreen]

Moved from tech corner to the Ranger forum. The tech corner is not for questions.

 

[dogfriend]

I can think of more questions than answers, although it seems pretty clear that you are running very rich. A common cause for that is a bad FPR (fuel pressure regulator). The FPR is located on the fuel rail and has a vacuum line leading to it. Pull the vac line and see if there is any fuel present in the line (there shouldn't be). If so, then the diaphragm is broken. If not, then I would buy, rent, or borrow a fuel gauge and check the pressure on the fuel rail.

Exhaust leaks could cause you to get a rich condition if the leaks are close to the O2 sensor and fool the sensor into thinking the mixture is too lean.

Did you ever get a Check Engine Light? Also, does the truck run better, worse or about the same when it is warmed up (closed loop) vs. when it first starts cold (open loop)?

 

[GR8TSCT]

Help with ranger

I can think of more questions than answers, although it seems pretty clear that you are running very rich. A common cause for that is a bad FPR (fuel pressure regulator). The FPR is located on the fuel rail and has a vacuum line leading to it. Pull the vac line and see if there is any fuel present in the line (there shouldn't be). If so, then the diaphragm is broken. If not, then I would buy, rent, or borrow a fuel gauge and check the pressure on the fuel rail.

Exhaust leaks could cause you to get a rich condition if the leaks are close to the O2 sensor and fool the sensor into thinking the mixture is too lean.

Did you ever get a Check Engine Light? Also, does the truck run better, worse or about the same when it is warmed up (closed loop) vs. when it first starts cold (open loop)?

No there is no check engine light on, before and after the new ECM. The truck seems to run better cold. The FPR has been replace. I have not check the fuel pressure, but if it is running rich it is defiantly getting enough fuel, so I have been looking in different areas. Oh, since I bought the truck, it has had exhaust leaks, and ran just fine. but I will try and fix the exhaust leaks.

 

[410Fortune]

fix exhaust leaks, check fuel pressure is a must
whenyou rebuilt the engine did they re-use the old fuel injectors?

Is the rest of the exhaust still factory?

 

[dogfriend]

If it runs better cold, that is a clue. When cold, the O2 sensor is not hot enough to work, so the fuel/air is set by a lookup table in the PCM. This is open loop operation. Once the O2 sensor is warm enough, the PCM switches over and starts to use the O2 sensor voltage to adjust fuel/air ratio. This is closed loop operation. If you only have the problem during closed loop, you may have a problem with the sensor, the wiring or the PCM.

I realize you already replaced a bunch of stuff, don't blindly replace anything again without figuring out how to test it first. The only part that you can't really test is the PCM, they rarely fail, so most troubleshooting routines list that as the last thing after everything else has been ruled out as the cause.

I would still verify that the fuel pressures are ok.

If you have a Check Engine Light, borrow or buy a scan tool and then search for that code (or codes) on this forum. You may be able to borrow a scan tool at Autozone or another parts house. If they scan it for you, make sure to get the number(s) of the code; don't rely on their interpretation of what is wrong.

The fact that the problem occurred all of a sudden, instead of gradually makes me think that a sensor or wiring got damaged or failed.

 

[GR8TSCT]

If it runs better cold, that is a clue. When cold, the O2 sensor is not hot enough to work, so the fuel/air is set by a lookup table in the PCM. This is open loop operation. Once the O2 sensor is warm enough, the PCM switches over and starts to use the O2 sensor voltage to adjust fuel/air ratio. This is closed loop operation. If you only have the problem during closed loop, you may have a problem with the sensor, the wiring or the PCM.

I realize you already replaced a bunch of stuff, don't blindly replace anything again without figuring out how to test it first. The only part that you can't really test is the PCM, they rarely fail, so most troubleshooting routines list that as the last thing after everything else has been ruled out as the cause.

I would still verify that the fuel pressures are ok.

If you have a Check Engine Light, borrow or buy a scan tool and then search for that code (or codes) on this forum. You may be able to borrow a scan tool at Autozone or another parts house. If they scan it for you, make sure to get the number(s) of the code; don't rely on their interpretation of what is wrong.

The fact that the problem occurred all of a sudden, instead of gradually makes me think that a sensor or wiring got damaged or failed.

No check engine light. I have used the breaker box, and the scanner tool, and tested voltage readings on the different sensors, o2 and others with no faults.

 

[GR8TSCT]

the voltage readings checked out with the breaker box, so the wiring loom is ok.

 

[GR8TSCT]

fix exhaust leaks, check fuel pressure is a must
whenyou rebuilt the engine did they re-use the old fuel injectors?

Is the rest of the exhaust still factory?

oh ok, I will check the fuel pressure, and no the injectors were replaced.

 

[94 Crawler]

Your injectors will only be a problem if one is hung wide open.
Have you replaced the coolent temp sensor? If the temp sensor has gone bad the pcm may think the engin is actuly colder than it realy is. This in turn will make the pcm comand the injectors to longer dwell time and send the engin more fuel. Also if you have a poor eec ground (should be on the radiator core support) this could cause you some major issues as well.

Also make shure that the egr valve is closing properly If your engim has one.

Good luck

 

[GR8TSCT]

Your injectors will only be a problem if one is hung wide open.
Have you replaced the coolent temp sensor? If the temp sensor has gone bad the pcm may think the engin is actuly colder than it realy is. This in turn will make the pcm comand the injectors to longer dwell time and send the engin more fuel. Also if you have a poor eec ground (should be on the radiator core support) this could cause you some major issues as well.

Also make shure that the egr valve is closing properly If your engim has one.

Good luck

Yes the Temp sensor was replaced

 

[dogfriend]

If I recall correctly, 89 2.9L CA Emissions doesn't have an EGR valve. I used to have an 89 Ranger.

It also doesn't have a MAF, it uses the MAP (manifold air pressure) sensor and a lookup table for air flow.

If you are getting too much fuel, it could be:

Too much fuel pressure
Stuck Fuel injector(s)
Problem with O2 sensor or circuit making the PCM think that you are too lean
One of the other sensors (e.g. CTS mentioned above) making the PCM think you are too lean.

Am I forgetting any?

At this point, I would not assume that the sensor(s) are working just because you replaced it already - I would test the sensor(s) because it is possible for a new sensor to be defective. Testing the sensor is the best approach to avoid throwing gobs of money trying to fix it.

 

[Kornerboy]

Hello Ranger Owners,new member here,not sure how this site worx??I just replaced alternator on 92 ranger/custom.3litre v/6 5/speed?Also installing a new serpentine belt,hence my problem,do not have a diagram for belt replacement??Need to see a view of v/6,with belt on??Cannot seem to get new belt on right pulleys??Also no a/c??Any help woud be appreciated?!!Thanxx Kornerboy57??

 

[GR8TSCT]

Found the problem

Well I have found it. I feel really dumb!!!! After all the testing, and all the computer and sensor parts. It ened up being a bad spark plug. It was running on 5 cycl. All the unburned fuel was being pumped out the exaughst. I figured the spark plugs were still good, as I had just replaced them, so I didnt look at them. The end of the spark plug was melted. I guess the timing was way off which casued the spark plug to melt, so I am told. It was wierd, as you couldnt feel the miss. It took two shops (one gave up, and said they couldnt find the problem.) and $420 later I got a new spark plug.

If it runs better cold, that is a clue. When cold, the O2 sensor is not hot enough to work, so the fuel/air is set by a lookup table in the PCM. This is open loop operation. Once the O2 sensor is warm enough, the PCM switches over and starts to use the O2 sensor voltage to adjust fuel/air ratio. This is closed loop operation. If you only have the problem during closed loop, you may have a problem with the sensor, the wiring or the PCM.

I realize you already replaced a bunch of stuff, don't blindly replace anything again without figuring out how to test it first. The only part that you can't really test is the PCM, they rarely fail, so most troubleshooting routines list that as the last thing after everything else has been ruled out as the cause.

I would still verify that the fuel pressures are ok.

If you have a Check Engine Light, borrow or buy a scan tool and then search for that code (or codes) on this forum. You may be able to borrow a scan tool at Autozone or another parts house. If they scan it for you, make sure to get the number(s) of the code; don't rely on their interpretation of what is wrong.

The fact that the problem occurred all of a sudden, instead of gradually makes me think that a sensor or wiring got damaged or failed.