DOHC - 2.3L Duratec / Mazda L Engines Discussions and Topics specific to the Duratec 4 cylinder engines

Low power at low RPM however only under cold weather conditions

  #1  
Old 01-09-2019
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Low power at low RPM however only under cold weather conditions

I recently just purchased a 2003 Ranger 2.3 L 5 speed manual. When I got it, it was running fine. I then noticed some significant power loss esp at lower RPM. First thing I thought maybe a fuel pump or fuel filter not allowing enough fuel through when needing more. I changed the fuel filter and it ran fine. However it was above averagely warm for a few days. I soon put together that when the temperature decreases and is cold the vehicle has no power. Iím talking canít keep it at 60 mph in 5th gear on flat ground. Today is 30 degrees and snowing, I had to drive to work in 4th gear as it just wonít keep speed. Fuel pedal down it just bogs the motor down. Yesterday was 65 on my way to work and I never had to take it out of 5th gear. Any help would be much appreciated!!
 
  #2  
Old 01-09-2019
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Originally Posted by JD85 View Post
I recently just purchased a 2003 Ranger 2.3 L 5 speed manual. When I got it, it was running fine. I then noticed some significant power loss esp at lower RPM. First thing I thought maybe a fuel pump or fuel filter not allowing enough fuel through when needing more. I changed the fuel filter and it ran fine. However it was above averagely warm for a few days. I soon put together that when the temperature decreases and is cold the vehicle has no power. Iím talking canít keep it at 60 mph in 5th gear on flat ground. Today is 30 degrees and snowing, I had to drive to work in 4th gear as it just wonít keep speed. Fuel pedal down it just bogs the motor down. Yesterday was 65 on my way to work and I never had to take it out of 5th gear. Any help would be much appreciated!!
i would see if you can with a scan tool, pull up the intake air temp reading along with air flow. also i would recommend an exhaust back pressure test
 
  #3  
Old 01-10-2019
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Yes, +1 ^^^

The 2003 2.3l was the last year of IMRC(intake manifold runner control), its a vacuum operated system that caused more problems than it was worth to increased horse power, so was dropped in 2004 and up 2.3l engines

You should have codes in memory if that system is having problems
Any auto parts store will read codes for free, WRITE DOWN the code numbers, "I think it was............" is worse than no code at all

There should also be Lean Codes if fuel flow was an issue previously addressed by new fuel filter
The computer tracks fuel flow using fuel injector open time and O2 sensor feedback
If computer "sees" that it is having to open fuel injectors longer than calculated it will set a Lean Code, that does NOT mean engine is running Lean, it means computer's calculations are off, so could be an air leak or low fuel flow


Other thing to test is Vacuum, $20 vacuum gauge is still one of the better diagnostic tools available...........100+ years in use on gasoline engine, lol

Good guide on how to do tests here: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine
 
  #4  
Old 01-11-2019
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As an update thinking this is definitely a fuel issue I unhooked my MAF sensor and boom all kinds of power. I was able to take the hill to my house in 3rd gear which previously struggled in 2nd gear. Absolutely zero power issues. I just replaced this previously but Iím sure it could be a faulty sensor. Does this seem to be the issue to anyone or could something else be causing this besides the MAF sensor. I have no check engine lights on. I had one and the runner control valve stuck open was a Code as well as lean in bank 1 which has never come back on since my buddy reset the codes and check engine has not came back on either. Iím thinking I should Just get another MAF sensor and see if that is it. Considering the only issues are when itís cold out.
 
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Old 01-11-2019
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If its a 6 wire MAF then the air temp sensor is in there as well, so yes I would replace it to see

The computer switches to internal memory air/fuel ratio tables when MAF is unplugged, if new MAF doesn't help then could be computer "on the fly" calculation issue
 
  #6  
Old 01-12-2019
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Originally Posted by JD85 View Post
As an update thinking this is definitely a fuel issue I unhooked my MAF sensor and boom all kinds of power. I was able to take the hill to my house in 3rd gear which previously struggled in 2nd gear. Absolutely zero power issues. I just replaced this previously but Iím sure it could be a faulty sensor. Does this seem to be the issue to anyone or could something else be causing this besides the MAF sensor. I have no check engine lights on. I had one and the runner control valve stuck open was a Code as well as lean in bank 1 which has never come back on since my buddy reset the codes and check engine has not came back on either. Iím thinking I should Just get another MAF sensor and see if that is it. Considering the only issues are when itís cold out.
make sure you get a ford / motorcraft sensor if you decide to replace it
 
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