2002 Ford F-150 Air to gas ratio

Tiny
MADDIE0944
  • MEMBER
  • 2002 FORD F-150
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
So my truck is a 2002 V8 5.4L Ford Lariat F150 Truck, it used to be supercharged before we had this problem, but we had to sell the supercharger for the labor the mechanic put into trying to find this seemingly unsolvable problem. The air to gas ratio has seems to be the biggest issue, the truck struggles to get up to speed and during its struggle the truck spits gas causing an unwanted surge forward until it gets to about 40 MPH and is all around shaky. Recently the catalytic converters burnt out so we sawed them off and ran straight pipes while reconnecting the co2 sensors to the new pipes. We have checked the coil packs, replaced the fuel filter and pump three times, and checked all the fuses, vacuums, and any wiring we can reach. I would hate to let this thing go, it would just break my heart. Any suggestions or answers would be appreciated, Thanks!
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Saturday, December 27th, 2014 AT 4:26 PM

4 Replies

Tiny
CARADIODOC
  • EXPERT
There is absolutely no way you're going to make this engine run properly with missing parts. I can't imagine what kind of deal you made with your mechanic but he should have known better. Turbocharged and supercharged engines have a lower compression ratio which those air pumps make up for. You need the supercharger to stuff the correct amount of air into the cylinders. Atmospheric pressure isn't going to do it.

You won't find any professional willing to help with removed catalytic converters. It is now illegal for us to work on the truck. The front oxygen sensors will still work properly and will tell the Engine Computer how to adjust fuel metering but with the missing converters, no change in the composition of the exhaust gas will take place between the front and rear O2 sensors. The Engine Computer watches the switching rate between too lean and too rich. That switching takes place about twice per second at the front sensors, but when the catalytic converters are working correctly, the switching takes place at the rear sensors perhaps once every minute or two. As it is now, both sensors will switch at exactly the same rate which is going to set a diagnostic fault code for "catalytic converter efficiency". That will turn on the Check Engine light. Since the light will always be on, you'll never know if a different, minor problem is detected that could turn serious if neglected.

Also, once those converter codes are set, some self-tests will be halted because the computer knows it can't rely on the O2 sensors to provide proper test results. You could have some running problems that won't even be detected until the converters are replaced.
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Saturday, December 27th, 2014 AT 4:57 PM
Tiny
MADDIE0944
  • MEMBER
Yes we must have had a crappie mechanic, but we have no money to get our supercharger back and no money for new catalytic converters. We are in a bind this will, by my guess, ultimately result in the loss of my truck. Hate to say it but that is probably going to be the result.
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Saturday, December 27th, 2014 AT 6:01 PM
Tiny
CARADIODOC
  • EXPERT
I understand the love you have for your truck. I'm driving a 25-year-old Grand Caravan in the middle of road salt country. The carpet is the only thing holding the front and rear halves together but it has been so reliable that I'm trying to find another one like it from down south.

My first suggestion is to find a conscientious mechanic who can find the parts to put your truck back together properly, but it will be very hard for anyone to jump in and figure out what other people did. A better alternative might be to find another 2002 model that is original and has the options you want. Trucks hold their value longer than cars, but still, it's 12 years old and you're likely to find one for less than the cost of repairing yours. You'll also get something for your old one on trade if you buy from a dealer, or you can sell yours outright.
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Saturday, December 27th, 2014 AT 9:34 PM
Tiny
MADDIE0944
  • MEMBER
Thank-you for all your advice, this was very helpful!
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Sunday, December 28th, 2014 AT 5:57 AM

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