94 b4000 4.0 to lean and to rich

[Meanman480]

I have a 94 mazda b4000 4wd it's no alway an issue but the truck dose run way to rich I will drive it with no problem moat of the time but on ocation the truck will start to bog down and rough idel a lot to the point it won't drive and increased throttle dose not fix it only turning the truck off fixes it usual for good but not always it will resume the stupidity I have a chopped exhaust no cats full length single pipe 2.5 in but both upstream o2 sensors are there when I test the codes I get bank 2 to rich and bank 2 to lean at the same time I have changed the Mas air flow sensor air temperature sensor and dpfe and fule pump still dose it just less often even swaped the fule injectors with used working ones no change any ideas

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[RonD]

What were the exact code numbers and did the CEL(check engine light) come on?

And has the CEL come on again after clearing the codes, if so what codes are there now?


Could be you computer has gone bad, exact code will help.

 

[Meanman480]

Don't have the codes I front of me bit I do know it's was bank 2 to rich and then bank 2 to lean only codes given and
My CEL dosent work right bad bulb or bad socket

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[RonD]

Then your computer is probably bad, bank 1 lean and bank 2 rich at the same time, wouldn't be MAF sensor or O2 sensors.
Both banks lean or both Rich could be MAF
One bank lean or rich but other bank normal could be one O2 sensor failing.

Lower intake vacuum leak could make one bank lean but other would be normal.
Upper intake vacuum leak makes both banks lean.

Leaking fuel injector makes one bank rich, the other is normal

Leaking Fuel Pressure regulator(FPR) could cause low fuel pressure and lean code, and if excess fuel was being sucked up via it's vacuum hose it "could" make one bank rich, should make both banks rich, so thats a long shot.
Remove the FPR's vacuum line and check it for fuel or fuel smell, replace FPR is fuel is found in the vacuum line.

I can't think of anything else but a bad computer that would cause the Lean/Rich and the rough running at times

I would pull out computer and check connector for water damage and then open the top of computer and look for "black areas" on circuit board.
This is what a good computer looks like, yours should look the same: http://www.auto-diagnostics.info/ford_eec_iv

 

[Meanman480]

I'll try it I have been leaning thorns o2 sensors but was not sure

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[monstermazda]

Check the fuel pressure mine ran fine for a little bit hit the interstate going 80 all of sudden the truck acted if I had a J-brake and I could smell the fuel. I pull over and it sounded like it was going to die or like it was ment to be on a drag strip.

My fuel pressure regulator was on the pump cause It to go lean and rich to.
98 b3000

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