Hello,
i have a 1997 mazda b4000 4x4 4.0l and 5r55e tranny. aproxx 130k miles
things already replaced:
fuel filter
tranny flush
IAS due to fog horn hiding under hood
plugs and wires due to cylynder #4 missfire
MAF cleaned
upper intake and fuel rail gaskets
cleaned egr ports while replacing gaskets
several small lenghts of bad looking vacuume line

i bought the truck used TMU due to bad speedo, that was recently fixed. it has a slight bucking at crusing speed. and if you get it to kick into passing gear or on a freeway onramp it seems to loose power and pop outta the intake. i have never owned a ranger or driven one for that matter, i dont know if this 4.0 just doesnt have the power i think it should. the power doesnt worry me as much as the backfire does. i really dont want to throw money and parts at it without getting some imput first. i have done what all i could think of based on what i've read on this forum. codes that have been pulled are 171, dont quite remember the others besides the missfire codes.
any help on this matter would be greatly appreciated. just to add another note, when it does go into passing gear it doesnt gain any speed, seems as if it isnt developing enough torque to shift the tranny.

 

Hi, I hope this helps a bit, code 171 is your O2 no.1 bank 1 has reached its adaptive limit.It might be just your O2 has gone bad but it could be that your fuel pressure is not right or your injectors are out, air leaks and bad wiring from your ECM can also throw this code.

 

Welcome to FTE!

Something I'd consider is checking the fuel system, particulalry the pressure. You ought to change the fuel filter no matter what if you haven't already.

 

hello and thank you for your quick responses,

i have now noticed after all this work done today that it is surging at idle in drive. i suspect the egr is sticking open because it ran fine on highyway, with the exception of the burping at high rev. i proly damaged the diaphragm when i was cleaning. i tried to remove the egr, it still has ford sticker on it, but damn that nut on the backside. i will check the fuel pressure , any ideas what numbers i should be seeing? i think i need to also check the exhaust for restriction with vacuum test. it may be time to add these tools to my collection.

 

The 4.0l's have a habit of leaking air around the intake, you want to check it out. do a search in the forum and you will see several posts on it.
Dave

 

in my original post i included what i have already done to it since i bought it 2 weeks ago.
fuel filter
tranny flush
upper intake and fuel rail gaskets
IAC
plugs and wires
cleaned maf
cleaned egr ports

 

If you did a proper job replacing it then that should not be the problem.
Dave

 

Dave,
i meant no disrepect when i posted that reply, this is just frustrating. thank you for your input.

i tested fuel system pressure
30Lb at idle
38lb w/o regulator

 

LOL
the heads were cracked, $1500 later like new truck. I had them replaced spring of 06 after i noticed it consumming about 1/2 gal coolant a day. Just figured id update.