Newbie has problem

[Ram007]

Hi all, I Have a 1996 dodge ram 1500 4x4 5.2L. The problem is it starts missing and then loses all power it will idle for awhile but it misses real bad then quits, once it cools down for an hour or two it starts up and runs fine again, sometimes for a couple days, short trips, then it happens again.
So I bought a scan tool and this is what I got last time.
P0300-random misfire
P0301-misfire #1 cyl
P0302-misfire #2 cyl
p0171-fuel trim system leanbank 1
p0138-HO2s circuit high voltage bank 1 sensor 2

The short term fuel trim on the scanner was reading +27.3% more fuel
long term was -5.4
I have changed plugs/wires/cap/rotor/coil
any help would be great, Thanks

[ctwright]

Couple things could be, I will get back later cooking now. Crankshaft position sensor, coil, or ignition module.

[Ram007]

Can the crankshaft position sensor act like this, I have been driving for about a week now with no problem, but it will happen again, as it always does. Is there any way to check that sensor. I do have a new coil on it but will check it.

[ctwright]

Yes it can make it do that. It is harder to diagnose an intermittent problem because you usually if not always have to wait til the problem is happening to check. I don't have a wiring diagram for your vehicle so I wouldn't be much help with you diagnosing the problem because I don't know which wires coming from the sensor are the right ones to check for pulses or to check other things like your ignition module either.

[Ram007]

Ok I found my repair manual and it tells me which wires are which, so I guess I have to check it when its acting up, also would a bad o2 sensor cause this? Can't find any info on ignition module in my book.

[jpb53]

Fuel pressure problem. You have a lean code and the short term fuel is high. The computer is trying to add fuel that is not there. Fuel pressure can cause all those codes.

[Shortbus]

Welcome Ram007 your in good hands here at AF!

[Ram007]

Originally Posted by Shortbus

Welcome Ram007 your in good hands here at AF!

Thanks for the welcome, and I am sure I will get the help I need.
Anyhow the truck has been running now for a week with no probs, so I have a new theory, its been warm and sunny for this past week with no probs, and I remember last thursday was cool and damp in the morning when it acted up, but ran fine later on when it was warm and suuny, plus it happened all winter long, also I am still getting the p0138 code everyday. so I am guessing I need a new o2 sensor, does my theory make sense.

Thanks for all the help

[Chris Stewart]

I had a similiar issue except the opposite code on an older OBDI car...sensed a rich condition. I bought another O2 sensor and it gave the same code the next day. The only fix was to replace a leaking fuel line inside the intake which stopped the rich condition and stopped the Check Engine light after a reset,
It sounds like you're right on the edge with fuel supply/pressure, especially with warmer, more humid air (less oxygen so actually requires less fuel) satisfying the O2 sensor. A fuel filter change or at least fuel pressure check should prove it out.