I have a dificult to diagnose problem that started recently, hopefully one of you guys has a good suggestion.

It's a '98 5.9 with 292.000km. Starts perfectly in the morning. Run's most of the time really smooth. Has more than enough power. But every now and then when warm it starts to surge, smells like gas, runs rough and can even stall. This lasts a few minutes and then its back to a normal all of a sudden. The Cam sensor is recently replaced because it gave two fake pulses with every rotation The new sensor is within specs.
The following things are done to try to solve it.
-new spark plugs (the factory recomended), distributor cap and wires
-full diagnostic of every sensor
-fuel pressure check
-injectors checked
-battery voltage with running engine stays arround 14V
There are no error codes and eveything on the OBD is within spec.

Waterpump / timing chain are replaces about 35.000km ago. TPS / IAC / MAP replaced about 15.000km ago
One mecahnic suggested that it could be worn bearings on the distributor shaft but I barely can feel play if any at all.

What else could it be that I missed with this issue?
Thanks for any suggestion.

 

check the oxygen sensor (pre cat) see if the wires up the plug are wet, if its getting water in there it will cause all sorts of odd behavior when the sensor shorts out (will NOT always throw a CEL code or be picked up by the PCM)

 

+1 shrps that could easily be it, but if its not I'm going to spitball here and suggest that if the o2 sensor aren't it that it is transmission related. Like the torque converter is engaging more when it shouldn't be or something to that effect. Like a tcm issue, I had some problems when my abs went haywire and I lost the speedometer, it wouldn't properly down shift and stalled a couple of times. So vehicle speed sensor might be a possibility. Some one with more transmission experience should reads this and shoot it down or is it a possibility?

 

its a 5.9 so there is not TCM on that truck, that was a 47 specific part.

 

+1 Sharps

The 45RFE and 545RFE transmissions are electronically controlled and use a TCM whereas the 42RE, 44RE, and 46RE are mostly hydraulic with limited electronics so it doesn't use them.


I'll back Sharps diagnosis with a failing pre-cat O2 sensor or a bad battery. You should have your battery load tested or replace if it is over about 4-5 years old. Personally I would go straight to the O2 and ohm the Air Charge Temperature Sensor.

Resistance of the Air Charge Temperature Sensor should be between 9,120 - 10,880 at 77 degrees F or between 11,370 - 13,610 at 68 degrees F.

 

Ok, that is something I didn't know. I was just theorizing, nice to know there is less electronics on the 46re and 44re then you guys are right again it should be o2 sensors.