97 5.4 Expy White Smoke Rough Idle at Startup

[Exp099]

I'm pretty sure that it leaks past the orings at the 4 corners of the intake seeing area. You can see how close the water "holes" are to the intake holes. I suppose deterioration over time. I am going to tackle mine when it warms up a bit. Looks like kind of a pain to do.

Is it suppose to have coolant there; like it is on the picture?? im sorry i dont know much and i feel like my truck is acting up just like yours. the CEL came on i havent check it but i will somewhere this week.
heres what i found after checking it.
i opened the engine coolant cap and it smells like burn oil kind of like when you open the engine oil cap on the engine to pour oil, the right side exhaust pipe throws out a lot of smoke with a wierd smell

 

[tedallen]

I ended up replacing the upstream O2 sensor on the passenger side and the P0133 code went away for about 3 months and then it came back again. Sometimes the CEL would go out but the code would still be present. A couple of weeks ago I started getting a miss under load which I suspected was a COP in the process of failing. Sure enough, yesterday, under acceleration on a hill, the miss became worse and the CEL came on and started flashing. I had my OBD scan tool with me and a P0303 (misfire cylinder #3) had been stored.

Today I intended to swap the COP on cylinder 3 (3rd back on passenger side) with one in the front, however, it is such a pain to get to the rear two on the passenger side, I decided to replace the front 3 plugs on that side and replace the #3 cylinder COP while I was in there. I should have gone ahead and tried to tackle the #4 but it was 97 degrees today and I was working outside. After putting things back together, it seemed to idle a bit rough for a short time. The codes were cleared, presumably because I had the battery disconnected. I took it for about a 6 mile test drive and by the time I got back home the P0133 code was back in the pending code list.

I find it hard to believe that the new O2 sensor failed that quickly. I was hoping that maybe the misfire of cylinder 3 on that side was maybe causing issues over time before the P0303 code finally was logged that was causing the computer to think there was an issue with the O2 sensor circuit being slow on the upstream sensor.

I'm pretty certain there is an exhaust manifold leak that I hear and I know exhaust leaks are one of the potential causes of the P0133 code as is low fuel pressure and I replaced the fuel pump about a year ago (with an Airtex from AA) and have noticed odd losses of power, almost like the vehicle is going to cut out, typically when going around a tight right hand turn (onramp/offramp) and starting to accelerate coming out of the turn. I checked fuel pressure at idle after installing the pump but I guess i need to hook up a gauge and check the pressure under load while driving to see if the pressure is dropping.

I did notice some rusty-brown colored powdery residue on the boot of the COP for the #3 cylinder. I recall reading of issues on some years with coolant leaking into that cylinder. I have had a coolant loss and was thinking it was maybe an intake manifold leak since the white smoke in the tail pipe pretty much went away (and the coolant leak decreased - there is a small leak in the passenger-side radiator tank). I don't see any signs of coolant leaking from the hoses going back across the passenger valve cover to the firewall.

Any thoughts are greatly appreciated.

Thanks,

Ted

 

[tedallen]

The CEL went off again today and the P0133 code still remains. I really don't believe the O2 sensor would have failed again in the same manner a few months after installing it unless something else is causing it to fail or appear to. I am still running with the expansion tank cap loose to minimize coolant loss. if there is an issue with the intake manifold gasket allowing coolant to get into the cylinder without being detected by combustion gases in the coolant, then I suppose the coolant could be causing issues with the O2 sensor. I would think that would have occurred in less than several months. If it is low fuel pressure, I would expect to see the corresponding code being triggered for the driver's side upstream sensor.

Does anyone have any ideas?

Thanks,

Ted

 

[thenaaks]

Yes, coolant can leak into the intake ports of the cylinder head. This will not cause any mixing of combustion gasses into the coolant, since the coolant is entering on the intake side. This is exactly what happened to mine. Replacing the gaskets cured it.