Hi again,
I've now driven roughly 70 miles after the LIM gasket change and so far I have not seen that it's loosing coolant and the oil looks good. Neither has any mechanical rattling developed.
Today I went to do the mandatory yearly check which also includes emission tests. They do the test at idling and at 2500 rpm to check various parameters, it got too high values on CO and HC on idling. CO was 1.5% (allowed 0.5&), HC was 367 ppm (allowed 100 ppm). Also CO at 2500 rpm was just at the limit 0.3%. The lambda value was 1.01 (which is a calculated value, not actually measured). As earlier mentioned the ODB reading gives code P0134 which is that the front O2 sensor is not working so I was not very supprised. The rear shock absorbers were also bad, which I had been feeling. The air lines was completly dried out and broken so I'll give it a try to replace them which has to be done anyway.
When driving to the test center I felt at speeds between roughly 90 and 100 km/h (approx 55 - 60 mph) some shoudering. It was like driving on a too high gear, I've felt it before when driving last summer at some occations. I then spontaneously diagnosed it as a tranny / torque converter issue and searching the forum today I find that it might be true as people describe that symptom when the torque converter lookup is malfunctioning. The tranny is shifting gears smothly, no hard shifting has been noticed. Accelerating up to 110 km/h removed the shoudering at that time. It was more of a feeling, the rpm of the tachometer did not fluctuate.
After finishing the tests and driving from the center I saw the temperature gauge reading higher than usual, it's usually at the middle at 100 degrees and now it was at 2/3, and the fans still didn't run. I verified yesterday that the fans themselves and their relays work fine. After driving for a few minutes the temperature had returned to the norma. When searching the forum I find that this might not be a fault after all as the temperature might not have been high enough for the fans to kick in.
When driving back it was raining and very humid. Then I experienced shoudering also at lower speeds, and it was very prone to stalling when releasing the accelerator to slow down at red lights. It's hard to tell if it was the torque converter lockup causing the problems, at some times it felt like that, or if it is sensitive to humidity for some reason. I plugged in my bluetooth ODB-II adapter but no new codes had been recorded. When I came home I let it idle for a while, maybe it was slightly uneven but very little and it couldn't be seen on the tachometer. At a short drive tonight when it's not raining I didn't feel any uneven operation.
The plan for next steps are as follows:
* There is a hose from the back valve cover to the air intake which is not perfectly seated in the valve cover. It's darn hard to reach but it will need to get in place properly. The engine would suck air that way otherwise.
* Verify that there are no vacuum leeks.
* Clean the MAF sensor, I read here on the forum that it may sometimes cause the O2 sensor code to appear. Doesn't hurt to try it.
* If the above doesn't solve the issue then change the O2 sensor. Spark plugs and wires are new, the old plugs looked normal so the high HC value is not caused by oil leaking into the cylinder (which also would cause it to be smoking).
* Check the actual engine temperature through ODB-II, to see if it becomes hot enough for the fans to kick in. I'm not sure if I can use the AC trick to make them start as my system is completly depresurized. If the engine do become hot enough then verify the wires to the PCM.
Btw, as it looks on the electrical circuit drawings it seems the PCM outputs are pull down. I.e. they operate by pulling the signal to the ground and doesn't have an active pull up. Is this true? If so then the signals can be externaly grounded to test the function without risking to fry the PCM.
* Change filter and fluid in the tranny, it's due anyway. Mine should be an 4T60-E if I understand correctly. As I understand the solution is to change the TCC solenoid and torque converter seal but that the tranny would have to be dropped to do that. The latter is not a major obstactle, a good friend of mine runs a workshop which among other things does automatic transmissions.
Any other suggestions to investigate for the above described symptoms? Idle air control valve? Air intake temperature sensor? MAP sensor? Fuel filter?