Help with Auto Trans not manually downshifting ?

[keitholivier]

Howdy folks...

We are part way through our Colorado vacation. Michigan to Colorado in 2 1/2 days. We had terriffic wind through Illlinois, Iowa and Nebraska. Speed at times down to 45mph and lugging in 3rd gear. I have found that manually shifting down to 2nd or 1st has absolutely no effect. The transmission will kick down to the next lower gear if the gas pedal is hard to the floor, but if it is an extended climb I would prefer not to thrash the engine at wide open throttle.

Does anyone have a clue what could cause this condition ? Besides refusing manual directions, the tranny seems to do everything else one expects it to do.

Presently we're in Colorado Springs CO at 6000 ft. The Engine feels like it only develops about 50hp at this altitude... I have for the moment abandoned our plans on taking our dolphin up in the mountain passes around Pikes Peak. Considering we could hardly make 40mph up some of the "hills" around Colorado Springs and the fact that I can't lock into a low gear, we have decided instead to rent a car locally to do some sightseeing up in the mountains.

Another interesting fact: The oil consumption has not dropped yet after 1200 miles. So far consumption is about 1/2 a quart every 200 miles. I don't know whether I should think that the oil control rings have not bedded in yet or what. The compression is much higher than before, to the point that I was forced to use premium gas at lower altitudes. This was not the case before the rebuild. Since the rebuild, I had pre-ignition occurring with regular fuel and steadily retarded the ignition until it went away, but by that point the engine performed about as well as a slug. Changed to premium gas and that allowed for factory timing again with no pinking whatsoever and better gas consumption. Not to mention better performance and "peppiness"... The head is brand new, so there should be no concerns regarding valve stem seals and guides (occasionally a problem on "rebuilt" engines).

I have the impression that the engine runs constantly rich, yet it has the O2 sensor and supposedly closed loop air fuel ratio control via the ECU. If I had an engine check light then it would clearly indicate that one of the sensors is malfunctioning, but I have no check engine light illuminated. The lamp dies light up when I turn the ignition on, so the bulb is not burnt out... Perhaps the single O2 sensor system is incapable of detecting a sensor problem ? Anybody dealt with a similar issue ? Right now, my first suspect is the mass flow meter, since it is electro mechanical. Pretty much anything mechanical on this vehicle that could be frozen up, was, so it could be that the vane that moves in the MFM is not moving at all or is restricted. I do have a multimeter and my manual, so I can check the position vs the resistance values.

Otherwise, no truly serious issues have arisen. On the first day out both steel straps under the black water tank broke (rusted through) after our trip down Illinois bumpy highways which about put me in a panic. But we have not been usng the toilet and the tank is empty and seems to be holding up just fine. Replacing the 2 straps looks like a nightmare job, since one requires access to some part of the structure under the siding of the RV and I can't see how this repair can be made without getting under the siding.

Any comments on the trans that would help, please post.

Thanks

Keith

[Shoprat]

howdy keith.

On your tranny, try checking out the shift cable adjustment. This is the cable thats under the throttle cable on the cable bracket on the intake plenum. Hold the throttle wide open and check to see if a brass colored plug on the shift cable is just a skosh ( 1mm) past the rubber boot on the cable end. This cable adjustment can do some strange things if it is out of adjustment.