96 Explorer runs unevenly up hills

[MrThorswold]

I have just bought a 1996 Explorer with the ohv V6 engine. The car has only been driven 75,500 miles and seems to be in almost mint condition.

However, when I drive up hills, the engine pulls unevenly. I have no idea why this happens. It seems to work fine in any other situation.

Furthermore, the engine coolant temperature indicator is always on low. Could there be a connection here? According to the service receipts the thermostat has been changed.

I appreciate any help.

 

[99SportX]

I would verify that your coolant gauge is functioning correctly. The thermostats commonly fail into a stuck open state so the engine would run cool. You could also feel the upper radiator hose once the engine runs for a while to see if it gets real warm. The factory thermostat is set to 195 deg F so the coolant coming out the top of the engine when up to temp should be about that.

There are two coolant temperature senders. One for the engines computer, and one for the gauge on the dash. They are both located on top of the engine either on or near the lower intake manifold.

One other thing to note is that when my AC refrigerant was low, the compressor would cycle on and off pretty frequently, a complete cycle was less than 10 seconds. When going up hills in one gear at a constant throttle, I would see my RPMs pull down for a short period and then jump back up. This would repeat and I found that it happened whenever my AC compressor cycled. It was lowering the engine RPMs just enough to see the tach move slightly and I could hear the engine pulling down. Just a thought...I m not sure if this would apply to you.

 

[imp]

......However, when I drive up hills, the engine pulls unevenly. I have no idea why this happens. It seems to work fine in any other situation.
I appreciate any help.

If what you mean by enevenly is that it seems to lose power, or the ability to continue pulling strongly up the hill, this can mean inadequate fuel to the engine. So, it must be asked, whether the vehicle accelerates fairly strongly on a level road, when asked to do so? If not, possible inadequate fuel delivery, both cases; look for partially clogged fuel filter as a possibility. imp

EDIT: Checking fuel pressure at idle speed will generally not reveal a clogged filter, since if the truck can pull itself along at all, it then is using far more fuel than at idle. Also, a bad fuel pressure regulator can be allowing too much fuel to be bypassed back to the tank, (if veh. has a return line), thereby reducing fuel pressure available to the injectors.

 

[MrThorswold]

Thanks for the answers

I did not know there were two temperature senders. I will look into that.

It loses power for a second, gets power back, loses power for a second etc until I have climbed the hill.

The car accelerates strongly on a level road, but it makes sense that the engine might not get enough fuel when it is required. I assume keeping up the speed going up hill is more fuel demanding that accelerating on a level road.

Fuel delivery is determined by a computer chip?

The fuel filter was replaced about a year ago, but of course, there might be contaminations.

 

[imp]

.....Fuel delivery is determined by a computer chip?....

You sound surprised.........In order to achieve mandated exhaust emissions levels, the designers gave up on dinosaurs (carburetors) and put in charge much more than just a computer chip. Properly called a "PCM" (Powertrain Control Module) it gathers operating information from appropriate sensors, then determines by the use of in-program fuel/air ratio tables just how long the fuel injectors should remain open, for each power stroke of the pistons. The exhaust gas is constantly viewed with respect to emissions levels, and the PCM is able to continuously vary fuel delivery based on that information as it tempers the standard fuel/air ratio numbers.

Fuel pressure is maintained at a fairly constant level by a pressure regulator, the pressure being about 10 times that of a carburetted engine. This makes for higher risk of fire should leaks occur, the pressure level being about similar to the water pressure at your kitchen sink.

If you find this all interesting, if you PM me, I can recommend an excellent book on the subject of Ford Electronic Fuel Injection. imp

 

[MrThorswold]

Not surprised

I am not surprised. Even my last car, from 1987, had an injection engine. I am more worried about there being something wrong with the computer chip.

PM sent.

 

[imp]

I am not surprised. Even my last car, from 1987, had an injection engine. I am more worried about there being something wrong with the computer chip.

PM sent.

The computers DO fail, but not as often as one might think. The last one I bought for use in an EFI-conversion from carburetted was $78.00 from Auto-Zone. imp