Weired Starting Issue

[jos]

Hi,

I'm having this issue for quite a while now on my 2001 Explorer 4x4 XLT:
when I start, I have to step on the pedal a bit and the vehicle starts every time (like in winter when it's cold). If I start without pressing the pedal, the vehicle will start only once in a while and when it doesn't start, it's really hard to get it running. It needs a couple minutes pause and I have to try five six times. Just wondering, if somebody had similar problems and knows what could cause this.

Thanks in advance.

 

[J_C]

How cold are you talking about? I've read suggestions in the past that below a certain temperature (about 15F?) the fuel doesn't vaporize well and more coats the cylinder walls, that it's just the nature of the engine. Flooring it cuts the fuel injectors off (if I recall correctly) but also lets more air in to help vaporize the fuel, and purge excess fuel.

I found it worse on mine when I was making shorter trips and the battery wasn't getting fully recharged, that even after starting and idling a minute it would still chug along and slightly bog the engine with gear shifts. Part of it was a combination of old spark plugs and wires, that the longer it had to crank before it started, when below 15F, the more it would tend to flood without the pedal down to purge cylinders.

Could be that your injectors are partially clogged too and not making the best spray pattern. A lot of things may have degraded a bit over time. What work has been done to it in recent years?

It might help to swap the coolant temperature sensor, clean the throttle body, and clean MAF sensor.

 

[koda2000]

If it's a 4.0L SOHC engine, have you tried replacing the intake manifold O-rings? With age they dry out and get stiff, then they don't make a good seal. This usually shows itself when it's cold outside. Once the engine warms up parts expand and then it will usually run ok.

 

[jos]

Thanks J C and koda2000 for your replies.
What I meant, is that I have to step on the pedal every time I start. Before I had to do this only in winter, when it was about 15F. But I have to be careful not to step on the pedal too much, otherwise the RPMs would be too high when the engine starts. Just a slightly touch. When the engine is running, everything seems to be ok, except occasionally it seems to run louder when idling. But it was doing this since at least two years.
Recently I replaced the fuel pump and the spark plugs and the wires and yes, it's a 4.0L SOHC engine.
I will do your suggestions and swap the coolant temperature sensor, clean the throttle body, clean MAF sensor and replace the intake manifold 0-rings.

 

[jos]

Yesterday I changed the air filter and cleaned the MAF sensor and starting the vehicle improved slightly. Today I did a scan and it came up with PO117 - ECT Circuit Malfunction. I checked the engine coolant level and it was missing 4.5 l. I guess, I'll have to replace the ETC sensor and hope, this problem is gone.

 

[J_C]

If it was too low on coolant that could set a sensor error code. Top off coolant, make sure it's bled, reset code then see if it comes back before replacing the sensor. More troubling is where is the coolant going? There is no indication of any misfires, no apparent leaks, no coolant in the oil nor excessive steam/smoke out the exhaust?

After reading your topic posted last November ( http://www.explorerforum.com/forums/showthread.php?t=436415 ) about rough running and replacing the fuel pump, I'm wondering if you have a (fuel) rich condition from stuck fuel injector(s) making it hard to start. Due to the ease and low cost, I'd put fuel injector cleaner in a half tank of fuel and drive it a while to see if that helps.

 

[jos]

Hi J C,
thanks for your input.
I topped off the coolant and after a few kilometers I had to add another liter again. So there must be a leak somewhere. I can see liquid on the frame on the passengers side. I hope I can find that leak myself.

 

[jester1023]

Do a search on the forum for Throttle Position Sensor (TPS) failure and adjustment. There may even be a sticky on it. The 1st thing you'll want to do regarding the TPS, is checking with a Multimeter. The PCM may be getting a low voltage reading from the TPS and this is why it actually starts with a little extra throttle. These things normally scoff at the idea of extra throttle during startup. The above post about a full throttle start is correct, but partial throttle normally gives a negative response. Any check engine or O/D on/off flashing?

 

[swshawaii]

Hi J C,
thanks for your input.
I topped off the coolant and after a few kilometers I had to add another liter again. So there must be a leak somewhere. I can see liquid on the frame on the passengers side. I hope I can find that leak myself.

Inspect the lower thermostat housing. Extremely common failure with the 4.0L SOHC.
If so, consider this upgrade using OEM parts (Motorcraft RH144) Avoid aftermarket junk.

http://www.explorerforum.com/forums/showthread.php?t=239493

 

[jos]

Do a search on the forum for Throttle Position Sensor (TPS) failure and adjustment. There may even be a sticky on it. The 1st thing you'll want to do regarding the TPS, is checking with a Multimeter. The PCM may be getting a low voltage reading from the TPS and this is why it actually starts with a little extra throttle. These things normally scoff at the idea of extra throttle during startup. The above post about a full throttle start is correct, but partial throttle normally gives a negative response. Any check engine or O/D on/off flashing?

I don't know if it's related with this problem: uphill on bumpy roads sometimes O/D on light comes on and the power gets low. When I turn the motor off and on again, everything is back to normal.

 

[jos]

Inspect the lower thermostat housing. Extremely common failure with the 4.0L SOHC.
If so, consider this upgrade using OEM parts (Motorcraft RH144) Avoid aftermarket junk.

http://www.explorerforum.com/forums/showthread.php?t=239493

I checked the surroundings of the thermostat housing and everything seems to be dry, but there is coolant coming on the passengers side. Could it be a cracked coolant tank, that it looses so much (I had to add half a liter again after a couple of kilometers).

 

[koda2000]

I'm thinking your starting issue is injector related.

 

[jos]

Thanks again guys.
I already got a fuel injector cleaner and will add it the next fill up at the gas station.

And I found the leak in the coolant system, it's somewhere at the Air Conditioner Evaporator.

 

[J_C]

I checked the surroundings of the thermostat housing and everything seems to be dry, but there is coolant coming on the passengers side. Could it be a cracked coolant tank, that it looses so much (I had to add half a liter again after a couple of kilometers).

For the time being, once engine cools down, see whether the radiator is full and top that off if not, then periodically recheck the radiator. It would lose some to expansion into the tank but it shouldn't drop really low in the radiator once it cools down again.

If you think it's the tank then you certainly could take it out and inspect it, but I wouldn't keep adding more to to the tank till it's fixed if that's the leak... just throwing money away.

 

[jos]

Thanks for the replies all. It was just a loose hose at the thermostat housing.

As for the starting issues, I cleaned the MAF sensor and the throttle body, I added a bottle of injection cleaner and I replaced the air filter. It got a lot better, but recently the engine howls up at times when starting. Also (not always, but more and more often), there are problems accelerating and uphill driving. I have to press the pedal unusual hard until the vehicle accelerates and sometimes the more I press, the worse it gets. It's like the board computer gets the wrong information. I did already the "relearning process", like clearing the memory and idling for 10 minutes.
Now I really could need some suggestions what to check next.
Could it be something electrically like a bad contact? Or a dirty or defective sensor? Or maybe the fuel pump?
I'm hoping, somebody experienced similar problems and found a fix.
Thanks for any help.

 

[Turdle]

I know it is another "problem" but your heater core is leaking also. That is a source of the coolant on passenger frame rail coming from HVAC box.