HARD TO START WHEN COLD

1999 Ford Explorer

Tiny

frontshadow

November, 29, 2008 AT 9:38 AM

Engine Performance problem
1999 Ford Explorer 6 cyl Two Wheel Drive Automatic 210000 miles

I've a 99 Eddie Bauer, 4.0l E code, 4x2. Bought it new. At about 190K is started to have a cold start problem. Engine cranks, catches but either barely idles and stops or revs really high and stops. After several attempts and using the accelator to rev the engine up/down, and working it it for maybe 2min, it will level out nicely, no misses, no rough idles, and will from that point on, start on command, just like new. This problem seems to appear after the engine is cooled down. The colder the engine and ambient temp, the worse it is and the longer it is before it corrects it is. Check engine code is always 171. Right bank too lean. I have changed both right side O2 sensors (have ones for left side but not installed), replaced MAF sensor, EGR vacuum control solenoid, tested/cleaned EGR, replaced EGR vacuum sensor, replaced plugs and wires, checked for leaking vacuum, and replaced engine coolant sensor (behind thermostat housing). I have read there is a temperature control sensor that feeds to the ECM (TCS) that could be the problem but cannot locate on engine. Anyway, am looking for ideas.

Again, this problem only happens when the engine is cold. I noticed it happening this past summer, but for a much shorter period of time with the warm weather. This winter it is unbearable! I am the original (new car) owner.

Thanks very much

FOUND 3503 RELATED QUESTIONS

12 Answers

Tiny

engineman 73

November, 29, 2008 AT 9:59 AM

REALLY SOUNDS LIKE IDLE AIR CONTROL. IT WILL MAKE IT IDLE TOO FAST DIE OUT AND OTHER SYMPTOMS. THEY RUN ABOUT $50.00 TO $65.00 AT AUTOZONE.

Tiny

frontshadow

November, 29, 2008 AT 10:05 AM

This summer the idle air control/solenoid. Sits top of intake. Went out and was holding the engine at a high speed when coming to a stop. As soon as I replaced the control solenoid, that problem stopped and was corrected.

I was having the aforementioned problem all along and dealing with it as time permitted. Changing the idle control solenoid DID NOT affect this problem.

. Back to the " drawing board"

Tiny

engineman 73

November, 29, 2008 AT 10:18 AM

CHECK YOUR MANUAL FOR COLD START INJECTOR LOCATION THIS WILL AFFECT IT COLD START ONLY.

Tiny

frontshadow

November, 29, 2008 AT 10:31 AM

Cannot locate a " cold start injector" for this model/engine per your message. Checked a couple of on-line parts stores also, they show nothing. Maybe for a 5.0L?

What is the purpose of this device? Maybe it goes by different nomenclature?

Tiny

frontshadow

November, 29, 2008 AT 10:40 AM

Posting that describes what I have been saying to a TEE......

http://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals

Tiny

engineman 73

November, 29, 2008 AT 1:22 PM

CHECK THE IAT SENSOR INTAKE AIR TEMP. SENSOR THIS AFFECTS TIMING AND FUEL DELIVERY AND COULD SET THE 171 CODE YOU ARE GETTING.

Tiny

frontshadow

November, 29, 2008 AT 2:07 PM

Is not the IAT Sensor built into the MAF sensor on this year/model? In original message. Have already replaced the MAF?

Tiny

engineman 73

November, 29, 2008 AT 2:19 PM

THE IAT IS LOCATED ON AIR BOX BETWEEN MAF AND THROTTLE BODY AND IS NOT PART OF MAF.

Tiny

frontshadow

November, 29, 2008 AT 3:14 PM

Nope. There are NO sensors between the MAF and throttle body. Just one pipe inserted into the intake hose which runs over to the EGR.

Tiny

engineman 73

November, 29, 2008 AT 10:52 PM

MOST EXPLORERS HAVE A IAT SENSOR BUT NOT ALL. ONE LAST SHOT AT YOUR PROBLEM CHECK ECT SENSOR. ENGINE COOLANT TEMP. SENSOR. SENDS VOLTAGE SIGNAL TO PCM AFFECTING FUEL MIXTURE-TIMING- AND EGR OPERATION. IF THIS DOES NOT HELP MAYBE ANOTHER TECHNICIAN PICK UP FROM HERE.

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