(issue resolved)Need insight on 4.0L sohc cold morning hard start issue( no codes)

squad272 · 12-08-2007, 06:03 PM

The IAC fixed the issue. Thank you for the help. I hope this can help someone else in the future.

I hope someone has knowledge of this problem. My wifes explorer Sport trac on cool mornings will only start and run if you put your foot on the gas pedal.

2001 sport trac 4.0 with 52000 miles has developed a startup issue. I searched the forum but it seems that there is not a definative answer although others seem to have the same issue with the 4.0. Weather and temp here in Nashville is 40-60 degrees and damp and rainy for the past 24 hours, the truck sat for about 16 hours, once again this morning it cranks but wont start and run unless I have foot on gas pedal. remove foot it stalls. If i keep it at 2500 rpm with my foot for a couple of minutes the temp guage starts to respond and it will idle on its own. Today I drove to mall and shopped and trucked started fine and got me back home. I went to advance auto and their code reader said system fine no codes found. thermostat ,anitfreeze & hoses were done in the summer. This seems to me to be a cold issue causing "no choke". if that makes sense?

Chopper · 12-08-2007, 06:20 PM

The Idle Air Control valve probably needs cleaned.
Driving the vehicle for short trips causes carbon and varnish to build up on the backs of the intake valves and injector tips.This carbon soaks up part of the fuel getting shot into the engine and makes the engine run lean for a few minutes during cold starts.That's why the engine runs fine after it warms up.Get a couple cans of spray carb cleaner and use both of them to clean everything up.I just posted the procedure somewhere a couple of weeks ago.A search should turn something up.

squad272 · 12-08-2007, 09:48 PM

So far so good! I replaced the IAC. the old one appeared to have a sprung spring. The spring on mine was the whole length of the shaft. the new one the spring looks like it is retained at half the lenght of the shaft and lot of black gook

The test will be in the morning. it is cool damp and foggy here tonight so if it fires up ok I will consider it fixed.

I put a new air cleaner in it and used a bunch of carb cleaner to clean the MAF sensor and the throttle plate area.( I got a ton of thick burnt smell smoke out the exhaust--I had to leave the neighborhood and go to a nearby country roadso nobody would call the fire Dept.-- I am guessing that all the loosened gook got blown out and burned off in the hot exhaust. smoke seems to be gone now.

I'll keep you posted

Captain J · 12-08-2007, 10:50 PM

Cleaning the IAC will cause you to always have to clean it because the coating that keeps gunk off gets removed in the process (same for fuelinjectors an the TB). If you must use TB cleaner and not carb cleaner or the contact cleaner we all use for our MAF. Just get a new one like you did and only use a motorcraft IAC! I have tried after marked and they never work right.

squad272 · 12-17-2007, 08:09 PM

The IAC fixed the issue. Thank you for the help. I hope this can help someone else in the future.