My 1989, 2.9 l, v6 has about 165000 miles on engine. When cold temps hit, like last week single digits, the engine is kind of tough to catch on the start. It is maybe not pressurized like usual. My understanding on fuel injection you do NOT want to push the accelerator prior to turning key and only after it catches?

any additives to try in the tank now, as winter is bearing down…

Andy

 

Fuel injected gasoline engines still need to be Choked when cold starting, same as ANY gasoline engine
Choke in this case can't be done with a plate that limits air flow so sucks in more fuel from JETS, because there are no Jets
So with fuel injection a coolant temp sensor is used, ECT sensor, 5volt 2 wire
Computer then runs Richer Mix and higher idle based on the temp its "seeing" from ECT sensor
(no connection to dash board Temp Gauge, that uses a 12volt 1 wire Sender)

So it could be your ECT sensor is not "telling" computer its VERY COLD, lol, it may tell computer its 70degF when its really 10degF, so not enough Choke is applied

You can test it, resistance seen here: https://www.explorerforum.com/forums...art.24365/full
It only shows down to 50degF but you can see resistance goes higher as ECT gets colder

When temp was warmer and cold started did it idle high, it should for the first few minutes, if not then I would just replace the ECT sensor on speculation

Does not hurt anything to push down gas pedal on fuel injected engines, but also doesn't help anything either, there is no accelerator pump or Jets, it just lets more air into the engine, i.e. its no longer a "gas pedal" its an "air pedal" at least on start up, lol
(heads up, if you press gas pedal down to the floor then try to start engine computer will TURN OFF fuel injectors, called Clear Flooded Engine Mode)



Why gasoline engines need to be Choked(run rich)
A spark plug can NOT ignite liquid gasoline, yes the movie guys take liberties with that fact, lol
A spark plug can ONLY ignite gasoline VAPOR
When gasoline is warm you can smell it easily, that's the Vapor, when its COLD it has almost no smell, low or no vapor the colder it gets

For a COLD engine to start it needs at least 30% gasoline vapor in the cylinder
If cold gasoline is 10% vapor then you need at least 3 times the amount of gasoline to get to 30%, thats what a Choke plate did on a carb, limits air flow into carb so more gasoline is sucked out of the Jets

Fuel injectors don't vaporize gasoline, they just squirt the liquid gasoline out
The heat of engine, and COMPRESSION, heat the gasoline to vaporize it
When engine is cold the compression heats up the gasoline but not enough to get to that 30%, especially when just cranking

Older engines also tend to have lower compression, just age

If ECT tests as OK or replacing it doesn't help then it maybe your compression is lower but not the end of the world
Try to run gasoline only when its cold, no ethanol mixed in, ethanol has a higher Vapor Point, so needs to be hotter than gasoline to turn to a vapor
Problem with that is "winter gas" has more ethanol to keep the water in the fuel from freezing, all gasoline has some water in it

Cranking the engine over a few times also heats up the cylinders, so cranking a few times can get enough heat/vapor for start up, but batteries don't like COLD either so a bit of a double whammy on that point, cranking is slower and voltage is also lower so spark voltage is less
Test battery voltage one morning when its cold and battery has set overnight
12.8v is newer battery
12.3v is minimum you want to see
12.2v or lower means you should replace battery sooner than later

SLIGHTLY wider gap on spark plugs, stock gap for 2.9l is 0.044", try 0.047"

Quick Start, ether in a spray can, ether has a low Vapor Point, always smells, lol, it is commonly used to start COLD engines, gas or diesel, spray some in via PCV hose or Power Brake booster hose, put hose back on and start engine

Block heater, replaces a freeze plug, keeps engine warm enough to vaporize gasoline if "choke" is working like it should, but not usable at work usually

 

Ron excellent advise. I will look for the ECT and have a VOM meter. I assume it is two terminal pen is pointing?

 

No, that's the IAC(idle air control) Valve, computer use that to set Idle RPMs, so it is used in Choke Mode

ECT sensor(and temp Sender) should be located near thermostat housing on lower intake manifold
So near where upper radiator hose attaches to thermostat housing

Drawing here: https://www.2carpros.com/images/ques...5/original.jpg

Red arrow
The ECT sensor will have TWO wires, Sender only one wire, they look similar but are not the same internally
If you decide to remove it Coolant will come out of the hole, so drain some coolant out first, or if its been over two years since coolant change then time to change it in any case, so drain it all

 

Must be this wire harness on pic. I topped off tank with ethanol free today. 60c more per gallon but we will see. Will hit below zero here Friday. I will also check resistance on this connection


Temp sensor

 

I just realized that is throttle position sensor so it must be a bit buried underneath….will find it!