Warm start issue

[KCSHIFT88]

<1996 ford explorer xlt 4.0l>
<warm start issue>

<parts changed>
IAC
ATC
PCV
CAM SENSOR
CRANK SENSOR
COIL PACK
MASS AIR
ECT
FUEL FILTER
SPARK PLUGS
FUEL INJECTORS
IGNITION BOX
VACUUM LINES
FUEL PUMP RELAY
...........................................................................................

<issue>

AFTER DRIVING 30MINS OR SO. I PARK THE CAR COME BACK BEFORE THE MOTOR HAS HAD TIME TO COOL OFF(OPERATING TEMP) AND IT HARD STARTS. (LOW SPIT SPUTTER IDLE THEN DIES). IF I START IT A FEW MORE TIMES IT GOES AWAY OR WILL NOT START (ETHER OR). IF IT DOES START
THE MOTOR RUNS LIKE CRAP FOR A FEW MINS THEN PICKS UP IDLE. WHEN I PUT IT IN GEAR THE IDLE IS STILL JUMPY. UNTIL I GET IT UP TO SPEED. THEN IT GOES AWAY.BUT AFTER A WARM START ISSUE AND THEN DRIVING IT. THE GAS MILAGE GOES TO CRAP..... A COLD START IN THE MORNING EVERYTHING IS FINE ALL KINDS OF POWER GOOD GAS MILAGE. EVERYTHING. MY FUEL PUMP MAX PSI. IS (30) NEVER HIGHER. IV BEEN READING AND READING AND ASKING PEOPLE ABOUT THIS AND IV HAD NO LUCK. COULD IT BE MY FUEL PUMP? OR VAPOR LOCK. AND IF ITS VAPOR LOCK HOW DO I FIX THAT???? SOMEONE PLEASE HELP ME WITH THIS. I CAN SEND SCREENSHOTS OF MY READ OUTS LIVE OR WHATEVER. NO CHECK ENGINE LIGHT.

 

[gatzdon]

I wrote about your issue here:
http://www.explorerforum.com/forums/showthread.php?t=435965

Not sure if you mean the engine coolant temp sensor when you wrote "ETC". If so, make sure it's the 2 wire sensor you are checking out and not the 1 wire sensor.

If you did change the 2 wire sensor and the PCM is still reading a low temperature, then you need to check your wiring to the sensor from the PCM. Engine Coolant Temp is an OBD PID, so you should be able to read the value with any OBD reader/software.

First thing I would do is make sure you are reading the extended codes and extended PID's.

 

[KCSHIFT88]

yes sorry for the type-o. ECT is what i meant. iv replaced that. i check the wire also. close to 5v on onewire and on the other 0v. the sensor ohms seems to be reading correctly.....

i got a p0171 code the other day. but it was from my egr not tightened down all the way. i fixed that. code gone......

today i got a p0174 code i checked for vacuum leaks. did not find any. took all my lines off and cleaned them. just incase. and this code come on during a hard warm start. first time that has ever happen. is 30psi a good fuel pressure? i know my mustang gets 60psi new fuel pump.



i do not know what (extended codes and extended PID's) are?

 

[gatzdon]

Forscan is free for computers, ~$5 for phones. I personally use Forscan Lite on an android phone to access the extended codes on my ford vehicles.

extended codes and extended PID's are all the diagnostic codes and sensor/control loop values that the vehicle has available, not just the OBDII required information (although Engine Coolant Temperature is an OBDII PID and you can access that with any OBDII Reader that let's you see PID values).

I would check and make sure the PCM is seeing the correct engine coolant temperature value (~190F when warmed up). If it's lower, one of your ECT wires or the connector may be corroded (higher resistance equals lower temp reading).

Until the PCM thinks the vehicle is up to operating temp, it will change how the engine is run and cause the issue you described.

Another cause for a lower temp is the thermostat itself. It may not be closing to allow the engine to get up to operating temp. Also a cheap part to replace, but I would confirm the temp reading in the PCM before replacing any more parts.

 

[KCSHIFT88]

ok thank you i will give all this a shot and let you know how it goes.

 

[KCSHIFT88]

i use the Lemur Monitors - BlueDriver - OBD2 Bluetooth Scan Tool.

 

[gatzdon]

i use the Lemur Monitors - BlueDriver - OBD2 Bluetooth Scan Tool.

I recommend spending the $5 for Forscan Lite, but you should be able to use the free demo version Torque Lite to see what value the PCM is reporting for Engine Coolant Temp.

Make sure the PCM is reporting ~190F for temp before spending more time chasing down other gremlins in the engine.

When the PCM thinks the engine is cold, but it really isn't, it will cause all kinds of havoc because it's throwing more fuel at the engine, limiting power, elevating the RPM's, and other changes I don't understand. All those changes on a hot engine will cause misleading trouble codes.