1993 Ranger 4.0 engine swap

[WILL-I-Am]

I recently installed a motor out of a 1992 explorer 4.0 automatic 4x4 into my 93 ranger 4.0 5 speed 2 wheel drive super cab, engine Boggs down at half throttle in all gears, but I can turn the switch back (off) and back on again and its fine for about a.minute and Boggs Down again, PLEASE HELP I WANNA GO HOME !!!

 

[RonD]

Does it recover with WOT(wide open throttle)?

The computer operating the engine(the PCM) has two operating states:
Open Loop, when engine is cold or at WOT, in this state the PCM ignores most sensors and runs a preset fuel/air mixture based on Throttle position(TPS) sensor.

Closed Loop, when engine is warmed up, the PCM uses sensors to set fuel/air mixture, and the TPS.

What tells the PCM that the engine is warm or cold is the Engine coolant temp(ECT) sensor, it is a two wire sensor near the t-stat housing, the 1 wire sensor near it is for the dash board temp gauge.

When you turn off the key on a warm engine and then turn it back on, the PCM has a timer that waits for a minute or so for the O2 sensors to warm back up, they need to be above 600deg to work properly.

A bad O2 sensor can cause running issues but not sure it would be as described.

The key off then on is interesting through.

Could be fuel pressure issue, when you cycle the key off then on again the PCM runs the fuel pump for 1 or 2 seconds to prime the system, which if pressure was low would get it back up until it dropped again.
That could be fuel pump failing or plugged fuel filter, even the fuel pressure regulator on the rail.
Fuel filter is only $10 and not to hard to change.
If possible check the pressure at the rail, should be 30-40psi, check it with engine off and with engine on.

 

[WILL-I-Am]

yes it does respond with WOT. I INSTALLED new fuel filter during installation, I will get fuel pressure checked, I'm goin to get ECT sensor now. Is there any way to check o2 sensors?

 

[adsm08]

The O2 sensors are kinda hard to check without a scan tool. I have had issues like you describe in my 87 on several occasions and it has always been either a bad O2 sensor or a bad/loose wiring connection near the battery.

What prompted the engine swap anyway?

 

[RonD]

You can test ECT sensors.

http://oldfuelinjection.com/?p=28

 

[70roadrunner]

did you replace the ECM with a manual trans ECM? I believe the 93 uses different sensors than a 92. will send wrong info to the ECM

 

[WILL-I-Am]

392,000 on original motor, blew head gasket due to water pump failure, more cost effective to get used motor . No I didnt change ECM I didnt know I needed to. So I should change ECM
even though the motor was put in the manual ranger?

 

[RonD]

The O2 sensors are not used until engine reaches operating temp, coolant at 200deg, so if engine bogs in the first 5 minutes of driving then I wouldn't think the O2 sensors would be the root cause.

The key off/key on giving you better running engine for a minute or so, could be a sensor reset or fuel pressure reset

 

[WILL-I-Am]

Ok today I put the TPS from the original ranger motor in and the truck ran great I was so happy I went to do my running around everything was fine! Went to parts store and had them scan it fot any codes no codes, went to my house still ok. 2 hrs later went to grocery store and it started bogging down again !! VERY FRUSTERATED !!

 

[Andy D]

I betcha that engine sounded good too.

Thanks for follow up

 

[WILL-I-Am]

Please somebody help me figure out why the engine is bogging down. I am frustrated with this crap

 

[disciplerocks]

So you didn't install the 4.0 ecu?

You can use an auto ecu on a manual, just bypass the NSS.