I have a 92 explorer manual five speed, and just yesterday it seems to only happen sometimes it will hesitate a little and almost buck in 2nd gear then the rpms will just stop working on the tech, when I turn it off and start it back the rpms will be fine and registering on the tech, other than this it runs fine, this only happens sometimes I don’t get any CEL or anything like that, after the rpms stop registering it still runs fine, I just don’t have a tech gauge I have no idea what the problem could be can anyone help me out?

 

Any codes from the computer?

 

I have not pulled the codes yet, the CEL did not come on i just figured there would be no codes... Would codes still show up if no CEL comes on? I can go to autozone and have them pull the codes and see if theres any

 

In some cases, especially in a case like this.

I won't stop you from going to Autozone if you want, but sometimes they have trouble with these older systems ("I can't pulll codes unless the CEL is on", "I can't pull OBD-1 codes." etc.). It's easy enough to do yourself, and only requires a paperclip (or other jumper wire). Ken00 has posted instructions in his tech info posts at the top of the Bronco II and Ranger forums, if you're interested in trying yourself.

 

Yeah you can have stored codes even if the CEL doesn't come on. Sometimes the CEL bulb is burned out and then it never comes on.

I get an ocasional buck on my 1993 X with manual trans. Maybe 2 times a year so I haven't really pursued it. Been happening for at least 5 years. But I don't have any associated tach reading issues.

I think the tach read comes off the Ignition control module - not from the PCM. The ICG feeds the PCM so I think it also feeds the tach. You might have a connection problem that looses the tach signal? I'm guessing here. Might want to take the connector off and clean the contacts...it is located infront of the battery - obvious when you see it.

But then again, maybe the tach is just telling you the real issue - no RPM spark signal. In this case, why did the spark stop going to the motor? Bad cam shaft position sensor, bad crank position sensor, bad ignition control module...?

 

What jharger said makes sense, bc it is still running even know the tach is showing nothing, so it could possibly be a loose connection i will check it out later