1993 4.0L V6 idling issues and running rough/Transmission issues connected?

[AndoAv8R]

Sorry I posted this in the wrong group a few moments ago

Good morning,

Long time viewer but just finally joined.

I apologize if this has been covered but I couldnt find anything exactly like issues. Just picked up a 1993 with the 4.0L. Current mileage is 151k. Its been sitting for about 8 years and Im having trouble diagnosing the issues.

When it starts up it runs at high idle and then drops to a very low idle and keeps cycling and shaking the engine, cannot get it to a constant smooth idle/running. If anyone here is familiar with the old Jeeps with the computer controlled carburetor its doing exactly what it does as it cant find a good idle speed. I dont have a tachometer (although I am planning on swapping out the cluster with one that has it eventually)

I dont know if this would be related but the transmission also shifts hard from 1st to 2nd and seems like its gear hunting constantly at 45-70mph.

I am thinking vacuum system but if anyone else has any ideas I would great appreciate it. I know OBD 2 you can connect to read the onboard computer, I assume this isnt possible with OBD1 from 1993?

Thanks in advance! Relatively new to fords and most of my experience is with rebuilding a 1987 Jeep Wrangler.

 

[TDG]

When mine sat in storage for 8 years rodents completely ate away most of the vacuum lines and some of the electrical wiring; in my situation someone decided to clean everything up for me before I picked it up leaving little (visible) trace of rodent damage or missing vacuum lines.

There are tools out there that can connect to OBD-1 and read a few real time data parameters (the connector is under the hood on the passenger side) but I believe they are commanded parameters only and not actual values.

If everything is present and tight in the vacuum system I would start looking at wiring to the mass air flow sensor and idle air control valves as well as ensuring everything is tight between the mass airflow sensor and throttle body (the intake tubes are prone to cracking) I've also read some things about the EEC itself (under the passenger side kick panel) becoming water damaged and causing some odd issues.

Before loading and firing the parts cannon on a vehicle that has been in storage for 8 years I would take a close look at everything electrical and also consider that the original reason it was put in storage was mechanical in nature. (i.e. it was put in storage because the transmission was screwing up, but now there are other issues as a result of lack of use)

 

[AGodlyCanuck]

Sorry I posted this in the wrong group a few moments ago

Good morning,

Long time viewer but just finally joined.

I apologize if this has been covered but I couldnt find anything exactly like issues. Just picked up a 1993 with the 4.0L. Current mileage is 151k. Its been sitting for about 8 years and Im having trouble diagnosing the issues.

When it starts up it runs at high idle and then drops to a very low idle and keeps cycling and shaking the engine, cannot get it to a constant smooth idle/running. If anyone here is familiar with the old Jeeps with the computer controlled carburetor its doing exactly what it does as it cant find a good idle speed. I dont have a tachometer (although I am planning on swapping out the cluster with one that has it eventually)

I dont know if this would be related but the transmission also shifts hard from 1st to 2nd and seems like its gear hunting constantly at 45-70mph.

I am thinking vacuum system but if anyone else has any ideas I would great appreciate it. I know OBD 2 you can connect to read the onboard computer, I assume this isnt possible with OBD1 from 1993?

Thanks in advance! Relatively new to fords and most of my experience is with rebuilding a 1987 Jeep Wrangler.

Vacuum could be a factor for sure... have you tried disconnecting the MAF to see if there is any change? My next guess would be Throttle Position Sensor