i just bought an 86 ranger, with a 2.9l v6. it runs good but idles very rough. i am not a very experienced mechanic. i think there have been some modifications done to the engine, but i cant tell because i dont know what the stock engine and componets look like. i cant find any pictures or drawings to compare. can anyone help me, i posted pictures here, and am more than happy to send them to anyone thats willing to look. thank you...

 

Idles rough. Do the basics.

Is the ignition components up to snuff with the spark gap within specs. Does it produce a good clean spark. If the fuel system working correctly? Do a compression check, make sure its producing proper pressure. Worrying about everything else is kinda pointless if don't even know if the engine itself is healthy.

 

Whenever my 87 2.9 is'nt runing right i do 3 simple tests.
1 check for any trouble codes
2 check fuel pressure
3 Test with a vacuum gauge.

Google equus + amazon & read the reviews from the folks that have bought & used the equus 3145. This will show you why seing if the PCM/computer has the quick & simple answer to your problem is so important. Your 86 is not equipped with a check engine light, so the only way to see if there are any trouble codes is to check.

The last problem i had with my 87 was hard starting. A quick fuel pressure test told me that the check valve in the frame mount fuel pump was shot. Replaced the pump & problem solved. Harbor freight has the pressure gauge for about 18 bucks & includes the adaptors you need. You want the one for fuel injection

OOPS make that google equus 3145 + amazon. What makes the 3145 so handy is that it stores & displays the codes. No need to count flashes which can be confusing to a newbie.

Cant remember what i paid for my vacuum gauge. See if amazon sells them.

Do these 3 quick & simple tests & post back with your test results.

Heres some problems i have solved by simply pulling the codes.

Bogging down & pinging off the line. Pulled the codes & got a 53 "TPS voltage too high"
Tested the TPS with my Actron CP9087 & sure enough the output voltage from the TPS was jumping all
over the place. No wonder the PCM had no idea where the throttle was.

Cruise control quit working. Got a code 29 "vehicle speed sensor signal voltage is too low" Replaced the VSS & problem solved.

Thats just 2 of the problems i've solved by simply pulling the codes.

So pull the codes & see if the answer to your problem is stored in the PCM.

 

Read'em codes:

Ford Check Engine light Codes

 

I had an '86. It has an aluminum manifold with a throttle body at the front. In addition, lots of vacuum and other hoses and electrical connectors.

In addition to reading the codes and other basic diagnostics as per prior posts, check for:

--cut or disconnected wires

--cut, disconnected or plugged hoses and fittings

--basic condition of air intake, trottle body exterior, cables etc. You are looking for damage or loose items.

--check the intake for vacuum leaks with a little carb cleaner--spray at the edge with the engine running and listen for a difference in the idle. Go slow, use as little a possible, and don't stick you chin or fingers into the fan.

 

the check engine light hasnt come on and i took it to auto zone and no trouble codes came up. so vacuum would be my next step from what everyone is telling me.