83 Ford Ranger Rough Idle

[Jason_1984]

I have an 83 Ford Ranger 2.3 4 speed. Carter YFA carb. The vehicle runs rough at idle. once above 2000 RPM it isn't noticeable. In the past it have heard it idle good. Doesn't seem to have any pattern. Compression is equal in all cylinders.. Manifold vacuum reading 21. Goes to 5-7 when I hit the gas and immediately back up to 27-29 then about 5 seconds and its back down to 21. I have done the head gasket, exhaust manifold gasket and intake manifold gasket, machined valves, timing belt distributor, 02 sensor, plugs, wires, rotor and cap, also a new carburetor, replaced most of the vacuum lines (tried carb spray trick and cannot locate leak and cannot afford the smoke test), new PCV valve, coil and ignition module all done within the last 7 months with minimal driving. Tried to adjust carb but still cannot get it to idle right. Choke seems to be operating like it should. Timing marks all line up and pointing at #1 on compression stroke. Firing order is correct. Getting to the point where I think it may be the mixture control solenoid. Or perhaps the computer itself. If anybody has any insight please don't hesitate. Started a thread for this vehicle already but the title of the original thread isn't really an issue anymore. (if this isn't proper procedure I apologize I am new to the forum)

http://www.therangerstation.com/forums/showthread.php?t=159715&page=6

I can locate the microprocessor unit but cannot find the Idle speed control unit. (kind of looks like the microprocessor on the wiring diagram) Is it all one device and just looks like 2 on the diagram or is this separate from the microprocessor?

I cannot find the idle speed control motor on my vehicle at all. But shows on wiring diagram and the part is listed as compatible at the auto parts store)

I cannot find the coolant temp sensor so I could test operation. (I did locate the sender)

I have tried tracing wires but have not been successful.

Wiring diagram:
http://www.autozone.com/repairguide...DIAGRAMS/WIRING-DIAGRAMS/_/P-0900c152800781b2


Any help In locating these components. Perhaps a testing procedure, or any insight on how to resolve this rough idle would be greatly appreciated.

 

[rangerin]

I'd double check to make sure you don't have any vacuum leaks by spraying some carb cleaner or something similar. Vacuum leaks really screw with a carb. It could easily be something else, but vacuum leaks are pretty easy to rule out. I know whenever my carb gets a vacuum leak it gets possessed (particuarly at idle too). lol

EDIT: If your '83 came with an EGR, check that too. Last summer I took the motor out of my '84 for a rebuild and it would not idle to save my life once I put it back in. The EGR got a piece of carbon stuck in it (must of got knocked loose from cleaning) and was causing a vacuum leak. A blockoff plate now prevents that from happening again.

 

[85_Ranger4x4]

Did you do all of this stuff chasing the rough idle or because it was bad?

Run rich at idle? Lean? You can use an ohm meter on a O2 sensor to see how it is running.

Have you set the ignition timing with a timing light? If not do that, base timing should be on your emissions label if not I am sure it would be easy to find. If you have, check your dampener. It is two pieces of steel with a rubber insulator between them. With age the rubber can deteriorate and the outer part can "slip" on the newer part and totally screw up where you think you are setting the timing to.

If you have power brakes you might pull the hose off of it and plug it to see if that helps too, it could be leaking in the booster. Same goes if you have a vacuum shift automatic trans (like a C5), undo the line and cap it at the carb/intake. I don't know how the emissions stuff would like that but some stuff you can temporarily eliminate for testing.

Usually vacuum should drop during accel not climb, don't know what you have going on to cause that.

 

[Jason_1984]

Hey thanks for the responses. My mistake vacuum does go from 21 to 5 when accelerating then up to 27-29 then back down to 21 ( I corrected the original post) Unfortunately I was a dummy and did all these new parts chasing the idle. It seemed to be running rich but then I adjusted carb and now I can no longer smell gas in exhaust. One of the first symptoms before swapping all the parts was rough idle and was blowing black smoke. Once new carb was in it no longer smoked and idled good. 2 weeks later its idling rough again. I would re-adjust the carb and it would run good for 2 weeks and then start idling rough again. Finally it got to a point where I could not get it to idle right at all. (seemed like a component was failing and finally failed but not sure) It doesn't seem to me like any idle screws or air fuel mixture screw are turning themselves out. They all seem to be where I left them. I did use the timing light to set the base idle. Removed vacuum advance and set to 6* BTDC with the timing light per the label under the hood. It does seem to run better around 20* BTDC at idle with vacuum advance removed. (cant find SPOUT and nobody can tell me a location, (I cannot find on wiring diagram) I thought perhaps a sensor is trying to compensate the timing but I set it down to 6* per the label even though it was running better at 20*BTDC with vacuum advance removed. Re- adjusted the carb and still getting a slightly rough idle. I did plug the brake booster vacuum because I could hear air by the brake pedal inside when I push on brakes but nothing changed when I plugged the vacuum line that led to the booster. I have a manual transmission. I think I'm to a point of testing sensors but I am a bit uncomfortable with that. (I don't know the correct procedure and don't want to mess something up by touching leads to the incorrect spot) I could also be totally insane at this point and be completely off. If anybody has specifics on testing procedures and perhaps specifications for the component that would be awesome. Also perhaps something I may have overlooked. My little 83 isn't that popular so its kind of hard for me to find specs on these components.


http://www.autozone.com/repairguide...S/_/P-0900c152800781b2?CJPID=6148022&cmpid=cj

Coolant temp sensor - cannot find idle speed control unit to trace wire. Cannot find on engine block or by thermostat.- someone said on heater bypass hose but cannot find a sensor or any wires.
Idle speed control motor - cannot find. tried to trace wires but couldn't locate
Idle speed control- cannot find ( is this part of the microprocessor?)
02 sensor was replaced but wiring to sensor not tested.
Idle fuel solenoid vacuum seems to work but unsure how to test wiring?
Idle fuel control solenoid I believe is the mixture control solenoid- clicks when applied 12V but not sure how to test wiring to sensor.
Barometric pressure switch (I am unfamiliar with this part but I think it has something to do with altitude)

 

[85_Ranger4x4]

It was bad, you changed the carb and it was good but slowly went bad again. Been inside the carb since? Look inside the old carb?

I kinda wonder about trash from the fuel tank or something. Not familiar with what the 2.3 has for a fuel filter but I didn't have much faith in the $3 thing that screwed into the front of my 2.8's carb.

Any more I supplement the factory "fuel strainers" with aftermarket inline fuel filters when I can, it really helps. Good bad or indifferent I use Wix ones.

 

[Andy D]

A total wild @$$ guess. The throttle plate shaft has worn its holes out and they need to be reamed out and bushings installed.

 

[bobbywalter]

https://www.holley.com/products/fuel_systems/carburetors/performance_2_barrels/parts/0-7448



http://www.guaranteedcarburetors.com/




all that feed back stuff i would shitcan personally. reliability and tuning make em better all around.

 

[Mark_88]

Any luck with this Jason? I left it alone when I saw your new thread to let some others join in...I'm sure most also read your other thread so good idea to put the link there.

I haven't been doing much searching lately due to being consumed with other things but I'm sure there is something out there. I know at times when I couldn't find answers here I strayed to other sites with some luck finding information. I just did a quick search and found a few sites but didn't go deeper than the names.

Hope this hasn't totally fizzled...I know how frustrating that can be...

Did you happen to have inspected the intake all over for cracks when you had it off to rebuild the head? A hairline crack somewhere could be a source of various problems...usually higher idle though but could also give a rough idle if small enough.

 

[Jason_1984]

I have not given up yet. I just got sidetracked by a Pontiac I was working on. I am still in the stage of checking my sensors and wiring. The coolant temp sensor, PCM itself, and mixture control solenoid are still in the back of my mind. If that all checks out I'm probably going to crack open the carb and check the internal measurements and see if there is any debris in there. Carb is less than 1 year old so I was hoping to avoid that. I didn't notice any damage to the intake manifold but I didn't take it completely out.

 

[Mark_88]

OK, good to hear.

There may be debris in the jets as one poster mentioned. I've had that a few times on my 2bbl and if one side (it was also 2 stage) got plugged there was one set of symptoms (poor acceleration or complete bogging depending on how plugged the jet was) and if the other side was plugged I'd have poor idle.

From what I saw of the video I posted, yours only has one jet (1 bbl, 1 jet) and I'm sure there would be other symptoms if it was severely plugged. Your carb may have some small debris in the jet that causes poor idle but it can draw past the debris with more demand...not sure.

I doubt that there are any internal sensors though...so cracking the carb open may only allow you to clean jets and adjust float. The bottom end there is what is called a power valve and that is often damaged. However, again, the power valve is probably good by the symptoms you describe (idle).

I still think it's either a vacuum leak or an external control (sensor) that is causing the problem, but you would see it being consistent rather than sporadic or cleaned up by adjustments...

So I'm saying I'm stumped too without seeing your layout and hanging over the hoodl as I did many times with my truck saying prayers, curses to designers (I take it back now), and scratching my nearly bald head!

 

[Jason_1984]

May have the culprit. Thinking it may be the ported vacuum switch. Here is my logic. Ported vacuum switch faulty reading causing the EGR to let in exhaust at idle. In turn causing the rough idle because the mixture is off due to some exhaust being let in. Thoughts?? Feedback??? Any ideas how to test this theory. I'm this deep into it if this sounds logical let me know. Also can this thing double as a coolant sensor?

http://www.autozone.com/engine-mana...ralast-ported-vacuum-switch/3066_427623_5937/

.

 

[Mark_88]

Since the EGR is not needed for engine function (only emissions) it can be blocked off or simply cap the switch. Just keep in mind that the emissions in your area (not sure where you live) may be vigorously enforced and anything you do may result in fines or vehicle impounding...

But that is a good place to start...just block off that switch...I bought a package of vacuum line caps years ago...a couple of them...and used them to cap lines or whatever often. They can be picked up at a local hardware or automotive store...maybe even Wal-Mart...or you could do what I've done and cut pieces of rubber tubing and cap them with screws or bolts and plug the lines...it's not pretty but it works in a pinch.