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I have an 86' Ranger 4x4, 2.9 L , with 63K Miles on it.
It failed smog real bad. I am buying it from a good friend who let it sit for a year 1/2. I have replaced the rear Cat, muffler, plugs, air filter, cap & rotor and the Oxy sensor. It still idols like crap. It is running very very rich. under power it seems fine but at an Idol it if flooding its self. I am out of ideas and almost out of money. does anone have an Idea????????
There is a valve that controls the air fol at idle. I forget its name, but there have been posts on here about it. I would look it up and check that. IAC, IAV or something like that.
Sounds as if maybe it needs a good injector cleaning/replacement! Injectors can be taken out and cleaned or replaced fairly easily.
Get some seafoam or some Berrymans and run it thru the system at a pretty good strength. tank almost empty and full can of cleaner. Run it let it sit, run it let it sit then fill with clean gas and see how it does.
If it has a carb do the same thing. You can also remove the line to the tank, run a hose to the inlet of the fuel pump and put the other end in the cleaner. Fill the carb and let it soak overnight, then rehook the fuel line to the pump and run the stuff thru the fule lines as above.
to be rich it has to be fuel/air. If the air filter is clear, make sure if a carb that the choke is full open.
Did you try replacing the thermostat? Do you have fuel injection or carburetor? I imagine if you have 02's it is fuel injection.
A bad EGR valve might be the source of your woes. This can cause high NOx readings in exhaust. 99xlt4.04x4 might be onto something also. Your Idle Air Control (IAC) valve might be bad/ need replacing. Therye not too much $$. Also, Did you check for any lose vacuum lines? Dont think that would cause a rich condition but might explain the running rough at idle.
Make sure when you bring the truck into be tested the engine is fully warmed up.
Thanks, It is Fuel injected. I have run cleaner thru it already. I have checked for vacume leaks. there is a small vacume inlet on the top front of the intake. I pulled this off and the idol smoothed out???? I will try replacing the IAC and see if that helps. It was aklso sugested that it may be the Max Airflow sensor. Im going to get some new plug wires and IAC tomorow and see if that helps.
You can use carb cleaner on the MASS air flow sensor (if thats what you are talking about), Just make sure you dont touch the filament, and make sure you get the carb cleaner that doesnt leave a residue. It might say MAF cleaner on the can???
Just got on and saw your problem. I'm not a certified mechanic but I'd say the MAP (manifold air pressure) sensor is the problem. This sensor will monitor "vaccum" in the intake and allow the fuel system to provide the proper amount of fuel to air ratio. If the vaccum line is unplugged from a working MAP sensor the sensor tells the system to go full rich. So it will barely run and pour out the black smoke from the exhaust due to unburned fuel unless you open the throttle up most of the way. It'll run pretty good at open throttle because that is what it thinks is going on. Same thing if the sensor is bad, the system goes full rich and only runs good at open throttle. The MAP sensor will normally be mounted to the firewall and has a vaccum line and electrical plug to it. You could probably got to a autoparts website and see a picture of one to know what your looking for. If your lucky the vaccum line is unplugged from it.
Thanks, I replaced the IAC and plug wires today and it smothed the idol out. It is still running rich but im gona try to smog it anyway. The MAP sensor is next on the list but will have to wait, $400. in the last 3 days is enough. I will have to wait until next payday.
her is a pic My Truck The shell is comming off as soon as I get all of the paperwork done for the title