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Idle issues


ranzerbinz

Member
Joined
May 8, 2016
Messages
11
City
Massachusetts
Vehicle Year
1985
Transmission
Automatic
1985 ford ranger
2.3l, 4 cylinder, fuel injected. EEC-IV computer. 32,000 original miles.

Having issues with idle ONLY at operating temps and a strange howling noise in crankcase area, only at passing temps as well. I am pretty mechanically inclined and have done quite a bit of work to the engine all ready. But I'm struggling to figure out what is going on.

So far, I have replaced every gasket (intake manifold gaskets, egr gasket, valve cover gasket, throttle body gasket). I've replaced the pcv and hose. All vacuum hoses were checked with a vacuum test gauge and passed. I've done a compression test to all 4cyl. Only number 3 cyl was slightly low, but well within specs. All 4 fuel injectors were replaced and wiring harness. New fuel regulator. New fuel filters. Throttle body cleaned. New air filter. New oil and oil filter. Checked all electrical wiring for bad Grounds. Checked ok. New water pump and tstat. New plugs and wires. New rotor and cap. New timing belt and engine belt. Timing set to ford engine specs. 10degrees btdc. New coolant, air temp and oil sensor. Battery putting out a constant 14volts during engine operation. 12volts off. I may be missing some stuff in there, but you can see I've done some work, but still can't resolve the idle issue during operating temps. Cold start it runs mint. As soon as it hits operating temp, it starts to idle rough and a strange howling noise appears down in crank area. Sometimes it will stall out. And when i go to goose the throttle it will hesitate and then accelerate. No emissions light appears on dash, so good there. I did check the computer for any codes with my automotive light tester. Only code is, a 31 or 32 I believe, for a low voltage signal to egr during test sequence. All wiring is ok to it. Not sure if it's computer issue or something I'm totally missing. I think the computer may be running the engine too lean with fuel. Hoping I could get some insight with someone very familiar with the 2.3l. My guess is something totally stupid I've missed. Ha! Open to any suggestions. Thanks so much.

Derek

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Fuel injected engines can't use an "idle screw"
So they use a controlled vacuum leak to maintain steady idle, cold or warm

Ford calls their unit the IAC(idle air control) Valve
This is an electric solenoid valve that bypasses the throttle plate to let more or less air bypass the throttle plate, increasing or decreasing RPMs
The computer pulses the voltage going to the IAC Valve to set the RPM it wants

After engine is warmed up and idling, unplug the IAC Valves wires, it will close all the way and idle should drop to 500rpm or engine will stall, either is good it means no vacuum leaks.

Since the engine spends more time running warmed up than running cold the IAC Valve can get sticky in the places it needs to be for warm idle, 700-800rpm.
They are easy to clean.
While it is off plug in its wires and turn key on, computer will open the IAC valve all the way for starting, then unplug the wire and IAC valve will close all the way.
Plug wires in and out a few times to make sure it isn't sticking.

And just as a heads up, if you see what looks like an "idle screw" on the throttle linkage, it isn't, that is an anti-diesel screw and also used to adjust TPS(throttle position sensor) minimum voltage
 
Two things... The MAP sensor (on the passenger side under the plastic cover) may be flaky as it is the signal to the computer reflecting the load on the engine, based on vacuum in the intake. If it dies, your idle may be all over the place as the fuel injected will vary from second to second(or less?)
Second thought is the PCV. With 32k, you may have stuff in the separator under the intake manifold on the drivers side of the engine. It vents the crankcase through a maze of material, fiber or metal shavings, to trap oil droplets and allow them to condense and drain back to the crankcase. Low mileage and short trips may have filled it with sludge and partially block the PCV flow. As engine speed increases, the flow through it may be affected. You should be able to pull the PCV valve from its inline position rearward of the alternator, and see flow from the crankcase. That could be the source of the whine/howl.
Have you checked the fuel pressure regulator? Located on the fuel rail, with a vacuum line attached, it should bump pressure when checked at idle and the vacuum line disconnected.
The system runs in 'open loop' while the coolant temperature is below XX degrees F, and the computer uses a fixed flow of fuel, rather than the O2 sensor, coolant temp, air temp sensor modulated fuel flow. The regulator will pop fuel pressure when intake manifold vacuum drops(acceleration), much like a accelerator pump on a carburetor.
Once you go into closed loop, (reach proper temp), the computer will use the sensors, and adjust fuel accordingly. Excess air from the PCV?, can diddle with the mix so it doesn't run properly.
The MAP also comes into play once the computer goes into closed loop...
tom
Oh, re-read, and pressure regulator replaced. What pressure do you get? I remember it being in the 40-odd psi range, bumped when the vacuum line is removed. I have a CA emissions EFI 85 2.3, from new, so sort of am familiar with it.
The EGR should not be applied at idle. Check that the valve doesn't leak, or one of the two vacuum solenoids over under the plastic cover are not fritzed. One opens the EGR diaphragm to vacuum, the other 'holds' the vacuum.
 
Hey guys. Thanks for your response! Yes, thank you Ron. I knew there was more I replaced. The iac is new. It did pass the plug test. I removed it during operating temps and at cold start. It stalled the engine right out, so no vacumm leaks. Kind of a real cool test. The map sensor is also new Tom. But I think you're on to something. Just to give you a history. It was owned by an older fellowwho only drove it very short distances. It basically never saw the high way until I brought it home. The idle issues increased more as time went on from use. That's when I stated replacing parts. To let you know, I did notice the cam journals/lobes very polished, when replacing the valve cover gasket. My thought is that he ran it low on oil a few times. There was an oil leak at the front pan gasket. The oil pump is working from what I can see. Oil is getting up to ports for cam. Gas pressure, last i checked was at around 30psi. It does have the high press fuel pump on frame near engine. The pcv and hoses are new and tight. I do need to replace the entire 4 piece oil pan gasket at some point. That will give me a chance to inspect the crank area, if I feel like that kind of big project. It is a pain to change those gaskets, as I'm sure you're aware. My thought was maybe the intake valves? The vacuum test gauge does appear to show a flutter back in forth during operating temps. It's within the proper vac specs, but does flutter back and forth as it idles. Typically, I belive this is a sign of intake valves not seating properly, I could be wrong. I have to recheck on that. I tested the egr to make sure it holds open when I apply a vacuum to it with my hand vac pump. It does hold. I have cleaned it inside. Was a little cruddy, but ok. I do wonder now, if maybe there is some kind of leak by from the egr during idle. I know this could be an issue. I'm just pretty stumped on this one. I love this truck and the engine has be fun to work on. Is there a way too remove the separator from the engine block, for the pcv? I haven't attempted it. That might be a good idea if I can, Tom. Thanks for the awesome insight Ron and Tom. This is an interesting one.

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Oh, and I have checked the throttle positioning sensor, new, of course ?. And it does have proper voltage output when opening and closing throttle. Tom, I have noticed the egr solenoids click back and forth when I slowly accelerate the engine. Then they fully energize when the throttle is up high enough, as I expect they should. But the clicking back and forth I'm not sure of should happen during a slight acceleration. Thoughts? I live in Mass and they don't test emissions when a vehicle is over 20 years old. Do I even need to have the egr operating for proper operation? I'm aware of how it works and that I aids in recirculation of exhaust gases, but I'm just not sure if it's mandatory for proper engine operation. Thanks

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EGR(exhaust gas recirculation) system is used to lower cylinder temperatures when engine is "Warmed up" and then under load.
When an engine is cold EGR system is not used at all.
When an engine is idling EGR system is not used.

After warm up when you place an engine under load, drive it, the cylinder temperatures will increase fairly fast, the more the load the higher the temp, this is why engine temp gauge will climb up on a long uphill grade, this higher cylinder temp will spike NOx emissions, a bad emission.
"NOx gases react to form smog and acid rain as well as being central to the formation of fine particles (PM) and ground level ozone, both of which are associated with adverse health effects"

Now if you add some exhaust gases to the intake it will cool the cylinders by slowing down the combustion process in the cylinders, yes hot exhaust gases cool it down, lol.
This lowers the NOx emission quite a bit.
It also has an added benefit in that Pinging/Knocking from pre-ignition of lower octane fuel is also caused by heat, fuel ignites in a hot cylinder before spark plug fires.
So keeping cylinder temps lower prevents possible pinging under load.

EGR solenoids should pulse when adding exhaust gases to intake, how much exhaust gas is added is critical, not enough allows cylinders to get to hot, too much will cause engine to loose power.
So the computer pulses the solenoids, to set vacuum level at the EGR valve, this opens EGR valve a little or alot.

On the older systems, like you have, there will be an EGR sensor on the valve, this tells computer how far open the EGR valve is, and when it is closed.

Newer systems use a DPFE sensor, it measures exhaust pressure in the EGR valves tube, this is a more accurate method since tube and valve can get carbon build up inside.
 
When you set the ignition timing, did you remove the plug located on or near the 'loom' from the inner fender to near the intake manifold? That plug must be removed to set the 'base' timing to 10 BTDC. I read the manual, which stated 'the computer won't mess with the timing for X minutes after startup'. Ha. Don't believer it. Remove the plug to set the timing.
I think I'd take the thing out and run it from Springfield to Boston and back. Or something equivalent. A good 90 mile run, good and hot, exercised. The valves have sat still, unmoving, for the majority of the time since they were assembled. The stems and guides may have had some sort of 'chemical cook off' that turned oil into come carbonicious mess that makes the valves slightly stick. Get thee on the highway and run it for several hours straight. It may come back home, rejuvenated from an "Irish tuneup", rather than the "Italian tuneup" used on some 'thoroughbred' vehicles - run up the rpms and cruise at 60mph in 1st gear for ten minutes....
The separator is a 'jam fit' into the hole in the block. The same type of fit as the dipstick tube. There are grades of metal fitment, so my ignorance of the labels is still intact, and I can't say it's a 'press fit' or an 'interference fit'... but it jams into the block without fasteners, I believe. Take a close look. You'd need a prybar to get it out. You should be able to check its 'flow capacity' by removing the PCV valve from the tube, and using a rag(to seal) and compressed air into the oil filler in the cam cover. Feel the outlet, and if it is flowing air freely, then it's ok. I'd think.
tom
 
Hey gents. Thanks for the input again. Thank you Ron for the very detailed info on the egr. I read the same info on it recently. You are right on the money. I need to double check to make sure the diaphragm is not leaking by, which i doubt. I did a full test on the vac system. I'll also double check that the exhaust gas is not leaking by during idle, as well.

Tom, there is no plug for my distributor. I have the universal TFI module. My shop manual shows both designs. I think I just may get up on it and do some highway driving, but it probably will not happen until next year. I'm putting the truck away for the winter. She's only going to see the other 3 seasons. The salt will eat the snots out of it. The body and frame are in mint shape. Unfortunately, this will probably only exacerbate the issue by sitting for the winter months. But I think I do need to do it. I just get nervous about stalling out and then needing a tow home. It may be worth it to give it a try though. I will try to see if I feel a solid positive flow with the pcv out. You guys have been a great help so far thank you. I'm trying to avoid sending it to the shop. It's a pretty simple engine to work on. Thanks.

Derek

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