86 ranger 2.3 egr solenoid leak?

[clam_bert]

Hey guys,

I bought a nice old pawpaw owned ranger, low mileage, in good shape a couple months back, have given it a tuneup and timing belt change, but I haven't been able to figure out why the idle hunts slightly. It's also getting bad fuel mileage for the engine (about 15 city).

The other day I Finally tracked a pesky hissing noise back to the egr solenoid. Assumed it was a vacuum leak, and today found another solenoid in the local junk yard. However it makes the same hissing noise. The only time I can get it to stop is by removing the hoses and plugging them with my fingers. The idle evens out a bit when I do that as well.

Is it possible I just have two faulty solenoids and need to shell out 70.00 for a new one? what can I do to check before spending the money and potentially wasting it? Any other advice?

 

[RonD]

Welcome to TRS

Certainly possible but long odds on getting two that leak.

Vacuum systems don't leak, wouldn't be much good if they did, so hissing noise is not good.
Unplug the wire from solenoid to see if hissing stops
Test solenoid by putting a hose on each port and blowing or sucking on it, to see if leak is mechanical defect in the solenoid/valve
If valve holds pressure then Computer may be the problem, computer pulses 12v/ground to the EGR solenoid to open the valve a little or alot, but EGR is only used while accelerating or when there is a load on the engine, never at idle.
EGR gases Cool Down cylinders to prevent excess NOx emissions which peak as cylinders get hot, i.e. accelerating or higher load.

 

[tomw]

The EGR has two solenoids on some, one to 'add' vacuum to the diaphragm, the other to 'hold' the vacuum. One solenoid will have two hoses, the other will have one hose, and a chunk of sponge rubber(filter) on the other port. The second is the 'hold/vent' solenoid which will hold the EGR at the set position (percent open) commanded by the computer.
Solenoids will be NO or NC. Normally Open or normally closed, with no juice applied. You can check ( I think) using a 9-volt battery, or jumper to the truck battery, and check if they are open or closed with/without juice to know if they are functional.
The EGR valve itself has a variable resistor built in that reports valve position to the computer. The computer sends 'add vacuum' to open the valve, and when it gets back a good(commanded) position percent open, it says "STOP with the vacuum already", and the hold/vent solenoid just sits there holding position with no other commands. Step on the brake and get to idle speed, and the computer will tell the hold/vent to dump the vacuum, which should allow the EGR valve to close. And so it goes...
tom

 

[clam_bert]

**updated** Thank you guys for your responses and help. I checked with scanner this morning. Passed off test but gets code 34 while running (egr control circuit fault/Evap control fault/defective egr pressure transducer) I attached a couple of images. I am not very familiar with egr stuff. So I'm assuming this is a combined 2 solenoids, one without the nipple adds vacuum and one with holds it? Stopping the hiss is as simple as removing the little cap and plugging said nipple. It DOES NOT hiss during acceleration. I jumped it with battery and the computer initiated and I heard a small click. Not really sure how to interpret that.

 

[tomw]

To repeat:
Solenoids will be NO or NC. Normally Open or normally closed, with no juice applied. You can check ( I think) using a 9-volt battery, or jumper to the truck battery, and check if they are open or closed with/without juice to know if they are functional.

Get a 9-volt and some tubing and jumper wire. Attach tubing to a barbed fitting. Suck. If you can flow, the valve is open. Apply 9-volts or battery voltage to the relay windings, suck or blow. If it now does not flow, it is working.
Check both solenoid valves. I *think* the valves are both to be closed, and open only when voltage is applied. One to 'fill the system'(actually evacuate), the other to 'release' when power is applied. I may have that wrong, but for sure you'd NOT want to flow vacuum and operate the EGR in a 'fail safe' mode, as it would cause a terribly crappy idle. EGR is not flowed at idle speeds for that reason.
tom

 

[clam_bert]

Ok here are results of battery test with both solenoids: with juice applied the hold/ vent solenoid closes. The hose fitting that the green vacuum wire attaches to no longer allows me to suck air through and the hissing out of the vent nipple stops. When juice is applied to the add vacuum solenoid, the hissing sound increases. Under either circumstance the hose fitting that attaches to the red hose didn't allow airflow through.

I've tested both sets of wires with my multimeter, and they don't appear to be receiving juice from the computer at idle. I guess it's time to start following the wires...

 

[clam_bert]

I fooled around with it more, and the vent solenoid does appear to be receiving juice under acceleration (hence the non hissing) " As does the other(albeit not near full voltage) Maybe I misunderstood, but shouldn't the nipple with the filter over top only being sucking in air during acceleration and not at all during idle, i.e. The opposite of what seems to be happening?

 

[tomw]

The EGR is not engaged at idle. The 'dump' solenoid(or 'hold' solenoid) should not have any vacuum to dump or hold at idle.(the one with the sponge filter or wide-open port)
The 'apply' solenoid should be closed until the computer wants some EGR flow. It would then open, allow vacuum to the diaphgragm, the EGR valve would move, changing the resistance of the feedback sensor, signal the computer 'where it was', and the computer close the 'apply' solenoid, and leave the 'dump' or 'hold' solenoid alone. The 'dump' solenoid would just 'hold that thought' for the computer, keeping the EGR at its current position until the computer told it to 'let out the vacuum' and close the EGR cuz we iz at idle(or coast, I don't know exactly when it happens).
tom

 

[clam_bert]

Well I've done some more tinkering this weekend, with some positive results. The resistance on the Egr position sensor tested poorly, and I replaced it. This did not change the issue with the solenoid constantly pulling vacuum at idle and didn't really seem to affect performance. What did seem to help the solenoid problem was to place a wire between the negative terminal on the battery and the green wire on the solenoid power connector. It now stays closed until acceleration occurs, and appears to be increasing air intake based on the egr valve position. The idle smoothed out dramatically. I've driven it a lot since then, and gas mileage initially appears to have gone up from 14.5 to 21mpg.

what I don't understand is why this affects the problem. I'm still throwing code 34. Via the Haynes manual wiring diagram, it appears the wire is a lead wire to the computer. Is it possible that it's a grounding issue?