Hey guys going to pick your minds today. Hope my long post doesn’t intimidate you guys. I recently bought an 86 ford ranger. Truck runs and drives great (except for the shimmy from a worn out tie rod end). Previous owners decided to get rid of it due to it not passing smog. To cut the story short it was very high in nox and it failed the Evap test. The cat was completely hollowed out and had a bad sending unit gasket. Fixed those two issues and re-smogged it and it was a shade over the required amount of nox again. Did some checks and found that the EGR was not getting any vacuum. So I removed it and checked the diaphragm. It held vacuum and moved freely hence proving the EGR is working correctly. So then I checked my vacuum lines. The EGR control solenoid was getting vacuum but not sending any to the EGR after warming up or at any point of throttle. So I checked the connector and found that I was receiving constant voltage but no ground. Checked my wiring diagram and realized that the ground signal comes from the ECM. Added 12v and ground to the connector and EGR got vacuum and opened and stalled the truck which meant that the EGR did its job. So I figured my ECM was bad and replaced it and guess what still no change. So what do you guys thing haha I’m stumped and need to get this thing going.


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I would ground the connector straight to the body if it doesn't come frome the ecm.

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But then wouldn’t the egr stay open 24/7. Wouldn’t that mess up my air/fuel mixture.


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One of the more likely reasons for failing on NOx is EGR, so I think you're on the right track.

Yes...if you ground it straight to body ground, you won't be able to drive the truck at all, or keep it running. The ECM switches the EGR "on" or "off" by providing a ground path for the solenoid that controls it.

At this point I'd try pulling codes and see what the computer thinks is going on. My understanding is that the ECM decides when to open the EGR based on throttle position, temperature, and engine load. Maybe you will get a code for a sensor being out of spec.

Another thought is that the EGR position sensor might be out of whack (common problem on most period Fords), and if its reading is invalid in the eyes of the computer, the computer decides not to try to operate the EGR at all.

In summary: you tested the parts, they seem to work. You replaced the ECM, and the chances of having TWO of them be bad in the exact same way are quite low (EEC-IVs are pretty robust). Most likely the computer is intentionally deciding not to open the EGR based on a sensor input it doesn't agree with.

This is "general Ford knowledge", not Ranger specific. I bring it here from experience gained on other EEC-IV Fords.

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'85 2.0>2.3 5-speed

The EGR system has two valves. One to feed vacuum to the EGR valve diaphragm, and one to 'hold' the vacuum. The computer decides how much EGR flow it wants, and commands the solenoids to open, allowing vacuum into the diaphragm. The valve moves, sending a signal to the computer telling 'where' it is in its travel.(resistance changes). Once the valve reaches the point desired. the vacuum is cut off. The valve will stay there until the computer decides it wants no more EGR flow. It then opens the other solenoid valve, dumping the vacuum, allowing the EGR to close.
The engine must be at operating temperature, above idle, and likely in a 'cruise' situation, such as going down the road at 45-50mph. The computer will then toggle the vacuum valve, open the EGR, and close the valve. The EGR sits, flowing at XX, until you slow, come to at stop, accelerate, whatever sets the computer to change its mind.
You will not see EGR at idle, nor when the engine is cold. You might check the ECT - coolant temp sensor- to insure the computer knows you are at full operating temp. If your thermostat is bum, you may not get there with a lima as they are pretty cold blooded, and might shed enough heat to keep the EGR disabled. (don't bet the farm)
You might want to check your base timing. If it is the opposite of advanced, (the word retarded is censored at some sites) it may cause the temp to be higher, causing more NOx formation than expected. High temperatures in the combustion chamber cause Nitrogen(pretty much inert) to react with O2's. Keep the temp down, and NOx formation is lessened. Something is causing higher combustion temps. Lean mix could, perhaps. Contrary to the thermostat question above, no?
tom

Thank you guys for your quick response. You know right from the get go I had in the back of my brain about the issue coming from that egr position sensor. So I think that’s my last thing to check. As far as coolant temp. My temp gauge is working so I wouldn’t think it would be an issue with coolant sensor. But also I haven’t done any tests so far with the vehicle in gear so maybe that is a possible cause.


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There is the temp gauge sender AND a separate coolant temp sensor. The latter reports to the computer. The former operates the temperature gauge or 'HOT' light depending on model equipment.
You could have a failed sender and the gauge showing everything hunky dory. The computer gets a resistance reading from the sending unit, so as long as there's resistance within proper range, it will assume the sending unit is working. If it went to zero or infinity, it might complain. Otherwise, get an ohmeter and test across the sender terminals. There is a temperature:resistance chart at a web site, to see if your reading is ballpark or not.
tom

Tom is correct, one sender for gauge, one sensor for computer.

There's a bit more to testing the accuracy. The EEC-IV self-test requires the vehicle be at operating temp for the test. If you run the self-test with the engine below operating temp, it will give you a code for the ECT being out of the acceptable range.

So, the computer tests for the ECT to be 1) within the overall valid range from ice cold to overheating; if it goes outside of that range at any time the key is turned on, a code will be set
and 2) specifically during the self test, the reading must be "close to a warmed up engine" but there's some flex room on the values. Edit: the sbftech link I edited in below describes the thresholds on a SBF...not sure if the same numbers apply to the Lima, since as mentioned they do run a little cooler.

Since the ECM is looking at a "return voltage", e.g. "5 volts sent from computer through this sensor, minus the resistance of the sensor", if you can find the chart for the return voltages and test for voltage rather than resistance at the sensor, you can see what the computer actually sees. This is done by poking a multimeter probe through the insulation on the back of the connector to back-probe it, and checking the voltage between the Signal Return wire and ground. Some info here...different engine but same principles: http://sbftech.com/index.php?topic=29608.0

I'd still start with the self-test, so you at least know if the computer is aware of the EGR problem (it probably is, but knowing helps). Without knowing what the computer thinks, we can only guess what it is doing in response to what we guess is happening. Address codes in the order in which they are received.

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'85 2.0>2.3 5-speed

Does anyone know where the two sensors are located and which is the one i need to check. Typically one is located next to thermostat housing right.


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The gauge sensor is on the drivers side of the block, above and rearward of the oil filter. It is screwed into the coolant 'water jacket'.
The computer's sensor is on the top side of the lower intake manifold(1985 EFI per the EVTM), hidden behind the upper intake manifold.(towards the centerline of the engine).
The EGR valve will make it hard to see, as will the prop rod holding the hood up.
If you can get access to an 1985 EVTM, it will be on page 33.
I think the 49-state 86 models were pretty much the same as 85 EFI models, FWIW.
tom

Just out of perhaps my OWN ignorance here... What State do you live in that requires more stringent, politically and/or bureaucratic, nonsensical, "climate changing" Statutory code, bullshit than California especially beyond 25 years let alone 30+ years - for SMOG?

Even when I lived in Detroit years ago they got rid of SMOG (Which they termed AET testing) because they found out that only 3 counties in the entire State had or "required" it and they found it to be not only a scam for revenue but the people basically said We aint doing it anymore and took a stand against it.

I say this because using logic. If there are laws stating that (and I am paraphrasing) NO LAW(s) can be applied for a corporation to make or force you to be a customer or force its products and services on to you or the open public body under the threat of violence or coercion.

Why would a) you b) the "body of politic" A.K.A. the "Citizen(s)" let some corporation nickle and dime its tax payers further with excise taxation without any representation other than the shear thoughts of self claimed "authority" said so? Open to racketeering are we now?

legal definition of:

- Racketeering ~ an organized conspiracy (two or more people) to commit the crimes of extortion or coercion, or attempts to commit extortion or coercion. From the standpoint of extortion, it is the obtaining of money or property from another, with his/her consent, induced by the wrongful use of force (see threat of violence/jail/loss of privilege) or fear.

Blacks Law Dictionary 4th edition Rev. pg 1423

- Required ~ to direct, order, demand, instruct, command, claim, compel, request, need, exact.

Blacks Law Dictionary 4th edition Rev. pg 1468

At which i would implore you to look up those individual words and then follow that up with asking under who's 'authority' Where does that come from? Who deemed you had it over me or others? When did you consent to it? Why do you believe other "(Wo)Men" at that point have authority over you, another (WO)MAN, that which you did NOT create? And further why as a public servant are you requesting that you/I perform for you outside of general authority?

How is it that people misconstrue who works for who in Government or its agents/agency's. They're all Private corporations working under the color of law and using threats of violence or coercion to take from you your currency you worked [expended energies] hard to get.

Now that I sound like a nut again.. If no answer can be found in anyone on the latter portion of my comment, my original statement stands.. 30+ years? SMOG required?

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If you look at his info, the answer is clear. Kuhlefornyuh. The C.A.R.B. - calif air resources board - decrees whatever they want as far as air quality and the means & methods to attain it. Used to was vehicles 'aged out' of emissions testing. Two reasons came to mind: 1)keeping track of old standards and methods to test them and 2)there weren't that many still on the road.
They (CARB) decided to get rid of all the 'old trucks and cars' on the road as THEY were the main polluter. The few that were still being used caused XX% of the air pollution, so they were targeted by A) buyout and B) testing. In the past, a 'referee' could issue a certificate of 'non-compliance' which was used instead of a passing SMOG certificate. I think they decided to increase the amount required to be spent to be in compliance, so older vehicles were less attractive to buy and keep. They also would buy old vehicles and destroy them. Their offers were low.
The fact that parts are NLA just helps them get the older vehicles off the road. Their action and the 'cash for clunkers' reduced the number of old vehicles, thus the emissions.
When my truck was new, it would not pass the emissions test. I spent multiple hours and money trying to get my license and registration on a new truck that had about 5k miles on it. It failed the first test, failed on a re-try after the suggested 'take it on the highway for 20 miles', and then failed at the dealer, who HAD to test a second time(again failing) at my expense, they suggested a 'cleaning service' for $100, and a re-test, again failing. Then the trip to the 'referee' who checked that the system was connected and operating (disconnected a control, noted computer response error) and issued the 'non-compliance' certificate, which allowed registration. THAT was in 1986, with an almost brand-new truck. Two sets of SMOG tests, at $25 each, and a $100 fee for diagnosis and cleaning, and it still failed.
That's California, of 30+ years ago, and it has not gotten better. Auto body paint shops have to submit monthly inventory of their VOC products(paint) by weight, and purchases, so THEY know how much is being released ... and of course, limit said emissions. Dunno if the shops are fined or what happens if the reports are over or incorrect. Water based paints are now mandatory.
In short, the state can take away the use of your vehicle by changing standards, and there's little you can do. CA is noted for requiring 'add-on' emissions controls back in the late 1970's, which were not factory, and reduced fuel mileage. They limited spark advance unless the engine was overheating(sensor taped to upper radiator hose), and delayed advance in other applications. ALL 'ex post facto' impositions. Guess it was legal, but, again, it has not gotten better since.
tom

Ok. So to update where I am now. I found the wire broken at the connector to the temp sensor for my ecm. But now where I am at now is I need to test it but it’s hard because I’m by myself and like you said I’m not getting any vacuum to egr with the vehicle in neutral. So just to save me the possibility of failing another smog test is there any way you guys know of that I can test my entire system under the hood just to make sure my egr system is working correctly before taking it in to the smog shop.


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If you want to know if it is functional, then get a leennnngggggtttthhhh of vacuum line and a tee. Connect the tee and line into the vacuum line to the diaphragm on the EGR valve. Run the line into the cab, and attach a vacuum gauge.
Drive.
Get to a good cruise and stay at a constant speed for a while. If the gauge shows vacuum, then the EGR is being applied by the computer. The vacuum should apply, and then hold steady as long as you maintain level ground cruise speed. Slow down or climb a hill, and it may change. Come to a stop or decelerate, and it may change. Come to a stop and it SHOULD go to no vacuum.
If it does all that, you should be pretty safe to assume it is working. Remove the added line & tee, and take the test.
You may consider using some 'catalytic converter safe' cleaner spray into the intake manifold before taking the test. I found that the inner surface of the intake manifold got coated with PCV gas condensates(oily crud), these would show as extra H's in the test, making it fail for over-rich mixture. I cleaned the intake manifold, just spraying all over after removing the throttle body, and allowed it so stay for a half hour or hour. Then did it again. Replace the throttle body, reconnect everything, and start it. Be prepared for a smoke bomb for the first few minutes.
The engine ran better, idled better, started, better, and, BTW, passed smog. Same engine that failed at ~4-5k miles, 4X in a row. Douche out the intake, and it was good to go.
tom