These codes come up with the Gray EVP. I removed the black one due to the code 33. They have different voltages.

These codes are memory only.

I think you guys are nailing it with the EGR valve not closing. I'll check whenever I have time. This whole week is VERY busy at work and I dont have time. Im gonna try to pull it off and clean it.

Is there a better greaser than WD-40? I sprayed TONS on the pipe and nothing. Its starting to strip a little.

 

I have found PB-Blaster and Kroil to be much better penetrants than WD-40.

You can buy PB-Blaster at local auto parts places. Kroil you have to mail order.

It is possible your original gray EVP has a dead spot on it. Would give the code 35.

If you can't get the EGR valve off the tube, try pulling the pintle off the seat with a vacuum pump and dumping some engine cleaner "backwards" into the square flange that normally ties to the intake plenum. Let the vacuum off, then reapply. You can probably clean the carbon out of the seat by working it up and down with external vacuum -- its range of motion in normal operation is not very much.

 

Ok, Did KOER test and got codes 21, 42, and 77....None of these seem EGR related. Whats a HEGO sensor?

Also, Is that rubber O-ring thing suppose to be installed with the EVP?

Thanks.

 

Did you fully warm up the engine before running the KOER test?

Code 21 -- ECT out of self test range -- maybe not warmed up

Code 42 -- HEGO not switching, always rich -- maybe computer keeping it rich because it isn't warmed up
(HEGO stands for Heated Exhaust Gas Oxygen sensor) -- it is screwed into the exhaust piping between the engine and the catalytic converter.

Code 77 -- When the check engine light flashes once, about 30 seconds into the test, you are supposed to stomp the throttle. This allows the computer to test the knock sensor and the MAP sensor. Code 77 means you didn't stomp, or didn't stomp hard enough.

The EVP has an O-ring, I think because it is exposed to the vacuum chamber in the EGR valve. The O-ring prevents vacuum leaks.

 

Hmm, guess it wasnt warm enough. I'll do it again. Isnt the sensor between the exhaust pipe and catalytic converter the O2 sensor?

Is the MAP sensor suppose to open after turning engine off? I noticed it opening after I turned engine off. This happens only sometimes. Maybe another broken line somewhere in there.

 

Redid KOER....hope i did it right. Codes: 12, 42.... I'll try it again and see what codes I get. Maybe it's time to drive this Ford off a cliff ...

 

Code 12 means the computer can't get the RPM high enough using the IAC during the KOER self test. This usually means a sticking/clogged IAC, a wiring problem to same, a misadjusted or carboned up throttle body, or retarded ignition timing. If everything else is satisfactory, it isn't that big a deal.

Code 42 is HEGO too rich, as before. Could be bad oxygen sensor. Could be bad fuel regulator. Pull the vacuum hose off, if there is fuel there the regulator has failed. Test the pressure with a pressure guage. If too high, you will get Code 42. Could be a leaking fuel injector. See if one spark plug runs darker than the others.

At least you've cleared up code 21 and code 77. You are making progress, even if it seems slow and frustrating.

 

Ok, the black EVP is back on (with O-ring). No codes have came up at all since yesterday (I was expecting 33 like the first time). Redid KOER and 42 is the only one that comes on. Checked FPR vacuum line and no fuel is in there. Is there a way to clean or check the O2 sensor?

The worst part is idling. If I give it light throttle while idling, it wants to stall. If heavy throttle, it revs back down normally.

 

The O2 sensor is considered a "wear item", like the spark plugs. It should be replaced every 60000 miles or so. They cost about $50.00 If the O2 sensor gets dirty, it will react slowly to the presense of oxygen in the exhaust gas stream, and will continue to indicate "rich" after the computer has already moved the mixture well past "too lean". This will give you a case of "the stumbles".

If the heating element does not work, the same thing will happen.

The sensor heater can be tested by ensuring the resistance of the heating element is 3 to 5 ohms. The truck wiring should supply 12 volts to the heater element whenever the key is on.

With the engine running at around 2000 RPM the voltage at the HEGO signal output should be 0.5 volts or greater. With the engine forced to run lean by inducing a vacuum leak, the voltage at the HEGO signal output should drop to around 0.1 volts.

You could try removing the O2 sensor and gently cleaning any crud off the portion that sticks into the exhaust crossover pipe.

Unless the O2 sensor is nearly new, or you feel emboldened by the above to whip out your DVM and test it, it may be easiest to just replace the O2 sensor.

 

Yea, im not sure if it ever has been replaced. It's a Bosch sensor. Is Bosch factory?

Quick question. A vacuum line runs from the Main vacuum to a 2-way splitter thingy. On of the lines goes to the MAP and one to something else. Before the line gets to the MAP, it goes into a big loom. It then comes out (white-colored) and then connects to the MAP. Will it be alright if I ran a clean line directly from the MAP to the 2-way splitter without running it in that loom?

 

Bosch makes emissions control sensors, transducers, etc for just about all the automakers. Your Bosch sensor is OEM. You can replace it with an "exact fit" or a generic version with a longer wiring pigtail. Your choice. It might cost a bit more than I said in an earlier post because it is a heated sensor. Still should be less than $80 at any discount auto parts place.

You should be able to re-route the vacuum lines as you propose. Just make sure everything is connected and that there are no leaks.

 

Hi, I've been reading this thread and using info here to try and figure out my own EGR woes on my '88 Bronco, .302 V8, EFI. It's throwing codes 32 and 41.

It did this about a month ago and was also surging at idle. I removed the EGR and cleaned it as best as I knew how with Chemtool. It quit surging, but the codes started coming back this week.

Using a vacuum pump to test, the engine stalls when I apply vacuum to the EGR valve. Green (EGR to EVR) and red (canister to intake) lines hold vacuum.

When testing the black (EVR to canister) line, it's not holding vacuum. I'm hooking the pump to the canister end of the line while the other end is still connected to the EVR. Did this with engine running and off. I inspected the line for cracks, breaks, and such and couldn't detect anything. Maybe I'm not testing correctly? I guess I should just unhook it from both ends and plug one end to test it to be certain.

Today, I replaced the EVR since the filter in the old one was in bad shape anyway. This didn't help with the black line test, though.

If I'm doing the vacuum testing correctly, then my guess is I'm now looking at a wiring problem. Either at the EVR or the EVP sensor.

Anyone have any advice?

 

The EVR provides a vent function. With the computer commanding "No EGR", with no current through the solenoid, it is necessary to release any trapped vacuum. Otherwise the EGR valve would stick open when the computer wanted it closed. This is why applying vacuum to the OUTPUT of the EVR results in the EVR not holding vacuum -- the EVR is trying to dump trapped vacuum.

With the engine stopped, apply vacuum to the input side of the EVR valve. If this holds vacuum, the EVR is probably OK.

There is the distant possibility that the EVR leaks when it is commanded to open and apply vacuum to the EGR. The only way I can think of to test this is to apply vacuum to the input of the EVR, with the output connected to your (proven good by this time) EGR valve, and then apply voltage and ground to the EVR solenoid. This should command the EVR to open and you can then check the integrity of the whole system.

The vacuum line routing you talk about does not match my truck, nor does it match the alldata schematic for my truck. In mine, the EVP is fed by a red line, which is Tee-ed into a red line connected to the vacuum reservoir (cannister?). The schematic shows the EVR should be connected directly to manifold vacuum, and that only the TAB and TAD solenoids work off the after-check-valve side of the vacuum reservoir.

 

Thanks for the quick reply.

The vacuum connections on this thing have been a nightmare to deal with from day one. I've owned it for 4 months and the previous owner apparently rerouted and rigged things in strange ways. You should see the way the PCV valve is hooked up. Jeepers! (BTW, anyone know what the trick is for sliding the PCV valve into place inbetween the intake and valve cover? Seems too big to fit to me.)

I'll try to sort this puzzle out tomorrow and get back to you.

 

Hey ignore that whole "rerouting vacuum line" post by me. I was BADLY mistaken..lol

anyway, got any tips on removing the EGR valve? I have went EXTREME trying to remove it. I hooked a 12GA wire to the end of the wrench, Tied the other end to a pole. Put truck in Reverse and SLOWLY pulled back. LOL, yea I know it's crazy, but I think it turned it a little, but thats it. Its stripping kinda bad now.

Ok, Right now NO codes have came up for a while. Mileage has jumped up a bit, but I can still smell the rich mixture. I'm kind ok leaning towards the leaky injector. I'm also glad this post is helping other people .