Failed smog :(

[rang-a-stang]

Upfront info
-86, 2.9l 4wd, 5speed, bone stock engine, Cat is not original and I know almost nothing about it (bought the truck about 2 months ago)
-Runs and idles like a top, passes KOEO and KOER with no codes
-Air filter, cap, rotor, and wires all look new, plugs ceramics look new but I did not pull them (yet)
-Verified all vacuum lines hold vacuum, replaced all the ones with cracks with new lines
-Timing with spout removed right at 10 degrees
-I tested EGR by applying vacuum to the EGR valve nipple and the truck stalls out. Valve DOES hold a vacuum

Symptoms
-Failed HC and NOx

Questions:
-When I got home, I put a vacuum gauge on the EGR signal line and it was twitching a little as I drove it around but not enough to open the EGR Valve. I would assume It would need at least 5" of mercury to open, right? I thought KOER tested EGR/it's solenoid. No?

-I have a new O2 sensor and am going to throw it on hoping that addresses the HCs. At what point do I assume my Cat is bad and go get a new one?

 

[Uncle Gump]

Hydrocarbons are straight unburned fuel. Was the vehicle fully warmed up and at full operating temp prior to testing?

 

[RonD]

Running a 180deg thermostat can raise HC a bit, should be 190deg, but that can raise NOx

EGR valve should only be used after engine is fully warmed up and then only when accelerating or at cruising speed, say above 25mph

I would run some Seafoam in the gas tank, or any injector cleaner

Have a look at a couple of spark plugs to see if you are burning oil, that raises HCs
Change PCV valve if they look blackish

New O2 will help, for sure

Cat is a big $$$ purchase so hold off on that

 

[rubydist]

The one other thing to do (if you don't do this regularly) is to take a 1 hour plus drive and drive it hard on the freeway at 80 or whatever you can run for that hour or more. That, combined with the injector cleaner / Seafoam will clean up some loose carbon from the cylinders and get the cats hot enough to clean them a bit. That combination has a reasonable chance of getting you there, since you are close. Also, make sure you have top tier gas in the tank, the cheap stuff does not burn as clean.

 

[rang-a-stang]

Copy all. I drove it like I stole it for about 10 minutes before I got there; wanted my cat as hot as I could get it. Temp gauge does not work so I assume it was nice and warm. I do have a 180 degree TStat in it. I plan to wrench on it tomorrow morning and will post of up some plug pictures then.

we SeaFoamed the intake about 200 miles ago. I did not run fuel injector cleaner through it thpifj

is there a way to test the EGR sole

 

[gaz]

When I lived in southern California I had to smog all.my out of state vehicles. The tech mentioned that even a leaking gas cap can through it out.

What are you getting for fuel economy; that can tell tons about the level of effeicentcy your dealing with.

It was years ago, 1998-2000 but I had an 85, 2 87's and 94 Firechicken that all ran like tops and passed smog 1st try, no issues. They were driven on premium only, all very well maintained and tuned regularly.

 

[rang-a-stang]

copy that. Just put a brand new gas cap on. It passed the Evap test (includes testing the cap).

Hard to tell what the MPG is because
a) we don't drive it much because it's not registered yet and we have been wrenching on it.
b) our speedo is off because of the over sized tires
c) every time we drive it, we drive it hard because we are trying to heat the cat up or we are troubleshooting other issue.

 

[bobbywalter]

Ten minutes won't do shit ...you need to drive a tank with cleaner thru it with good plugs...4th gear 70 mph ..at least 45 min out and 45 back.

If the injectors are ok...and clean up you should be good. I am assuming the valve events are good and compression is ok because you would have seen it on the vac gauge.

Is the cat close enough to the O2? O2 in proper place? I ask because you said it looked after market. No exhaust leaks is assumed .. you are used to smog being Cali resident is assumed so the easy stuff is second nature

 

[Uncle Gump]

I think you said you had issues filling the fuel tank also. Could be a venting issue and the EVAP system could have filled partially with fuel. I also wouldn't try to squeeze every last drop into the tank either. When it clicks off don't keep trying to top it off.

 

[rang-a-stang]

Ten minutes won't do shit ...you need to drive a tank with cleaner thru it with good plugs...4th gear 70 mph ..at least 45 min out and 45 back.

If the injectors are ok...and clean up you should be good. I am assuming the valve events are good and compression is ok because you would have seen it on the vac gauge.

Is the cat close enough to the O2? O2 in proper place? I ask because you said it looked after market. No exhaust leaks is assumed .. you are used to smog being Cali resident is assumed so the easy stuff is second nature

yeah, good point. I may need to make a road trip early this week.

Yeah, vacuum gauge is solid. The cat is in the stock location. I forgot to get a picture but it looks like previous owner had the stock 2 part cat cut out and replaced with a single cat. There is an exhaust leak after the O2 sensor, before the cat but that should be fixed by tomorrow afternoon (gasket is in my mail box right now).

I think you said you had issues filling the fuel tank also. Could be a venting issue and the EVAP system could have filled partially with fuel. I also wouldn't try to squeeze every last drop into the tank either. When it clicks off don't keep trying to top it off.

I did have issues filling the gas tank but that was fixed. When I tested the Evap line, I pugged the carbon can side and stuck a vacuum gauge on the tank side and put vacuum on it to make sure it held (it did). I will pull the carbon can side again and put vacuum on it and make sure it does not hold a vacuum anymore.
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I only had about an hour to wrench today. Went straight to EGR control solenoid. Ran KOEO and got no codes. I let it go through all the cycles and blipped the throttle. My understanding is that puts the computer in Solenoid check test. My understanding is once the computer is in this test mode, each time I blip the throttle it is supposed to cycle the solenoids on then off.

I blipped the throttle a few times and the EGR control solenoid did not click so I pulled the connector. It has 12v across the 2 pins. It always has 12v across the two pins (unless I turn the ignition off). So I plugged the connector back in and put vacuum on the lower nipple; It would not hold vacuum. I put vacuum on the upper nipple; It also would not hold vacuum. I unhooked the connector and neither nipple held vacuum then either. That told me the EGR solenoid was dead (it did not switch whether it has 12v or not). Pulled it out and it's the original FoMoCo part. The filter on the top was nasty (yes, it had a cap over it and I took the cap off to inspect).

Found a replacement my local McParts for $40/lifetime warranty.

Took it home and it also does not hold vacuum on any nipple (either plugged in or not). Plugged in my connector and still no change. grrrr... Multimeter across the pins shows an open on my new solenoid. Old solenoid get 44ohms. I am also getting a code 83 now with KOEO. I guess I got a bad one right out of the box. I'll get it replaced tomorrow.

I am also bugged that I ALWAYS have 12v across that connector. Anyone got any thoughts on this?

 

[RonD]

EGR solenoid will have 12volts on the red wire with key on, that's normal
The other wire runs to the computer, and is the ground for the solenoid, but its ONLY a ground when computer wants to use the EGR valve

Because its a solenoid there is just a Coil of wire inside, so 12volts in = 12volts out, so with key on you should read 12volts on both wires if they are connected to solenoid
And that's how the computer "tests" that the solenoid is OK(in any year), computer "sees" 12volts on the "ground wire" with key on, that means the EGR Solenoid "circuit" is OK, the 12v is making it to the solenoid, thru the solenoid, and to the computers EGR pin, complete circuit
Code 83 would be one of the codes if EGR solenoid was unplugged or no 12v was making to computer on the "control wire", the ground wire

When computer wants to activate the EGR Valve it will Pulse the EGR solenoid Ground wire/pin, slower pulse opens the valve a little, faster pulse opens it more
This is how IAC Valve works, Pulsed Ground, EVAP solenoid as well

In any case yes, if you apply 12v and ground to the solenoid it should "click" open, 9v battery works as well
And yes, the hose ports should be closed with no power to solenoid, can't blow thru either port

 

[broncc]

Honestly it might be worth getting the injectors cleaned. My local guy did it for $100 and I'm sure glad I did. It will make a huge difference. All my friends who also own old efi cars are always shocked by the before and after flow test results.

That $100 gets you new o-rings, internal filters, and a flow test to prove they work. You could buy 10 cans of sea foam and maybe address one of those issues for the same price. Injector cleaner isn't great for the cats I hear, too.

 

[cbxer55]

When I lived in CA, moved out in 2002 (Thank God!), vehicles 25 years and older didn't require smog. They do now? 82 is a 35 year old vehicle. Where I live, no smog checks.

 

[rang-a-stang]

EGR solenoid will have 12volts on the red wire with key on, that's normal
The other wire runs to the computer, and is the ground for the solenoid, but its ONLY a ground when computer wants to use the EGR valve

Because its a solenoid there is just a Coil of wire inside, so 12volts in = 12volts out, so with key on you should read 12volts on both wires if they are connected to solenoid
And that's how the computer "tests" that the solenoid is OK(in any year), computer "sees" 12volts on the "ground wire" with key on, that means the EGR Solenoid "circuit" is OK, the 12v is making it to the solenoid, thru the solenoid, and to the computers EGR pin, complete circuit
Code 83 would be one of the codes if EGR solenoid was unplugged or no 12v was making to computer on the "control wire", the ground wire

When computer wants to activate the EGR Valve it will Pulse the EGR solenoid Ground wire/pin, slower pulse opens the valve a little, faster pulse opens it more
This is how IAC Valve works, Pulsed Ground, EVAP solenoid as well

In any case yes, if you apply 12v and ground to the solenoid it should "click" open, 9v battery works as well
And yes, the hose ports should be closed with no power to solenoid, can't blow thru either port

Oh my gosh, that makes perfect sense! More below.

Honestly it might be worth getting the injectors cleaned. My local guy did it for $100 and I'm sure glad I did. It will make a huge difference. All my friends who also own old efi cars are always shocked by the before and after flow test results.

That $100 gets you new o-rings, internal filters, and a flow test to prove they work. You could buy 10 cans of sea foam and maybe address one of those issues for the same price. Injector cleaner isn't great for the cats I hear, too.

I might do that. That's a good idea.

When I lived in CA, moved out in 2002 (Thank God!), vehicles 25 years and older didn't require smog. They do now? 82 is a 35 year old vehicle. Where I live, no smog checks.

Yeah, the Governator killed the rolling exemption. It stopped at 1976 and newer must be smogged. I don't mind the dyno, Evap, or functional parts of the smog check. I mind the visual inspection. Why should it matter if I have a cast-iron exhaust manifold or a header? It shouldn't. What should matter is what comes out the tailpipe. But I digress.
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OK, so after what RonD wrote, I went out and measured each wire to ground. I found the 12v source. And the other wire that goes to the computer. Resistance from that pin to ground was 4.2m ohms. Blip the throttle and it drops to 3.98m ohms.

With all 3 solenoids (exchanged the one I got last night) sitting on the bench, if I plug one nipple and apply vacuum to the other it does not hold vacuum. I hooked this 3rd one up to the connector and tried the blip test and I still don't get a click. Should I be checking my computer grounds?

 

[RonD]

Computer PULSES the ground to EGR solenoid, it never "grounds it"
And it pulses the ground based on engine load not throttle position

In an 1986 engine load would be from MAP sensor and throttle position VS RPMs
Not sure there is any way to do a Static Test on EGR solenoid operation

Basically you test the solenoid's coil, 60 ohms, +/- 30 ohms is OK
Then blow thru either port, if you can't then valve is close, apply 9 to 12volts and blow again, if you can then valve opened
Working solenoid

If you wanted to run a vacuum hose from EGR solenoid and into the cab and put a gauge on it, then go driving you could see if computer is applying vacuum to the EGR valve