Emissions/engine issue

2trux · Mar 3, 2015

Hey all, my son bought a 90 B2 and has not been able to pass the emissions test. It is failing the idle HC portion of the test. It needs to be under 200 and runs about 375. I have done all the external stuff I can think of: Air charge temp sensor, IAC, O2, MAP, & timing. It actually did its best when the vacuum hose for the cruise was disconnected & idle set with the screw to 1100 rpm. It's obviously getting too much fuel as the exhaust and O2 sensor were covered in soot.

Also to throw into the mix, the truck uses about 1qt of oil in 1000 mi. There is no smoke at the exhaust and no leaks. Do you think this oil is getting sucked into the intake through the PCV and causing the extra HC at idle? The old air charge sensor was covered with an oily film.
Should I have him run it with the PCV disconnected with a filter in the hole? Can you suggest any other troubleshooting ideas?

Thanks.

RonD · Mar 3, 2015

High HC at idle could be misfires, how does it idle at 500rpm, warmed up engine an IAC valve unplugged?

You would need to turn the anti-diesel screw(looks like idle screw) back out so you can get the idle down that low.

If engine misses then that's adding to the HC at idle, idle is suppose to be rich, computer runs it that way.

You could add a PCV catchcan, Google: PCV oil catchcan
This will cut down any oil entering the intake that way, and give you an idea of how much oil might be being lost that way.
This is also totally Legal, unlike some methods of disabling PCV for test, lol.

More common way for oil to be burned is older intake valve guide seals, they get brittle and hard.
The intake has vacuum present and rocker area has oil present, so......oil gets sucked down the valve stem and into the cylinder.
Easy way to test for this is to go down a hill in gear, lower gear using the engine as a brake to slow you down, this builds up a very high vacuum in the intake, when you get to the bottom of the hill give it a little gas and watch the tail pipe, puff of smoke means old guide seals.
Cat converter will eat most of the smoke so even a little means alot of oil going into engine that way.
And it means it might have been that way a long while which means Cat will most likely be "used up" and can't deal with all the HC.

If you are burning oil not dripping it, then you may want to change spark plug type(next level hotter plug) or gap it differently, wider

How high were the NOx readings?
They are a good indication of Cat function levels

2trux · Mar 4, 2015

Thanks, the oil catch can sounds like a great idea. We might also replace the valve guide seals. Since the engine is 25 yrs old this could be a problem.
The NOx reading was within spec to pass (I don't remember the number).
I haven't had the idle as low as 500rpm with IAC disconnected, but I can try that to see how it runs.
My son is in college and is short on cash so he is not ready to do a full rebuild on this engine. Since it is running "good" at this time he just wants it to pass emissions right now so he can get it registered.

2trux · Mar 5, 2015

Well after some thought and reading, this is the plan I have decided on.

Replace valve stem seals
Add PCV oil seperator
Adjust valves.

This seems like the lowest cost, least intrusive method to try to eliminate oil burning as the cause of high HC at idle.

Also while I am in there:
Replace fuel injectors (I already have a good set at home)

What do you think?

PAWGEdward · Mar 5, 2015

Don't think the valves on this engine need adjustment unless the adjustment has been altered or your having issues with it. When I pulled my engine apart the manual said to leave everything set how it was unless the rocker arm assembly was dismantled.

Not sure if this is correct but it is what I read/did and it worked for me.

Good luck

RonD · Mar 5, 2015

Valve guide seals can be replaced without removing the heads.
Need a valve spring compressor that fits in tight places, and put lots of towels/rags around to catch those "stupid" keepers that hold the springs, they can be hard to find when they come off, and down into the oil pan is where they like to go, lol.

When an engine gets higher miles the rings get worn, while all piston engines have blow-by, the blow-by increases as the rings wear.
The cylinder walls are bathed in oil so when the super hot blow-by comes past the rings/pistons some of the oil vaporizes, that's the oil that gets sucked into the intake via PCV, and that is the whole point of the PCV system, to burn that oil vapor vs expelling it thru the old breather tubes that used to be on lower block or upper oil pans on all engines in the "old days".
Using a higher quality oil can reduce the vapor levels, not sure about synthetic oils and vaporization.

2trux · Mar 31, 2015

Well I replaced the valve guide seals, the injectors, and put in the PCV catch. Sadly :sad:

the HC at idle didn't really change. Since I am out of ideas I did the unthinkable and took it to a mechanic who does emission repairs.
My next step would have been to rebuild the engine since it seems to have excessive oil useage. My son was afraid to spend the money for that and still not have it pass. Hopefully the mechanic can figure out what is wrong before we spend any more money/effort on this truck.

It would be nice to have a sniff tester since the guys at the free county retest station are tired of seeing me. It's hard knowing if any of the changes are doing anything without going down and putting it on their machine over and over again.

I will update when I hear something.

kimcrwbr1 · Mar 31, 2015

I didnt see that you replaced the PCV valve? There is no way to clean it just replace it with spark plugs.

kimcrwbr1 · Mar 31, 2015

Also if it has been burning oil for a while it will destroy the cat. A sure sign of valve guide seals is a puff of black smoke when to start it after sitting at the store for about 15 minutes. Thats the oil dripping down the valves on a hot motor.

2trux · Mar 31, 2015

kimcrwbr1 said:
I didnt see that you replaced the PCV valve?

kimcrwbr1 said:
Also if it has been burning oil for a while it will destroy the cat. A sure sign of valve guide seals is a puff of black smoke when to start it after sitting at the store for about 15 minutes. Thats the oil dripping down the valves on a hot motor.

The PCV was replaced, just have a hard time remembering all that has been replaced.

I am concerned that the cats are shot, maybe good working cats would clean the HC enough to pass. Until the oil use problem is fixed they probably wouldn't last long.

2trux · Apr 7, 2015

Well after spending a bunch of money at an "emissions repair" shop, it finally passed. The truck ran terrible afterwards and we barely got it home.
The first thing we did was pull the engine out to rebuild it. Hopefully we can get the truck to be a reliable driver for him.
We probably needed to do this first but he was running out of time to get it registered and needed the emission certificate for that.

2trux · May 12, 2015

Update on the "emissions repair" shop. He told me he had to get the engine running hot. I figured this was to burn out any oil on cat. I found out how hot when putting the engine back in after the rebuild. The heater box had a 2" hole melted in it near the exhaust, and the clutch hose had a hole melted into it.

He also lost the SPOUT plug, (he said it was missing when we took it). Is there anywhere that sells these, or is the JY the best place? Were they used on any other cars/engines? Last time I was at U-Pull I could not find one on the B2/Rangers they had. I am using a jumper wire for now but would like to replace it with the correct part.

RonD · May 12, 2015

Pretty much all Ford TFI ignition systems used the same SPOUT connector, as far as I can tell, 4cyl, V6 and V8, TFI was first used in 1983 and until around 1993

Google: Ford SPOUT connector

Click on the images link to see where they were located, they were not always close to the distributor.

I see the Mustang 5.0l SPOUT plug for sale new, $10, but site didn't list any other applications so maybe there are different sizes, although that wouldn't make much sense money wise for Ford to do that.

Yes, I know, I used Ford and Sense in the same sentence, I still have hope

Emissions/engine issue

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