Smog test problems

[PeterP11c]

Hello,
After a long absence from the forum enjoying driving my Scorpio and not fixing it, I faced the biennial test of the California smog test. In the past it wasn't a problem, I put a bottle of CRC in the tank, drove it on the freeway and submitted for a test. This time despite all precautionary measures I failed and the test results showed excessive Noxis (NOx) to the tune of 931 (max 772) at 15 mph and 1151 (max 711) at 25 mph. All other components and indicators like 02 and CO were OK and passed well within range. So next day after some additional driving on the freeway, I did a retest and although the numbers went down somewhat, I still was above the limit 816 (max 772) and 1109 (max 711). The guy at the test station indicated a malfunctioning EGR valve, probably stuck in a closed position thus causing abnormal NOx levels. Facing a dilemma, the part is readily available but it's a job for a mechanic given my lack of garage accommodations. Appreciate some advice on the matter because I am running into an uncharted territory. Previous smog test results from 2016, 2018, 2020 were just fine and only this year it spiked so much.
Thank you,
PeterP11c

[john keefe]

After cleaning up the EGR and ports, you'll probably get good results with this (works every time with the 5.0L, and last time with the Scorpio):

Check all your emissions related hoses, plastic vac trees and lines, etc., including the vent line from the charcoal cannister back to the tank. For testing, retard the timing 2-3 deg. (you're allowed +/- 3deg). If you've got low fuel in the tank, drive it until it's almost empty, then fill a few gallons of highest octane (or add a bottle or two of octane boost, if your tank is near full).

[Ed Lijewski]

If you have or can borrow use a MityVac hand vacuum pump on the EGR to raise and lower and repeat the pintle valve. Pump up to ~20/30 psi, release and repeat several times. That would free a stock valve.

As John noted, the vacuum solenoid has to be able to draw on a steady source of vacuum so when called to provide vacuum to EGR the source vacuum, from the vacuum ball, is there and steady (hoses are good and tight-fitting).

YMMV

[brokencase]

If you replace the EGR valve, and I recommend replacement, then be sure to get a quality part. Standard Motor products makes two different versions. Get the more expensive one (EGV271). The low end units (EGV271T) do not have stainless steel parts and are junk.

[PeterP11c]

I was wondering about that. RockAuto.com and O'Reilly both list Standard Motor Products EGR, EGV271 and the former has a T model as well. The price difference is about 10 bucks, so not a big deal. Appreciate the tip, will go for the 271 model.

[brokencase]

It would be a good idea to check eeciv error codes. You might have an issue with the PFE sensor.

[PeterP11c]

The car goes to a shop on Tuesday. I am not sure if they got STAR ROTUNDA, perhaps not. The Shop Manual 4-66, says to first check for damaged EGR valve before testing the PFE sensor. High level of NO indicates some issue with EGR valve assembly. Well, I will rely on pros, this is way above my pay grade. The good thing is that both parts are still available.

[john keefe]

High level of NO indicates some issue with EGR valve assembly.

I.e., combustion running too hot, which points to EGR if mechanical cause. Retarding timing and boosting octane lowers combustion temps.

[PeterP11c]

I will mention the timing issue to my mechanic. As far as the octanes are concerned, only once I filled her with 89 grade fuel. Got instant pinging in the engine and learnt my lesson well. Only 91 premium gas applies.

[john keefe]

... only once I filled her with 89 grade fuel. Got instant pinging in the engine and learnt my lesson well. Only 91 premium gas applies.

We're talking Scorpio, right, not an XR? I can understand 91 with an XR, but I'd think that was very unusual for a non-modified 2.9L. I've never had to go higher than 87 in mine. Sounds like something else is amiss, like a lot of carbon build up in the combustion chambers creating high heat spots. Was the cam ever replaced/reinstalled, or the timing chain and sprockets swapped out at some time? Could be a notch off from TDC in the reinstall.

[PeterP11c]

None of the above. I was just being cheap that day and bought low grade fuel. The engine reaction was instantaneous and I got loud pinging. Scared the hell out of me.
BTW, tomorrow got an appointment for the mechanic shop and after reading previous posts started looking for a PFE sensor. Found one in my spare parts bag, so one less thing to buy if needed.

[Ed Lijewski]

If I were you I would download any codes stored in the ECU. You may trust your mechanic. But with your own list of codes in hand, you can verify some of what he/she will say...and charge for.

YMMV

[PeterP11c]

Sounds good but I have no idea how to do it. Not to mention, that I don't own the STAR ROTUNDA.

[Ed Lijewski]

Sheesh. Any aftermarket Ford OBD-1 code reader works.

And costs less than Rotunda tools.

YMMV

[brokencase]

Yes, an Innova 3145 is not expensive.
https://www.google.com/search?q=Innova+3145