Emissions issues on 1992 Flare Side, 5.0, 5 speed manual

High HC (336 vs. 147 standard) and high CO (9.99 vs. 1.24 standard) on the low speed (15 mph) dyno test. It passed the high speed (25 mph) dyno test ok with an HC reading of 99 vs. 143 and a CO reading of 0.52 vs. 1.6, though the inspector said those readings are still on the high side as well.

Also it periodically, mostly when at operating temperature, stumbles when taking off from a start, and you can feel it “hiccup” when cruising. It feels like either the ignition system or the injectors are shutting off completely. If I am rolling, it will “restart” and keep going.

It had a complete tune up including Motorcraft ASF42P platinum plugs, new Borg Warner Premium wires, cap, and rotor, and a new air filter a year ago (5500 miles)(yes 5500) to combat these same issues. It passed, BARELY. I even replaced the stator in the distributor and the TPS last year as well. (for the stumble issue) The truck has 229,??? Miles on it. I’ve checked every module you can remove and have checked. I pulled the ECM and had all of the capacitors replaced, and solder joints checked. I have not replaced the oxygen or the map sensors. I believe the oxygen sensor was replaced once at about 90,000 miles.

The only code I get, when I can get one, is an EGR issue. Engine off or engine running tests. I have tested the EGR Position Sensor, and it seems to work as per the test procedures I was using. The EGR valve is clean, and opens with vacuum, and seems to close and seal.

Any help or information will be greatly appreciated.

Peace.

 

https://www.ford-trucks.com/forums/9...em-solved.html Have a read here for ideas.

 

thanks. I will look it over and see if there is anything I haven't tried

 

a slight timing advance will reduce HC emissions, but might increase NOx. I'd get rid of the platinum plugs for sure. They gave me trouble when I used them.

If you only want to pass the test. add a couple gallons of e85 to your tank. That will drop your HC readings quite a bit.

Also, make sure the PCV is clean and functioning. How old is the coil?

 

Just so you'll know, I was the one who started that thread that was linked above. I did pass the emissions test, but I just ran another KOER to test the AutoXray I got off of Ebay and I still have the 44 fault code coming up. I may try to dump the CM and try to do the self test again and see what happens.

Since you aren't getting any codes, you could always try the suggestions above and see if it'll pass; no sense replacing anything that may not be faulty.

The following has nothing to do with your problem. (sorry in advance)But thought I should mention it and see if anyone following your thread has any input. I also got a 21 code (Coolant Temp out of range), which may just be that my coolant level being too low or the engine not being warmed up enough; I have a new ECT sensor ready to go in though. And also got a 52 fault code which points to the PS switch circuit. Could be something as simple as not turning the steering wheel soon enough or not far enough. Or possibly something to do with a defective or fluid soaked switch connector; it leaks PS fluid, which needs to be corrected.

 

Thanks everyone. I will hopefully have a chance to work on it again in a few days. I will let everyone know as soon as I can.

 

Well I missed my last available free re-test day today. Too much work, not enough time... anyway, I made the executive decision to just finish replaceing EVERYTHING that I couldn't eliminate as not the problem... new plugs, new MAP sensor, new O2 sensor, new ignition module, new thermostat, and I was going to clean the temp sensor.... well I managed to break the temp sensor , so it too will be replaced (just not being careful with the socket) and THEN I twisted the upper T-Stat housing bolt off in the manifold... WOO-HOO!!! I'm currently drilling out the broken bolt. I may end up with a Heli-Coil, and a larger bolt at the rate I'm going.

anyway, Thanks for the info, and I will let you know the final outcome when I have it.

Peace, Jared

 

In know it's been awhile, but here's the scoop!

After replacing all of the other pieces: O2 sensor, Ignition Module, Temperature Sensor, MAP Sensor, Thermostat, Spark plugs, All vacuum lines. The truck still failed the test. Worse than before.

So I finally broke down and bought a "remanufactured" ECU from "OH Really Auto Parts". Installed it. Test drove the truck. It seemed to perfectly. The richness in the exhaust seemed to be gone. It pulled strong through all of the gears. I was ready for the next test.

I immediately took the truck to the inspection station and it passed. WOOOOO HOOOOO!!!!! Quite quickly even. (if the HC and CO are in check from the start, the test will cycle to the next step before the time is up). The NOX was high, but not high enough to fail.

I took the truck back to the woman who drives it daily, and it was fine for a day. Then it started dying again, as you start to take off, with a significant jerk, almost completely stopping dead in its tracks then taking off again. It also does this at speed, but inertia keeps it from being so pronounced. Around 1500 to 2200 RPM.

I think it is possibly a bad ECU (again).

I could really use some help on this. Thanks. Big Jared

 

Man that just sucks! At least you got it to pass the smog test. I would check the ECM/U plug and see if it is still securely fastened to the port. Maybe even check that the pins are still in good shape and not corroded. Is it getting fuel? What about doing the KOEO and KOER self test to see if it has any new codes?