Failed Emissions (Texas)

Ok I'm back again.
1992 Ford Taurus SHO 3.0 24 valve DOHC
Looking for possible reasons for the HC reading on an Emissions Test to raise after changing out catylitic converters.
The car was running rough, missing, lagging. First try on inspection found exhaust leak in the 90 degree pipe from the resonator back to the mufflers, replaced. Second try found gasket leaking rear side of the driver's side catylitic converter and replaced that. Rough idle and missing seemed to clear up.
Third try on inspection we finally made it as far as the emissions testing where we failed.
Readings were:
High Speed HC
standard 220, current 423
Low speed HC
standard 220, current 369
High speed CO
standard 1.20, current 1.64
Low speed CO
standard 1.20, current 1.35
After checking and questioning decided catylic converters was most likely cause. Probably just me being blond since I usually go for the cheapest answer first.
Bought new Magnaflow direct fit converters part number 23355 had them installed by Midas. Filled up the gas, added Lucas fuel treatment since the car has not been being used regularly since September last year. Seems to be running great and no problems until I take it back for the reinspection.
Today's readings on the emissions:
High Speed HC
standard 220, current 1230
Low speed HC
standard 220, current 2845
High speed CO
standard 1.20, current 1.59
Low speed CO
standard 1.20, current 1.17
So the CO readings did come down. But why the huge jump in the HC readings? :banghead: Any Ideas?
Am looking into Oxygen sensors since I guess that the next logical step as far as the Co readings go. Again I could be just being blond but the oxygen sensors are cheaper than the rest of the magnaflow exhaust that my husband says I cannot have :crying: Which I guess makes sense because as it sets the exhaust would be worth more than the car if I was to finish it out lol

I've never been through emissions testing, so I don't really know how they work. But is the standard number normalized for the model year of vehicle? I would hope they don't expect an 18 year old car to meet today's emissions standards. Maybe their "standard" numbers are for a newer vehicle and the person performing the test is new and doesn't understand the numbers need to be adjusted by model year?

-Rod

Rod,
Thank you for your response.
I am not real familiar with the exact procedures for the emissions testing they do here either. But from what I see when I am watching them (I tend to stay in the bay or at the door) all vehicle information including the VIN is put into the computer before testing is started. The computer then walks through a series of steps before instructing the probe placed in the tail pipe. Then on my Taurus a lead (for lack of better word) is attached to the plugwire. RPM's revved to specified range. The computer then seems to connect ot the state data base or something like and the pass or fail comes back through. At least that what it looked like since at the end of testing it flashed a sending to state message onscreen. the lady that does them for me has been doing so for several years and this is the first year we have had a fail.
What had us stumped was the fact that the HC readings were so much higher on the reinspect after replacing the catylitic converters than before.
Is it possible for the timing to be off enough to cause that high of readings and the car still run good? It had been giving me so many problems but as I have been fixing the exhaust it has cleared up. I went from barely making it up a hill here on my way to work in second gear to topping it in 5th with no problems or loss of speed. It had been hard to start and keep running, stalling out more times than not at stops to starting right up and holding an idle with no problems at stops except for operator errors now and then :D

I also don't understand why new converters would cause the hydrocarbons to be high, unless there are still some manufacturing oils in the converters/exhaust that are burning off. That seems unlikely to me though, I would expect them to burn off pretty quickly.

As for replacing the oxygen sensors, even if they are not causing the high HCs they probably won't be a bad investment if you plan to keep the car, they may actually improve the fuel economy which I suppose by default should help the emissions. Also, if your car hasn't had a tune up recently, at least spark plugs and plug wires, that might be a good investment as well. The Yamaha V6 in your SHO has been known to have leaking spark plug well seals that can lead to misfires. Also, if it has aftermarket plug wires, the wire boots may not be sealing well to the valve cover and allowing water to get into the wells if the engine gets wet. The vacuum lines also should be inspected for cracks, breaks, even loose connections. Any of these scenarios could lead to misfires that, over time, can cause the catalytic converters to overheat and restrict exhaust flow. Often if the converters plug up, it's because something isn't right in the exhaust gases. If you have a misfire, even intermittent, and don't fix it, the new oxygen sensors and converters are not going to last as long as they should either.

-Rod

Ok sorry it has taken me so long to get back. With work and family things get crazy. I haven't gotten the oxygen sensors to replace them yet. But I had time this morning to pull a couple plug wires and look, also pulled one plug, I have a lot of carbon on the one I pulled so I will be getting new plugs. I have read the OE is platinum. The Bosch platinum plus are in stock here at Advance Auto and the Xact standard wires. Hopefully these will be ok to use on this vehicle. They say they fit this vehicle. I am fairly at a loss on this car. Give me a 63 and I have no problems but I raise the hood and get the shakes on this thing since I am mostly going by what the book tells me and what I can find online or what my brother can walk me through on the phone lol.
Also I know on the 63 we have a problem with blow back if we tighten the oil cap down completely, would this be an issue on this car? The center front plug well has old oil around the plug. I cannot find a leak so it could be from adding the oil since it is just above the cap? Am running a cloth down into it to clean it out before pulling the plug. I did notice the boot for that plug is extremely hard to get seated properly.
Could going from Castrol synthetic to regular Valvoline cause valves to be sticky? When I had the oil change done after I got it I had Valvoline since that is what we use. (the cleanest rebuild we did was on a vehicle running valvoline) After the fact they said the records showed the previous owner used the Castrol synthetic.

Another thought is it going to be ok to replace the plugs and wires and not replace the coil? This will need to wait until a later date since price I am finding is a BWD for around 75$

Blow back from tightening the oil cap on the '63 would seem to suggest a PCV issue. I suppose you could have a worn or faulty PCV on the SHO, it's probably a rather inexpensive part to shotgun. Be sure to carefully inspect the hose for the PCV as well since they seem to degrade quickly from the oil.

The oil in the front center plug well could be from the oil fill cap, but if that's the case, that would suggest that the plug wires already on the car do not have the proper boots either. I would NOT suggest going with the Bosch plugs, there are a lot of threads on many different makes and models of cars that caution against anything but the OEM style platinum spark plugs. Since you're looking for an emissions issue which could easily be related to the completeness of the combustion process, I'd suggest you stick with Motorcraft or Autolite plugs for the application. I have had good luck with NGK and Denso Iridium plugs in several applications, including two SHO's, but I don't need to pass any emissions training either.

Unless you are suspecting a misfire I wouldn't worry yet about replacing the coil. Your '92 would probably allow you to activate the Cylinder Balance Test through the on-board diagnostics. That might go a long way in helping you understand if you have a cylinder or two that is/are not contributing fully.

-Rod

1992 OBDI system -
1) A compression leak down test on each cylinder will tell you if it's worth the fix.
2) Start with a good tuneup + make sure the car is @ normal operating Temp when the testing is done.
3) Clean EGR valve, Air filter, PCV valve, and throttle body.

From the factory service manual regarding entering the Cylinder Balance Test and what it means:

The purpose of the cylinder balance test is to assist the technician in finding a weak or non-contributing cylinder. The test is entered by depressing and releasing the throttle within two minutes after the Engine Running Self-Test DTCs have been output.

Once the test is entered, the IAC duty cycle is fixed and the engine is allowed to stabilize. Engine rpm is measured and stored for later use. Next, the fuel is shut off to one of the cylinders depending on the engine. After a brief stabilization period the engine rpm is again measured and stored. The injector is turned on again and the process is repeated for each of the injectors down to one. At this point, the maximum rpm drop that occurred is selected from the table of rpm drops for each cylinder. This maximum rpm drop is multiplied by a calibratable percentage. The resulting number (rpm) is used as the minimum rpm that each cylinder must have dropped to pass this test.

Example: 150 rpm x 65% = 98 rpm

If all cylinders drop at least this amount, then a code 90 is output indicating a pass. No further testing is necessary. If a cylinder did not drop at least this amount, then the cylinder number would be output. For example, 30 for cylinder number 3. This indicates that cylinder number 3 is either weak or non-contributing.

The test can be repeated a second time if the throttle is depressed and released within two minutes of the last code output. This time the maximum rpm drop that occurs is multiplied by a lower percentage. This number is used as the minimum rpm drop for each cylinder to pass this test.

Example: 150 rpm x 43% = 65 rpm

If all the rpm drops are greater than 65 rpm, then a code 90 is output. If cylinder number 3 had failed the first level and passed the second, then cylinder number 3 is considered to be weak. If cylinder number 3 failed again, the code 30 would be output again.

The test can be repeated a third time by depressing and releasing the throttle within two minutes of the last code output. This time the maximum rpm drop that results is multiplied by a still lower percentage. This number is used as the minimum rpm drop for each cylinder to pass this test.

Example: 150 rpm x 20% = 30 rpm

If all the rpm drops are greater than 30 rpm then a code 90 is output. If cylinder number 3 had failed the first and second level, but passed the third, then it is considered to be a very weak cylinder. If cylinder number 3 failed the third level, then a code 30 would again be output. In this case, cylinder number three would be considered a non-contributing cylinder.
The Cylinder Balance DTM may still be repeated as many times as desired by depressing and releasing the throttle within two minutes of the last code output. All further testing (i.e. 4th, 5th pass) will be done using the third level percentage.

-Rod

>1996 (OBD II) needs to Pass the Federal Emission laws in North Carolina, but 1995 and less don't.I would check the rules in Texas, befor throwing too much money at it.

Round Rock city, Texas = Williamsom county
Auto 2-24 years old emission testing-
1995 and older vehicles receive the two speed idle test.

Ok. Feeling optimistic here. :grinno: Got the plugs and wires changed a few minutes ago. Thanks to someone who had posted in a thread a couple years ago his way of getting to the back plugs. I can't remember who it was. I was overwhelmed by the thought of having to remove the intake to get to the back plugs. But this person had said they used a piece of plywood to bridge across the motor from the front. It worked great and there was enough room to lay on my stomach and tip my head so I could actually see the plugs. the pivoting plug remover socket works great with a 6" extension. Took me about 45 minutes. The hardest part was getting the wires routed back up through. This made a major difference in the way she runs. No missing, no backfiring or bucking. I had worried about sticking valves since she would bog down but she is running beautiful.
The only thing that worries me now about the plugs is oil. I had mentioned earlier that the #5 had oil in the well. Thought it may have been from improperly seated wire letting it in from fill. Now I don't think so.The #2 was even worse. The # 3 a bit but not so much.#'s 1,4,6 were dry.
As for the cylinder self test from the On board diagnostics. After reading and re-reading I still don't understand how to do it. Someone show me once and I could do it, but for some reason I just can't get some things without seeing it. But if there was a problem wouldn't the obd pick it up? If that the case shouldn't I get a check engine light? The only lights I have throwing codes are the airbags and the abs.
Thank you for helping me with this. I am going to give the inspection another shot Monday if I get back from the VA in time. I am hoping the emissions problem was the misfiring due to the plugs.
On another note:
Rod, I just notice you list your town as Cedar Rapids. The brother I mentioned getting to walk me through things o the phone is in Maquoketa lol.
Another question: while doing the plugs I noticed the evaporative emission hose (according to my chilton) is dryrotting. I got hose to replace it, along the line there is what Chilton lists as a evaporative emission canister purge solenoid. can this be removed and cleaned, reused? I don't have the 60$ to replace it right now.

Hopefully you're right and the new plugs and wires will help you pass inspection. Of course if the plug well seals are leaking your misfire will come back once the wells begin to fill up again. For as intimidating as these engines look, they really aren't too bad to work on. If you decide to change the valve cover gasket sets you can pull the snake tubes pretty easily, clean the secondary intake runners and butterfly valves all out, pull the valve covers, change the gaskets, and get everything all back together within a couple of hours if you've done that type of work before and have a reasonable selection of metric tools.

I'm not sure I'd worry about pulling the purge solenoid and cleaning it. I imagine it can be done, but I never had to deal with that on my '93 SHO so I'm not sure where it's at or what is involved with it. You'll probably be fine with just replacing the hose.

The OBD-I system which your '92 SHO has is not as thorough as today's OBD-2 systems. It would likely pick up a misfire, but won't have the resolution to know if a cylinder is not contributing as much without someone manually running the cylinder balance test.

I stayed overnight in Maquoketa several years ago (2005 I believe it was) during that leg of RAGBRAI. One of my co-workers grew up there and his mom still lives there so we stayed at her house.

-Rod

I have done valve cover gaskets before. Just nothing that I had to remove the upper intake to do it. This one does look intimidating but on looking closer it seems to be pretty straight forward. I have a decent set of sockets and wrenchs. Not quite the set I want but it gets the job done lol. Might check with the local for house what their charge would be for this as well. I have found it is sometimes more cost and time effective to let them do the work.
Right now my main objective is getting this current on inspection so I can get my daughter back in it and get my car back. She keeps saying she will just save up and buy another used car and I keep telling her the best route is to take what she would spend on another used and put it into getting this one in top form.
The reason I asked about the purge canister is because it is in the middle of the vacuum line I am replacing. The vacuum line comes off the top of the motor drops down about 3 foot and has the canister then continues on about another foot where it connects to a T. Thought about leaving it out but as it has a plug that I believe plugs into the computer I figured that would cause it to start throwing codes. I am going to try and attach a pic of it as it comes off the top.

Ok thought I would do a quick update. We passed the inspection. It was the plugs and wires. The new emissions readings were well with in range. Now I have to figure out the problem with the cruise control and fix it since it is hard to keep under 80 on the highway. Just one of those vehicles that you don't realize how fast you are going until you notice everyone is way behind you.

Congratulations, and thank you for following up on your thread!!!

-Rod