Emissions Problem - Very High Hc

Dart68

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I'm hoping someone can point me in the right direction. I've searched the forums but have not seen a similar problem.

My '85 GT has had an '88 5.0 HO swapped in (not by me).

I took my '85 GT to get an emission inspection. I live in Colorado and for an '85 it's a dynamometer test to simulate driving. The car failed with a high HC emission that looked like it pegged the meter on the graph but the NOx and CO emissions were in tolerance. I can post a picture of the graph but to describe it - the HC emission is nearly 0 at idle but as the car accelerates, when it reaches 20-30 mph the HC shoots straight up going from 0 to 10 (10 is the limit of the graph). The HC stays at that level with some slight fluctuations at higher speeds until the car has been brought back down and after a few seconds at idle. They do this twice in the test and upon the second acceleration the HC shot up again like before and at approximately the same speed.

I've pulled codes from the EEC and I get from KOER 44 and 94. I've checked for vacuum leaks and low fuel pump pressure. Fuel pump is ~32 with vacuum at regulator and 40 with vacuum off. Engine has 14" vacuum at idle. I've also been going though jrichker's check list and haven't found anything off yet.

If I can't get this horse to pass emissions, it's doomed as a parts car. Any help is greatly appreciated!
 
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jrichker

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The 85 cars were carb when they had 5 Speed transmissions . Automatic transmission cars came with CFI fuel injection. What system do you have at this time? Has the car been converted to Speed Density or Mass Air?


You vacuum is low, which suggests a vacuum leak. Start looking for cracked vacuum lines or vacuum operated emissions equipment that may have been disconnected.

How to pass emissions testing:

High NO - high combustion temps - retard timing, check EGR for operation.
High CO – Rich condition - fuel pressure too high, check O2 sensors, replace air filter, Clean MAF element.
High HC – Lean misfire, vacuum leak, common misfire due to worn or weak ignition system components. On rare occasions, an overly rich mixture may be the cause. Do the ethanol/E10 fill up as suggested.
High CO & HC - Cat converters, smog pump, and smog pump controls. Make sure the smog pump has good air output at 1200-1700 RPM

How to pass emissions testing:

1.) Make sure all the emissions gear the car was made with is present and connected up properly. That includes a working smog pump and cats. The smog tech will do a visual check to make sure that all the original equipment is present and connected up.

2.) Make sure that you have fresh tune up with spark plugs, plug wires, cap, rotor, fuel & air filters. An oil & filter change is a good idea while you are at it.

3.) [Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

Underhoodpictures007-01.jpg


Underhoodpictures010.jpg


If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

attachment.php?attachmentid=58312&stc=1&d=1242744354%20.gif
The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10




Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.


Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, clutch depressed to the floor and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.
Cylinder balance test
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures.
Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure



4.) Post the codes and get help to fix them. Don’t try to pass with codes not fixed. Clearing the computer just temporarily removes them from memory, it doesn’t fix the problem that caused the code to be set.

5.) Be sure to do the testing on a hot engine. Drive for 15-20 minutes prior to taking the test to get operating temps up into the normal range. Do not shut off the engine while waiting for your turn on the test machine. An engine up to full operating temperature puts out fewer emissions.




Codes 44 & 94 - AIR system inoperative - Air Injection. Check vacuum lines for leaks, & cracks. Check for a clogged air crossover tube, where one or both sides of the tube clog with carbon.



Revised 21 Sep 2012 to correct the description of the process that sets the code and include Thermactor Air System diagram.

If you have a catalytic converter H pipe, you need to fix these codes. If you don't, then don't worry about them.

Code 44 RH side air not functioning.
Code 94 LH side air not functioning.

The TAD solenoid/TAD diverter valve directs smog pump output to either the crossover tube attached to the cylinder heads or to the catalytic converters.

The O2 sensors are placed before the catalytic converters, so they do not see the extra O2 when the smog pump's output is directed to the converters or the input just before the converter.

The 44/94 code uses the O2 sensors to detect a shift in the O2 level in the exhaust. The smog pump provides extra air to the exhaust which raises the O2 level in the exhaust when the smog pump output is directed through the crossover tube.

When there is an absence of increase in the O2 levels when the TAD solenoid/TAD diverter valve directs air through the crossover tube, it detects the lower O2 level and sets the code.

Failure mode is usually due to a clogged air crossover tube, where one or both sides of the tube clog with carbon. The air crossover tube mounts on the back of the cylinder heads and supplies air to each of the Thermactor air passages cast into the cylinder heads. When the heads do not get the proper air delivery, they set codes 44 & 94, depending on which passage is clogged. It is possible to get both 44 & 94, which would suggest that the air pump or control valves are not working correctly, or the crossover tube is full of carbon or missing.

Testing the system:
Note that the engine must be running to do the tests unless stated otherwise. For safety’s sake, do test preparation like loosening clamps, disconnecting hoses and connecting things to a vacuum source with the engine off.


Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve.

The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.

The two electrical controlled vacuum valves mounted on the rear of the passenger side wheel well turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.

Remember that the computer does not source power for any actuator or relay, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

The following computer tests are done with the engine not running.
The computer provides the ground to complete the circuit to power the solenoid valve that turns the
vacuum on or off. The computer is located under the passenger side kick panel. Remove the kick panel & the cover over the computer wiring connector pins. Check Pin 38 Solenoid valve #1 that provides vacuum to the first Thermactor control valve for a switch from 12-14 volts to 1 volt or less. Do the same with pin 32 solenoid valve #2 that provides vacuum to the second Thermactor control valve. Turning the ignition to Run with the computer jumpered to self-test mode will cause all the actuators to toggle on and off. If after doing this and you see no switching of the voltage on and off, you can start testing the wiring for shorts to ground and broken wiring. An Ohm check to ground with the computer connector disconnected & the solenoid valves disconnected should show open circuit between the pin 32 and ground and again on pin 38 and ground. In like manner, there should be less than 1 ohm between pin 32 and solenoid valve #2 and pin 38 & Solenoid valve #1.

The following computer tests are done with the engine running.
If after checking the resistance of the wiring & you are sure that there are no wiring faults, start looking at the solenoid valves. If you disconnect them, you can jumper power & ground to them to verify operation with the engine running. Power & ground supplied should turn on the vacuum flow, remove either one and the vacuum should stop flowing.

Typical resistance of the solenoid valves is in the range of 20-70 Ohms.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

If you have a catalytic converter H pipe, you need to fix these codes. If you don't, then don't worry about them
 

Dart68

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Thank you for the help.

The car has been converted to speed density. I think whoever did the swap just grabbed everything, but it still has the '85-'86 EEC (VM1). At this altitude (~5500') what vacuum reading should I get at idle?

BTW, I went for the $30 code reader. MUCH easier and I don't have to count flashes!
 

jrichker

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Thank you for the help.

The car has been converted to speed density. I think whoever did the swap just grabbed everything, but it still has the '85-'86 EEC (VM1). At this altitude (~5500') what vacuum reading should I get at idle?

BTW, I went for the $30 code reader. MUCH easier and I don't have to count flashes!
At 5500 feet, you probably will get less vacuum. Check the vacuum lines and connections as part of the troubleshooting task anyway, you may have leak.

Follow the code 44/94 test path and do your best to fix the 44/94 codes. Those have a direct effect on how well the catalytic converters work to reduce emissions.
 

Dart68

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At 5500 feet, you probably will get less vacuum. Check the vacuum lines and connections as part of the troubleshooting task anyway, you may have leak.

Follow the code 44/94 test path and do your best to fix the 44/94 codes. Those have a direct effect on how well the catalytic converters work to reduce emissions.

Ugh! The previous owner removed the cats and the air tube to them. I've welded on new cats from Magnaflow but the air injection pipe is still missing. However the rest of the air injection system is there including the air pump and thermactors. Both thermactor valves (?) dump to atmosphere instead of one going to the cats.

Jrichker, I've read your responses in other threads and you're always a great help! Thank you!
 

jrichker

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At this point in time you have no fresh air to go to the cat converters. If you had a tube to put air in the exhaust, it could reduce the HC levels to the point you would pass the emissions test.
 

Dart68

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It's been a bit so I thought I'd give an update.

I've been trying fix the 44 & 94 codes. I pulled the reactor pipe from the engine to see if it was clogged (and what a joy that was). It wasn't. I've checked the air pump and diverter valves and all are working. The only thing I'm not sure about are the diverter solenoids. I think they are working but I'll have to do some more checking. There is 12v at the solenoids but I'm not sure about the ground actuator wires working.

Question: If the engine is cold air should be going to the back of the heads? And if the engine is fully warmed up air should be going to the converters?

Also, could the O2 sensors be bad, reading the exhaust incorrectly triggering the 44 & 94 codes but not trigger a bad O2 sensor code?
 

jrichker

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You got the flow path right: cold = heads, hot = converters.

When you start to dump the codes, all the engine compartment actuators cycle on and off. A test light placed across the TAB or TAD solenoid wiring connectors should blink when the ignition is turned on and the dump codes jumper is inserted.

do that and see what happens
 

Dart68

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You got the flow path right: cold = heads, hot = converters.

When you start to dump the codes, all the engine compartment actuators cycle on and off. A test light placed across the TAB or TAD solenoid wiring connectors should blink when the ignition is turned on and the dump codes jumper is inserted.

do that and see what happens
The test light flickered ever so slightly. Definitely did not blink. The light was also very dim, indicating a much lower voltage than what I saw with the other wire.
 

John Dirks Jr

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Not sure if it would work in this case but I've had experiences with difficulty getting mid 80's cars through the sniff test. In both cases on two different cars, the only thing that got the HC's in the passing range was to retard the ignition timing. Way back like somewhere between 0 and 5 deg BTDC. Ran very sluggish but passed emissions. Then reset timing after the test.
 

Dart68

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Do both TAB & TAD solenoids behave the same way when the test cycle triggers them?
Update, the test light flickers about the same for both solenoids. However, I noticed that the test light was dimmer on one solenoid. I did another KOER test and got the same 94/44 codes. The good news is that I finally figured out how to get it to do a balance test and it passed (code 90)!
 

jrichker

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Measure the power side of both TAB & TAD solenoids with the engine running. You should see battery voltage +/- .5 volt.

Use a DVM or multimeter to measure the ground side voltage of the TAB & TAD solenoids. The lower the voltage on the ground side, the better the computer is working
 

Dart68

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Measure the power side of both TAB & TAD solenoids with the engine running. You should see battery voltage +/- .5 volt.

Use a DVM or multimeter to measure the ground side voltage of the TAB & TAD solenoids. The lower the voltage on the ground side, the better the computer is working
Thanks! I'll check that and get back. It'll have to wait till I get it back together as I'm replacing the valve stem seals.
 

Dart68

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Measure the power side of both TAB & TAD solenoids with the engine running. You should see battery voltage +/- .5 volt.

Use a DVM or multimeter to measure the ground side voltage of the TAB & TAD solenoids. The lower the voltage on the ground side, the better the computer is working
I checked the TAB and TAD solenoids. With engine at full temp the hot side was 14.17 volts (same as measured at the battery) and the ground side was the same 14.17 volts. Got 14.17 volts from all 4 (2 hot, 2 ground). It seems the ecm is more or less shot?
 

Dart68

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Measure the power side of both TAB & TAD solenoids with the engine running. You should see battery voltage +/- .5 volt.

Use a DVM or multimeter to measure the ground side voltage of the TAB & TAD solenoids. The lower the voltage on the ground side, the better the computer is working
Maybe a dumb question but I assume the ground side voltage is measured with the engine fully warmed up?

Thanks again!
 

jrichker

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Maybe a dumb question but I assume the ground side voltage is measured with the engine fully warmed up?

Thanks again!
Do the ground voltage checks when you dump the codes. The first thing that happens with a code dump is that the computer toggles all the relays, solenoids and actuators. If you miss it the first time, remove the test jumper and do it again.
 

Dart68

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Do the ground voltage checks when you dump the codes. The first thing that happens with a code dump is that the computer toggles all the relays, solenoids and actuators. If you miss it the first time, remove the test jumper and do it again.
 
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