Emission problem on 93 lightning
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New User
Joined: Sep 2011
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From: Round Rock
Emission problem on 93 lightning
Ok i got hopefully a small problem, i just bought a 93 lightning with 100253 miles with a b303 cam, MAF conversion, msd ignition, dual cats, The problem is that i tried to get inspected and it failed the emission portion of the test. Standard for Hydrocarbons at 2400rpm is 220 mine was 43 passed, Standard for Carbon monoxide is 1.20 mine is 0.27 passed also at 2400rpms, now at idle it jumped to 1172 hydrocarbon standard 220 failed but the carbon monoxide was at 1.09 standard 1.20 passed its weird every thing else passed, if the timing is off a little could it cause it to run rich or what could caused it to fail that one part of the test the rest passed. I'll appreciate any help, i really need it to passed emission thanks.
Lead Driver
Joined: Jul 2007
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From: Rhode Island
From what I understand, the b303 cam has a relatively low LSA with mildly high duration, which creates a choppy idle. The choppy idle means misfires, which means unburnt fuel getting pumped into the exhaust - which means high HC numbers.
Now, what you can do is try a general tune up of things. Replace the O2 sensor(s)s, clean the MAF (with MAF cleaner, not carb cleaner) and change the plugs/wires. Verify that the smog/AIR system is still in place and functioning.
If you can do/verify all of that, and it still won't pass, I suggest possibly looking into replacing your catalytic converter with a new one - they do wear out eventually.
If it still doesn't pass, you may have to dilute your fuel with a bunch of E-85, or denatured alcohol. That usually can get a high HC engine to pass, but the fuel system components might not enjoy it too much. Alternatively you can try raising your idle speed manually with the idle stop screw - but I do not recommend this.
If you don't like those ideas, your only other real choice is to ditch the old b303 cam for a more modern, emissions friendly camshaft.
Now, what you can do is try a general tune up of things. Replace the O2 sensor(s)s, clean the MAF (with MAF cleaner, not carb cleaner) and change the plugs/wires. Verify that the smog/AIR system is still in place and functioning.
If you can do/verify all of that, and it still won't pass, I suggest possibly looking into replacing your catalytic converter with a new one - they do wear out eventually.
If it still doesn't pass, you may have to dilute your fuel with a bunch of E-85, or denatured alcohol. That usually can get a high HC engine to pass, but the fuel system components might not enjoy it too much. Alternatively you can try raising your idle speed manually with the idle stop screw - but I do not recommend this.
If you don't like those ideas, your only other real choice is to ditch the old b303 cam for a more modern, emissions friendly camshaft.
Senior User
Joined: Jun 2004
Posts: 282
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From: Winchester
From what I understand, the b303 cam has a relatively low LSA with mildly high duration, which creates a choppy idle. The choppy idle means misfires, which means unburnt fuel getting pumped into the exhaust - which means high HC numbers.
Now, what you can do is try a general tune up of things. Replace the O2 sensor(s)s, clean the MAF (with MAF cleaner, not carb cleaner) and change the plugs/wires. Verify that the smog/AIR system is still in place and functioning.
If you can do/verify all of that, and it still won't pass, I suggest possibly looking into replacing your catalytic converter with a new one - they do wear out eventually.
If it still doesn't pass, you may have to dilute your fuel with a bunch of E-85, or denatured alcohol. That usually can get a high HC engine to pass, but the fuel system components might not enjoy it too much. Alternatively you can try raising your idle speed manually with the idle stop screw - but I do not recommend this.
If you don't like those ideas, your only other real choice is to ditch the old b303 cam for a more modern, emissions friendly camshaft.
Now, what you can do is try a general tune up of things. Replace the O2 sensor(s)s, clean the MAF (with MAF cleaner, not carb cleaner) and change the plugs/wires. Verify that the smog/AIR system is still in place and functioning.
If you can do/verify all of that, and it still won't pass, I suggest possibly looking into replacing your catalytic converter with a new one - they do wear out eventually.
If it still doesn't pass, you may have to dilute your fuel with a bunch of E-85, or denatured alcohol. That usually can get a high HC engine to pass, but the fuel system components might not enjoy it too much. Alternatively you can try raising your idle speed manually with the idle stop screw - but I do not recommend this.
If you don't like those ideas, your only other real choice is to ditch the old b303 cam for a more modern, emissions friendly camshaft.
,,,,,,,,,,,what I was thinking too, since it does pass at 2500rpm. Good luck. and.............wow sounds like a great truck. I do miss my 93 lightning.
Logistics Pro
Joined: Jul 2009
Posts: 3,635
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From: Lansdale, PA
"The solution to pollution is dilution"
Make sure your air pump is working correctly. I had it written down a tone point, which additives did what to emissions results, but dry gas is either isopropyl or methanol alcohol. It will change your results.
If you can't get the truck to pass emissions then I suggest going to junkyard and getting an air pump with more output, and locate a smaller pulley to put on it. Ford made like 3 different pumps with different outputs, and different size pulleys. Find the smallest one to overdrive the pump at idle.
Next thing is make sure that the truck is operating at normal temps. Colder it will still be on warmup and hotter gives different numbers as well. If your coolant temp sensor is off, ecu could be fueling the engine improperly at idle.
Few things to think about.
Make sure your air pump is working correctly. I had it written down a tone point, which additives did what to emissions results, but dry gas is either isopropyl or methanol alcohol. It will change your results.
If you can't get the truck to pass emissions then I suggest going to junkyard and getting an air pump with more output, and locate a smaller pulley to put on it. Ford made like 3 different pumps with different outputs, and different size pulleys. Find the smallest one to overdrive the pump at idle.
Next thing is make sure that the truck is operating at normal temps. Colder it will still be on warmup and hotter gives different numbers as well. If your coolant temp sensor is off, ecu could be fueling the engine improperly at idle.
Few things to think about.
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From: Round Rock
thanks for the info guys, i might try the air pump solution but first i want to see the timing i heard if its not timed right it wont pass emission.
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From: Ottawa, Ontario
I'm seeing the same problem with the XE264HR I have in my truck, it passes easily at higher rpm but fails badly at idle. This truck has MAF, is timed right, and has a brand new cat on it. I disconnected the air pump when I put the new cat on but maybe that was a mistake, I was gonna reconnect it and take it for another try but I'm not confident that will be enough. I did get this motor to pass emissions one time before but it had a tuner on it and it was running so lean at idle it would hardly idle so it sounded a lot worse. None of this is good news for you with that B cam, I'm afraid your only option might be to change it out to something more tame.
Logistics Pro
Joined: Jul 2009
Posts: 3,635
Likes: 3
From: Lansdale, PA
I never unhook the air pump. I always keep it hooked up to the heads without the diverted valve. I'm not really sure why some cats have the air fitting and some don't.
If I had a way to post my emissions numbers I would. Maybe tomorrow I'll just type the numbers in here.
The b cam passes emissions in a mustang so you can make it work in the truck.
Make sure you're running in tip top shape. Additives in gas, plug gap, timing, o2 sensor, evap system, and many other things will help or fail you. Certain things help one set of numbers and hurt others. Need to balance it out.
If I had a way to post my emissions numbers I would. Maybe tomorrow I'll just type the numbers in here.
The b cam passes emissions in a mustang so you can make it work in the truck.
Make sure you're running in tip top shape. Additives in gas, plug gap, timing, o2 sensor, evap system, and many other things will help or fail you. Certain things help one set of numbers and hurt others. Need to balance it out.
Senior User
Joined: Jun 2004
Posts: 282
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From: Winchester
I am not sure how the inspection is in your state but,,,,,,,,, I have seen this work. If there is a visual this would not work.
.......... unplug one injector. It turns that one cylinder into an air pump, runs like crap but sometimes will pass. Again good luck and, miss my dang 93 Lightning.
.......... unplug one injector. It turns that one cylinder into an air pump, runs like crap but sometimes will pass. Again good luck and, miss my dang 93 Lightning.
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From: Round Rock
I ended up checking the timing and its at 12 i might set it back to 10 and also check the plugs and switch the spark plug wires, just curious how many o2 sensors did the 93 lightning come with and again thanks for all the responses it has really help thanks
Lead Driver
Joined: Jul 2007
Posts: 7,868
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From: Rhode Island
It'd be best to crawl underneath and check it out.