Failed emmision test with high hydrocarbon (two times higher than the allowed limit).
The truck had its ICM module replaced about two years ago. The ICM failure was gradualy starting with rpm dip to almost zero while at idle, and this became more frequent before the complete failure of the module. An after-market module was installed (not made by Ford) and it was working fine for a few months. Then similar things happened again, i.e., the rpm dip to very low while at idle. This may happen once a week or so, not very often.
The truck was not on daily use for three months before the emmision test (probably driving once a week for 20 miles).
It is suspected that the ICM replacement might be the cause of the emmision failure.
IF you can retard the spark about 4 to 6 degrees for testing (to help after burn HC in exhaust) and add several bottles of "Dry Gas" or "Gasoline Antifreeze" which is Methanol and will add oxygen to fuel and help with the afterburn. THose two together should bring HC down in test enough to pass.
Thanks for the help, but how do I "retard the spark"? I was told that all the timing and fuel mix are controlled by a on-board computer, will an old fashion teming gun work on those computer controlled gargets?
BTW, the HC reading is twice the allowable limit, so I might have a long way to go.
On that model you can retard the base line timing. I have a freind that had a 86 ford that was failing miserably. We retarded the spark a good bit (so much that they could not get it up to 60 on dyno) and added alchol and it easily passed the second time.
Could you please explain what you did with your freind's 86 in more details, such as how many degrees you retard the spark and what's the ratio of alcohol to gas you put in when you took it in for the test.
Since I have never adjusted timing on this truck before, could you please let me know the procedure, step by step, of how to adjust the timing.
I took the spark plugs out and it appears that they need to be changed, the gap is still within the specs, by the electrods erroded. I also took the distributor apart and all the contact have a lot of carbon deposite. I'm going to change the plugs, the rator and the cap, do you thing this may help?
Do you have a good libray around where you are at to "borrow" a service manual? (pictures help a lot if you are new to this) If you can get one I can fill in the "blanks" for you.
Yes it will help; enough to pass? I don't know. But as I said before hydrocarbon is unburned fuel and at gas 3.00 a gallon you would like to think your now wasting it. think about fixing the car and it will pass emissions.
I'm working on transcribing a article on 5 gas analyzers and this is what it says so far:
Exhaust Analyzer One of the more useful Diagnostic Devices available to a technician is the 4 or 5 gas analyzer. Not only are they readily available but many of them can be taken out for a test drive. This feature makes them an ideal tool for base lining a vehicle that has failed an inspection maintenance test. Most state inspections are in grams per mile (GPM) of pollutants while most shop exhaust analyzers measure in Parts Per Million (PPM) or in percentage (%). The difference does make the readings difficult to compare, but does not eliminate the use of the shop analyzer for diagnosis purposes. Most analyzers available today will measure HC in PPM, C0 in %, C02 on %, and O2 in %. An option to measure NOX in PPM can be added to most units. Lets look at the individual gases and analyze why they are produced.
Gasoline is comprised of mostly hydrocarbons (HC). When HC is burned it combines with oxygen (O2) and under ideal conditions produces water (H20) and carbon dioxide (CO2). Notice the emphasis on the Ideal. To be practical, ideal conditions really do not exist in engines that have to operate under varying loads and speeds. As a result, we not only get water and carbon dioxide but we also see some raw gas come out of the tailpipe (HC) and some carbon monoxide (CO). Under extreme heat conditions we also see some varying conditions for excessive HC and CO. Some states additionally check for NOX
You will remember that gasoline was composed of HC and yet after the burn in the cylinders we still see some HC coming out of the tailpipe, or going into the catalytic converters. How can this be? The burn in the cylinder is never totally complete; some gasoline will always be left over. The amount left over will be relatively small, sometimes as low as 100 PPM. This 100-PPM will enter the converter and be converted to CO2 and H2O reducing the HC emissions to near zero. However, lets add another element, a complete misfire from an open spark plug wire. What will this do?
Think about what should be occurring in a cylinder: we should ignite the HC with ignition. If ignition never takes place, all of the HC that the fuel system put into the cylinder will come out the engine and possible the tailpipe. This may be in excess of 5000 PPM. Quite a difference between 100 PPM and 5000-PPM HC! Actually the amount of HC that will come out of the cylinder is imposable to predict because of the variables of load, speed, engine size, temperature, etc., must be calculated in. Put HC into a cylinder, don't ignite it, and it will exit the cylinder in the same form it went in - raw gas. HC emissions from dead cylinders are generally easy to diagnose. Dead cylinders that produce excessive HC are generally the result of ignition or compression problems isolated to the cylinder in question.
Run a compression test and an ignition scope test and you will probably identify the problem without much difficulty. Partial burns are much more difficult to track down. By partial, we mean some of the fuel has been burned, but not all Again ignition or compression may be at fault. A plug that tends toward fouling or has a badly eroded gap, or an ignition coil that has lost some of its capacity might cause part, but not all of the fuel charge to burn.
Also, weak or lower compression might cause the cylinder to only partially burn the fuel. A partial burn will result in increased HC emissions. Another factor to consider besides compression or ignition is fuel control. Fuel control is a simple way of saying that the air fuel ratio is held within design parameters of the engine. Generally this is 1407:1 (14.7 pounds of air to 1 lb of fuel). If the fuel system cannot hold or control this ratio then the engine is not in fuel control
Lets look at the two ends of not being in fuel control, too rich or too lean. Adding much more fuel than the engine needs or is designed to handle (running rich) can produce an inefficient burn in the cylinder. This usually results in excessive C0 production, as you will se in the next section, however it can increase HC emissions. If the cylinder has way too much fuel, some of it might not be ignited. You know what happens when we do not ignite the fuel - it comes out as HC, just like it went into the engine. An excessively rich engine will increase the HC emissions. At the other end of not being in fuel control is the too lean condition. Being "too lean" is another way of saying an excessive amount of air has entered the cylinder: excessive for the amount of fuel.
Another way of saying this would be to say that a smaller amount of fuel than specified is in the cylinder. A partially plugged fuel injector, or a vacuum leak are both examples of a lean condition. Cut back on the fuel and add the air and you are creating a lean condition. If the cylinder is running lean, than the burn within the cylinder will result in excessive HC, because the amount of fuel present does not support combustion. This is generally referred to as a "lean misfire" There was fuel in the cylinder, but not enough to burn and produce power. This smaller than specified fuel charge will exit the engine as HC.
Make no mistake about it; a vehicle that is not in fuel control can and frequently does produce excessive HC. Go back to the basics, for cylinders to produce equal power they must have equal compression, ignition and be in fuel control.
Nice comment Steve H but I yhink this guy is looking for a quick fix to get by emissions testing. I know what that is like because we have had it here for over 10 years but they are phasing it out at the end of the year here so I am done with it.
I thought emissions were here to stay, or are you referring to the vehicle being exempt?
I'm learning advanced diagnostics, and learning allot. Am thinking about buying a 5 gas analyzer to help properly read what the car is doing. I don't live in a emissions area either.
They build for Snap-On, Mac, Matco and also do hardware and software for a number of state and provincial emissions programs. Their prices are impossible to beat.
100% full sized Andros gas benches.
The pocket gas is capable of extrapolating grams per mile.
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