88 5.0 failed emmisions.

I doubt the problem(s) causing it to fail emissions is that severe. It might need the throttle body cleaned, the O2 sensors replaced, MAF element cleaned, spark plugs or other light maintenance type repairs. If the car runs good and burns little oil then the fix should be relatively routine and inexpensive. Don't give up on the car so easily.

Reply to
Michael Johnson, PE
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What's the condition of the cats? I don't suppose there's an "off-road" H-pipe under there?

Reply to
jmvannoy

The previous owner had a H-pipe under there for around the last 15 years. He had kept the cats and the o2 sensors all of this time. We put all that back up under the car. So maybe the cats are still good and the o2 sensors have gone bad.

Reply to
Cameron

Reply to
Michael Johnson, PE

Pinched this from a usenet post, may be helpful.

- John V

==================================== Emission (smog) test problems. ==============================

What to look for when any of CO, HC, NOx too high.

CO: rich fuel mixture HC: incomplete combustion NOx: hot combustion and rich fuel mixture CO, HC, and NOx: incomplete exhaust conversion

80%-85% of vehicles pass emissions tests. an in-tune well-maintained vehicle should pass. allowances are made for the age of the vehicle. for the rest some details are provded below.

note that both CO and HC rise in the absence of O2 (oxygen) in combustion and in exhaust, and that NOx rises in the abscence of O2 at high combustion temperature. HC also rises when there is too much O2 in combustion.

  1. CO (carbon monoxide) too high.

---------------------------------

causes:

a) not enough air (oxygen) in air/fuel mixture to make carbon dioxide (CO2) so get carbon monoxide (CO) instead (mixture too rich). can be too little air or too much fuel in mixture.

b) not enough air (oxygen) in exhaust system to convert CO to CO2

c) faulty catalytic converter.

look for:

a) too little air - dirty air filter, stuck choke, plugged or sticking PCV or EGR system, plugged carbuettor or injector air passage

b) too much fuel - carburettor or fuel injection system supplying too much fuel

c) too little air or too much fuel - engine control system - vacuum hoses, sensors (eg exhaust oxygen, temperature, air flow), computer, actuators (eg fuel metering solenoid, air metering solenoids), wires and connections (control system voltages are so low that small resistances from dirty or loose connections make a big difference), the computer uses the input from the sensors to send signals to the actuators to keep the air/fuel mixture at the optimum for power, fuel efficiency, and low emissions.

d) too little air in exhaust system - restricted outside air feed to converter (eg air pump or pulse air system - hoses, electrical connections, valve, pump, drive belt, sensors)

  1. HC (hydrocarbons, ie unburned fuel) too high.

------------------------------------------------

causes:

a) not enough oxygen in combustion to burn all the fuel, or too much fuel (mixture too rich), so excess fuel blows out exhaust.

b) too much oxygen in combustion or too little fuel (mixture too lean) for uninterrupted combustion (engine misses), so unburned fuel blows out exhaust.

c) sparkplugs not firing properly to ignite air/fuel mixture (ignition system), so unburned fuel blows out exhaust.

d) combustion chamber too cold for complete combustion, so unburned fuel blows out exhaust.

e) combustion chamber hot spots preventing complete combustion, so unburned fuel blows out exhaust.

f) not enough air (oxygen) in exhaust system to convert HC to H2O and CO2.

g) faulty catalytic converter.

note that HC in exhaust can combine with S (sulphur) from fuel to produce rotten egg smell.

look for:

---------

a) mixture too rich - see a,b,c in CO section above. note that if HC is too high but CO is okay then the problem is not a rich mixture.

b) too much oxygen in combustion - leaks of air (hoses, gaskets) and routing of hoses into intake manifold, leaks in EGR and PCV valves

c) too little fuel - dirt in fuel/filtre/tank/lines, leaks in fuel lines or connections, weak fuel pump, - mechnical problems in carburettor (dirty valves or passages or linkages, worn parts or gaskets) or fuel injection system

d) too much air or too little fuel - computer not mixing air and fuel properly (see c in CO section above)

d) ignition system - sparkplugs fouled (type of fouling may indicate problem), poor contact or insulation in high voltage ignition wires or in distributor (cap, rotor), poor contact in coil wires, low voltage in charging system (alternator, regulator), faulty transistorized ignition control module

e) combustion chamber too cold - sticking EGR valve or sitcking cylinder exhaust valve or bad cylinder valve timming letting "cooler" exhaust gas into the combustion chamber.

f) combustion chamber hot spots - bits of junk (dirt, carbon) or nicked or burned metal parts glowing red hot in combustion chamber and igniting air/fuel mixture (engine misses) - can use chemical cleaner in combustion chamber or take engine out on the highway or both to burn off junk - overhaul engine to remove nicked or burned metal parts or hardened junk

g) too little air in exhaust system - see d in CO section above.

  1. NOx (oxides of nitrogen) too high:

-------------------------------------

causes:

a) too much heat in combustion chamber - air contains about 78% N2 (nitrogen gas) which becomes chemically unstable above 2500 def F and combines with O2 (oxygen, making up about 21% of air) to form NO which, released into the atmosphere, forms NO2 which in the presence of sunlight combines with HC (hydrocarbons) to form smog. note that NOx only happens when engine is under load (car at crusing speed on road or rollers).

b) too much CO in exhaust (CO enhances the conversion of NO to NO2).

look for:

a) too much heat in combustion chamber - the EGR system or the valve timing is used to bring exhaust gas back into the combustion chamber to cool it off when the engine is hot under load at cruising speed - check the EGR system valves, solenoids, wiring, hoses - if the car does not have an EGR system check valve timing - (engine cooling (water) and lubricating (oil) systems may have some effect on combustion chamber temperature?)

b) computerized engine control system - adjusts engine operation to minimize emissions (see c in CO section above).

----------------------------------------------------------------

sources:

"Automechanics" (Prentice-Hall, 1988) "Import Car Manual 1983-1990" (Chilton, 1989)

------------------------------------------------------------------

Camer> Hey all! You probably have been seeing all my recent posts about the use 88

Reply to
jmvannoy

Reply to
jmvannoy

Plugs and Wires are good, dont know about the other things. I'm trying to do the minimum here to get it to pass emissions and not to restore the car to awesome status. My fear is I will spend $500 replacing various old components that may or may not be bad and then end up needing one giant engine repair that I'm not willing to do and end up having to sell the car with wasted money into it.

Once I get this bad boy to pass emissions then its time to tune it up to fine status.

Reply to
Cameron

:-) that lists about a billion things

Reply to
Cameron

Have you considering just cracking the bolts somewhere in the exhaust JUST A BIT to let a little some exhaust out? And lower the timing.

Brad

The HC was 691 where yesterday it was 651 and the CO was .44 where yesterday it was .22. I drove downdown to the FREE mechanic paid by the state that will tell you whats wrong. What a waste of time, he couldnt tell me anything. But at that place my HC reading was back in the 1300s and the CO was 2.0.

I have the mustang now at a local mechanic that says for $70 he can tell me whats wrong, or whats leaking, etc. If that fails I guess anyone that wants a nice t-top mustang that will never pass emissions can buy one on ebay from me.

Reply to
BradandBrooks

You also want to set the timing, pull the SPOUT connector before doing so or your initial setting (the one the computer uses to determine the advance.) will be off.

Reply to
KEITH MCCUMBER

Is the AIR still plumbed into the exhaust, if the cats were off all this time it seems reasonable that the former owner would have removed the AIR pump too.

Reply to
KEITH MCCUMBER

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