well i went 2 jiffy lube in the good ol state of colorado 2 get a emissions test done. i just bought my 77 f250 and it failed bad and i was hoping someone could tell me what i might be able 2 do?
this is what they came up with.
@ idle 2500 (my guess is the rpms)
HC PPM 2292 3154 they said my limit was 1200
so what is the HC PPM? and then my CO%
CO% .12 .44 and my limit for that was 6.00 ( sound
low to me)
and what is CO2% my readings were 7.3 10.3
rpm 729 2334


so if any 1 can break these numbers down and explain them 2 me i would love it.

the guy said it might just need carb adjustment or it may have bad compression.

thanks skunktruck

 

HC is Hydrocarbons...They supposedly hit the ground, react with sunlight, and damage the ozone layer. CO is Carbon Monoxide...That's the one that kills you when you run the truck in the garage with the garage door closed (bonds to blood cells in lieu of oxygen, you get a headache, feel a sense of well-being (drunk like), fingernails and lips turn purple, and then it "suffocates" you (please pardon the details, but this is important stuff for folks to know so you can recognize it should you get an exhaust leak in your vehicle...like when idling in a parking lot in winter)).

It basically is too much fuel rich air coming out your tailpipe due to inefficient burning of the fuel / air mixture. Carb could be too rich or idle too high, it could be your EGR system is clogged (pull your carb and check your EGR spacer...(these are notorious for clogging on our engines and also the spacer between the two carb barrels burns out easily)...it can also be a bad thermactor (AIR system pump and passages could be clogged). I'd start with the carb adjustment (cheapest) then go to the EGR plate and check it out, followed by the Air pump, and lastly the catalytic converter.

In short, the EGR (Exhaust Gas Recirculation) re-injects the exhaust gases into the intake manifold via the under-carb EGR plate to more thoroughly burn any remaining gas in the exhaust...saves fuel and decreases emissions, but needs maintenance to keep it from clogging over the years. AIR systems(Ford calls it Thermactor System) injects air into the heads, exhaust manifold, and catalytic converter to help unburned gas continue to burn (more oxygen), resulting in more thorough combustion and less emissions.

Lastly, your catalytic converter could be tired and clogged. Most guys trouble shoot in order of cost...cheapest to most expensive. Save your receipts...sometimes, even if you cannot pass, if you spend enough $$$ they will exempt you for trying

Also, Auto parts stores sell bottles of junk you can dump in the gas tank that can "mask" problems, allowing a pass, which is a band-aid approach but may work.

This may be help in understanding:

http://www.txdps.state.tx.us/vi/Misc/all_asm.pdf

Regards,

DiMora

 

ok so do u think that it may be a compression problem? the carb is or rebuilt and the motor is a 351m also the heads were redone cause of a lack of compression and the spark plugs, wires and cap r all new. so would this motor have a air pump and if so where would i find it? and thanks that link did explaine it a lot

 

The A.I.R. pump would be on the front of the engine with a belt driving it usually on the passenger side, if your engine has one on it it isn't hard to find, if it doesn't but was supposed to then look for an unused bracket, or check the for plugged off hoses, or better yet check the emissions sticker. these were frequently taken off as alot of them would freeze up, and the do rob some hp.

 

Yeah, if you have an AIR pump, it will be obvious. Usually located under the alternator. It will have a hose about 3/4" to an inch in diameter that runs to a filter (just slightly smaller than a Coke can), and from that filter, a hose will run to a pipe / valve that goes into the front (slightly passenger side) of your intake manifold.

This first picture on Bubba's site shows the filter I am referring to, and the AIR check valve (pipe / valve that feeds the intake manifold)...you can see the check valve just to the passenger side of the distributor cap. Just trace the plumbing backwards if you have the check valve...to the filter...then follow the hose from the filter to the Thermactor (AIR) pump. If your pump is bad, I think they are $15.00 or so. Also, look at your pulley and see if there is a pulley position for a missing belt - If you have an empty pulley groove, I bet the AIR pump got removed and tossed.

http://www.clubfte.com/users/bubbaf250/

If you want another link, it is not specific to our engine / vehicles, but it is Ford, and shows you waht an AIR pump looks like, along with the check valve, filter, etc. It will get you pointed in the right direction:

http://429mustangcougarinfo.50megs.c..._emissions.htm

I would check the Carb adjustments and EGR system first before I'd worry about AIR...My car passed Idaho emissions WITHOUT an AIR (Thermactor) system a few years back. IF you only have to do an idle test (no dyno) you can often pass just by tweaking the carburetor. Also, make sure the car is good and warmed up before you do the test. Take her for a couple full throttle runs on the way to go to the the test - may blow out some of the crap in your engine.

I am lucky, I live in Georgia, and I am now emissions exempt (I removed all my emissions stuff when I rebuilt) but I remember what a nightmare keeping all that stuff in working order was.


DiMora

 

ok thanks and it dose not have an air pump. i did adj. the carb and the numbers are still high. so im going do do a compression test 2 see where i stand thanks agine

 

Have you looked at the spark plugs? Is the truck running a little rich? Do you know for a fact the carb is factory? Maybe the carb needs to be jetted to match the motor? Who knows if you get it jetted you might gain a few MPG.

 

well just yesterday i checked the timing and boy was it off reading 30+ btdc. so i adj. to 10 btdc and it passed. i did change the plugs, cap and wires. still i think the choke is in need of adj. but ill need to read on that one.
but thanks for the help

 

Check your timing again. Was the vac modulator hooked up and was it hooked to manifold vacuum?

 

well i did just that w/the vac line off the dist. and it is the same.
what makes me think it is the choke is that when it was hooked up to the emissions tester at idle its HC was about 2000. and when we increased the rpms it went down to 200. then at idle it should 300-400.

 

I don't quite understand what your numbers are. Could you list them with all numbers (CO, HC, and CO2) for each test speed, that is "idle" and 2500 rpm?

If your 2500 rpm numbers are passing, and the idle numbers are not, then your idle mixture needs to be adjusted, and nothing else.

Low CO and high HCs at idle almost always means the idle mixture is over-lean. To correct it, you need to turn the idle mixture needles counter-clockwise to enrich the mixture. The idle mixture needles are located down low, on the front of the carb, one on each side. They should both be adjusted the same number of turns out from closed.

Here's a good rule of thumb for curb idle emissions failures:

CO low and HC high = idle mixture too lean

CO high = idle mixture too rich

This assumes everything else is working correctly (ignition system, Thermactor AIR, EGR, catalyst, if so equipped, etc.).