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  #16  
Old 11-17-2004, 02:20 PM
SL Owner
 
Join Date: Sep 2004
Location: East Coast U.S.
Posts: 131
your readings

are excellent for the car, don't overanalyze it. Your Co and HC are very good. Run some diesel fuel injector cleaner in there as I suggested and see how it goes. The state of Virginia has actually made it harder on these cars, if you go back to your tests 2 and 4 years ago you'll probably see the NOX limit has been lowered meaning the car must perform better.

High NOX is not 700 or so. It may be for the state of virginia but isn't for an older car. I've been amazed by my own propensity, and that of many folks, to react to a number that is at or slightly above a state limit. The state limits are somewhat arbitrary and do not take into account age of the car, age of the catalytic converter, etc. I've studied the equations, relationships, etc between NoX, oxygen, etc etc etc. I can tell you that you are on the path to hell here if you overdo it-- I did that. If you sense the car is UNDERpowered then you have a reason to go in there and determine if the cat is clogged, etc. Of course check for vacuum leaks but I don't see that as a likely cause here per my other post, but what do any of us know really in the end since we guess with an esoteric thing like NOX value.

If you are experiencing less power with the car, then you probably have a clogged cat. I don't know if your car has pre-cats, but they can clog. If your power is good and everything else is good, run some cleaner in there and leave it alone. Trust me, you're on the way to a very big litany of stuff that may result in a better car in the end (maybe more power) but great expense as every mechanic or you go in there and try to guess the thing out. If it really bothers you, other than cheap and easy things you can do, the other thing is to put a Miller cat AND pre-cats on there costing you $1200 to $1500 for someone else to do it or I think about $600 parts plus whatever labor you can find-- that's a quote for another MB (mine).

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  #17  
Old 11-18-2004, 01:53 AM
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Thanks for the comments.

I had driven the car from work to the testing station, I work at night, for a distance of approx. 35 miles. The car was operating at it's normal temperature of 87C. I told the inspector this and he let it idle for a while anyway. I've dealt with this inspector before and he knows I work on my cars. I'm always up front about what I've done mechanically to the cars. The inspection stations in Va. perform mechanical and smog testing.

I suspect the rubber hoses have hardened and need to be replaced. The plugs, wires and cap need to be replaced. There are many little hoses which also need to be replaced because I suspect they are mostly original. I'll also get a generic O2 sensor and replace it.

When the car is cold and the air temp is around 50F, there is a low speed lean condition or stumble. When the air temp is less than 40F, it runs well. I suspect a temp sensor or vacuum switch. The injector seals may also be bad. I think the PO's did minimal maintenance on the car based on some of the things I've seen. I also have to replace the serp belt pulleys because they are making some noises.

The car is really nice but it's a money pit.
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Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.
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  #18  
Old 11-18-2004, 12:14 PM
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Quote:
Originally Posted by Duke2.6
The rate of flame propagation does not vary significantly between gasolines with different octane ratings as long as there is no detonation, and the same applies to peak temperature of the flame front, which is where NOx forms. "Premium gas burns slower" is a myth!

To the thread originator - I don't think there is a "problem" with your converters, but it will help in diagnosis if you would post the entire test results for both 15 and 25 MPH including the 02 content.

Duke
I don't want to hijack the thread, but your comments got my attention. Some time ago, I had classes in college that were tought by the same prof: thermo and internal combustion engines. I remember considerable time spent on flame front propogation, heat transfer, etc. It was stated emphatically that octane is designed to "provide a slower flame front" to maximize power output and minimize detonation. Too low octane in some engines, usually higher compression and timing design, will assure detonation. It can get so hot in some engines that you can get autogenous ignition - same as diesel - when the piston is compressing the fuel/air in the cylinder. It's been a few years since those classes, but I'm guessing the Laws of Thermo have not been thrown out.

Also, here is some written info:
______________________________________________________
Quote:
WHAT IS DETONATION?

Detonation (also called "spark knock") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.

Mild or occasional detonation can occur in almost any engine and usually causes no harm. But prolonged or heavy detonation can be very damaging. So if you hear knocking or pinging when accelerating or lugging your engine, you probably have a detonation problem.

A DOZEN WAYS TO PREVENT DETONATION

1. Try a higher octane fuel. The octane rating of a given grade of gasoline is a measure of its detonation resistance. The higher the octane number, the better able the fuel is to resist detonation. Most engines in good condition will run fine on regular grade 87 octane fuel. But engines with high compression ratios (over 9:1), turbochargers, superchargers, or with accumulated carbon deposits in the combustion chamber may require 89 or higher octane fuel. How a vehicle is used can also affect its octane requirements. If a vehicle is used for towing or some other application where the engine is forced to work hard under load, a higher octane fuel may be necessary to prevent detonation.

If switching to a higher octane fuel fails to eliminate a persistent detonation problem, it probably means something else is amiss. Anything that increases normal combustion temperatures or pressures, leans out the air/fuel mixture, or causes the engine to run hotter than normal can cause detonation.
This is not meant as a challenge to you, rather asking for more information or explanation.
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  #19  
Old 11-18-2004, 12:22 PM
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Join Date: Jun 2001
Location: Northern Calif. (Fairfield Area)
Posts: 2,225
Duke,
I won't get into the required octane bit right now, because I don't have time to dig up, scan, and post the documentation. I wouldlike to discuss changing timing on the M103. I don't understand what you are talking about with vacuum advance. The distributer is bolted to the front of the cam with no advance capability. Your thoughts on replacing the resistor that maps the EZL are interesting. I'll have to experiment with that. I got rid of my 90 300SEL, which was a bear to pass smog, but, I still have an 88 300SEL. The 88 has a problm just getting by on the 15mph and 25mph HC readings and my O2 is .5 %. I'm trying to figure out why some M103s fly through the test and others get bogged down in the HC category. NOX has never been a problem. About plugging the vacuum line to the EZL, you might get away with that on most year Federal cars, because the only thing that will trigger the MIL in Federal cars is the oxygen sensor. Not so with California cars, because you will trigger a code 16 and set the MIL. TRhis is also applicable to the M104 engines.

Warren,
If you are hearing sounds from places like the fan pulley, the bearings are probably about to grenade on you. As too your stumble, Folks in other threads have been very successful in curing cold idle problems by tweaking the screw on the back of the EHA. I haven't had a chance to experiment yet.

You have a luxurious $3000 car that still gets attention, costs you several hundred dollars, and you call it a money pit. Buy something like a new 04 Dodge Neon if you want to own a money pit. Yes, you have to keep putting money into that old car, but save your receipts for 5 years. Acturial tables show that the $13,000 Neon will cost you over $30,000 in the first 5 years of ownership. Many years ago a friend got a job that required a 60 mile or so commute for about a year. He started a car pool with 3 other guys. They all went out and bought new little economical rice burners. My friend bought a 65 Pontiac Bonneville for $500. They always wanted to use his car, because of the room and A/c, but they all shared as per the agreement. Afret the year was up, they had car payments, registration, maintenance, and insurance on cars they didn/t need. My friend sold his Pontiac to a low rider for $500. He had cheap registration, basic insurance, and a few hundred extra dollars in fuel costs.

Peter
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  #20  
Old 11-18-2004, 01:06 PM
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Regarding the flame front propagation issue, note that I said that in the ABSENCE or DETONATION there is no significant difference in flame front speed and your information does not dispute this. Detonation is "abnormal combustion" and is a whole other ball game than normal combustion, which is detonation free. If you can use regular unleaded without signficant detonation as I can in my 2.6, then there is no difference in normal combustion flame front propagation speed. You have to differentiate between normal (no detonation) and abnormal (detonation) combustion. Generalities such as "premium gas burns slower" does not capture this critical distinction!

If your engine detonates consistently on a given fuel octane, you better increase the octane in short order before you cause permanent damage. Brief transient detonatation, such as what might occur if you short shift, will not cause any harm, and can usually be avoided by changing your driving habits - like shifting at higher revs and easing into the throttle.

On the vacuum advance issue. I have not actually tried to block the vacuum line to my EZL module, but I will probably try it when I bring the 2.6 out of summer storage for use this winter. It's due for an emission test in February. It appears that the vacuum line to the EZL is an input to igntion timing. Why else would it be there? I'll report on the results of my experiments and my emission test results.

Like your M103s, mine is on the ragged edge of the HC limit at 15 MPH. My theory is that the catayst bed cools off after several minutes of idling, which reduces oxidation efficiency, and this shows up as high HC and (relatively) high 02 on the 15 MPH test. The load during this test causes the converter to heat up and the HC and O2 go down due to higher catalyst oxidation efficiency; 0.5 percent O2 is very high and inidicates poor catalyst performance - probably due to low temperature. Good converter action should result in no more than 0.1, maybe 0.2 percent, O2. If the O2 level is zero, the converter is operating at "100 percent efficiency" using all the available O2, and at this point no further reduction in measured emissions is possible. My other theory is that 02 sensors may "drift" in their calibration, but I have not been able to confirm this. Reports I have read indicate that O2 sensor degradation results in increased response time, but this too could cause higher emissions.

If you have an IR gun run the following experiement. After 20 minutes of normal driving check the converter inlet temperature with the IR gun. Then let the engine idle and check temp. every minute. It will probably go down significantly within five minutes, which would indicate that the catalyst bed is also seeing a signficant reduction in temperature, which will reduce its oxidation efficiency and increase HC and CO.

Duke
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  #21  
Old 11-19-2004, 02:07 AM
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Join Date: Jul 2000
Posts: 638
Reason for hi NOx maybe

It well could be the passaged for exhaust gas recirculation are partially or nearly completely closed off(plugged). Not uncommon, particularly on higher mileage cars. Some shops even clean them out every 30K service. Easy to use a 'spedometer cable' as a snake drill in a variable speed drill, and dribble carb cleaner down the spinning cable as you feed it in.
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  #22  
Old 11-19-2004, 02:54 AM
wbain5280's Avatar
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Location: Northern Va.
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Quote:
Originally Posted by autozen
Duke,


Warren,
If you are hearing sounds from places like the fan pulley, the bearings are probably about to grenade on you. As too your stumble, Folks in other threads have been very successful in curing cold idle problems by tweaking the screw on the back of the EHA. I haven't had a chance to experiment yet.

You have a luxurious $3000 car that still gets attention, costs you several hundred dollars, and you call it a money pit. Buy something like a new 04 Dodge Neon if you want to own a money pit. Yes, you have to keep putting money into that old car, but save your receipts for 5 years. Acturial tables show that the $13,000 Neon will cost you over $30,000 in the first 5 years of ownership. Many years ago a friend got a job that required a 60 mile or so commute for about a year. He started a car pool with 3 other guys. They all went out and bought new little economical rice burners. My friend bought a 65 Pontiac Bonneville for $500. They always wanted to use his car, because of the room and A/c, but they all shared as per the agreement. Afret the year was up, they had car payments, registration, maintenance, and insurance on cars they didn/t need. My friend sold his Pontiac to a low rider for $500. He had cheap registration, basic insurance, and a few hundred extra dollars in fuel costs.

Peter
Thanks Peter.

I bought the car a year ago for $5K and I knew it was going to need some work. I've overhauled most of the front suspension but I'm going to have to do more. I have a used PS gear to install because the current one is loose and knocking (not the mount). I also have a replacement rear window to install.

I'm convinced that used cars are the way to go, let someone else take the hit on depreciation. I can fix cars and I don't mind. I get to drive a fabulous car and people do look at it.

I'm going to try tweaking the EHA as you suggest.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.
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