help! plugs sooty black

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  #1  
Old 04-13-07, 05:25 PM
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Unhappy help! plugs sooty black

i have an 89 dodge ram 318 with throttle body that runs very rich with little power. the plugs are sooty black. the engine has a throttle body that holds the the 2 fuel injectors. i just paid a so called mechanic $640 to replace 2 fuel injectors and a fuel pressure regulator. now the truck runs worse than it ever did. he said i dont know. it isnt throwing any codes. after 3 mos that the so called professional mechanic had it, i brought the truck home. it runs like it is choking itself out with unburnt gas smell coming from exhaust and engine. plugs are new and wires 3 yrs. old. dist. cap new. truck ran fine until it sat out one nite in the winter after driving it in a misty rain. i was hoping someone out there might have a clue as to what i can do to fix this. i have a good understanding of engines up until cars became computerized. what controls air/fuel mix on these new ones. in the old days i would just slap another carb on it and be done with it. any help greatly appreciated. thank you.
 
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  #2  
Old 04-13-07, 05:35 PM
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I would check the O2 sensor for starters, or simply replace it if it has mega-miles on it; although a defective one should give you a code.
 
  #3  
Old 04-13-07, 06:27 PM
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called auto zone. he sais he was out. they are 50.99. he said it was located on exhaust. i went out and traced it from exhaust. there is one steel tube coming from exhaust that branches in to two steel tubes that leads to 2 rubber hoses that lead to device the size of your fist mounted on the smog pump loacted just above power steering pump in front on top. there is a wire on on one end of this device leading to spaghetti insulation which trail disappears. the # on device is chrysler 4227670. is this o2 sensor?
 
  #4  
Old 04-14-07, 03:35 AM
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Talking plugs

You said your spark plugs are sooty black. Did you smell the plugs? Does it smell like gas or oil fouled? If it is gas than check for a dirty air filter. A dirty air filter will cut off the air supply and make the fuel-air mixture too rich. If it is oil fouled than check for a clogged PCV valve. Also, if the plugs are oil fouled you could be getting too much blow by. Meaning too much oil is getting by worn piston rings or worn valve guides. Also, sometimes the small return drain holes in the top of the heads become clogged and won't allow oil to drain back down holes, thus filling up the top of the head and leaking down past the valve guides. You can use a coat-hanger to clean out these holes. Do a good oil change with something to loosen up and drain out any sludge. Does your exhaust pipe blow out blue or black smoke? Blue means oil and black means gas...
 
  #5  
Old 04-14-07, 05:29 AM
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Originally Posted by l.mitchell View Post
is this o2 sensor?
No. The O2 sensor is mounted directly into the exhaust system.

Click on one of the images here:

http://replacement.autopartswarehouse.com/parts/autopartswarehouse/wizard.jsp?year=1989&make=DG&model=RAMC--002&part=Oxygen%20Sensor&dp=true

Should look something like that.

And going in Homeowner's direction, you're sure this is a fuel problem and not because it's burning oil?

You can also try checking for codes if nobody has done that yet. Here's how:

http://www.troublecodes.net/chrysler/
 
  #6  
Old 04-14-07, 05:41 AM
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any codes?

its a shot in the dark with no codes. I had a 89 chevrolet that ran like that smoke (black) from the exaust no power etc. It turnened out to be the coolant temp sensor. I read it out with a mutimeter and it was out of spec. Replaced it and all was good.
 
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Old 04-14-07, 05:54 AM
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Good thought, mv; could be the computer is making it run in the "choke" mode because it's not sensing the engine temp coming up.
 
  #8  
Old 04-14-07, 09:59 PM
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found 02 sensor-located on exhaust manifold near cylinder #3. has socket i can get to with two white wires, one gray, and one black wire. can i test this myself by disconnecting to see if it affects running of truck? can i test it by using ohmmeter or voltmeter? is coolant temp sensor located near distributor in back of engine or is it near thermostat housing. can i disconnect it to see if it affects running of truck? do i measure for ohms or voltage to ck it? have not located it yet but saw pictures of it. looks like it has a 3 prong terminal and screws into block. the sensor by distributor might be oil sensor. where is computer located? truck is 318 89 dodge d 150 ram charger. i am thinking it is behind glove box? i disconnected battery overnite hoping it may reboot itself. can i temporarily trick computer by shorting across either of these sensors to make the truck think its hot and needs a leaner mixture. right now it is drowning itself out hot or cold and running like it is retarded on timing. it used to to have a healthy wah to it when you opened the throttle plate and the engine would rock back when it was running right. now when you open the throttle plate rpms dont pick up and kind of shudders. it takes time to get it up to 45mph and that is about all it can go.
 
  #9  
Old 04-15-07, 05:18 AM
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temp sensor

Yes an ohm meter is used for the coolant temp sensor. As engine temp goes up resistance changes. There is good reading on it if you google coolant temp sensor. You will have to find out what reading yours should be.
Location is close to the temp sensor that runs your temp guage.(chevy)
 
  #10  
Old 04-15-07, 07:30 AM
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if you can backprobe the wires the O2 sensor can be read with your multimeter too. Set it to millivolts. you will want to backprobe the two wires that are not the same color...the two that ARE the same color are for the O2 heater and simply help the engine to go into "closed loop" faster. Also, you need to make sure that you only have ONE O2 sensor.....on this engine there could actually be as many as four. Some have an upstream sensor and downstream sensor for each bank. Some have an upstream for each bank and then a shared downstream sensor for both banks. It is important that you check/change only the upstream sensors as the downstream will not affect the fuel mixture. If the sensor is located after the catalytic converter in the flow of exhaust then it is a downstream sensor...if it is mounted before then it is an upstream. If you DO find an upstream sensor and DO manage to backprobe it with your meter you will want to watch the millivolt output of the sensor. With the engine in closed loop (usually this occurs by the time the cooling system reaches normal operating temperature) the O2 sensor should fluctuate anywhere between .001 to .999 volts. What that tells you is the sensors rich/lean output to the computer. When the sensor is reading above .500 it is telling the computer the fuel mixture is too rich and the computer adjusts the mixture to lean it out. When it reads below .500 then the sensor indicates lean and the computer will add extra fuel to the mixture. NORMAL readings in closed loop should show the sensor switching back and forth between rich and lean outputs pretty regulary. For example: It will probably go from like .256 up to .810 then back to .174 then up to .792...and so on. IF it STAYS either above or below .500 for a long time and does not switch then you have a problem.

The engine coolant temperature (ECT) sensor is what allows the system to go into closed loop. When the engine is started cold the computer will temorarily ignore the output of the O2 sensors and produce a rich fuel mixture until it recieves information that the engine is warm enough to start using the O2 sensors to determine fuel mixture (closed loop). If your ECT is bad or has a bad connection sometimes the computer will never be allowed to enter closed loop and therefore you will have a perpetually rich fuel mixture. THis can be a difficult condition to determine without a datastream capable scanner but as was suggested before if you can find the specifications of what the resistence is supposed to be you can test the sensor at different temperatures. If its a two wire sensor most of them behave similarly in the sense that if you unplug them they go to -40 degrees and thus cause a rich condition...the same might be true if there is a poor connection at the sensor. I have run across a few though that peg out in the opposite direction when unplugged (300+ degrees) causing a hard start and possibly some other issues. Just for testing purposes you can unplug the sensor to see if that makes a difference (though it may turn the check engine light on) and then you can take a paper clip and jump across the two terminals of the ECT plug and see if that makes a difference. I must warn you though that all of that testing may be in vain unless you first change your spark plugs because fuel fouled spark plugs themselves may only further your rich condition and possibly even trick you into thinking you still have a rich condition when in actuality all you have is inadequate spark due to fouled plugs.

Good luck.

Joe
 
  #11  
Old 04-15-07, 08:54 AM
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Why replace fuel injectors and regulator while you are already have too much fuel dumping down.

Have you look at the MAP sensor?, check for good vacuum goes to the MAP sensor and also check the vacuum hose to the MAP for restriction..ie..kinked hose or water/moisture trapped in the hose.

Also look at the ignition coil for crack/carbon trace.

O2 sensors on early computerized engines works different, there's not much of info that feeds back to PCM for air/fuel mix adjustment like today computerized engine works, it was more of the output device than input/output device as of today O2 sensorr.
 

Last edited by the_tow_guy; 04-15-07 at 05:26 PM. Reason: Not necessary to quote entire post.
  #12  
Old 04-15-07, 09:59 PM
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conducted tests as advised. the engine coolant sensor has about about 28k resistance cold. there is no effect shorting across it or disconnecting it. upon testing the o2 sensor, i noticed a gray wire and one of the white wires were loose inside the male sensor side of the socket. apparently there was intermittent or no contact with wiring harness. i then manually inserted the wires from the sensor side into the socket side being careful not to get them out of place. the voltage on the 2 colored wires was .o1 at idle. with no change. when i reved it up voltage would maybe raise to .02 after several minutes i revved it up farther to see if it would incrase voltage. it briefly go to .04 for a millisecond upon deaccelaration but then quickly sank to .02. at no time did the voltage reach any higher which you say must occur for a lean burn. in the meantime the engine about gassed me out from the fumes which i was outside. the 02 sensor is mounted to the exhaust manifold in a place with no room to see or work. it looks like it it would require a 3 in. open end or a bent open end to get to because the frame is in the way. question is if o2 sensor is bad and replaced will this be the end of it or will it be the tip of the iceberg?
 
  #13  
Old 04-16-07, 04:37 AM
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Could go either way. Often when a bad O2 sensor (we're assuming yours is) is replaced the fix is immediate and noticeable. But, we're talking about a vehicle that is pushing 20, so I wouldn't be TOO optimistic.
 
  #14  
Old 04-16-07, 04:40 AM
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if that is your only O2 sensor then that could very well be your problem. If the sensor is stuck lean then it is constantly telling the computer to add more fuel. No matter how much feul the computer keeps adding, the sensor keeps telling it to add more. This would certainly cause black spark plugs, horrible drivability problems, and a very rich condition. I would certainly start by replacing the O2 sensor. Did you verify that it IS an upstream sensor??? DId you verify that this is the ONLY O2 sensor on the vehicle???
 
  #15  
Old 04-16-07, 04:42 AM
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I would replace the spark plugs too.
 
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Old 04-16-07, 10:48 PM
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Smile

i would like to thank the tow guy and fallen4shell members for helping the past few days. the 02 sensor flunked your test and i bought one today. it took a special 7/8 socket with a slit in it to screw into the exhaust manifold. i started to screw it in but had problems. a couple of wires stripped out and bared because i did snug the rubber spaghetti to slit. i repaired the wires by soldering new pieces of wire from old sensor. i might add the old sensor was tough to get out. i used spaghetti insululation and electrical tape to wrap wires tight so they would not get torn again. it took about 4 hours to get the sensor in because the manifold was rusty and it was hard to get to. i used a breaker bar.3/4 socket. and a cheater to move sensor 1 click at a time being careful with the wires. it made at least 3 rotations with short threads. when i got to where it would not budge, i tried to get socket out. socket would come out as it was hung up on motor mount. the socket was a loaner from auto class so i called for suggestions after trying diligently. he said loosen the exhaust manifold. i took off these 6 bolts and pryed the manifold out about 1/4 in. with a screwdriver and the socket came out easy. i looked from underneath to see if the sensor was in all the way and it was. i reassembled manifold and plugged in sensor. i started it up. i could tell an immediate difference even though the truck is cold natured. at 11:30 at nite it was time for a test drive. i wasnt used to all this power and was peeling rubber. i took it out on the highway. when i accelerated normally there was no problem and it was nice to set the cruise ar 65mph. however when you stomp the accelrator to the floor quickly it would cut out. but if i accelarated moderately there was no problem. i am very happy because i can use it to haul things and i am not a hot rod anyway. i hope this helps others. once again i am in deep gratitude to members tow guy and fallen4shell. thank you!!!
 

Last edited by the_tow_guy; 04-17-07 at 09:31 AM. Reason: Fixed unnecessary censoring.
  #17  
Old 04-17-07, 04:49 AM
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you're welcome and I'm happy to hear that took care of your problems. Those fouled spark plugs may be causing it to cut out like that under load like you described...I would change those too if it doesn't go away.
 
  #18  
Old 04-17-07, 09:33 AM
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Not sure on that old a vehicle, but the computer might have some "learning" to do, too. Sounds like it was quite the project.
 
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