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Less than 7 mpg in my 94 Ram

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Old Dec 9, 2010 | 09:21 AM
  #31  
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Second one is on the other side of the thermostat housing. It is just for the gauge, so, if the gauge works, don't worry about it.

Have you changed your oxygen sensor?
 
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Old Dec 10, 2010 | 09:41 AM
  #32  
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so - no change at all ?
still got black smoke and rich smell ?

quick review - replaced lots of stuff including junkyard PCM, new O2's, egr, several other sensors and new to you injectors - all with no change. and its still going through gas at 1.5-2 times normal rate.
has it been connected to a diagnostic scanner yet. its probably time.
 

Last edited by dhvaughan; Dec 10, 2010 at 09:51 AM.
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Old Dec 10, 2010 | 09:44 AM
  #33  
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Originally Posted by L0krin
because it was throwing an internal PCM error code.
i just picked this tidbit out. do you have any CEL codes ?

edit - i think i found the answer in your first post.
you originally had a 53 error, and swapped out the pcm from an identical truck in the junkyard.
 

Last edited by dhvaughan; Dec 10, 2010 at 09:47 AM.
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Old Dec 10, 2010 | 10:42 AM
  #34  
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I have taken it to the shop twice, and both times I got to see the scanner hooked to the truck, all the sensors are reading within the recommended values, however the scanner showed the truck running rich and occasionally it would go to center but it would almost never read lean.

It is getting about 5.5-6.5 mpg now, I think its because of the cold weather, but it is still puffing the black smoke.

The only thing I can think of is if there is a vacuum leak that i missed, or if something is internally wrong with the engine.

I'm going to have to get out the WD-40 again and go over the vacuum lines again i think.

Another question, when the plenum goes bad, how wet will the inside of the intake be?
I pulled the throttle body off again, and the inside of the intake is completely black, and looks just a little damp, I cant really tell if it is gas or oil or a mixture of both, but if I slide my fingers along the sides they come out black.
 
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Old Dec 10, 2010 | 11:43 AM
  #35  
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Just a thought, did you check your air inlet tube for some kind of restriction. How about your firing order, are the wires on your cap going to the proper cylinder? Is there any way the distributer is off a tooth. Good Luck!!!
 
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Old Dec 10, 2010 | 12:09 PM
  #36  
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Originally Posted by L0krin
I have taken it to the shop twice, and both times I got to see the scanner hooked to the truck, all the sensors are reading within the recommended values, however the scanner showed the truck running rich and occasionally it would go to center but it would almost never read lean.

It is getting about 5.5-6.5 mpg now, I think its because of the cold weather, but it is still puffing the black smoke.

The only thing I can think of is if there is a vacuum leak that i missed, or if something is internally wrong with the engine.

I'm going to have to get out the WD-40 again and go over the vacuum lines again i think.

Another question, when the plenum goes bad, how wet will the inside of the intake be?
I pulled the throttle body off again, and the inside of the intake is completely black, and looks just a little damp, I cant really tell if it is gas or oil or a mixture of both, but if I slide my fingers along the sides they come out black.
There should be no gas in the intake as the fuel injectors are at the end of the runners by the heads. The intake should also be bare metal with maybe a hint of oil from the pcv valve.

If your intake is completely black then your plenum has been blown for a long time. When I bought my 360 out of a '94 2500HD the plenum was completely black and it had obviously been blown for a long time (only 103K on truck). What I found on the valves is what suprised my the most. The back of the valves were completely caked in carbon. It was thick too over 1/8" in most places. I wonder if your valves are in a similar condition. This would cause very poor airflow at all rpms and could cause the truck to run rich even if the injectors are supplying the proper fuel. The computer can only slightly modify the fuel curve so it may be unable to compensate for the lack of air and lean the motor.

I would suggest buying a couple cans of seafoam and mopar combustion chamber cleaner. Run them through the engine using the proper sequence on the back of the can. If there is an improvement in mileage you may have found your problem. I am not sure if the chemicals will clean the back of the valves all that effectively though. My parts washer would not clean any carbon off. I had to use a putty knife on every intake valve.
 
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Old Dec 10, 2010 | 12:59 PM
  #37  
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Maybe you should just sell the truck to me for $100 and stop dumping money into it and i could turn it into a trail truck haha im just looking out for your best interest
 

Last edited by jpsycoboy5; Dec 10, 2010 at 01:19 PM.
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Old Dec 10, 2010 | 01:16 PM
  #38  
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Originally Posted by L0krin
The compression was right around 130 when I last checked it, I will try to do another compression test this weekend.
I would assume its running on all cylinders, it doesn't sound like it has a misfire
I replaced the air filter
I was able to spin all four tires when i had it on jacks.
I believe there were two metal connectors in the coolant temp sensor, where is the second temp sensor? I changed the one that is up and to the right of the thermostat when looking at the engine from the front of the truck. I wasnt able to find a second one. I could change that this weekend as well.
Hey buddy you never assume you don't a one of a kind 7 cylinder dodge until you do a compression test on those back 4 cylinders stop being lazy and do those back 4 my truck didnt sound like it had a dead cylinder either until i did the compression test at your house haha
 
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Old Dec 12, 2010 | 05:11 PM
  #39  
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The spark plugs are hooked up right, I dont know if the distributor is off a tooth though. There is no restricting the airflow, I just put a new air filter, and the passage is completely open to the fender, and there isnt crap inside the fender.

I might try that seafoam, I dont like running different things through the engine, but I'm running out of other options, however the intake is completely black inside. I might be able to get pictures next time I work on the truck, that leads me to believe it might be the plenum.
 
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Old Dec 12, 2010 | 05:44 PM
  #40  
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Hi LOKrin, I am wondering if you have a shop manual for your 94 Ram. The reason I ask is because I have recently needed one to help me with my 99 Ram 1500 and I happened to find a person who has the manual online and believe it helps. Here is the link. Colin
http://cgi.ebay.ca/1994-1995-1996-19...item20b5b0a2ee
 
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