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    Author Topic: Air Fuel Spark -- limited rev-ing  (Read 1992 times)

    Offline Robb

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    Air Fuel Spark -- limited rev-ing
    « on: February 26, 2007 - 12:15:44 PM »
    at least its Dodge...  

    I have a 98 Dodge Ram 4X4 with the 5.7L motor and automatic transmission   135,000 miles.  Engine and trans have given me very little (none) problems since I got it with 24,500 miles back in 2000.

    Just had some service work done to the front of the motor to fix some oil leaks and a Coolant leak.  Replaced Water pump, timing cover seals, and crank seal.   That was about a week ago, and a cost of about 1/4 of what the truck is worth, cause I was in a hurry. :stomp:

    Over the weekend was towing a 'Crawling Jeep back from Las Cruces, New Mexico when engine performance started degrading over the course of about 20 mins.  Drove there just fine, towing the Jeep and halfway back.  Degradation resulted in top speed of 20pmh on flat ground with accelerator pushed to floor, with little change of performance when disconnecting the trailer.  

    Doesnt seem to be the transmission.  Engine just not revving past 2000 rpm even in Neutral  

    Engine starts fine.  Engine Idles fine.   (Engine Idled for 3 hours straight while towstrapping it home, no problem)  Just wont rev past 2000 Rpm, whether in Drive or in Neutral.....   No Check Engine lights, no pinging. No leaks apparent.

    Got any guesses ?    Bad Fuel pump ?
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    70 Challenger SE  (440 SIX PACK / Keisler 5 speed, R/T SE replication)       68 Sport Satellite Convertible 383 Super Commando / 727  Survivor

    2002 Trans AM WS6 convertible:  DD
    1999 4Runner 4x4:  lifted-locked-armored  expedition vehicle
    1990 Jeep XJ 4x4:  Front Dana 60, GM-14bolt rear, 3 link, 4link, 5.38 detroits, beadlocked 40's, stretched to 110" wb  Rock Crawler


    Offline moper

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #1 on: February 26, 2007 - 12:58:23 PM »
    Unbolt the catalytic convertor, and try running it that way as an experiment. They have been known to melt cats during towing and heavy throttle driving. The cats melt, restrict the exh, and it just slows down or stalls. That would be first guess. Any check engine lights on?
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    Offline Robb

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #2 on: February 26, 2007 - 01:10:39 PM »

    Interesting, hadnt thought of that...


    Nope, no check engine lights.   No funny smells either.
    Logged

    70 Challenger SE  (440 SIX PACK / Keisler 5 speed, R/T SE replication)       68 Sport Satellite Convertible 383 Super Commando / 727  Survivor

    2002 Trans AM WS6 convertible:  DD
    1999 4Runner 4x4:  lifted-locked-armored  expedition vehicle
    1990 Jeep XJ 4x4:  Front Dana 60, GM-14bolt rear, 3 link, 4link, 5.38 detroits, beadlocked 40's, stretched to 110" wb  Rock Crawler

    Offline HemiDog

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #3 on: February 26, 2007 - 01:40:21 PM »
    First thing I would check is the fuel delivery system.  Fuel filters first and then the pump.
    Fuel filters should be changed about every 60,000 to be safe and is a cheap thing to check first.
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    Offline Oldschool

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #4 on: February 26, 2007 - 02:14:49 PM »
    Might wanna check the TPS...  (Throttle Position Sensor)    :2cents:   
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    Ken  --  In Georgia

    MOPAR-------"Built To Run------Here To Stay"

    Offline jvike

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #5 on: February 26, 2007 - 04:58:04 PM »
    Catalysator would be my guess. But it's more common on diesels. Maybe the trans have gone into "safe mode".
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    Member of The Rapid Transit System

    Offline Bullitt-

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #6 on: February 26, 2007 - 05:01:15 PM »
    Reminds me of when I had water in the fuel tank, would run with very low power but would not idle...but with todays computor controlls who knows.
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    Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
    Screwed by Photobucket!

    Offline matt63

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #7 on: February 26, 2007 - 05:58:21 PM »
    Does it have OBD2?  Just get a scanner plugged into it and see what faults are logged.  I know some garages will do it for a nominal charge if you don't get repairs done.
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    Matt in Edmonton

    '68 Valiant
    '73 Cuda 340 4 speed (408) SOLD

    sleepychallenger

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #8 on: February 26, 2007 - 07:19:37 PM »
    Quote from: Old's  Cool on February 26, 2007 - 02:14:49 PM
    Might wanna check the TPS...  (Throttle Position Sensor)    :2cents:   
    :iagree: this would be my first check point.
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    sleepychallenger

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #9 on: February 26, 2007 - 07:20:13 PM »
    Quote from: matt63 on February 26, 2007 - 05:58:21 PM
    Does it have OBD2?  Just get a scanner plugged into it and see what faults are logged.  I know some garages will do it for a nominal charge if you don't get repairs done.

    not the best place but auto zone will scan for free
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    Offline 67vertman

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #10 on: February 26, 2007 - 08:34:03 PM »
    Quote from: moper on February 26, 2007 - 12:58:23 PM
    Unbolt the catalytic convertor, and try running it that way as an experiment. They have been known to melt cats during towing and heavy throttle driving. The cats melt, restrict the exh, and it just slows down or stalls. That would be first guess. Any check engine lights on?

     :iagree:

    I had this happen on a 1997 Ram 1500, blocked catalytic converter.  It gave me the same symptoms yours is having. 
    It never gave a warning light or smelled funny, just lost power and wouldn't go over 30MPH.
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    Ron - Born and raised in Southern California

    I got the 1970 Cuda, but still need the hot blonde to ride shotgun!

    First car -1969 Road Runner 383 4sp

    Current ride - 1970 Barracuda 440-6 4 sp Dana 60  (4:10)

    Offline Robb

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #11 on: February 27, 2007 - 08:56:59 AM »
    Thanks everyone.

    Ill followup with results when I get it figured out. 

    Current plan is to start with Catl' Converter, and then if it checks out, hit the Fuel-Pressure port on the manifold with a guage before dropping the fuel tank. Maybe this weekend.
    Logged

    70 Challenger SE  (440 SIX PACK / Keisler 5 speed, R/T SE replication)       68 Sport Satellite Convertible 383 Super Commando / 727  Survivor

    2002 Trans AM WS6 convertible:  DD
    1999 4Runner 4x4:  lifted-locked-armored  expedition vehicle
    1990 Jeep XJ 4x4:  Front Dana 60, GM-14bolt rear, 3 link, 4link, 5.38 detroits, beadlocked 40's, stretched to 110" wb  Rock Crawler

    Offline basement

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #12 on: February 27, 2007 - 12:48:10 PM »
    My brother inlaw has a 98 dodge 4x4 and his cat plugged up, would idle ok but wouldn't rev above 2500rpm. Can you say 'sawzall'. :smilielol:
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    Offline Robb

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #13 on: May 21, 2007 - 07:38:51 AM »
    FOLLOW UP:


    It was the catalytic convertor that was the problem.    Ordered a new one online, and though I had to "massage it" to actually fit, it runs great again.

    Robb
    Logged

    70 Challenger SE  (440 SIX PACK / Keisler 5 speed, R/T SE replication)       68 Sport Satellite Convertible 383 Super Commando / 727  Survivor

    2002 Trans AM WS6 convertible:  DD
    1999 4Runner 4x4:  lifted-locked-armored  expedition vehicle
    1990 Jeep XJ 4x4:  Front Dana 60, GM-14bolt rear, 3 link, 4link, 5.38 detroits, beadlocked 40's, stretched to 110" wb  Rock Crawler

    Offline tactransman

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    Re: Air Fuel Spark -- limited rev-ing
    « Reply #14 on: May 21, 2007 - 09:57:57 AM »
    A little late but if anyone ever needs a cat for a Dodge Ram 3.9,5.2 or 5.9 engine,you can buy this Stainless Steel MagnaFlow y-pipe and cat for the same price as a cat by itself.It does flow better than a stock y-pipe,I replaced it on my truck and it made it louder and you can actually feel alittle more "seat of the pants" power in the upper RPM range. :grinyes: (I do exhaust as a business and I couldn't get a better deal)  :dunno:

    http://store.summitracing.com/partdetail.asp?autofilter=1&part=MPE%2D23285&N=700+4294923429+4294838974+4294908110+115&autoview=sku
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    Terry-tactransman 
    Torqueflite/Automatic Transmission Specialist
    Union, Mo.
    Give a man a fish and he eats for a day,teach him to fish and he eats for a lifetime.
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