annoying, unexplained problem
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Joined: Mar 2006
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annoying, unexplained problem
anyone had this problem? or have any suggestions?
1997 F-250 HD 7.3L PowerStroke TD
110,000 miles
Periodically, without warning, engine suddenly drops RPMs , similar to the drop when you let up on the accelerator to slow down or brake. For a second or two, Wait to Start light comes on; then goes out. No other dash warning lights come on. All gauges remain in normal range, with no fluctuation. If you maintain pressure on the accelerator, truck won’t accelerate. RPMs do not drop below idle speed. If you let up on the accelerator and push down again, truck responds normally; accelerates, etc.
Usually only does it once. Can happen at highway speed or at low speed. Might not do it for a week or two. Might not do it for months. Might do it every day for a few days.
Has been doing it since January. Did this about a year and a half ago. Usual diesel mechanic was unable to duplicate the problem or figure out what it was. During a routine checkup, however, he did replace GPR and it didn’t do it for a year and a half.
Two other diesel mechanics I talked to said they didn’t have a clue. Never heard of it before.
1997 F-250 HD 7.3L PowerStroke TD
110,000 miles
Periodically, without warning, engine suddenly drops RPMs , similar to the drop when you let up on the accelerator to slow down or brake. For a second or two, Wait to Start light comes on; then goes out. No other dash warning lights come on. All gauges remain in normal range, with no fluctuation. If you maintain pressure on the accelerator, truck won’t accelerate. RPMs do not drop below idle speed. If you let up on the accelerator and push down again, truck responds normally; accelerates, etc.
Usually only does it once. Can happen at highway speed or at low speed. Might not do it for a week or two. Might not do it for months. Might do it every day for a few days.
Has been doing it since January. Did this about a year and a half ago. Usual diesel mechanic was unable to duplicate the problem or figure out what it was. During a routine checkup, however, he did replace GPR and it didn’t do it for a year and a half.
Two other diesel mechanics I talked to said they didn’t have a clue. Never heard of it before.
Posting Guru
Joined: Oct 2005
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From: Wisconsin
Hey there. welcome to FTE!
it sounds like a fuel problem to me. have you checked your fuel filter??? may be time for a new 1. or even the fuel pump may be going out.
my last guess would be the CPS {cam positioning sensor} but im not 100 % sure what it is. some other guys really know what there talking about on her, so hang tight and wait for some replys. they can help you out so much!
Mitch
it sounds like a fuel problem to me. have you checked your fuel filter??? may be time for a new 1. or even the fuel pump may be going out.
my last guess would be the CPS {cam positioning sensor} but im not 100 % sure what it is. some other guys really know what there talking about on her, so hang tight and wait for some replys. they can help you out so much!
Mitch
Post Fiend
Joined: Apr 2004
Posts: 12,835
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From: Silver Lake Dunes, MI
well the gpr would have nothing to do with what you describe. the cps is possible. another possible problem is a intermittent wiring issue with the tps on the throttle pedal. these trucks don't have a throttle cable, its all eletronic. there may also be a dead spot in the tps but you would notice this everytime you accelerate. is there a check engine light on? even if there isn't i would have it scanned for codes.
does the engine die right out or does it still run?
does the engine die right out or does it still run?
Senior User
Joined: Feb 2004
Posts: 392
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From: Lamesa,Texas
tach acting funny? Sounds like a cps is a possibility. Even if it is not the problem, you might consider changing it or atleast getting a replacement. 110,000 is about where mine started acting up very intermittently. good luck.
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thanks for the ideas.
fuel filter was replaced. no other indications of fuel pump problem.
check engine light doesn't come on. truck has been scanned for codes the last time this problem arose.
don't have an after-market chip.
engine doesn't die. keeps running.
will have CPS/TPS checked out.
fuel filter was replaced. no other indications of fuel pump problem.
check engine light doesn't come on. truck has been scanned for codes the last time this problem arose.
don't have an after-market chip.
engine doesn't die. keeps running.
will have CPS/TPS checked out.
Last edited by bob_k; Mar 10, 2006 at 05:52 PM.
Senior User
Joined: Feb 2004
Posts: 392
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From: Lamesa,Texas
my truck never showed a code. It would sputter or die(if idleing) then it might run fine for an hour, a day, or weeks before it would happen again. Good luck
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From: STEPHENVILLE,TX!!!!!
sounds like its loosing power for just a split second. could be a loose ignition switch?? battery with a shorted plate and its droppin voltage for a second?
it dosnt seem like its the self test since only the WTS light is coming on. its like someone turned the key off and on really fast. what sensors make the pcm think the motor isnt running?
dang electrical probs are the worst.
do you have a chip in the truck?
it dosnt seem like its the self test since only the WTS light is coming on. its like someone turned the key off and on really fast. what sensors make the pcm think the motor isnt running?
dang electrical probs are the worst.
do you have a chip in the truck?