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Old 08-31-2013, 11:37 AM   #1
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Surging Stuttering at highway speed

I have an 02 sport 4.0 with auto trans and haven't had any codes or cel but have been having a stumble or surge while driving highway speeds. (60-70) I first thought I had gotten some really crappy gas and that still may be true but I started searching the forum and this is what I came up with.

After treating the fuel and no longer filling up at the suspect location, stumble was still there. Not major just a seat of the pants sensation and maybe couple hundred rpm drop. Having read up on the torque converter lock up issue in the 32rh I added an anti-shudder treatment and dont think that was the issue either. ( I have about 20k on a fluid and filter change and it has been shifting flawlessly - I also have a deep pan on it for the extra quart capacity) I wasn't having any stalling or dying issues so I didn't want to replace the crank or cam sensors. I wound up replacing the TPS and IAC to see if that would solve the problem and it seems to have corrected the issue. I still think I feel a faint surge at highway speed but it could be in my head.

My question for those who have experienced something like this, should I go ahead and replace the engine management sensors like the MAP or crank or cam sensors? Would it do any good or would it just be spending money that isn't necessary? I normally don't replace anything unless its an upgrade, because I don't believe in throwing parts at a problem but remember, I am not getting any codes at all.

As a side note, I have noticed a 1.5 mpg increase after the two sensors were replaced. Nothing else has changed. Could my TPS have been bad and not thrown a code? Any insight would be appreciated, thanks.

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Old 09-09-2013, 12:05 AM   #2
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Still looking for input if anyone can help.

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Old 09-09-2013, 12:42 AM   #3
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Clogged cat? That would be more of a loss of power though
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Old 09-09-2013, 07:08 AM   #4
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To answer your last question, yes these sensors can go bad and not throw codes.
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Old 09-09-2013, 09:23 AM   #5
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sounds to me like the throttle body might need cleaning..........
some fuel additives / injector cleaners might help.
most shops can clean the throttle body in just a few minutes.
just food for thought
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Old 09-11-2013, 10:08 AM   #6
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Last year I cleaned the throttle body to shiny new status. I've been running some seafoam in the last two tanks to clean out the fuel system.
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Old 09-11-2013, 08:34 PM   #7
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Had the same issue and replaced my tps. Thought it was cured, but problem came back. Bought after market tps, not a Mopar. From what I've read this could be a problem. I'm going to try a new Mopar TPS. Good Luck
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Old 09-11-2013, 08:41 PM   #8
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It doesn't hurt to have your cat checked. If it is going bad, eventually you will know. Mine went bad and was changed, and obviously I had all your signs and worse by the time I figured it out.
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Old 09-16-2013, 08:02 AM   #9
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I'm hoping that is not it as I have three cats. Still no codes from the computer so I'm a little stumped on this one.
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Old 10-05-2013, 07:35 PM   #10
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Update: I began suspecting the fuel injectors after a little research. I went with precision auto injectors for a lower price over new ones from NAPA or Oreillys. Much quicker start up, no loss of power on hills or surging at highway speed. I think the stock injectors (at least one or two) were spitting lots of fuel. Anyway, these are the "upgrade" injectors with the 4 hole instead of one. Honestly I would have used stock again except for price. These are marked ford but fit the rail perfectly, and my fuel pressure was almost at 49psi so it appears to have solved the minor problem. Time will tell if I get any increase in mileage. If anything I'll bet back to stock numbers.
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Old 10-05-2013, 07:38 PM   #11
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probably the ford 19 pound injectors. Don't think you will see an MPG increase over what it was stock though.
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Old 10-29-2013, 08:45 AM   #12
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Originally Posted by Big Sarge View Post
probably the ford 19 pound injectors. Don't think you will see an MPG increase over what it was stock though.
You are right, my stock numbers are between 14-16 on the factory window sticker and I've been getting 14 or 15. I have noticed better drivability and oil is cleaner. I think calling it an upgrade is a stretch, just routine maintenance. I am up from 12-13 mpg that I was getting due to a bad injector so I'll call it good.
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Old 11-15-2013, 12:32 PM   #13
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lost torque converter

Just to update this thread, a couple days ago I got a CEL and the code showed P0740. Torque Converter was not locking up. When I got home I drained the pan (I have a plug on a deep pan) and the fluid was ugly brown with clutch material in it. So a rebuild is in order. I am not having much luck with this TJ but at least I have finally found the mild surge problem.

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