# Flat Spot In Acceleration



## mootsman (Oct 21, 2006)

My 97 ka24e has developed a very noticeable flat spot in the acceleration from about 3100 to 3500 rpm. It almost feels like it suddenly retards the spark when I pass 3000. The plugs, wires, cap and rotor are all good. I ran some 44k through it, so the injectors should be clean. The fuel filter only has about 10,000 miles on it, but I could change that. I'm wondering what else to check.


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## zanegrey (Dec 5, 2005)

check the codes...


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## mootsman (Oct 21, 2006)

zanegrey said:


> check the codes...


OK. No light on, but I will see what it shows.

Thanks


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## mootsman (Oct 21, 2006)

No codes. What would cause this?


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## 4X4D21 (Mar 9, 2009)

vacuum leak possibly, but possibly not since engine had no codes, o2 sensor maybe, check your plugs and let us know what color they are


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## mootsman (Oct 21, 2006)

Thanks 4x4. The plugs are so new they barely have any color at all, but they look perfect. I could try putting a vacuum gauge on it I guess. It's not terrible, it's just a change, so I am trying to track it down. i need to do the fuel filter and see if that helps.


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## 4X4D21 (Mar 9, 2009)

that would be a good idea since its like 12 bucks and takes five minutes to change


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## bongo667 (Mar 2, 2009)

Is it always those RPM's or at those RPM's are you pushing the throttle down more?


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## mootsman (Oct 21, 2006)

Yeah, always at those RPM's. Don't know what you mean by pushing the throttle down more. I am pushing the throttle to accelerate. It accelerates smoothly at a rate corresponding to how much gas I'm giving it, and at about 3100 or 3200, it just seems to hesitate a bit, then at about 3500 or 3600 it takes off again. i have been busy and haven't worked on it again.


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## cjserio (Mar 18, 2008)

Do you happen to get a loud hum at those RPMs? So far, it sounds like yours is doing the exact same thing that mine does...even at the same RPM range. Either we both have the same problem or these engines just exhibit this behavior by their nature. I'm very interested to see if you can solve this.


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## mootsman (Oct 21, 2006)

No hum. This just feels like the spark suddenly retards a bit for a few seconds, or else the fuel flow gets restricted. That's what it "feels" like, I'm not saying that is what is happening. No missing, no humming, nothing else, just hesitation. Our lives got very chaotic right after my last post, so i haven't done anything about it yet. My wife drives the truck all the time and isn't even aware of it. Besides, we are getting an 02 Tacoma in a few weeks, so I don't know when I will get around to doing this.

My next step is to replace the fuel filter. Our 88 HB one time got really sluggish on the highway, or going up long grades, because of a plugged fuel filter. But i was young and foolish then, and I generally change them more frequently now.


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## zanegrey (Dec 5, 2005)

with the no codes or 55 i would clean out the gas tank..

it is prollie full of crap...


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