Engine rough on acceleration

[KelOfTheRockies]

Happy Saturday, Everyone!

So, I searched threads first, like a good boy. Didn't find much help beyond what I've already done.
Here's the story:

2000 Limited
240,000 miles
Been running great until about a month ago. I started getting very rough engine on acceleration.

If I barely press the small pedal, it accelerates fairly smoothly, but if I press any level from basic get-off-the-line, to WOT, the engine shudders and struggles for the first hundred yards or so, then smooths out.

I haven't been able to spot a particular gear or RPM where the shudder stops.

Hot or cold (even in negative degrees), the engine always starts instantly on turning the key.
Gas usage has been steady at just over 17mpg.
No CEL so far, except this morning. I was on the freeway at about 75mph when I noticed it blinking for a minute or so, then it went out.

I have a Foxwell diag box, but I don't see anything glaring out of order.

Steps I've taken so far:
New spark plugs
Replaced air filter
Cleaned MAF

I have a new MAF I plan to install in the morning, but I'm not confident it will have an effect.

Any suggestions on how to troubleshoot this would be enthusiastically appreciated.

—K

 

[19963.4lsr5]

Your check engine was flashing and then went out?

Usually in a missfire condition it will flash then go steady.

Your dialogue box is a code reader? If so what codes do you have when you say nothing out of the ordinary.

How old are your plug wires and the coil booties.


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[KelOfTheRockies]

Your check engine was flashing and then went out?

Usually in a missfire condition it will flash then go steady.

Your dialogue box is a code reader? If so what codes do you have when you say nothing out of the ordinary.

How old are your plug wires and the coil booties.


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Yes, the CEL was flashing while I was at highway cruising speed - no acceleration. After about a minute or so, the light went out, but the truck ran smooth and normal throughout.

Don't know age, but they wires and boots look fine.

What I meant was that my code-reader(Foxwell N630) had no codes and the live data for stuff like MAF and o2 looked within range

Anyway, I saw your post yesterday, but wasn't able to reply due to this site not responding for some reason.

In order to make a more informed reply, I put the Foxwell back on the car and this time, I looked at the "pending" codes, not the stored ones.

Pending was a Cyl 3 misfire code. Since I didn't know when that code was recorded, I cleared it and went running errands.

Twenty miles later I got home and put the Fox back on the car and this time I had a P0300 Random Misfire code.

Thinking it through, I concluded that it was possible that either coil 3 was failing, or just flakey. My thought being the one Cyl 3 misfire code, followed by 'random' misfire could be from the flakey coil missing back and forth on 3 and 5.

So I took a gamble and picked up a replacement coil on the way home from work and installed it before dinner.

Problem solved. The truck runs like new again. Smooth as glass acceleration and much better pull. Should really help my commute to work.

Thanks for the input, hope someone else can get some help from my story.

—K

 

[19963.4lsr5]

That’s good to hear.

Toyotas missfire algorithm isn’t that good. IMO.

Depending on brand of coil you purchased I’d look for a Denso if you didn’t get one. Put the non Denso coil in your toolbox as an emergency spare.


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[KelOfTheRockies]

That’s good to hear.

Toyotas missfire algorithm isn’t that good. IMO.

Depending on brand of coil you purchased I’d look for a Denso if you didn’t get one. Put the non Denso coil in your toolbox as an emergency spare.


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that's a great suggestion. I have several Toyota coils I grabbed a while back at salvage, but I can't find where I put them, so I broke down and spent the money.

Soon as I find them, I'll follow your advice

THX

—K