Surging 2004 Honda Accord

My ’04 Honda Accord 4 has a warm-up problem. It will serge for 5 or 10 seconds when it is nearly warmed up. I keep my hand on the shifter when I think this will happen. Sometimes it will jump to 5000 rpm. It can be very dangerous when stopped at an intersection. I, of course, have had it into the shop for days, but they couldn’t reproduce the problem. Any suggestions?
geneblumke@gmail.com

First, clean the throttle body and IACV (intake air control valve).

Does this car have a driver’s side floor mat? If it does, is it a secured Honda floor mat or is it a loose floor mat? If you have one, and it isn’t a secured Honda floor mat, remove it to rule it out as a factor. Actually, you might want to remove it regardless of what kind of floor mat you have, just to be safe.

Alternatively, you could take the car for a drive through an empty parking lot (but not on public roads until the problem is solved). If the problem repeats itself with the floor mat, look down and see if it is on top of the gas pedal.

Normally, I wouldn’t put so much stock into my floor mat theory, but if a mechanic has ruled out any other issues with your throttle control, I’m pretty confident this could be a factor.

If the car had a sticky throttle, and wasn’t surging, I’d suspect that too, but if the car is surging, it is likely to be something other than a sticky throttle plate. Still, it couldn’t hurt to have the throttle taken apart and thoroughly cleaned to rule it out, especially on a car this old.

I was thinking IACV issue, but while in there might as well clean the throttle too.

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Having recently replaced the IACV on my '98 Civic, I wouldn’t be surprised at all if that was the cause on a 15-year-old Honda, especially since my IACV problem was intermittent at first, and I had to wait for it go get worse before it could be diagnosed.

My IACV started out as a lack of power when the engine was cold, and the engine would stall when I gave it gas. It would self-correct if I let it sit idling for a few minutes. Eventually, when the problem got worse, the idle would surge up and down, but under load, it was fine. I didn’t experience it as surging of the car because my car is a stick shift, not an automatic, and it was in neutral when it would happen.

Oh, wow. Now that I’ve said that, I realize the IACV is a really good place to start after ruling out the floor mat.

@Blumke, after you rule out the floor mat, you might want to suggest to the shop that has the car to check the IACV. However, I’d replace it rather than clean it.