I brought my 2003 S in for 60K service to my local Honda dealer a few weeks ago. To the dealer's credit, they did figure out 2 of the 3 problems I was having with the car, but they seem to have no clue what to do about the 3rd, which has unfortunately gotten worse. The mechanic was able to experience the problem, but appeared to have no clue (he went from "it could be fuel" to "it could be electronic").

Generally happening most often when the car is cold, and when I'm in 1st or 2nd grear at around 2500RPM accelerating lightly, the car will actually drop in RPMs for a second before increasing. It can do that multiple times between 2000 and 5000 RPMs, making it feel a bit like a bumper car due to the sudden drop in RPM.

When this happens, the car is correctly in gear (not touching the clutch), and I've experienced it on a number of different gears, although it's most obvious in 1st/2nd. To add to the problem, I started the car this morning and it stalled twice while it was idling at a light. It mght be a different issue, but I saw it drop in RPMs the same way it has often done as described above.

The dealer suggested I drop it off with them overnight so they could start it cold, but given they get paid by the hour, I'm somewhat hestitant to let them "investigate" without having any clue as to what it could be. If anyone has experienced something similar, it would be helpful to know what a potential cause could be.

Thanks!

 

Sounds like a MAP or throttle position sensor is out of whack.

 

check fuel pressure...

 

So after leaving it with the dealer, the car is apparently reporting a problem with the engine thermostat. Could a faulty thermostat cause these issues?

 

No. Sounds like typical dealer BS to me.

I'm not even sure you can get a report that says problem with thermostat.

 

Are you talking about ECT sensor?

 

Some things you can do yourself before you get the dealer to milk you.

Clean out your IAC, throttle body (carb cleaner).

Map whack. Check your plugs make sure they all look similar.

 

Thanks guys! Based on your info, and after pressing the dealer, they admitted the thermostat was a temporary code that may not mean anything (although they kept showing me weird flow charts from Honda as justification for replacement). I also managed to get them to pay for the inspection, although they were clearly not happy

From doing some more research in the forum, it seems like others have also reported the low RPM "bucking" as likely being the MAP or TPS (although I hope it's MAP, as TPS sounds hard to fix). I'll give your suggestions a try.

Thanks again for helping me avoid getting fooled by the dealer

 

That's what we're here for.