hunting idle/rough idle/transmission/my paranoia

[vc]

I just became interested in DIY auto stuff after coming across ETCG on you-tube and so started paying some attention to my CRV (2004 Honda CRV automatic FWD 4 cylinder with 105K miles). My observations are as follows.

-When I start the car from cold, engine rpm is 1100 and comes down to 600-700 once it warms up. Is this ok?
-While driving when I accelerate (up to 40 mph), the engine rpm go up to 2500 and will drop suddenly to 2000 or maybe 2000 to 1500 rpm(even though my foot is on gas pedal and I am still accelerating). On highways when I accelerating to get to 65-70 mph, rpm will go unto 3000-3200 rpm(and not more) and drop back to 2500. If I keep accelerating it will go back up (and of course I feel a jerk).

Some additional information-
-Sparks plugs have been changed NGK. This issue (above) existed before the spark plug change.
-Power steering fluid seems a bit low.
-Transmission oil has not been changed.I checked transmission oil-level seems ok and it’s not dirty.
-Check engine light is not on.

Question
Is this ‘hunting idle’ or ‘rough idle’? If so I will look up the sticky on the forum. If not, what do I need to look for. Any insight will be appreciated.

And a suggestion-If the sticky can describe what a hunting and/or rough idle is that will make it even more helpful for newbies like me.

Thanks guys

Topic

[EricTheCarGuy]

More detailed information on idle issues can be found here. I would suggest reading through it first.

http://www.ericthecarguy.com/faq/solving-automotive-idle-problems

Good luck and keep us posted.

[vc]

Thanks Eric. I read the faq and the sticky. They tell me stepwise what to do, after it’s determined that a hunting idle or rough idle observed/experienced. Also by idle I understand that car is not being driven while My car is experiencing rpm fluctuations while being driven. So I am confused and if my message comes across as disjointed/incoherent, my apologies.

I am trying to determine if my observation’s about rpms while driving point to an idle/hunting idle /rough idle or something else? BTW I pulled codes on my car and there are no codes. Any insight will be appreciated.

Thanks again for all the prompt reply and superb videos. I have your videos playing on an ipad in garage and follow them step by step.

[Tom]

Idle means when the engine is running, not in gear, in either neutral or park, and you are not pressing the gas pedal down.

What you are describing is not during idle.

RPM’s normally fluctuated while driving, even while accelerating, as the transmission changes gears, and when it locks up the torque converter. This is normal behavior. If any of those RPM changes cause a clunking, or a harsh shuddering of the car, then perhaps there is something that needs to be paid attention to, such as a worn engine mount, low transmission fluid level, or some other issue at play. If the RPM changes are smooth, then there is very likely nothing to be concerned about.

[vc]

Thanks Tomh

I did not hear experience clunking, or a harsh shuddering of the car(2004 Honda CRV automatic FWD 4 cylinder with 105K miles) during the rpm drops (while accelerating). The car shifts nicely. However, while driving when I accelerate (up to 40 mph), the engine rpm go up to 2500 and will drop suddenly to 2000 or maybe 2000 to 1500 rpm(even though my foot is on gas pedal and I am still accelerating). On highways when I accelerating to get to 65-70 mph, rpm will go unto 3000-3200 rpm(and it will not go up any more) and drop back to 2500. If I keep accelerating it will go back up (and of course I feel a jerk).

So is this an engine issue or transmission issue or I am just being paranoid? Any insights will be appreciated

[Vic Sorlie]

From reading your description I think you’re seeing normal transmission operation. When accelerating from a stop the transmission starts out in 1st gear (low ratio) then will shift to higher gears automatically as your speed builds. As the transmission shifts to higher gears the engine does not have to turn as fast, hence the drop in RPM. When at cruise and you want to accelerate, pressing the gas pedal causes the transmission to shift down to a lower gear, increasing engine RPM.

[Lorrin Barth]

To increase gas mileage a little in automatics the makers put clutches in transmission torque convertors that remove the normal slippage in the convertor. However, when the clutch in the convertor is locked you get good mileage but don’t have much power. So, the computer unlocks the convertor clutch when you try to accelerate. This causes the rpm to go up. When the convertor clutch locks again the rpm goes down.

[Author]

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