normal idling rpm? + other questions

[dwalin]

If im right i believe the target mark should be 750, but i mean a few hundred RPMs shouldnt make too much of a difference

few hundred rpms do make difference. first, it's a symptome of something wrong with an engine and this does disturb me, and second, it doesn't any good to fuel economy. considering that i have 11-12 mpg on a city cycle (instead of 15), i try to find every problem i can.

 

[dwalin]

My GM stuff says 700 for auto trans type vehicles (small 6 cylinder). That's what I am kind of use to. I can't find anything on my ford documentation.... all they say is that "it is not adjustable and is electronically controlled". I would say my Ex is nowhere near that... maybe 800 but probably closer to 900. I think it is high but it would appear alot of people have this. I think that this might be an indication of perhaps running too cool (ie. improper thermostat)... that's one of the diagnostic symptoms chart but they do specify any speed. Anyways, I am not saying that it will cause any problems but I think it is reflected in poor gas mileage as the vehicle tries to correct things by enriching the fuel mixture a bit and we all know what great gas mileage an EX gets already... :-(

yeah, the thermostat is already scheduled for replacement. today i've got a nice picture: i stand still waiting for a signal, engine's idling but engine temp gauge is jumping back and forth between 1/4 and 1/2 of the scale. i think that's a last nail in thermostat's coffin.
as for gas mileage, i've got awful one, 11-12 mpg instead of 15, that's city cycle. well, i guess creeping a lot in traffic jams doesn't improve mileage but still. that's why i'm so concerned with idling rpms, i think my engine eats up too much gas idling.
well, i do understand i'll never get great mileage, considering that i drive 50-60 miles every day and it takes four or more hours total time but still i can hope...

 

[dwalin]

Actually, I just did a search on the net and saw a "spec" for a 2007 ford sport and it indicate 625 in drive for a v6.... that's more like what I am thinking. Anyways, I replaced my IAC about 4 months ago because of the famous moose call and cleaned the maf. It didn't have any effect on the idle but the "moose" is gone.

well, 2007 explorer sport does have a little bit different engine, don't you think? anyways, what's that famous moose call? i'm sorry but i'm not native american speaker so i just don't understand this idiom.

 

[budwich]

That was just an example... :-0 anyways, I think that from my experience, that 800-900 rpm idle in drive is too high and probably indicates a problem somewhere although in general it runs fine. As you indicate, it probably results in a few % difference in MPG depending on your driving habits.

As far as the "moose", the IAC diaphram / unit "emits" this loud noise when it has a problem. Search on posts for IAC , loud noise. When your truck has the problem, you will know it....

 

[96limitedX]

i'm not talking about idle in drive...i'm saying sitting in park.. in drive it allways drops down to 500-600 or so rpms.

 

[budwich]

I think that I and dwalin were always referring referring to "in drive" conditions as these have the most impact on gas mileage and overall "in traffic" operation. Thanks for clearing it up. And as expected, the rpms should be closer to the 500 mark (on the wonderful tach) as opposed to closer to the 1000 mark. Now how do we get there. I check my ECT sensor (engine coolant)... it appears to be operating correctly. The IAT (intake air) seems to be a little high (temp wise lower resistance than expected) but I would have expected that to make the engine run slower.... but maybe because its "asking" for "leaner" that causes it to run faster????? Anyways, it would be nice if I could get it to drop a bit. It is stable and its an OHV 4.0.... so hopefully the intake is good, have check most of the bolt downs, seem good. Probably needs a visit to a machine and someone with good knowledge on what to look for as opposed to "let's change this sensor and see what happens and $$$$$ later".

 

[thewishkah]

Check your TPS(throttle posistion sensor) I had same Idle as you do and when I changed the sensor it dropped down and my idle is now consistant, I hope this helps.

 

[budwich]

Consistant isn't a problem.... its consistantly high.... ie. in the 800-900 range after "warm-up", it doesn't vary. I did some "work" today on things. Checked the ect... plug and unplug, measure resistant. Looked "reasonable".... tough to get at but eventually was able to do the "simple" test. Moved on to the iat, unplug measured resistance, seemed low indicating high temperature.... 20+C on a 8+C day but maybe the engine heat "helps" it. Removed sensor and cleaned it... for the fun of it... put it in a cup of cold water and then hot water.... seemed to respond appropriately 20C cold, 45C hot. Put things back together BUT also during replacing stuff including the shroud over the throttle linkage, I sprayed the linkage with lubricant. Not sure if it helped or not. Try the truck later today.... guess what.... after warmup, idle is now down a "bit".... maybe closer to middle (ie. between 500 and 1000... great tach...:-( ) maybe even a little closer to the 500 than the 1000. Not sure whether pulling /replugging plugs did something, the cleaning of the iat, or the lub on the throttle linkage (probably) but this is closer to what i would expect as "normal". Hope it helps.... if only I knew which one it was....???????????

 

[dwalin]

far as i know thats the idle speed for the 4.0 OHV..and i get 16mpg in town and 20mpg highway. i like that fact myself..higher idle means alittle more voltage from the alt.

*sigh* i guess i'll never get such a cool mpg. ;( though theoretically it's possible, if i'll do a full engine/tranny/transfer case/axles rebuild, fill 'em with synt liquids, load the vehicle with mods and then drive it like a grandma, maybe i'll be able to get 16 mpg in city. ;(

 

[dwalin]

That was just an example... :-0 anyways, I think that from my experience, that 800-900 rpm idle in drive is too high and probably indicates a problem somewhere although in general it runs fine. As you indicate, it probably results in a few % difference in MPG depending on your driving habits.

yes, i think so too. the current plan is to replace spark plugs and wires, thermostat, check pcv, tps and throttle body. after that, let's see what happens.

As far as the "moose", the IAC diaphram / unit "emits" this loud noise when it has a problem. Search on posts for IAC , loud noise. When your truck has the problem, you will know it....

ahem... my truck has SO many problems and emits SO many different loud noises that i just can't distinguish between them.
the other large problem is that i'm not a mechanic myself and there are just no decent explorer repair shops in this frigging town. ;( some garage shops do know how explorers tick but that's a real lottery... maybe they'll do, maybe they won't. you just pay 'em money and pray that they know what they're doing. ;( *sigh*

 

[dwalin]

i'm not talking about idle in drive...i'm saying sitting in park.. in drive it allways drops down to 500-600 or so rpms.

i'm sorry i didn't say that before but i get just a bit less than 1k rpms BOTH in drive and in park. it just doesn't drop below that line, and that's what i'm concerned with.

 

[budwich]

well, I don't know what happen to a previous post.... but anyways, after doing the things mentioned in the previous previous post, my idle has dropped to something closer to the 500 mark as opposed to something closer to the 1000 mark. I don't know if plugging / unplugging the ECT, unplugging / plugging / cleaning the IAT, or spraying lub on the throttle linkage (probably) has helped bring the idle down to probably something around 600-700. Wish I knew which one for sure but in the end, the result is what I am after. Hope it helps Dwalin.

 

[96limitedX]

i'm sorry i didn't say that before but i get just a bit less than 1k rpms BOTH in drive and in park. it just doesn't drop below that line, and that's what i'm concerned with.

ahh...i didnt catch that part

funny thing about my MPG...i drive it pretty hard..thats why i was so surprised when i did the math to figure out what i was getting

 

[Viper81]

to dwalin:

do you hear a hissing coming from your engine? if so i would say check all your vacuum hoses. maybe you have a leak somewhere. that will cause your rpm's to go up. My rpm's are around 900 on warmup and drop to just around 400-500 on warm idle (in park and in gear)

 

[exploder55]

i changed the upper and lower o-rings on my intake disconnect batt. for 10 min. reconect let it idle for five min. now it starts cold at 900 and idles warm at 550 rpm u can feel it chug a lil but never 1ce had itstall Ps i had a problem before replace them i wasnt just doing it