3.4 V6 - Poor Fuel Economy and High Idle
02-08-2010, 07:19 PM
#22
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02-08-2010, 07:33 PM
#23
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I replaced the IAC with one from a junk yard with no change. The original and the used IAC both tested ok according to the FSM. The TPS tests fine according to the FSM.
My running theory is that the gunk that I cleaned out was helping to seal up the perimeter of the butterfly valve. The next thing I am going to adjust is the 'idle opener' which is the 'piston' that is actuated by the vacuum hose on the back of the throttle body. It's basically a set screw and lock nut that controls where the closed throttle position is. I think its just not allowing the butterfly to close as far as it should...
I'm currently averaging around 17.5 mpg since I recently replaced the front O2 sensor (after the CEL came on). I have heard a lot of rumblings from others about getting poor mileage with the winter gas this year, so I'm chalking it up to that.
Good luck!
Jeremy
Last edited by ubermoto; 02-08-2010 at 07:37 PM.
02-08-2010, 08:01 PM
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Exactly the same problem.
Damn and I was thinking of replacing/cleaning the if IAC valve. Looks like this guy had the same problem https://www.yotatech.com/forums/f2/h...h-idle-165944/ He cleaned his and had success, different motor but same story.
BTW, not that it matters I have a 99 4runner 5VZ.
EDIT: Re: the little screw behind the throttle body, I wouldn't bother; I fiddled with it and it don't do a thing.
My Taco is still having high idle issues. It's a bit of a sore spot. When I'm just putzing around town with little throttle, and let off the pedal gently it still settles at about 1700 rpm; if I give it a good throttle squirt and then let off the gas pedal rapidly, the idle settles around 1100-1200 rpm. If I stop and its idling high then shut off the engine, then restart, it usually idles around 1100 rpm.
I replaced the IAC with one from a junk yard with no change. The original and the used IAC both tested ok according to the FSM. The TPS tests fine according to the FSM.
My running theory is that the gunk that I cleaned out was helping to seal up the perimeter of the butterfly valve. The next thing I am going to adjust is the 'idle opener' which is the 'piston' that is actuated by the vacuum hose on the back of the throttle body. It's basically a set screw and lock nut that controls where the closed throttle position is. I think its just not allowing the butterfly to close as far as it should...
I'm currently averaging around 17.5 mpg since I recently replaced the front O2 sensor (after the CEL came on). I have heard a lot of rumblings from others about getting poor mileage with the winter gas this year, so I'm chalking it up to that.
Good luck!
Jeremy
I replaced the IAC with one from a junk yard with no change. The original and the used IAC both tested ok according to the FSM. The TPS tests fine according to the FSM.
My running theory is that the gunk that I cleaned out was helping to seal up the perimeter of the butterfly valve. The next thing I am going to adjust is the 'idle opener' which is the 'piston' that is actuated by the vacuum hose on the back of the throttle body. It's basically a set screw and lock nut that controls where the closed throttle position is. I think its just not allowing the butterfly to close as far as it should...
I'm currently averaging around 17.5 mpg since I recently replaced the front O2 sensor (after the CEL came on). I have heard a lot of rumblings from others about getting poor mileage with the winter gas this year, so I'm chalking it up to that.
Good luck!
Jeremy
BTW, not that it matters I have a 99 4runner 5VZ.
EDIT: Re: the little screw behind the throttle body, I wouldn't bother; I fiddled with it and it don't do a thing.
Last edited by RAB1; 02-08-2010 at 08:21 PM.
02-08-2010, 08:46 PM
#26
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I fixed this same issue on mine by squirting PB Blaster in the rod that goes through the throttle body and excersizing it as well I backed off on the throttle set screw on the butterfly and reset it when it stopped... I attribute this to there being gunk in the rod area, then reset the ECM
I had this issue after replacing my engine and the ECM was already reset
I had this issue after replacing my engine and the ECM was already reset
Last edited by eddieleephd; 02-08-2010 at 08:48 PM.
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mikeworks (12-14-2020)
02-08-2010, 08:52 PM
#27
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The little screw did not seem to help me either but I believe it was the PB that did the job however I am not sure that the screw did not help... do not use WD-40 will cause issues later
02-08-2010, 09:19 PM
#28
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Ubermoto, I know you unplugged the TPS earlier with no change, but I recommend putting a volt meter on that thing and see if it's within range. The ECU may not have had enough time to adjust when you unplugged it back then and therefore ran high idle still. Just a thought. I think this would be a good idea for you too RAB1.
02-09-2010, 06:41 PM
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Well I drove it around today with the same symptoms but on the way home from work the idle started to get back to normal. By the time I was on my way to a friends house to rip the throttle body apart the idle was completely back to normal, 700 rpm in park or neutral.
So I guess the computer just need to learn that the throttle body was no longer gunked up??? Oh and I did the "O" gasket mod initially.
One happy camper here.
So I guess the computer just need to learn that the throttle body was no longer gunked up??? Oh and I did the "O" gasket mod initially.
One happy camper here.
02-20-2010, 11:45 AM
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So the saga continues... I am annoyed.
Still tends to idle around 1700-1800 on its own.
If the throttle valve is allowed to 'slam' shut (i.e. goose the throttle) when you are coming to a stop, the idle will drop to around 1100-1200 rpm.
If I stop and it's idling high, I can turn the engine off, then start it back up and it will idle pretty normal around 1000 rpm.
I haven't had a chance to get out and experiment with it recently since its been snowing.
Thanks for any ideas guys...
Cheers,
Jeremy
P.S. I put the ohm meter on both the tps and iac leads and they both check out within spec.
Still tends to idle around 1700-1800 on its own.
If the throttle valve is allowed to 'slam' shut (i.e. goose the throttle) when you are coming to a stop, the idle will drop to around 1100-1200 rpm.
If I stop and it's idling high, I can turn the engine off, then start it back up and it will idle pretty normal around 1000 rpm.
I haven't had a chance to get out and experiment with it recently since its been snowing.
Thanks for any ideas guys...
Cheers,
Jeremy
P.S. I put the ohm meter on both the tps and iac leads and they both check out within spec.
Last edited by ubermoto; 02-20-2010 at 11:48 AM.
03-07-2010, 11:58 PM
#33
From reading this whole thread not once did I hear you say you lubed the linkage on the throttle body!!!
From your stated facts i can shut it off and restart it idles fine you drive moving the linkage it hangs up and idles high . With the engine warm when it idles high have you tried moving the throttle linkage towards the closed position.
Now of course the cold weather will only make it worse. I see this happen quite often with the throttle sticking and not closing to quite where it should be.
Lubing this is part of my oil change routine
From your stated facts i can shut it off and restart it idles fine you drive moving the linkage it hangs up and idles high . With the engine warm when it idles high have you tried moving the throttle linkage towards the closed position.
Now of course the cold weather will only make it worse. I see this happen quite often with the throttle sticking and not closing to quite where it should be.
Lubing this is part of my oil change routine
03-08-2010, 07:37 AM
#34
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From reading this whole thread not once did I hear you say you lubed the linkage on the throttle body!!!
From your stated facts i can shut it off and restart it idles fine you drive moving the linkage it hangs up and idles high . With the engine warm when it idles high have you tried moving the throttle linkage towards the closed position.
Now of course the cold weather will only make it worse. I see this happen quite often with the throttle sticking and not closing to quite where it should be.
Lubing this is part of my oil change routine
From your stated facts i can shut it off and restart it idles fine you drive moving the linkage it hangs up and idles high . With the engine warm when it idles high have you tried moving the throttle linkage towards the closed position.
Now of course the cold weather will only make it worse. I see this happen quite often with the throttle sticking and not closing to quite where it should be.
Lubing this is part of my oil change routine
03-08-2010, 07:58 AM
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From reading this whole thread not once did I hear you say you lubed the linkage on the throttle body!!!
From your stated facts i can shut it off and restart it idles fine you drive moving the linkage it hangs up and idles high . With the engine warm when it idles high have you tried moving the throttle linkage towards the closed position.
Now of course the cold weather will only make it worse. I see this happen quite often with the throttle sticking and not closing to quite where it should be.
Lubing this is part of my oil change routine
From your stated facts i can shut it off and restart it idles fine you drive moving the linkage it hangs up and idles high . With the engine warm when it idles high have you tried moving the throttle linkage towards the closed position.
Now of course the cold weather will only make it worse. I see this happen quite often with the throttle sticking and not closing to quite where it should be.
Lubing this is part of my oil change routine
Thanks for the thoughts guys...
Please keep 'em coming!
Cheers,
Jeremy
03-08-2010, 08:28 AM
#36
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my next question on this is your coolant temp sensor giving a false reading to the ECM??
this could cause this as well and I believe that the one for the inside temp guage and the coolant sensor are different.. I remember this being attributed to this issue in a post I have read before!!
And have you checked for Vacuum leaks?? as Mt.Goat suggested??
this could cause this as well and I believe that the one for the inside temp guage and the coolant sensor are different.. I remember this being attributed to this issue in a post I have read before!!
And have you checked for Vacuum leaks?? as Mt.Goat suggested??
03-08-2010, 08:35 AM
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Ok im not a mechanic and im deffinately not familiar with yotas...But i had the same problem with my 86 p/u yota, what my problem was is that my idle sensor on my carb looked like some one had taken a ball ping hammer and smashed it lol. so when it would run fine when it was cold, when it got warmed up it would idle high as hell until it cooled back off. not shure if this helps but that was my problem...
03-29-2011, 04:55 AM
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It is still an intermittent issue. Never really solved it. When it settles on a high idle, I usually just 'blip' the throttle and it settles down.
I think my fuel economy was just cold temps and blended winter gas. I've been tracking my mpg over the last year + and it happened again this winter. Drops around 2-3 mpg in the winter.
I think my fuel economy was just cold temps and blended winter gas. I've been tracking my mpg over the last year + and it happened again this winter. Drops around 2-3 mpg in the winter.
