Not Happy Right Now! Sensor problem I think.

Markjr

Markjr

New member
My 4runner has been idling at random at 2,000 rpm's and has been getting more and more frequent now. It also does not start sometimes, just cranks and cranks. I tested the TP sensor with the meter and if I did it correct with all the ohm readings it looks like its good. Today I ripped it apart and sprayed cleaner in the Idle Air Control valve, let it sit then let it dry. Well I put it back together and it didnt do a thing. I read somewhere that the IAC regulates the motor when the car idles but when you step on the gas it lets the TP take care of the rest. So when I have trouble starting I step on the gas and it worked right away instead of cranking and cranking. So what would this mean, getting a new IAC sensor??? I hope not, there not cheap.
 
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Check your PVC valve and hose. It might be sticking and then unsticking causing havoc for the 4runner's ecm.
 
Thanks for the tip, I popped the PCV out, put it in gasoline, shook it, then dried it out. The gas practically turned black and the car runs great now!
 
So I started having problems again so just bought a new PCV valve, since then the truck has idled at 2200rmps. WTF. I'v tested the MAS, cleaned the IAC, replaced the PCV, such a headache. I have no time to even mess with this, what would it be? anyone?
 
Still having problems. Tonight I cleaned the MAF with MAF cleaner. I also took one of the battery terminals off to reset everything. Car would not start till I took both terminals off and cleaned them. So far from a 2 min test drive it still idles high. Tomorrow when I go to work its a 40 min drive 25% normal road, 75% highway so maybe it will reset when I drive. As for codes there are none but if this keeps up Im plugging in the OBD2 to my laptop and driving around to see what is going on with the sensors. Any suggestions with testing with the OBD2, like any numbers/codes to look for. Thanks for all your help so far guys!
 
There is a dashpot on the left side of the TB. Check the vacuum hose from it and see if your idle goes back down to normal. It might be out of adjustment.

You might have to put a vacuum on it and see if it sucks in. If it leaks, it could cause high idle issues.
 
Well the drive to work was ok, the first 10 min. were a little sketchy but after that I didnt have any problems. Hoping it stays that way.
 
So did you actually remove the TB and then separate the IAC from the TB to clean it, or did you just spray cleaner crap down the hole? Unlike a Jeep, spraying down into the hole won't work. In fact it'll make it even worse.

Check the butterfly on your TB also. Make sure it's not bent or getting hung up so it's not closing all the way. J-money$$$ had idling issues after cleaning his TB. Once he removed all the carbon behind the butterfly, it wouldn't make a good seal anymore and his idle went way up afterwards. The built up carbon itself was acting like a gasket to seal the TB opening. He ended up just buying a new TB from a junkyard IIRC and it idles good now.
 
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When it's idling high can you physically push down on the throttle to lower it back down? Have you tried adjusting the throttle cable? It's unlikely that it would tighten up over time but your issue sounds mechanical to me so I would start with the basics.
 
brian2sun said:
So did you actually remove the TB and then separate the IAC from the TB to clean it, or did you just spray cleaner crap down the hole? Unlike a Jeep, spraying down into the hole won't work. In fact it'll make it even worse.

Check the butterfly on your TB also. Make sure it's not bent or getting hung up so it's not closing all the way. J-money$$$ had idling issues after cleaning his TB. Once he removed all the carbon behind the butterfly, it wouldn't make a good seal anymore and his idle went way up afterwards. The built up carbon itself was acting like a gasket to seal the TB opening. He ended up just buying a new TB from a junkyard IIRC and it idles good now.
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I took the TB off, took off the IAC and cleaned it out completely. My butterfly is fine as well, it started idling high and then I cleaned it out so Im pretty sure thats not the problem.

As for the cable, that not has been changed or moved, I have not manually tried making it idle lower due to the fact that I am driving most of the time this happens.

Today it was sketchy till I hit highway, then once off of the highway it was fine. After work it was sketchy again. Then after some time driving around highway and city it worked great. Only problem is that it has worked great in the past, then 30 miles later or whenever, it just starts acting up again. I will be testing it with the OBD2 asap (probably Saturday)

Thanks guys for the help, I appreciate it.
 
The next time it idles high pull over and see if you can push the throttle plate closed at the trottle body. I'm having a hard time believing this is an electrical issue, throttle by wire didn't start until 01 or 02. I've never heard of it being an issue but unhook your cruise control throttle cable from the TB and see if that does anything.
 
It sounds like IAC or a vacuum leak to me. Do you have a haynes manual? They have lots of stuff you can check. For starters, if you pull of the three pin connector from the IAC and put power to terminals RSC and +B it should close the shutter and reduce idle speed.
 
I did mess with the TB when it was idling high and nothing worked. I just did a test with the OBDII and one we read it when it idled high, and then at normal. Everything stayed the same except something called the Timing advance. At 700Rpm's the timing advance meter read 10, when it idled at 2500Rpm's it read 30. Both times we read the meter we were stopped out of gear so there was no load on the engine. Other than this everything else was pretty much the same. Does anyone know what this would mean? I have been google searching and haven't found much yet.

Tomsiriv, I do not have a haynes manual and I have cleaned out the IAC with MAF cleaner and didn't skimp on cleaning it either, but are you thinking its either a faulty IAC or bad connection?
 
Some more info that I forgot was that the TPS always reads that its at 12% no matter what the RPM's were at. The only thing with this is that the OBD sensor was reading the RPM's just fine. Another thing I found was that if the Air-Fuel ratio is messed up then it makes the engine rev high. I'll continue to research and when I fix this I will post it. Hopefully that post will be coming soon :)
 
I'm surprised you don't have a trouble code of some kind. If the TPS is always 12% regardless of throttle position then it is not working correctly.

10deg timing advance at idle and 30 degs at 2500 is normal. The spark plug fires earlier when the engine goes faster so that the flame is not chasing the cylinder down the bore, but actually pushing it down. So to do this they have to start combustion before top dead center. In the old day they used to use centrifugal force and springs in the distributer to change the timing with speed. Now we have a crank position sensor and a computer to do the job right, so its a lot more reliable.
 
Tomsriv said:
I'm surprised you don't have a trouble code of some kind. If the TPS is always 12% regardless of throttle position then it is not working correctly.

10deg timing advance at idle and 30 degs at 2500 is normal. The spark plug fires earlier when the engine goes faster so that the flame is not chasing the cylinder down the bore, but actually pushing it down. So to do this they have to start combustion before top dead center. In the old day they used to use centrifugal force and springs in the distributer to change the timing with speed. Now we have a crank position sensor and a computer to do the job right, so its a lot more reliable.
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Ok thanks for the input the timing advance info helps because I couldn't find much on that from google. And there are no codes which is causing this problem to take longer to diagnose. Ill hopefully get more time to work on it some more this week.
 
Testing Sensors

Ok guys I need a little more input. Tomorrow I have some time before I go to work so I want to test my IAC and TPS. Someone told me that one way to test it to just unplug one and see if it lowers the RPMs or what not. Any suggestions, thanks guys!
 
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