Engine surges when idling

4

4Runner93

New member
Hey guys, so went to look at a 99 today and mr an my dad test drove it. When checking the outside for cosmetic stuff, the engine would idle at ~800-900 but would surge and sound like it was almost going to die. When I watched it, it would bottom at 500 before recovering to 900. Any idea of what it could be? The seller said it could either be the throttle body needs cleaning or an air idle sensor...anything else it could be?
 
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Could also be your Idle Control Valve. The valve you are referring to is the EACV, electronic air control valve. That could be bad. I would also load test the alternator. It could be revving up to try and get more power to run the car, and then idling down because of lack of power.
 
been having this problem for a while. i wish i could fix it!
i've cleaned the IAC valve
cleaned TB plenty of times
cleaned MAF
replaced sparkplugs/ wire set
replaced fuel filter
been running injection cleaner from cheveron every 5 fillups or so
been filling up with only chevron and shell gasoline

still i get these surges when at idle...and it still shuts off every now and then...

what else to do???
 
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Surging is usually associated with a bad TPS (throttle position sensor). Dirty IAC is usually stumbly and rough idle and dirty MAF usually causes hesitiations as well as bad idle. The TPS can be tested for resistance, but they aren't too expensive to replace.
 
brian2sun said:
Surging is usually associated with a bad TPS (throttle position sensor). Dirty IAC is usually stumbly and rough idle and dirty MAF usually causes hesitiations as well as bad idle. The TPS can be tested for resistance, but they aren't too expensive to replace.
Click to expand...

TPS replacement. talk more plz!
edit* not that i want to go replacing stuff..but just some more info i can store
 
I was getting surging and after research and cleaning everthing else I could, I tried out an Autozone TPS for ~$15 IIRC. I didn't plan on actually using their crap parts, but I figured for $15 it was worth that to see if it made a difference. It did so I took it off, cleaned it up, brought it back, got my $$ back and bought an OEM one off ebay for ~$60. Problem solved and it's been about a year since.
 
brian2sun said:
I was getting surging and after research and cleaning everthing else I could, I tried out an Autozone TPS for ~$15 IIRC. I didn't plan on actually using their crap parts, but I figured for $15 it was worth that to see if it made a difference. It did so I took it off, cleaned it up, brought it back, got my $$ back and bought an OEM one off ebay for ~$60. Problem solved and it's been about a year since.
Click to expand...

Thanks for sharing your experience. It's posts like these that make this a great forum for sharing AND learning. :peace:
 
Anyone have a part number, Toyota is telling me this is a complete kit and come with the throttle body..... (sensor not sold separately).

A
 
Everyone beat me to it. I was going to suggest the TPS as well.

Check rock auto. They have them for my 2000 3.4L from $30-46. However it is not an OEM one I think.
 
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Can cleaning the Throttle Body cause the TPS or IAC to go bad?
I have a similar issue that only arrose after I decided to clean the MAF and Throttle Body. (If it aint broke...)
 
cleanin the throttle body thoe can make all the carbon build up get into the iacv i actually have to clean mine out since it doesnt like to start only when cold so its pretty much leaning towards that since i just cleaned out the throttle body not to long ago
 
Yoter said:
Can cleaning the Throttle Body cause the TPS or IAC to go bad?
I have a similar issue that only arrose after I decided to clean the MAF and Throttle Body. (If it aint broke...)
Click to expand...

If you get throttle body cleaner in the IAC Valve it can cause the truck to idle high. Sometimes extremely high around 2000 RPM's. If this does happen you have to remove the throttle body and then remove the IAC from the throttle body. Be really careful removing the IAC screws because they are very easy to strip. The Screws are brass and the Phillips head strips very easily. Ask me how I know. Spray TB cleaner liberally into thr IAC and let it soak. A pipe cleaner works well to clean it. Blow it out with compressed air and reinstall it. If you have done a good job cleaning it your idle will return to normal (750) as soon as the truck reaches operating temperature. It's hard not to get any TB cleaner in the IAC when spraying the TB. You can try to put a thick rag over the hole but it's almost impossible to keep the cleaner out. Hope this helps.
 
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