Crazy idle problem on 5VZ-FE - surging from 1500-2500rpm every second.
01-20-2017, 09:17 AM
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Crazy idle problem on 5VZ-FE - surging from 1500-2500rpm every second.
Hey guys, I'm actually a T100 guy but posting here because there are so many more of you with 5VZ-FEs. My usually trustworthy '97 Toyota T100, 2wd, AC, 3.4L, 5sp started acting really weird. I first noticed that the idle went way up from its normal 700rpm to 2500rpm over the course of a couple days. Then it started to surge the idle from 1500 to 2500rpm. It does this at idle and while driving. AC on or off is the same.
I reviewed a bunch of videos and forums which led me to clean out the MAF sensor, the IAC valve, and the throttle body. The MAF looked clean to begin with and I tested it with a multimeter and it seems to be responding normally. The IAC and throttle body were a little dirty but everything moved fine before cleaning. I also checked for degraded vacuum hose lines and replaced one with a little split on the end (the one with the blue zip tie in the video). Still no change. The coolant was about a quarter gallon low so I topped that off but it also made no change.
I should note that throughout all this, the Check Engine Light never came on except when I unplugged the MAF sensor to test if the CEL was even working.
I'm now out of ideas. I'm going to order a OBD2 scanner to see if I can find anything but don't have any idea what to look for.
Here's a video of what it's doing. Can anyone offer more leads? Thanks!
https://youtu.be/oRDxPiH82RQ
I reviewed a bunch of videos and forums which led me to clean out the MAF sensor, the IAC valve, and the throttle body. The MAF looked clean to begin with and I tested it with a multimeter and it seems to be responding normally. The IAC and throttle body were a little dirty but everything moved fine before cleaning. I also checked for degraded vacuum hose lines and replaced one with a little split on the end (the one with the blue zip tie in the video). Still no change. The coolant was about a quarter gallon low so I topped that off but it also made no change.
I should note that throughout all this, the Check Engine Light never came on except when I unplugged the MAF sensor to test if the CEL was even working.
I'm now out of ideas. I'm going to order a OBD2 scanner to see if I can find anything but don't have any idea what to look for.
Here's a video of what it's doing. Can anyone offer more leads? Thanks!
https://youtu.be/oRDxPiH82RQ
Last edited by partytime-excellent; 01-20-2017 at 09:22 AM.
01-20-2017, 09:36 AM
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Check for intake leaks around the TB using propane to see if idle increases more, and throughly check for hidden cracked rubber intake pipes on the "flexible" sections, sounds like Un-metered air is getting in after the MAF. Did you move or remove the throttle plate, it can hang up if not centered, I would also check the throttle, cruise (and kick down cable -Auto only)to make sure non are holding the throttle plate slightly open, the mount for the cable can also get bent but usually the opposite way giving you less throttle not a slightly open throttle plate. Not sure but perhaps the TPS could cause this if it was adjusted so that the throttle plate can't close aswell.
Last edited by Malcolm99; 01-20-2017 at 09:38 AM.
01-22-2017, 06:15 AM
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Went through the same problem recently.
I ended up replacing the throttle body. The new throttle body ($800) comes with a TPS and IACV so be aware of this before you start replacing parts of the TB .You can easily spend $400 replacing TB components and then still have the same problem.
Hope your fix is something simple.
I ended up replacing the throttle body. The new throttle body ($800) comes with a TPS and IACV so be aware of this before you start replacing parts of the TB .You can easily spend $400 replacing TB components and then still have the same problem.
Hope your fix is something simple.
