5vz-fe idle issues

Hey TW,
First post here, been a lurker on here for a little over a year, very helpful forums! Anyways my truck will not seem to idle right. Needed to replace original IAC because the truck would be a pain to start intermittently when the engine was cold and almost all the time when hot, and after a few months of that issue I tracked it down to the IAC and cleaned it, and made no difference, so I replaced it. The new IAC solved the starting issues, but now has weird idling issues along with the new 2nd IAC I got hoping the 1st new one was defective. When cold starting with either of the new IAC's, the truck cold idles at 1000, used to be 1500 with the old IAC. It doesnt even drop when warmed up, it stays at 1000. Then when its in drive or reverse, it will go to around 700, then sometimes creep down to 500. Im at a loss because I have replaced:

MAF
2 new IAC's with that share the same issue (One from Oreilly, other from Napa)
Engine coolant temp sensor (ECU sensor not gauge sender)
TPS (truck threw a code for it 3 months prior to this issue)
PCV (because I was checking the old one and it was so old it broke, had to buy a new one)

Im basically at a loss, as I have reset the ECU 2 times and it still is doing it. I dont know what else to do because once warmed up and besides idling issues, it drives fine. Nice to get more ideas of what else I could be missing. Me replacing the original IAC, and buying 2 new ones all happened within these 2 days. Hopefully this issue is something thats obvious to you guys but not me. Sorry if my explanation is weird, if you need to ill ellaborate if needed. Thanks!

 

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I would want to see what the sensors are reading when the issue is occurring (coolant temp and TPS would be 2 of the major ones when it comes to idle speed).
Are you getting any codes? If so what code numbers?
Files below are from FSM on testing Idle Control Valve operation.

 

What are you expecting it to idle around? Is it just me or does it sound like it’s actually gotten better for you, not worse? I believe a normal idle in PARK should be around 750-850 give or take a little. So it seems like you’ve actually gotten closer to that… which is good.
I think 1000 rpm cold idle is more of what you want than a 1500 rpm cold idle.

 

x2

 

Might have some wear in the throttle shaft in the throttle body.

 

Thanks, I appreciate the FSMs. I dont have any OBDII scanner to read what the sensors are reading nor have anything to test the testing port (on vehicle IAC test). Thats why I basically just bought new IAC's, might end up buying the OEM Toyota one. The old IAC idling was within specs and worked fine besides the crappy starting, seems the new IAC's are causing the issue, but I dont understand why.

The old IAC was in idling spec, 1500 at cold start then would drop down to normal idle which is 750 +/- 100, sorry if you got it confused as it held at 1500 the whole time cold . These new ones start at 1000 and hold at 1000 cold and hot engine temps, then when in gear D or R it is normal 700ish idling, then would sometimes drop down to 500, which some people get, so im more concerned about the cold start idle. My friends 1st gen tacoma starts at 1500-1400 rpm on cold starts then drops down, and his truck idles at 800 in park, while mine is 1000 in park when the engine is at operating temp. Like mentioned above though the only reason why I replaced the old IAC is because the engine wouldnt want to start and keep running.

Thank you all of you for responding, I appreciate it.

 

Dirt cheap OBD2 scanner. Here's the one I use.

$25 Foseal OBD2 Scanner, WiFi Car Code Reader Check Engine Light Diagnostic Scan Tool for iOS and Android

https://www.amazon.com/Foseal-Impro...ix=obd2+elm+scanner+bluetooth,aps,127&sr=8-13

 

Thank you for the OBDII scanner, ill make sure to order it.

As an update this morning I started it and it now has a high idle of 1900. Wont drop down even when the engine is at operating temp. I hope im just getting crappy parts, because usually I have really bad luck with getting defective parts, im like a magnet for them. Last time I did brakes I went through 5 sets of defective brake calipers.... Im probably just going to order the OEM Toyota IAC, and see how that works out compared to the ones I have now from Napa and Oreilly. If anyone has more suggestions let me know, im open to them, this isnt a daily driver so at least im not scrambling to fix it. Thanks!

 

Wrong account logged in.. just realized that.. I found my old account from like 5 years ago and forgot I logged into it.

 

Wouldn't suprise me to get crap parts, we deal with it every day at the shop.