1997, Taco, 2RZFE, 2.4L Idle Air Control Valve?

Symptom: Idles high until it warms completely; Engine Light; PO500 OBD

I haven't done much research yet, but found somewhere that this could be the Idle Air Control Valve.

1. Any other possible causes?
2. AutoZone price $185.00 - $225.00
3. RockAuto Price $112.00 - $178.00
4. JC Whitney $43.56 - $49.99

Not sure if this is a case where I should buy the $225.00 Duralast from Autozone, or, RockAuto which lists AirTex/Wells, or JC Whitney which does not seem to list the Mfgr.

If anyone has any experience with this engine code/repair, any other possible causes, please give any input that may be helpful.

Also, if anyone has any experience with JC Whitney and if their parts are quality, or not, please let me know.

Thank you for your time and efforts!

 

If you are going to spend $225 for an aftermarket one, you might as well get an OEM one. Also, I have read that this is one of those parts that you want to replace with OEM only.

 

Found a great download here on Tacoma World. A complete Manual, from Toyota, on my model. Prior to spending a bunch of money, I think I will remove the throttle body and give this thing a thorough cleaning, a new throttle body gasket and then see what I have. What I could see past the throttle plate was gunky. I just read something about a scan tool needed to adjust the throttle position sensor, can anyone explain this to me?

Thanks for the reply nzbrock

 

What "Scan Tool" are they talking about? Sounds like a Oscilloscope!

 

A $10,000 Snap On Verus scanner. Lol.

 

With that said, is there any way to adjust the Throttle Position Sensor without a $10k scanner? Ideas anyone?

 

So, I removed and thoroughly cleaned the entire throttle body. It was gunked up pretty badly on the back of the throttle plate and everything downstream from there. I also cleaned all the passages thoroughly. I positioned the throttle position sensor according to where the clean spots where the screws had always sat before. I don't have access to a scanner. It runs much better, but it seems that the idle is just a bit fast.

Can this thing be dialed in without a $10K scanner?

 

I don't believe that you have to adjust the TPS on 1st Gen Tacoma's (except 03-04 6cyl. models -with throttle by wire).. Do you have a pic of your TPS..

 

Yes you can adjust it, the procedure is in the FSM. You want the throttle position to read between 7-11% at idle.

 

Yeah it is adjustable.. You should be able to adjust it with a OHM meter and feeler gauges

 

I have a four pin connector. My Haynes does not have an ohm chart for 4 pin set up. Only 3 pin. Between the top two pins I read 3.36k ohm at throttle closed. When Throttle 100% open I read 1.08k ohm.

Scratching my head. ???

 

I know this probably won't help, but this is from the 99 Tacoma service manual... I could have swore the 95-97 were the same (3wire TPS), but I guess not...You may want to try doing the procedure with the ohm meter and feeler gauges here.. I had a 91 toyota truck i replace the tps on and adjusted it with a ohm meter and feeler gauges(it was 4 pin TPS on it as well)

 

Here's a link for the feeler gauge sizes on the older models.
http://www.lcengineering.com/LCTechPages/pdf/Throttle Position Sensor Adjustment.pdf

 

all of these adjustments are in vain if the throttle body shaft is wore... the throttle blade may or may not sit perfectly square in the bore and if it does not too much air bypasses the edge of the throttle blade for the IAC to adjust for.

 

Maybe so, but i would at least try to adjust it first

 

Good morning everyone and my thanks to those who contributed; every little bit helps. I was looking at the Haynes manual and a FSM that I downloaded from this site. (Good job, whoever did that.) The FSM said to check the ECM then says to replace TPS, assuming the TPS to be bad. The Haynes only shows the diagram for the 3 pin TPS set up. However, I finally decided to do it "by ear." and test drive it. So, before the test drive I got in, found my OBD was still connected, I cleared the code, and I found "Live Feed" engine stats on the OBD. Included in the live feed was the percentage of TPS. I remembered what nzbrock said about 7 - 11%

So, I used the OBD and tried for a "perfect" 8.5%, but I couldn't make that happen, so I settled for 9%. I drove to work this morning and the truck is doing great so far.

I started this with the Intake Air Control Valve (IAC) giving me problems, so I removed the throttle body, found thick gunk everywhere downstream of the throttle plate and in the various vacuum ports. I cleaned the entire assembly thoroughly. The IAC has a long magnetized shaft that is controlled by a solenoid which controls the flow of the IAC. As suspected the shaft could not function properly due to the gunk. When I first tried to turn the shaft I could feel sticky spots. I cleaned it very thoroughly. Then, after I reinstalled the throttle body and ran the truck I got the TPS code. You already know the rest.

I got a good signal from the ECM. The resistance values were different from the 3 pin set up in the Haynes, so I had no reference to go by to adjust by resistance readings, but through the travel of the throttle the readings did stay smooth and without dead spots. Time will tell for sure. I drove the 20 miles to work today, up on to I70 through downtown INDY and to my job. It ran well. I am hoping I got off lucky only having to buy a gasket and a couple cans of Gumout.

Again my thanks to everyone who contributes by sharing their knowledge. I love being able to come here and talk to people who are familiar with Tacos.

I will post again in a day or two about how it is doing.

HairBear

 

Final comments. Truck started acting up again. So, I replaced the IAC $185.00, I also bought the TPS. Then I was able to adjust the TPS easily. Now it is doing well.

Upon disassembly, I found scratches in the cylinder of the IAC Valve gate that ran in the direction of rotation. Considering the nature of the problem, I thought new OEM was best. I don't like "Throwing Parts" at a problem, but in this case a new set up is best. I finally found the procedure for adjusting the 4-pin TPS in the Haynes manual, it was, of course, in a complete different chapter than the 3-pin.

As always, I am grateful for all suggestions/advice.