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Old 08-11-2006, 02:26 PM   #1
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Re: 3.4L V6 Hard Start "hot" Cleaned IAC (Pics)

I was having a similar problem with my 99 as someone that posted this thread.

http://www.yotatech.com/showthread.p...r+idle+control

I went ahead and cleaned the Idle Air Control(AIC) as someone had suggested. It has been almost 2 months and I haven't had any issues with the "hot" starting since the cleaning.

The procedure is pretty much straight forward. You can use brake cleaner, carb spray, or mineral spirit to clean as well as a small parts brush and possibly a small flathead screwdriver to scrape off gunk in the hard to get area. I reused the rubber o-ring gasket and replaced the throttlebody gasket. I suggest replacing the rubber o-ring gasket moreso than the metal throttlebody gasket.

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Old 09-22-2006, 06:02 AM   #2
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Thanks for the pictures.

Can you please tell me why you used Kwick Seal? Were those two screws originally sealed? Did you remove those screws? If so, why?

Thanks.
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Old 09-22-2006, 10:03 AM   #3
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Quote:
Originally Posted by creekfisher View Post
Thanks for the pictures.

Can you please tell me why you used Kwick Seal? Were those two screws originally sealed? Did you remove those screws? If so, why?

Thanks.
Yes, those screws were originally sealed. I went in there to clean the inside as well. It looked pretty clean when I dismantled it. You could leave it alone if you'd like. I went ahead and used Kwik Seal to make sure it's sealed again. I could've used clear RTV Silicone as well, but I couldn't find it in my tool box at the time.

Also, make sure you use a Phillips head screwdriver with a good tip. It's easy to strip the heads of the screws anywhere on the throttlebody when dismantling. As you can see in the photos, I was using an impact screwdriver.

Haven't hard a problem with the truck starting since the cleaning.
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Old 02-27-2007, 04:47 AM   #4
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couldnt you just spray carb/injector cleaner through the intake while the truck was running?? i have done that numerous times with jeeps and it helps a lot with idleing but i havent tried on the tacos yet.........
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Old 03-30-2007, 04:55 PM   #5
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Do some vehicles not have an IAC? Awhile ago we asked autozone for one for a 1994 pickup 22RE and they said it doesn't have one?
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Old 04-20-2007, 08:32 PM   #6
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all EFI engines have an IAC valve, at least until '02. From then, im not 100% sure. But all 22RE's and 3VZ engines have an IAC.
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Old 03-18-2010, 04:57 PM   #7
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Just did this today (thanks for the write-up!) and thought I'd add my thoughts.

Ditto on using the impact driver on those 4 screws. They'd easily strip otherwise, but the impact driver did a great job.

Removing the two sealed screws from the solenoid will give you access to the magnet that actuates the valve, allowing you to open it and clean the IAC valve more thoroughly.

I ended up re-using both gaskets. I bought very cheap (~$1.50/ea) replacements from rockauto.com. The Fel-Pro replacement part numbers were 61087 (rubber one) and 61038 (metal one), both listed as throttle body gaskets for the 4runner 5VZ-FE V6 engine. The replacements, however, didn't seem to be quite the same shape as the originals, despite being labeled as OEM parts. They'd probably have worked, but both my originals seemed as good as new (the metal one needed a little scrubbing in TB cleaner), so I figured "Why mess with what works?" and left them alone. I'd just add that the Fel-Pro metal gasket seemed a little thicker and rougher in finish than the original gasket, but I don't think it would have affected performance.

As far as losing coolant when I removed the bottom two hoses on the throttle body...I just pulled them (they're a bit hard to access) and raised them up in the air, above the fluid level. I wrapped a little duct tape around them and taped them up in that position, but I didn't plug them or anything. I lost maybe a tablespoon or two of coolant, mostly from the IAC, but nothing worth mentioning.
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Last edited by pendrag; 03-29-2010 at 02:56 AM.
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Old 11-23-2011, 07:55 PM   #8
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I recently did this cleaning of the iac on my truck(did throttle body also), as well as replacing/cleaning injectors. I also cleaned the MAF trying to nail down my starting issue.

Before i did the cleaning/injector job, my truck would start fine although idle a bit high (2100/2000 cold) It would always start right up cold no problem. When starting warm, sometimes it would start/die immediately, or need more cranking than usual. (although, i learned that if it was going to "start up/die" I could give the gas pedal a quick punch, it wouldn't die.) So i'm thinking that its not a leaky injector as i had some problems before i replaced those.

After new injectors:
Now, my truck runs better than when i bought it from the dealer (@156k mi.) I am now at 199k, and the engine is hard to start most of the time(even cold). Now, when starting cold, the idle doesnt go higher than 1300 or 1400. Not sure if that's normal, but compared to before it doesnt seem ok. This might sound wierd, but its like the engine is stuck in hot-start mode. It definately is taking more cranking than before for some reason.

My question is this. On the back of the IAC, there are 2 screws which remove a small plate. I noticed by rotating the plate, the open/close can be adjusted on the IAC. Is it possible that when i put this plate back on, i didn't get it in the right position or would this not effect starting? Once i took the plate off, i quickly realized that removal of this part is unnecessary as it was rather clean inside.

My other hunch is the TPS. I had to replace this 2 years ago because i kept getting TPS error codes. I calibrated it the best i could (you hook a meter up to the TPS, and rotate until it shows an open circuit, as close as you can get it to reading resistance, then tighten it down)

I'm a little stumped by this issue. It doesnt take a lot of cranking, just more than it should. Could the throttle body cables be to blame? The one that goes to the passenger side maybe? Is this what controls 'cold engine' idle?

edit: Oh i should mention this is on a 5VZ-FE in my 96 taco

Last edited by post office; 11-23-2011 at 08:03 PM.
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Old 11-23-2011, 09:08 PM   #9
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Success!



Looks like i beat you all to it. I figured out my problem. Cookies to the first person to guess how i fixed it.

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Old 11-28-2011, 06:46 PM   #10
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I have no idea, but I sure would like to know!!!
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Old 12-01-2011, 12:18 PM   #11
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Well, actually i thought i had fixed the starting trouble but i was mistaken.

Runs awesome, has some trouble starting usually when its been sitting warm for 5-30 minutes (possibly longer.) Giving the accelerator a push helps it start quicker as well.

Idle is 690-710 or so, which seems a bit low correct? Proper idle should be 750 for a manual transmission?

I am using bosch spark plugs which i hear toyotas dont like. Not sure if that would cause a starting issue where performance is fine. I would think if a coil pack were needing to be replaced, the problems wouldn't be only start related. I tested the iac by jumping TE1 and E1 on DLC1. It responds correctly.

If i had an air leak at an intake gasket i would see higher idle?
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Old 12-26-2011, 10:53 AM   #12
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Hey Post Office, I have no idea how you fixed it, but I'm having similar problems. What did you do?
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Old 01-26-2012, 05:12 AM   #13
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Any updates?
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Old 02-20-2012, 05:56 PM   #14
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So I did the new plugsm wiresm O2 sensor, cleaned the MAF and finally the throttle body butterfly valve. Then when I started it, it roared to life with the high idle. What I noticed was the truck warmed up pretty quickly which leads me to think it was running lean with a vacuum leak. Took it apart and rechecked everything. Long story short, I got the truck to idle properly again.

I ended up pulling off the plastic intake tubing and gave a couple of squirts of MAF cleaner down the hole in front of the throttle plate. I left off the plastic intake tube and started the engine and it fired and then died. I did that 3 times. What I was hoping is that the cleaner would dissolve the carbon and then suck it past the IAC valve letting it function again and close. I was right. After reconnecting the plastic intake tube it fired up and the idle dropped to 750. I didn't have to remove the IAC either. Don't flood the hole, just two quick shots of MAF cleaner should dissolve any crud.

The reason I used MAF cleaner is it doesn't leave a residue and is less aggressive than carb cleaner.

I hope this proves to be an easier fix for this problem.

Last edited by DRCOFFEE; 02-20-2012 at 06:01 PM.
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Old 02-20-2012, 06:07 PM   #15
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Quote:
Originally Posted by post office View Post
I am using bosch spark plugs which i hear toyotas dont like. Not sure if that would cause a starting issue where performance is fine. I would think if a coil pack were needing to be replaced, the problems wouldn't be only start related. I tested the iac by jumping TE1 and E1 on DLC1. It responds correctly.
Look up wasted spark ignition. Bosch doesn't work well in these systems because half the cylinders will have the spark travel from the ground to the center electrode, which is tiny on the Bosch plugs. I decided to go with NGK Iridiums for longer life and less errosion of the electrode. So far they seem to run great.

NGK on wasted spark ignition

Bosch acknowledges a problem with using their Bosch Platinum spark plugs
in engines with ignition systems that employ 1 coil for each pair of spark
plugs (also known as a "waste spark ignition system").
In cars with conventional (1 coil, distributor/rotor) ignition systems
(including the 850 Turbo with Bosch 4.3, 4.4 engine mgmt systems), there
is no problem. In fact, not too surprisingly, according to Bosch, the
maker of the 850's engine management system, the recommended plug is the
Bosch Platinum FR7DP, which is what passed with flying
colors my tests-under-fire in my engine.
The problem that Bosch has acknowledged when using their Platinum plugs
in engines with waste spark ignition systems stems from the tendency of
electrode metal to get transferred depending upon the polarity (direction
of current flow) of the spark. In waste spark ignition systems, 1/2 of the
plugs always see reverse polarity sparks. Given the very narrow platinum
center electrode of the Bosch Platinums, performance will be degraded more
significantly when reverse polarity sparks will cause material to be
transferred from the large ground/outer electrode onto the narrow platinum
center electrode's exposed end surface.
In cars with conventional (1 coil) ignition systems, every spark is of
the same polarity, for which the Bosch Platinums are optimized, leaving
them to deliver their designed-in advantages, which include:
o reaching self-cleaning temperature faster ("than any other plug")
o maintaining the spark gap and low firing voltage requirement throughout
their service life. (even in my high-stress turbocharged application) While there remain some cars with conventional ignition systems which
do not seem to get along very well with Bosch Platinums, which seemingly
no one can explain (maybe all their sparks are of the 'wrong' polarity
in some cases), they did and do good work in my '95 854 Turbo.

Last edited by DRCOFFEE; 02-20-2012 at 06:13 PM.
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Old 02-24-2012, 04:41 AM   #16
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Exclamation 2002 Same problems

This is great info! I am also having this issue on my 2002 toyota truck with a 170k on her. Im about ready to trade her in but I think ill have to try and clean these items b4 I go that route. Already cleaned the MAF and no luck!!

Just wondering if anyone knows any tricks to getting their truck started when this happens? Mine will start if I give it gas but then as soon as I let off it it shuts down. I guess its gotta go through its cycles of about 10 or so cranks & then will start up and run fine! I dunno!! It always happens to me when I am comming home from work and I stop to get gas! I thought I was gonna be stranded several times now with this issue! Runs great when it is running though! Thats why I dont wanna get rid of her just yet! Latley I just have been leaving the truck run while I go in the store or get gas. (Its a work truck and its not a real big deal cause I really only drive it 35mi. to work and I have the Runner to drive when I am off) Starts great b4 going to work and also when I am leaving work. Seems like it just happens when the truck is warmed up and I shut it off just for a few minutes.

It has been doing this for about 4 years now! I actually thought I found a trick to starting it when this happens and it has worked for the last 3 or 4 years for me now. When I would try and start it and it would die like usual & I would just let it sit for a bit! Long enough for me to put my glasses on and put my seatbelt on and then I would crank her again and BOOM she always seemd to fire right up!! But latley it has been really bad and my lil trick has not been working as much so I guess im gonna have to look into this issue a bit more so I don't get possibly stranded!

Definatley gonna look into getting the IAC cleaned and the throttle body cleaned! I am not real gutzy/knowedgable nor have the help when it comes to messing with major parts of the motor on these vehicles! Atleast I think those are major parts anyways! So I might look into having someone or Toyota do this for me.

Hopfully more people will chime in on this subject and give us all some more hints on this issue..

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Old 02-24-2012, 04:47 AM   #17
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I'd probably check the fuel pump and filter as well as the IAC. Try this. Without starting the engine, turn the key from off to on several times. Again, don't turn far enough to start it. If you do this about 5 times and then on the 6th time start the engine and it fires up, its probably the fuel pump. A clogged fuel filter can cause starvation at start up as well.

Last edited by DRCOFFEE; 02-24-2012 at 04:48 AM.
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Old 03-24-2012, 08:39 PM   #18
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has anyone tried to replace the fuel pump with this problem.
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Old 05-03-2012, 06:57 PM   #19
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Ha yeah right
So i just replaced my IAC completely and when i did it i reset the computer. My engine light is gone but my idle is at 3000rpm. I have read everything here and is seems as though coolent is spoced to be in the tube on my IAC. None came from mine. Not sure what to do now. Been driving with. It un plugged and then it sits at 1200 rpm. Any ideas guys? Thanks -Steven
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Old 05-03-2012, 07:43 PM   #20
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harley ough
im having this kind of problem on my 94 3.4 swapped truck. starts cold fine, then when hot restarting it is hard. it pops and burps back through the intake and acts like the fuel pressure is not there and the ign is way out. but i think it is the cam position sensor.
or the wiring to it. once it "comes too" it runs strong and just like normal.
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Old 05-03-2012, 07:43 PM
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