Dominus

Ok I need some expert advice and what better place to ask right. I got a 2001 Tacoma ext cab 4x4 3.4 v6 with 134,000 miles on it. It runs good except sometimes when I come to a stop light or idle. It will idle bout 750 rpm then go way down almost to die, than idle fine, then do it all over again. One time it did die, and started right back up. It only does it when its warmed up, and not all the time. It did it the other day just idling whie i put tranny fluid in, it kept almost dying. I have cleaned the MAF, TB, IAC, replaced plugs, pcv, fuel filter, air filter, all that stuff. I didnt replace the coils, or plug wires. I dont beleive much maintenance has been done on it prior to e gettig it. Anyone know what could cause it to idle funny.

yotaman85

check the TPS

Dominus

forgot to say the tps is new...well 6 months new

eddieleephd

https://www.yotatech.com/forums/f2/1...med-up-206543/

Dominus

That was a good post to read. I just spent an hour in traffic, and the thing never once stumbled so I don't know what to think now. I'm leaning towards a fuel pump, or possibly the coil packs.

eddieleephd

Before it would be the Fuel Pump it would be the filter... and the coil packs are less likely..
the most likely culprits would be the TPS and the plugs or wires. The next likely culprit for such an issue I would say the injectors or the crank shaft sensor!!!

eddieleephd

as well these sensors and the TPS are much cheaper to replace and would benefit even if they were not the issue...

Dominus

The filter has been changed like a month ago. I was thinkin plug wires to so im going to change them today and see what happens. It dont throw a code when it cuts out, i wish it would. maybe ill just buy a new tps while im at it. i hate just buying stuff and changing parts hoping it fixes it, but the wires could use a change anyway

PismoJoe

My friend had a v6 (02) that had this problem, as did my 3rzfe (02)

For him and I, the problem ceased on its own. I went to my buddy Daniel's shop, he's a toyota technician with his own shop. He said that its most likely the IAC, and he's seen a handful go out. He advised me that if its not bad (dies all the time, rough idle every start, etc) wait and see what it does.

Turns out, mine went away, back to normal idle for more than a year now with no problems. Maybe mine isn't as bad as yours, because I only had about a week of random idle cut outs, as did my friend with his 02 v6. I guess it is what it is, but my money is on that IAC valve, which seemed to be a common issue on the Tacomas.

Dominus

It only does it sometimes. Like today i went hunting all day and it didnt do it. go to les shwab come out to start it and bam, it cuts out and almost dies for the first ten seconds..the IAC is alot of moola so ill take your advice and just wait and see. I think ill see what the fuel pump is puttin out for pressure though. This forum kicks ass. alot of people know alot of stuff.

brian2sun

Do the plug wires and then clean the IAC and throttle body because it's free (but if you buy new gaskets for the IAC and the TB, they're about $10 or less a the dealer):
https://www.yotatech.com/forums/f123...ac-pics-92286/

EDIT: sorry, haven't read your first post since yesterday, forgot you already did that stuff.

brian2sun

Could be the air flow meter or front O2 sensor, whatever you have on there.

atistang

i would figure that its the iac, if your fuel pump was weak then you would probably have some major issues accelerating

eddieleephd

Hey I think I have a really good idea, some thing that has worked for me is when it is idling rough ROMP on it!!! Get it up to like 4400RPM and see if it throws a code, quite possibly will be a misfire code but may point to a Cylinder...

If there is a possibility that it is the IAC then It really could be air trapped at the highest point on the coolant line of what is a closed circuit system meaning that the IAC is higher than the radiator!!!!! and there is possibly air trapped in it!!!

clear that bubble from the IAC and see if it clears up...

and Where are you Dominus

Dominus

Ok at first i thought you were kidding when you said to romp on it. I never thought about an air bubble. So i shall romp on it next time it does it. I hope it throws a code then i can pin point this thing. I replaced both o2 sensors and the cat so idk. Im leaning now towards the IAC. Maybe ill take it off and clean it again, and check to see if the plunger is working properly.

Dominus

How do i clear out a bubble?

Dominus

Im in Boise, Id

PismoJoe

I would be all for the "bubble theory" except it wouldn't add up that it only does it sometimes. If the IAC is truly the highest point, that means that the bubble would always be there, thus causing the problem every time.

you replaced the cat (wouldnt add up that only sometimes an improper backflow causes rough idle, but it was probably due anyways)
You replaced the 02 sensor (would throw a code for sure if that was out)
fuel filter issues would be noticeable on acceleration, unless a chunk was stuck in there, only sometimes plugging upon startup causing the fuel pressure up system to never reach its proper pressure.

Then your left with 2 problems (well main ones)
1. cold start sensors
2. IAC sensor (dont clean out your old one IMO its F***d anyways, so get a new one)

Pay attention to the engines temperature when it does it. Is it after an extended dead soak (first start of the day) or just a hot soak (maybe 10-20 mins then started again) Paying attention to this would eliminate the cold start system. I would bet you $20 it was the IAC if you were in cali, but i dont want to ship it to you too lol. Let us know about your observations!

eddieleephd

The thing is that physics is at work here and yeah it may not be a bubble but it maybe so burp it...

to burp it you will see the coolant line running out the back of the IAC and down to a tube on the back of the engine where you can disconnect it while the engine is running... first take the hose clamp loose with a pair of needle nose pliers, then start the truck, get back out and disconnect that hose for a moment then reconnect does not take long just make sure coolant is coming out of it solid...

I would be less likely to think this was the issue but when you first start your truck the air is cold and can get pushed past the IAC where it can bubble up and stay there in a vertical line! when you shut it off it runs back to the top!!! now since it is hot the air is expanded and more boyant not wanting to go any where...

I can not say for sure this is the issue but wouldn't we all feel like ASSES if it was and you kept throwing money at it??????????????

Dominus

Good point eddieleephd. I will try and burp it and see what happens. I have noticed it only does this when it is warmed up. When it is doing it i give it a little gas but i can still feel it trying to idle down..then it just stops and runs fine. IAC is expensive. do ya think a junk yard one woul dbe ok..prob not. prob wanna just buy new. Psmojoe...what kind of lift do you got on your truck?