engine starts.. then dies.. must keep gas applied to keep it running. vacuum leak?

[airbag]

So for about the past year or so my 1999 V6 4R has been randomly dying at stop lights and taco bell drive throughs after idling really rough for a couple seconds. today on my way home from work this jackass wouldnt let me over to my exit on the frontage road so i braked hard let him pass then floored it back up to everyones speed to make my turn (admittedly road rage induced driving but not excessive to the point of damage IMO. i don't do this often) after that i lost all power and coasted to a stop... then beat my head on the steering wheel.

tried to start again and no success... it powers on for a couple seconds then shuts down. the only way to get it running is to start it and immediately apply the gas and keep on it at least a little bit. i pulled in to the HEB and made sure all the hoses were still on and if there was any obvious damage or smells... everything looked alright at first glance in the dark.

so i made it home but i had to keep a little gas applied at all times, including stop lights (which was a pain and of course i hit every red light )

Im assuming its some sort of vacuum leak, does anyone have any other ideas or specific hoses i should take a look at? im the second owner and it seems like everything is original as far as hoses go. i take good care of it and change my oil regularly.

thanks for any assistance!

 

[lexustech]

your iac is dirty and sticking causing not enough air flow into the engine when the throttle plate is closed,you can clean them to free it up

 

[trd_4runnin]

My 4Runner is having a very little problem and I was told to clean the IAC also. Today I'm going to clean the IAC and throttle body and I'll let you know how that works out. If I still have rough idle and occasional dieing, then I'm going to clean the MAF too and see what happens then. I'll also be replacing spark plugs soon, but I don't want to do everything at one time because I want to know what was the actual fix of the problem. Anyhow, I'll post results.

 

[airbag]

any word on how it went? did you have the exact problem i did? the next day i went out to start it and it had the same problem.. then i tried it later in the day and it started running like a champ. i really dont know what to think, its only died once this week. im confused...:beer:

 

[trd_4runnin]

any word on how it went? did you have the exact problem i did? the next day i went out to start it and it had the same problem.. then i tried it later in the day and it started running like a champ. i really dont know what to think, its only died once this week. im confused...:beer:

Sorry for the late response. I had a unexpectedly busy week and wasnt able to get to it until this weekend. My 4Runner's problem was that when I gassed it to pass someone or for whatever reason, the truck would die the next time I came to a stop. Not a huge problem since I don't floor it very often but I wanted to fix it before it became an issue.

...Anyways, I wasn't able to find a throttle body gasket so I ordered one from the dealership and went ahead and cleaned it without removal since I dont know when Id be able to get around to it again. Overall, it was a success. I cleaned out the throttle body with carb. cleaner and sprayed some down into the IAC valve as well. After I went out and really pushed the engine some I ended up with a much smoother idle and was unable to get it to stall out again. Only speed bump I got was the CEL for forgetting to plug the MAF sensor back in.... :bash:

 

[judoant]

where is the AIC? I have taken the intake off before to clean the butterfly in the throtle body. is it in that area?

I am having the same issue. it died after I got off the interstate, and now it seems to die 1/3 of the time I stop at lights.

 

[trd_4runnin]

The IAC is located on the underside of the throttle body. There is an electrical clip that attaches to it as well as two coolant hoses. It's held to the throttle body with 4 super tight screws. Good Luck, it did wonders on mine!

 

[judoant]

does anything need to be removed to clean it?

 

[4runny]

It could be fuel related. Maybe a fuel filter, fuel injectors, or fuel pump.

 

[Supra725]

I had the same problem time couple months ago too. The car was having a rough idle, check engine light is on and such. It came to one point when the car died when I was getting the mail.


The month before I went to the shop and have it checked out( the check engine light) and they told me my isc valve ( idle speed control) and it was dirty from what they (the dealership) told me it needed to replace. So I did that and ever since then everything has been good.

The thing was wrong with my isc valve was the carbon build up and thus my engine was getting enough air into it to keep it going.

 

[judoant]

how much did the isc valve cost you total?

 

[Supra725]

Is around $360 total for everything, the new isc valve and the labor.

How's your holding up?

btw, if you do replace it. Give them a call before heading in, caused I called and the stealership didn't have it in stock.

 

[judoant]

well since i originally posted i stalled 2 days in a row, twice each day. but over the last 2 days i have not stalled once.???

I have no idea what the deal is.

 

[Supra725]

Mine was loaded with carbon build up.

 

[trd_4runnin]

I had the same problem time couple months ago too. The car was having a rough idle, check engine light is on and such. It came to one point when the car died when I was getting the mail.


The month before I went to the shop and have it checked out( the check engine light) and they told me my isc valve ( idle speed control) and it was dirty from what they (the dealership) told me it needed to replace. So I did that and ever since then everything has been good.

The thing was wrong with my isc valve was the carbon build up and thus my engine was getting enough air into it to keep it going.

Are you sure that it wasn't the IAC (Idle Air Control)? I have never heard of an Idle Speed Control valve, and the IAC valve does get loaded up with carbon, just as you described.

You sorta have to remove the throttle body to get to it, but when I removed mine I was unable to get the screws holding the IAC on out, so I just reattached the TB and sprayed through the IAC via holes on the bottom of the TB. My truck has not died since the day I did that.

 

[Asmara]

IAC - Idle Air Control

Just thought I post that I had the exact same problems reported here: engine sort of starts then dies, wouldn't idle unless you kept a little gas applied.

As suggested, it was the Idle Air Control (IAC). You really have to pull the throttle body off, which isn't as bad as it looks, to check it out. I didn't disconnect any of the throttle cables, just the clamps that held them down.

Once you pull the IAC off, and clean it with carb cleaner. You'll see the carbon pouring off of it. After it looks shiny and used check its functioning. There is an electrical connection with 3 poles. Middle is ground and the other two are +12V. To test it connect the middle pole to ground, and then one side to +12v. It should either open or close all the way. Then connect the other side to +12v and it should do the opposite of what the first side did.

As long as it is opening and closing, the part is fine. Replace it and you are good to go. Easy fix for a troubling problem.

1998 4Runner Limited

 

[bill9009]

I was having the same problem, I am in the middle of replacing the IAC, I got a hell of a deal for one off ebay.
item # 150222757740
He has more of them as well if anyone needs, It cost like 85 with shipping,
Autozone and all those places wanted $200 for the valve.