Taji328

Hello all,
My name is Rich and I own a 1997 4Runner Limited 3.4L. I bought it used a year ago and this August I replaced the exhaust from CAT back with OEM exhaust and O2 sensors.

My problem now is it won't stay running when the truck is started. It turns right over like normal operation when started. The truck runs for 2-3 seconds and then shuts off. This began last Thursday. The day before it ran great. The CEL would come on for a few minutes to a few hours and then go off for about a week prior to this event.

So I checked all my vacuume hoses and electrical conections and all are tight. One mechanic suggested that it might be my fuel pump, but it starts. Two suggested that it could be my MAF or a dirty throttle body, and one suggested that it could be my crank sensor.

I took my MAF off and looked in and the filter in the center appears to be white/grey. I took the air filter out, which was changed in June this year and noticed a lot of dirt in the bottom of the air filter housing and dirt caked on the bottom of the filter.

There is a cable that runs from the throttle body to the left side of the engine bay and sits on the weel well as your looking at it and this cable goes into this "box". I have not been able to find a reliable source to figure out what it is, it clicks when the key is turned. I assume this has something to do with air intake. When the gas pedal is pushed this does not move.

I hope that this is enough information for you to help me figure this out. I will try and get a pic of this part and post it.

Thank you. Taji328

blake.nemitz

i think thats your cruise control

vital22re

iTrader: (2)

get a scanner and check for codes. Could be your maf though. Check the codes before you throw money at it.

hross14

Start by scanning for codes. Guess work only goes so far. Also, search your condition.....

Have you tried using a little starting fluid to keep it running when it first starts??

Are you familiar with the big 3 engine needs

Air, Spark, Fuel

hross14

And how to test for the BIG 3?

And how many miles are on the rig?

Taji328

They sell the cheap ones at Auto Zone and Pep-Boys right? I just hope its something easy to fix.
Sorry, 236+k miles. Plugs were changed in June with filter and oil change. The plug wires looked clean inside. Fuel tank has 1/2 tank. Haven't checked fuel pressure.
I searched for dirty throttle body and found someone with a similar problem. His was a bad fuel pump.
So my plan now is to cleam the MAF, throttle body and if that does not help get a code reader and consider a fuel pump.

kball

So it was running fine until you replaced the cat and O2 sensors? Are you sure you got the right sensors?

Taji328

Sorry, the exhaust was replaced excluding the CAT. The O2 sensors were the right ones. The exhaust and sensors were replaced August 6. It ran great until last Thursday. I did a more extensive search and found a few more members here who had a similar problem. They cleaned the TB and MAF. I won't get to it until Friday since I work 16 hour shifts the next 2 days.

Taji328

So I took the air intake off from the filter housing to the throttle body and the TB off. The TB is nasty with thick black and brown junk inside. I have not cleaned them as of yet but will try and get some pics and post them. I hope to have it cleaned and put back on tonight and see if that fixes the problem.
Also, could this be the IAC?
Can the inside of the air plenum be cleaned as well? or is that a little more involved?

Taji328

Ok so after the 20 minute cleaning of the TB and a few sprays of MAF cleaner to the MAF it still wont run.
So I went to Auto Zone and bought a Actron CP9125 code reader and it threw the following two codes.
P0100 MAF or VAF A circuit malfunction
P0110 IAT sensor circuit malfunction

TheDurk

IAT=Intake Air Temperature (this is separate sensor built into MAF)

FSM has procedure for checking if it is sensor or wiring problem. But as both are giving out of range signals I'd take the plug out of the MAF and clean the contacts with contact cleaner and see if that helps. Then I'd clean the MAF again really well--make sure you get BOTH sensors. If still no go, do the electrical checks in the FSM.

That will tell you if you have to start looking for a new MAF.

Taji328

I'll work on it tomorrow. Question, the inside of the MAF looks like it has a filter. It looks white and when I sprayed it you could see the screen, is this normal?

Taji328

replaced the MAF and it started and stayed running.
Thanks for all the assistance and advice.