93runner223

Ok, i know you will all say search, search, search, but i have been doing so for 3 days.

Heres the problem, 1993 4runner 3.0 manual trans. Starts and idles perfectly hit gas and everything is normal. The problem is when im driving down the road and take it out of gear and into neutral the idle goes all the way down to 200rpm and occasionally dies.

My mechanic has adjusted the vafm, new cap, cleaned the fuel filter (which was bad), and checked all cables etc.

What more could it be?
Iac, bad vafm,

It runs great but when taken out of gear idle drops severly

Gamefreakgc

There's an idle adjust screw on the throttle body (faces towards front bumper). Adjust that until you are at 800 RPM.

If that doesn't fix it, check your Throttle Position Sensor on the throttle body and adjust as necessary, per the instructions here: http://personal.utulsa.edu/~nathan-b...93throttle.pdf

93runner223

Thanks for a quick response, i have done all screw adjustments.
I have noticed that whoever i bought this from or possibly another mechanic had the idle bypass screw fully seated. I put it to 2.5 turns out, 1.5 didnt help, and it has gotten very slightly better which leads me to believe that what was happening is the vafm was cutting off all air and would kill it. That is just a theory and as of now i am still experiencing problems.

Gamefreakgc

Check the TPS first, mine was bad when I got it and would idle at 400. If it checks out ok (you need a multi-meter and a feeler gauge, $15 total at harbor freight) then at least you've ruled it out. If not, adjust it by loosening the screws and rotating until it does.

93runner223

Ok so you guys know i had to adjust dashpot screw which slows the rpm drop and it seems to have helped, now i am chasing other problems

Gamefreakgc

I suppose that works, but that doesn't fix the issue. The dashpot should not be holding the throttle open, it should be the same whether it's on the vehicle or off. That's just avoiding the problem...

Also, check for vacuum leaks. Take a can of carb cleaner and spray at the ends of hoses.
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ksti

Just curious as to what adjustment was done on VAFM?
Also was the fuel filter cleaned or replaced?
I suspect a vacuum leak.

93runner223

the vafm was adjusted to be i believe two clicks leaner, to pass smog. and the fuel filter was just blown out untill i get the new one. Vacuum leak wouldnt make sense, the engine was just put in with every hose replaced. Unfortunately today it actually died lost full power after doing about 35 miles. Towed to the mechanic and i will just leave it with him to fix everything its all under warranty

ksti

Ok, Here's what doesn't make sense,
(1) Adjusting VAFM in order to pass smog especially on a fresh motor.

(2) Cleaning out a fuel filter, not replacing it on a fresh motor.

(3) As for a vacuum leak, that makes more sense, just because all hoses were replaced doesn't mean squat.

Gamefreakgc

Your mechanic could have very well connected the hoses incorrectly. Loss of pressure or backwards pressure in some of those lines could cause it to fail.

93runner223

ok today i got the truck back and the mechanic switched the egr vacuum modulator which seemed to help, and to answer the question as to way a fuel filter wasnt replaced, i am doing that myself stupid to pay him to do it.