974Runner

Hello All,
I have a 1997 4Runner (3rd Gen) with a I4(3RZ-FE). When it starts it idles really rough for 5-15 seconds when it is cold. After the first 5-15 seconds it runs fine. and this only happens when it is a cold start. The engine has about 150,000 miles on it. Any ideas on what the problem could be?
Thanks,
Jon

EDIT: Also I smell a little bit of gas after it starts. I dont know if that helps narrow it down at all.

974Runner

Just trying to bump this to the top because I still cant figure out whats wrong. We took the car to the dealership and they said we had poor compression on one cylinder and they want $3000 to fix it. I cant beleive that it is that bad with only 150k on it.

rdlsz24

Your cold start sensor or injector could be bad.

Rob

MLiebal

We just picked up a 97 I4 4Runner (our second 4runner).

Great gas milage (28+ on highway).

Was starting a bit rough.

Do the seafoam thing. For us it works wonders. Add 1/2 to 3/4 can through pcv valve hose (engine running, thumb partially over hose and let vacuum suck fluid in). Turn engine off immediately after adding seafoam. Leave of for 1-2 hours. Start and drive hard to burn out smoke (a lot of smoke!).

After vehicle stops smoking, you should have much smoother running engine.

974Runner

Do you know how to check if either of these are bad? If i had an OBD 2 scanner would it tell me?
Thanks

974Runner

Cool I will give that a try

974Runner

Just an update for anyone else that may have this problem. We took the 4runner down to another mechanic yesterday. He seemed to think that it was the ICV (Idle Control Valve). For a better description of what is happening when we start the car the rpms shoot up like every car. But when it comes down it comes down to far when it is cold. It will come all the way down to its normal warm idle of about 600-750. While the idle is that low and its cold it is extremely rough. It takes about 5 - 15 seconds for the idle to creep up to about 1100+ or so. When it gets to the higher rpm it sounds like a normal car that is cold. When I start my mustang the RPMs shoot up but then when they come back down they dont go below the 1100 mark or so.

So does this sound like the ICV to everyone else?

Thanks

Adam F

Or ECU temp sensor.

Get an FSM and check resistance values at the ECM