3rd Gen Hard Start When Cold

[tbryanh]

2000 4Runner V6

When the engine is cold, the starter has to run longer than normal to get the car started. The car runs real good when it warms up, and is easier to start when it is warm.

I bet the fuel mixture is supposed to run richer when the engine is cold, but I am not familiar with how this system works and what part failure might be the most common to cause this problem.

Any help will be much appreciated.

 

[Zhehan]

Clean the MAF.

Check your Engine ground point. Make sure the bolt is tight.

Check your battery terminals.

 

[alumarine]

How long is longer?

 

[tbryanh]

I will clean the MAF, check my engine ground point and make sure the bolt is tight, and check your battery terminals as Zhehan suggested.

In response to alumarine's "How long is longer?" I would say long enough to make my wife worried that she will break down. (She is the one driving the car.) (She has broke down more than one time in that car.) I do see it as a problem that needs to be fixed ASAP. I certainly wouldn't want the problem to still be there when the winter comes. My wife has been driving it for the past 4 or 5 days since she showed me the problem.

The video Texmax shared is very helpful. Thanks for sharing it.

The video appears to indicate that the butterfly valve in the IAC is either fully open or fully closed depending on which coil in the solenoid is energized.

The video also indicates that a dirty butterfly valve in the IAC will not close all the way. This will let too much air through and cause a high idle.

The video, and the comments to the video, does not appear to discuss my problem: The starter must run significantly longet than normal to start the engine when it is cold.

What I gather from other threads is that my problem could be caused by the butterfly valve in the IAC not opening to allow extra air to the engine so that it will start easy and run good until it warms up.

Could I test for this (when I am starting the engine when it is cold) by pushing on the gas pedal a little bit to open the butterfly valve in the throttle body a tiny amount to allow extra air to get to the engine?

If the engine starts easy when I do this, then I would know the IAC is at fault, correct? If the engine is still hard to start when I do this, then I need to look somewhere else to solve the problem, correct?

 

[Pyral]

Your battery could be getting old. The cold can make old batteries really struggle

 

[tbryanh]

I will swap batteries with my 4Runner and see what happens.

 

[phattyduck]

My guess is that fuel pressure is leaking down between starts. The fuel pump only runs with the key in the START position or if the engine is running - there is no fuel pump prime function. If there is 0 fuel pressure to start, it takes a bit for the pump to get enough pressure in the system to start the engine.

Could be a bad check valve in the pump or a leaking fuel injector.

I can't remember if the 4Runner has connections in both the "Fp" and "B+" connections under the hood, but if it does, jumper them for a test. Then turn the key to the run position for a bit before starting it in a situation where it would otherwise take a long time to start. If it starts quickly, it is a fuel pressure at start issue to track down.

-Charlie

 

[tbryanh]

[MENTION=16576]charlie[/MENTION]:

Thanks for the comment. Nice to have that information in this thread for future use. I did see similar information about this in some of the threads I found before I posted this one. I tried that test for the leaking check valve, but it did not help.

@Group:

I did get a chance to work on the car this morning.

RULED OUT FUEL CHECK VALVE
See above.

RULED OUT IAC
After car started, it went to high idle for awhile and then went back to normal idle when it warmed up some or most of the way. This appears to indicate the IAC is functioning properly.

WORK DONE
Swapped batteries and air filters between 4Runner with problem and 4Runner without problem.

Cleaned battery terminals in both vehicles.

Cleaned MAF in problem vehicle. MAF appeared maybe it had a brownish coating on the silver heating element. Spray-cleaner made it a bright and shiny silver color.

RESULTS
Wife drove problem vehicle on errand and said everything seemed much better (normal), but she will check how well it does when its cold tomorrow morning. (Car was already warmed up when she test drove it.)

I drove car without problem. It seems maybe it was harder to start than normal. I will know more when I drive home tonight and also when I start car tomorrow morning.

COMMENTS
The car with the problem had the oldest battery in it. (It has the newest battery in it now.) My wife does alot of stop-and-go errand type driving while I mostly cruise on the highway, so my wife is harder on batteries than me.

Might be I need a new battery in the car I am driving. (Battery used to be in the car that had the problem, and is currently in the car I am driving.)

 

[tbryanh]

AIR FILTERS
Forgot about the air filters. If the car I am driving is having a problem starting now, before buying a new battery, I should rule out the air filter first by temporarily removing it and seeing if that helps. (The car I'm driving has the air filter in it from the car that had the problem.)

 

[tbryanh]

Tried to start my car this morning. Battery was dead. Measured 8vdc. (This is the battery from the car that had the hard starting problem.)

Put in battery from spare 4Runner and car started right up.

Bad battery appears to have been the main problem, but I am sure the other tuneup items are helpfull too.

A good learning process for me. Thanks for the great help from everyone. Much appreciated.