TIM COSTA

In the past month my car, 2000 2.7, has developed a very rough idle issue. In that time I have done some repairs to it but nothing that I can contribute to this problem considering it was running rough before I did any of these.
About 3 weeks ago I had the coolant tank let go. It took me about a week to replace it, working in the evenings and procuring the parts and tools. After I finished that when I started the car it smoked A LOT. Turns out the spark plug tubes were shot. Replaced them along with the rubbers that attach the coils to the plugs. No more smoke but still very rough idle. I took out the throttle body and cleaned it even though it wasnt very dirty. I even went so far as to try another throttle body but still the same. The motor is all stock including the air filter and intake. There is no pressure or vacuum on the oil fill tube. There is a bizarre intermittent howling noise coming from the fuel filler area. Ive removed the cap while the car was running and still nothing changes. Im at a lose. Any suggestions???

Thanks,
Tim

Macster

Well, I take it the check engine light bulb works and it is not on after the engine starts?

Based on what you write I'm thinking something's wrong in the fuel tank ventilation system/vapor recovery system and there's an air leak.

Now if this is the case chances are it is a relatively small air leak. It only seems large since at idle the unmetered air represents a large percentage of the total air consumed by the engine but if you were to increase rpms the engine will smooth out.

Anyhow, the vapor recovery system can be tested but it requires a diagnostics computer to operate/trigger the various switches/controls and monitor the behavior of the various sensors (mainly O2 sensors) to verify the system is working properly.

Since you were at the engine, to some extent, when you replaced the coolant tank you may want to carefully inspect all the hoses/lines that are in the engine compartment looking for one that broke, came loose. Run your hands along each one feeling carefully as you go.

I'm hoping that a line was disturbed by you - or given the age of the car a hose has just received the end of its life -- and is allowing the vent valve to remain open. Said valve intended to allow fresh air (from the intake manifold IIRC) to pass through the canister to remain open and this is the air leak and it accounts of the howl.

But the leak may at the front of the car. The vapor recovery system and the charcol canister and other related/assorted hardware is located under the passenger fender just under the gas tank filler tube bay while the canister is located down lower behind the front wheel.

You can gain access to this area by removing the passenger side front wheel and removing the wheel well liner. Now you may not have to remove it completely (and IIRC if you want to you have to remove the front bumper cover first), all you have to do is loosen/remove enough fasteners to free the rearward portion and pull the liner away and down to expose the tank vent/vapor recovery hardware.

Sincerely,

Macster.

insite

my guess is that it's your idle air control valve. they get gummed up / rusty and make the car run like crap at idle.

remove it from the throttle body & drill out the roll pin. this will allow you to twist & open its cover. clean it up with scotch brite & reassemble.

TIM COSTA

Thanks Guys,
Looks like I have another buisy weekend. I'll keep you posted.

Tim

Byprodriver

2000+ models don't have a idle air control valve.

insite

are you sure? i though '01+ were eGas, but '97-'00 were cable.

insite

EDIT: my bad; brain fart. 2.7L is '00+


so that means in addition to the other items, the issue could be your electronic throttle

Paul 996

Tim,

Does it have a low idle practically stalling unless you rev it?

chsu74

Did you check for leaks from the MAF to the throttle body if you removed the throttle body for cleaning? I had a problem with erratic idling because air was going into the TB after the MAF throwing off mixture readings.

TIM COSTA

Paul,
Yes, very much so.

Byprodriver,
You are correct. 2000 is fly by wire and therefore no ICV.

CHSU74,
Ive checked as much as I can from the air box through the intake and no leaks. I'll be digging deaper this weekend.

Tim

Paul 996

Tim,
When you pop off the oil cap does it stay the same or run worse? It should run like crap and practically stall with the oil cap off. There is a long plastic oil filler tube under where you fill the oil running to the engine that may be cracked. Happened on my car. It is a total pain to replace

TIM COSTA

It doesnt really change when I take the cap off HOWEVER, Im very suspisious of that tube. When I changed out the resivior I really had to work at getting that tube disconnected. While working it I heard a very nasty cracking noise.

Paul 996

Hate to say it but that is "exactly" how mine happened. Swaping the coolant tank and messed with that pipe and mine crumbled on me.

Try taking the oil cap off the spec box when it is running, it should start to stumble. Hope this helps.

TIM COSTA

Think I found the problem....

Macster

Oh, yeah. That'll do it.

Sincerely,

Macster.