Starting Problem

[Lots-o-Pappa]

I've got a 2000 LS. In just the past couple of weeks, as the weather has turned cold, it intermittently has trouble starting. It turns over but quits right away. If you pump the gas, you can keep it going. In the old days - when I knew what I was doing - the problem would've been the automatic choke. I took it to the dealer and, of course, it wouldn't happen for them. They ran the diags on it, and nothing showed up. It's getting to be a pain in the butt. Any ideas?? Thanks.

[rwilber]

Originally Posted by Lots-o-Pappa

I've got a 2000 LS. In just the past couple of weeks, as the weather has turned cold, it intermittently has trouble starting. It turns over but quits right away. If you pump the gas, you can keep it going. In the old days - when I knew what I was doing - the problem would've been the automatic choke. I took it to the dealer and, of course, it wouldn't happen for them. They ran the diags on it, and nothing showed up. It's getting to be a pain in the butt. Any ideas?? Thanks.

thats the same thing my 1999 grand marquis is doing...
won't idle and dies unless I warm it up manually.

[Loekee75]

Originally Posted by Lots-o-Pappa

I've got a 2000 LS. In just the past couple of weeks, as the weather has turned cold, it intermittently has trouble starting. It turns over but quits right away. If you pump the gas, you can keep it going. In the old days - when I knew what I was doing - the problem would've been the automatic choke. I took it to the dealer and, of course, it wouldn't happen for them. They ran the diags on it, and nothing showed up. It's getting to be a pain in the butt. Any ideas?? Thanks.

Try a complete tune-up, but also try cleaning the throttle body out. Change your PCV valve, also..if its clogged it will cause the engine to stall out

[rwilber]

Originally Posted by Loekee75

Try a complete tune-up, but also try cleaning the throttle body out. Change your PCV valve, also..if its clogged it will cause the engine to stall out

i found the problem but i don't know what it is. its a metal cylinder w/ a black cap that pops off, looks like a vacumn tube....or breather

i tapped the cylinder with a screwdriver and the car runs perfectly.

http://www.poolesville.biz/marquis.htm

i drew an X on it...anybody know what it is?

HELP!!!!

[rwilber]

thanks for the help. i didn't know it was called throttle body soo when I did a search on that and idle and 4.6L

i found waht I was looking for.

so its the IAC Valve...


"""So let's revisit this IAC problem. I have a '00 GT 4.6L. My car would not idle, I figured it was running lean because of the K&N FIPK and the new throttle body. Since it was a work in progress with the intake and exhaust mods to follow I didn't really worry about it. Two weeks ago my car went in for a tune-up and the service manager told me I had a bad IAC. He said he could have it replaced for $300. I said no because of the work that I had planned. Well, later on I started to research it and thought about doing it myself. The IAC is located on the front of the intake. It is held on with two 5/8ths bolts. You unscrew the bolts, unplug a vaccuum hose and a sensor plug, take the assembly off and replace it with a new one, reversing the steps. The part from Ford is $100. I bought it from Autozone for $53 and replaced it in 10 minutes.

On a side note, while I was in line at Autozone three people with various years of the 4.6L told me they had to replace their IAC valve, some more than once. It seems to me that Ford is either overlooking a defective piece of equipment on this engine or it is a wearable item that should be included in the tune-up schedule."""

http://www.autozone.com/servlet/UiBr...3d8014da1c.jsp

i also found a quick fix that I didn't try and tahts just to disconnect the wiring from the IAC and adjust the idle screw on the linkage. instead of screwing around w/ the screw i'd probably just glue a piece of rubber to the idle plate...
you probably won't pass emmisions and the car might run hot at idle.

[rwilber]

i took the black breather cap off the idle control valve
and while the engine was idleing fast i sprayed WD40 into the
breather hole. lots of WD40.


it works

not more sticky valve

[miamibob]

Now I'm confused - did you replace the IAC or just "lube" it?? How difficult was it to replace it. Is is "easy" to get to? Any gaskets?? Any additioanl info on it would be most appreciated!! MB

[miamibob]

BUMP!! I'm REAL curious about this one!!

[Stevo2]

Originally Posted by miamibob

BUMP!! I'm REAL curious about this one!!

These are very easy to replace and have been causing a pain in the buns for over 15 years! There were many service bulletins released and I dont think Ford really cares, it's more repair work for them. As mentioned, you can usually pick up new ones for $50-$100 at most any auto parts store. Mine takes 5 minutes to replace and that includes coffee time! Remember to put a dab of dielectric grease on the electrical connection. you can get a small tube at the auto parts store. This will help prevent corrosion.


Here's some basic theory...

Description and Operation

PURPOSE
The Idle Air Control (IAC ) solenoid allows the Powertrain Control Module (PCM ) to accurately control engine idle speed under a variety of conditions. The IAC solenoid is driven by an output signal from the PCM and allows intake airflow to bypass the throttle plates.

In addition to normal idle speed control the IAC solenoid also functions as a deceleration dashpot and allows for idle speed changes during periods of increased engine load (A/C, electrical).

The IAC solenoid also plays an integral role in Adaptive Strategy correction. The PCM monitors the engine condition and adjusts the IAC calibration to correct for wear and aging of components.

NOTE : Whenever an IAC component is replaced or cleaned it is recommended that the Keep Alive Memory (KAM ) be be cleared. The vehicle may exhibit idle concerns until new adaptive values are learned.

CONSTRUCTION
A duty cycle driven solenoid is directly linked to a reverse seated pintle valve. The IAC solenoid may be constructed in one of two different styles.

Hitachi With Vent/Filter
This type of IAC solenoid is not serviceable and cannot be cleaned.

OPERATION
The IAC solenoid receives a 12 volt signal from circuit VPWR. The ground supply to the IAC solenoid is controlled by the PCM. The PCM controls the amount of IAC operation by varying the duty cycle of the ground signal.

The IAC solenoid is linked directly to a pintle valve which controls the amount of intake airflow allowed to bypass the throttle plates.

RELATED DIAGNOSTIC TROUBLE CODES

DTC 412 Indicates that during the Key On Engine Running (KOER ) self-test, engine rpm could not be controlled within the self-test limit band.

DTC 415 Indicates the IAC adaptive learning has reached the minimum learning limit (the valve is reducing air flow as much as possible).

DTC 416 Indicates the IAC adaptive learning has reached the maximum learning limit (the valve is admitting as much air flow as possible).

NOTE : Idle speed surging commonly results when the IAC solenoid reaches the limits of its operation. The IAC solenoid cannot compensate for the required change in idle speed which results in the engine surging between the upper and lower limits of the IAC system.

[miamibob]

Thanks Stevo - that was a REAL education on this part! Since you have already changed it what are the EXACT remove/replace procedures?? Thanks in advance....MB By the way, I have a '93 GM!

[miamibob]

Just for my clarification - my '93 has nice power and runs real smoothe on the road. However, when I am at a stop light or sign with my foot on the brake and car in Drive the idle is not as smoothe as I would like. I have done plugs, spark plug wires, fuel filter and also air filter (K&N). Does this indicate a IAC problem? If not, what else?? Thanks....MB

[Stevo2]

Originally Posted by miamibob

Thanks Stevo - that was a REAL education on this part! Since you have already changed it what are the EXACT remove/replace procedures?? Thanks in advance....MB By the way, I have a '93 GM!

MiamiBob....this is on a 93? Here's the procedure from my 92 info. Should be the same. Also check the air passage on the engine under the IAC for crud. Try not to use harsh cleaners as the inside of the upper air intake is coated to reduce sludge, or so they say?

Also run a can of SeaFoam throught the gas tank. You can get it at NAPA/CarQuest for about $6. www.seafoamsales.com

[miamibob]

STEVO2 - Many thanks for the exact info. Please see my posting from 1/17/06- It describes my exact conditions. Does it sound like I need a IAC?? MB

[miamibob]

Shameless Bump!!

[Stevo2]

Originally Posted by miamibob

STEVO2 - Many thanks for the exact info. Please see my posting from 1/17/06- It describes my exact conditions. Does it sound like I need a IAC?? MB

First thing I would do is run the SeaFoam and use up most of a full tank of gas.You could have a vacuum leak or even some other problems. If this is the original IAC than I would say it probably needs to be replaced and the passage under it checked/cleaned for carbon buildup. Do not clean or lube this style IAC as it may make things worse, the older style from 91 on down is a different style and can be cleaned. Might want to think about the EGR valve operation also. Clean your MAF too.
How many miles on the GM?
You would be wise to pull the error codes off the computer to see what's stored there. Also read this Service Bulletin.
http://v8sho.com/SHO/TSB982310MassAi...tamination.htm