Frustrated with Idle Air Control Valve.

[Chris Baker]

I have an 04 Land Rover Disco II with the 4.6 V8. I have put 3 idle air control valves on it. But it continues to throw that code! Also I have continued miss fires and the bank 1 and 2 O2 sensors are indicating the truck is running lean. I feel this it due to the idle air control valve letting in too much air in the mixture. I have put in new plugs, wires and cores. So all of that is good. When it is started the first time of the day, it will rev up to about 2000 rpms and will bounce up and down for a minute. But when you put it in gear it will drop it down to around 700-800 rpms. But even at idle in park or at a red light, the rpms will still jump up at times to 1100 rpms.
Can anyone out there tell me what can I do to straighten this damn thing out!! I am getting so frustrated. I mean after the first start of the day and it warms up, it runs pretty good accept the occasional jump in rpms at idle to 1100 rpms.

 

[best4x4]

have you ever had the adaptive settings reset after all the new stuff?

 

[jymmiejamz]

What is the code? Sounds like you have a vacuum leak.

 

[michaels]

have you done a smoke test to see if there are any leaks? checked all of your vaccuum hoses? You may want to reseal the top end. I had similar misfires on my old one and it turns out to be bad injector o-rings.

 

[Chris Baker]

have you ever had the adaptive settings reset after all the new stuff?

How do you do that? I have never heard that before..

 

[Chris Baker]

What is the code? Sounds like you have a vacuum leak.

I have hosed the engine down with carb cleaner and no leaks have been detected.

 

[jymmiejamz]

I have hosed the engine down with carb cleaner and no leaks have been detected.

That isn’t a very good way to look for a vacuum leak. You need to smoke test it. You can buy a smoke tester on amazon for around $100 or pay a shop that has one.

 

[JUKE179r]

Or you can get a cheap cigar for the smoke, a rubber glove to seal up the intake manifold at the throttle body and a hose to blow in the cigar smoke through one of the cut open fingers in the glove.

Also try cleaning the throttle body and plate.

 

[rovercanus]

It's hard to diagnose leaking injectors using throttle body cleaner since they are tucked in there. I chased a similar problem last year and it ended up being leaking injector o-rings.

 

[Chris Baker]

It's hard to diagnose leaking injectors using throttle body cleaner since they are tucked in there. I chased a similar problem last year and it ended up being leaking injector o-rings.

I assume you fixed it by replacing the fuel injectors?

 

[rovercanus]

I assume you fixed it by replacing the fuel injectors?

I did. I bought a set off of ebay that have been rebuilt.