New VX Owner and Rough Idle

[etlsport]

was looking for a dome light through google and somehow ended up at a general maintence site?? anyway found this little tidbit and figured it might be helpful

Eratic Idle Speed:

Isuzu engines commonly exhibit eratic idle problems, the engine revving and dropping in rpms, sometimes dropping almost to the point of dying. There are several things that can cause this problem:
Leaks in the vacume hoses or aged, cracked hoses can let in air that is not being metered by the ECU's sensors.
Leaking or sticking EGR Bypass valve may be allowing exhaust gasses into the intake when the engine is not under load (idling).
Loose electrical connections in the engine sensors can cause problems.

doesnt specifically talk about VXs or even the 6VE1... but it does give good random isuzu advice

http://www.isuzuperformance.com/isupage/tech/tips.html

[Beavertractors]

When my intake gasket went, the engine started to run rough and you could hear the air hissing.The gasket gets brittle with age and heat.Call merlin for the new and improved gasket..good luck Tony B

[TEN36VX]

Mine had the exact same idle problem you describe, especially in warmer weather. All problems solved with the Intake Manifold Gasket replacement. As others suggested, I'd start there.

[newthings]

I would suspect a vacuum leak. Bolts holding brackets to the intake maniford go clear through into the intake passages. The bolts get loose and you have a leak. Check the EGR to intake maniford bracket ( At firewall on the pass side). A long bolt goes straight down and can fall up and out producing a monster leak.
Welcome, Roy

[VXtreme]

Another thing to look at is the throttle body and specifically the Idle Control Valve located on the throttle body. Many times particulary with the number of miles you have on your VX, the Idle Control Valve gets very dirty and sticks or stops working all together.

I had been dealing with P0101 codes setting and then turning off and rough idle especially after freeway driving for some time now. My VX had been to 3 different mechanics trying to diagnose the problem. None of them could find the problem. We determined that there was nothing wrong with the MAF as it is new and there were no vacuum leaks since we smoked the entire engine. The O2 sensors are all new and all other sensors and operating parameters checked out on the diagnostic equipment.

Finally last weekend I decided to take a look at the throttle body. It was in need of cleaning, but the ICV was really nasty. I cleaned the throttle body and ICV with throttle body cleaner. Now my VX runs better then it has in quite a long time with no idle problems and no codes. I also decided to buy a new ICV and I will install it this weekend. It's not that expensive about $45. I'd rather have a new one that I know is in perfect working order.