High Idle at 2300 rpm and dumping gas

[mybirdcanfly]

Had the VX sitting for a while then tried to get it going just before winter hit. It ran OK for a while then started to gradually get higher idle. Then suddenly at start up it would start and fly quickly to 3500 rpm and then die....the only way to keep it going was to keep flicking the gas peddle. After it warms up it will run, has power, but will not idle less than 2300 rpm.

Have replaced:

Manifold Pressure (MAP) Sensor
Idle Air Control (IAC) Valve
Throttle Position Sensor (TPS)
Oxygen Sensor

did not replace the Fuel Injection Pressure Regulator, I'm ordering that now but not hopeful that could be the problem.

The car has power, if running on the highway you would not suspect there is anything wrong, it's running well on all cylinders. I had a local mechanic check the codes and he says all the sensors are reading good, and he suspects the computer is the culprit.

Does the VX have a ignition module AND and computer?
could either of those be the culprit?

[Triathlete]

How long was it sitting? Did you use a fuel stabalizer (fuel could be bad). Also check your fuel filler cap...if not sealed properly it will cause irratic idle. Bad head gaskets and the MAF will cause this also. Try cleaning the MAF (use only MAF cleaner). There are several treads on checking for leaking head gaskets.

[circmand]

Had the VX sitting for a while then tried to get it going just before winter hit. It ran OK for a while then started to gradually get higher idle. Then suddenly at start up it would start and fly quickly to 3500 rpm and then die....the only way to keep it going was to keep flicking the gas peddle. After it warms up it will run, has power, but will not idle less than 2300 rpm.

Have replaced:

Manifold Pressure (MAP) Sensor
Idle Air Control (IAC) Valve
Throttle Position Sensor (TPS)
Oxygen Sensor

did not replace the Fuel Injection Pressure Regulator, I'm ordering that now but not hopeful that could be the problem.

The car has power, if running on the highway you would not suspect there is anything wrong, it's running well on all cylinders. I had a local mechanic check the codes and he says all the sensors are reading good, and he suspects the computer is the culprit.

Does the VX have a ignition module AND and computer?
could either of those be the culprit?

make sure floor mats not shoved forward
fuel pump

[mybirdcanfly]

Did get another MAF and no change....and the VX actually seemed to run a bit better with it disconnected....more reason to believe the computer?

Been online for hours still can't confirm if there is an ignition control module and a computer. I called Isuzu and they said a computer is $800 but I can't believe the main computer would do this....possibly an ignition module?...in my experience such things either work or not.

[Ldub]

There are several treads on checking for leaking head gaskets.

I'm pretty sure Billy meant intake gaskets...:_wrench:

Search "high idle" for WAY more on the subject...:yesgray:

[deermagnet]

You've already spent a bunch of money with no results and you're just guessing trying to fix this problem on your own. There's an authorized Isuzu Service Center at an old Isuzu dealer over in Wayne, NJ. It's now Maroon Kia (http://www.maroonkia.com/).

They'll charge you a lot for labor, but they may have someone who knows these Isuzu engines and can fix it quick. They may have an Isuzu Tech2 Scan Tool and find the problem fast. I don't know this dealer and they may be a bunch of bums looking to steal your money, or they may fix it in one day for not much money. :_confused

Call them or drive over there and tell them your problem and ask if they have anyone who can track down this problem. Then make a judgment call on whether you want them to work on your VX.

The intake gaskets are a possibility. It's more involved than changing the sensors you've done so far. It's up to you. Keep trying on your own, or find some good professional help. Good luck whatever you decide.

Mark Griffin

[Triathlete]

I'm pretty sure Billy meant intake gaskets...:_wrench:

Search "high idle" for WAY more on the subject...:yesgray:

Ah....yea,what he said.:yesy::bwgy:

[mybirdcanfly]

Thanks for the tips, Yes I called the Kia, I was pleasantly surprised to find they existed after the one in Newton NJ went south...my prior source for parts. That's where I got the estimate of $800 for the computer, I'll try the fuel regulator then it's down to the dealer...I'll let you know what happens. After mucho searching still have not determined if there is an ignition module and computer on this car or just one computer. I found references to ignition module connectors making me think there is an ignition module. In my experience ignition modules (and wrong ones) can cause such mischief.

While sitting this car had mice in the intake, I took all their nest out and thought I cleaned it thoroughly, put in new filter, but I'm wondering if anything would go shooting into the intake plenum would that possibly make this happen.

[tjh]

Two weeks ago my VX started to idle at 3500 rpm , and the engine would shut off if I had it in gear with my foot on the brake . Prior to this happening I had replaced a plethora of components that were suspect for erratic idle.

So, last week I discovered that my battery terminals were loose ,despite the fact that the nuts that tighten them down were tight as they could possibly be . So I replaced the terminals and now the VX is back to normal . YAY!

[mindaugas]

So, last week I discovered that my battery terminals were loose ,despite the fact that the nuts that tighten them down were tight as they could possibly be . So I replaced the terminals and now the VX is back to normal . YAY!

I hope this is my issue as well, I know the terminals are loose. When I start up first time in the morning it's fine. After running for a bit and I start up again, it revs slightly above 1k rpm, then dies. Hit the ignition again and starts right up. If I tap the gas before the motor dies, it's ok too.

Today, while driving in the snow, on a corner, it died. Just shut off. Battery was ok, because still had lights and everything on dash. It started right up, but not before I slid into a curb. thankfully I was only going about 10mph. Ran fine after that, for 3 hours.

[mybirdcanfly]

Fuel pressure regulator in, no change.
But I had a new exhaust put on and now for the first time I can hear the sucking wind while inside the VX, it almost sounds like something behind the speedo.

So that's it, the intake manifold gasket?
Is the leak in the back typically, and hard to find?

I've checked the manual download and on-line "how-to" but still a bit puzzled.
I can't find a thread with a how-to, is it so obvious and easy no need for a how-to?

[Amnesia]

Mine started having a faster idle since this summer / fall. Initially it was around 1800-2200 & now it's that at startup & as soon as it's warm (very soon), it idles around 3000-3200. Years ago I had a leaking intake gasket & fixed it myself, but due to being low on coolant & using it to drag an 18' trailer w/ a couple of CL car finds on it back to my house (and getting it hot) - I suspect I lost the intake gasket again.

If I spray carb cleaner on the lower back right corner of the intake manifold, my idle actually slows down for as long as I spray. I haven't gotten around to replacing the gasket again yet, but doing this should confirm your issue.

Good luck!

[Junster]

The only thing I haven't seen you did was the EGR valve. A stuck open EGR will make the sucking sound and cause the very high idle. If it's stuck open it causes a huge vacuum leak. Would also explain running better with the mass air flow disconnected. That forces the fuel injection to work as if the rig is very cold and dumps a lot of fuel thru the injectors.

[Amnesia]

Update: I finally replace my intake gaskets 2 days ago. Unfortunately, the idle isn't back to normal yet. It is back down to around 1800-2200, which is a HUGE improvement over the 3200 which gives you bone shattering shifts into gear.

I may have damaged the new gaskets upon installation, but so far I haven't been able to confirm a new leak. I could see where the previous leak was upon dissassembly on the back right side. When I was putting the new gaskets on I found out where I may have messes on originally and caused this leak. (It took a couple of years before it happened.)

Be very careful once you set the manifold (common chamber) back into place. The fuel line bracket that bolt to the backside of the intake is a PITA. I was only able to unbold it after lifting the intake up & pulling forward a little. ...problem is, this is the same way I reattached it. I realized after it was too late that while i was bolting this bracket back into place & re-attaching the fuel return line on the left side, that I was letting the right side of the intake rest on the new gasket. When I realized this, I felt the gasket surface & could detect a slight depression or dent.

So now that my idle is still higher than it ought to be - I'm not sure if I need to replace the gaskets again (being more careful this time), or if it's something else. Using carb cleaner, I'm not able to find any new leaks, but you can really only check the outside edges of the intake manifold sealing surfaces. I'm wondering if I have a leak in the inner surface, but I can't get to it to check.

I hate to start replacing random parts as mentioned above, but I also hate to blow another $40 & 6 hours to replace the gaskets again... God, it sucks when your truck doesn't run right!!

I also need to find a replacement muffler, but it seems that there are none available, other than a universal or OEM...

Any suggestions welcomed!