Hey guys, my wife and I have had this Isuzu Rodeo for about 9 years now, and it's been a decent truck. It's a 2.6 litre 2wd model, stick. About 5 months ago, it starting having a rough idle and I've spent over 300 bucks trying to figure out why it's happening with no luck. I've replaced the pcv valve, EGR valve, cleaned fuel injectors, new plugs, new wires, new distributor, and numerous vacuum hoses replaced. The dang thing still idles horribly 50% of the time even though with my little fixes, it does run much better under load. It's weird because the truck will idle fine for a minute, then I hear a click under the hood like a relay or solenoid has made a change, then the idle gets very bad and most likely, the truck dies.

Anyone out there have a Isuzu 2.6 litre and experience idle problems before? Any advice would be appreciated.

 

have you checked out you IAC ti see if it is working corectly ?

 

Not sure on your vehicle but my guess is that one or more of the oxygen sensors are not working correctly. Have you pulled the codes?

 

The first thing I would check is the entire EGR system. I just finished figting a battle with my Accord and the EGR system. Trace the vacuum lines from the EGR vavle all the way back to the source of vacuum (the intake manafold). Mine had a problem with the vacuum control solinoid wich regulated vacuum to the EGR valve. It would stick open at times and cause the car to run very rough. Check the voltage at that solenoid and see if the time that you notice it start to ide bad, is the time you are getting voltage to the solenoid. A vacuum gauge is also handy to check the coltrol of the vacuum pre/post the vacuum control solenoid. Mine does make an audiable "click", so this could be your problem.

Also, as duffer26 mentioned, check the Idle Air Control valve. Besides checking the operation, check to see if it's dirty. They tend to get varnish on them over time. My Accord was starting to react very slowly to loads (a/c compressor, headlights, etc.). I took cleaned off and gave it a good dose of throtle body cleaner (don't use carb cleaner, these things have a coating on them that carb cleaner will stip off). While your in the area, clean the throttle body. The IAC valve may be built into the TB. On my Accord it is built in, but I used to have a Volvo that had the valve external with plubing to bypass the throttle body.

Let me know if I can be of any further assistance.

Good luck,
Josh

 

Any update on the Rodeo, Jack?

 

I turned up the idle screw.

Nobody can figure it out. The sensors seeem okay. Next trip is to an acutal Isuzu dealer. The bad thing is that the pinion gear is going bad too, and it's expensive to fix. I hate to do it, but I may just drive it until it dies, then call it quits.

 

Then it will be time for another Cummins in the garage.

Maybe the new Diesel Liberty (if it ever comes to pass)


phox

 

I wish I could get another Cummins, but I really need something that's good for transporting the dog. I have been seriously thinking about buying a used police K9 vehicle, but most departments strip the kennel inside when they sell them. Ray Allen and other manufacturers only make them for Tahoes, Durangos, Crown Vics etc. If I could find something for my truck, I'd do it but having one custome made is 3 times what a standard one would be.

I think the ultimate dog vehicle is a Suburban, but it's not easy to afford one. Right now, I've stripped the rodeo behind the front seat. His crate is there, as well as all my gear, and two fans mounted to the windows.

 

I feel for you at the frustration it can cause. I buy inexpensive transportation cars to commute to work and i have a 86 olds that does the same type of thing, it just switches from smooth as silk to stumble and miss, back and forth at idle.
Have you pulled any codes.Is the check engine light working? is your EGR electronically controlled? it seems a lot of asian rigs are. Im guessing the computer is telling the EGR to open intermittenly causing the poor idle. stick a vacume guage on a good manifold source and see if the vacume drops when it starts to idle poorly. try placing your finger on the EGR and feel for it opening, closing as it idles up and down. I know how costly it can get throwing parts into something without results.
You might also try putting a timing light on it and watching for large fluctuations in timing at idle. dropping back retarded will cause near stall idling. this might at least help narrow it down some. Yep suburbans are nice but big and suck fuel. might wanna try a jeep wagon. there cheap, and pretty tough and arent bad on fuel 20 mpg or so. but stay away from the old 2.8 v6 rigs.
good luck.
Apache

 

Thanks for the tips guys. I appreciate it. Now THIS has me drooling. This is exactly what I need! Anybody have one?

 

There is a good site - www.itog.com that is like ours (not as good ) but I have learned a lot about my wife's 90 Trooper. I put a new head on it and it took me 40 days and 40 nights to get it to idle good,although after 600 bucks I wanted it perfect. I finally advanced the TPS about an 1/8 inch after setting the throttle plates to specs and now it is smooth as silk. Also check to see if the secondary throttle plate is closing ALL the way at idle. I hope this helps, ours is a 90 with the 2.6 in it. I have a little knowledge in these, if you cant get 'er give me a buzz - 775-241-7251 and we'll cover the basics. Jim

 

One more thing came to me overnight-(I'm weird about this kind of stuff) The relay that clicks is the high idle control, it will come on when you use the air cond. and I also believe it is the speed sensor that keeps the idle up until you slow down till 3mph or something like that. Your throttle plate setting is critical and works in conjuntion with TPS. Does your warm up regulator work when it's cold? should be around 1500 rpm and after around 30 seconds it will slow down till around 800 or so. All 2.6's have idle problems, but with carefull adjustment and a lot of patience (which I almost ran out of) ours idles great. 171,000 miles and runs perfect. Jim.

 

The high idle works when cold. You're right. It runs about 30 seconds then starts to slow down. Unfortunately, until I rigged the idle screw, that's when it would die much of the time because it would go down to like 400 rpms, then croak. I haven't been able to check the TPS, because I honestly don't know how to, and I plan on taking it to the dealer.

Sometimes even after running for a long time, it'll idle fine, and fairly smooth. Once I hear that click though, everything goes bad and the truck dies. It's driving me nuts because I have taken it to numerous shops and none of them can figure it out. I'm about running out of patience with this thing. the sad thing is that when it's running normally, it runs great. I would hate to have to get rid of it.

 

Hey, we are talking about a 2.6 4 cylinder, aren't we? if it is, let's go over a few things before you take it in. I've been down this road several times and finally have it figured out. E-mail if you don't want to take up space here. They are great vehicles when running properly. Jim.