I purchased a 2000 Rodeo V6 today with 98k miles. The vehicle looks showroom new. Driving it home the check engine light started to come on only when I hit the accelerator, basically flashing on and off. Then when I came to a complete stop, it has a rough idle. Parked the car for an hour or so then went to drive it, it was fine and idle was fine. After it warmed up and idled for a while, idle returned to rough. While idleing rough, every couple minutes the idle drops very low like its going to stall and then picks itself back up to 500-600 rpms. Check engine light is on permanetely now. I have a full book of maintenance history, at 92k miles the timing belt and water pump were replaced. Also it has new plugs, at least it says so on the receipts. Finally the intake manifold gasket was replaced. Any suggestions would be great. I also read how some people have a ticking noise, I can here a weird noise like that after it starts idleing rough. Also listening to the exhaust it sounds like it has a miss too me.

 

It could be several things... but I'd say there's a good likely hood that it's the EGR valve or any other sensor pertaining to the EGR valve. The fact that you're noticing this issue when the vehicle is warm is a good indicator. Take it to AutoZone and have them run a diagnostic scan, they do it for free. That should get you pointed in the right direction.

 

Thx for the response. I pulled the egr valve off, and cleaned the carbon out. I also plugged up the exhaust hole on the base and sprayed throttle body cleaner in the intake hole. The plunger in the egr valve seemed to move up and down freely. Afterwards the check engine light went off, but still rough idle. I drove the truck for about 30 miles, no check engine light, seemed to accelerate fine. When I got back home and stopped it still was ideing rough and i can hear a ticking noise ( louder then the noise from the injectors firing) that goes away when i rev it. Also when I was reving it in park the check engine light comes on when I'm giving it gas, then goes away. Finally while sitting there at idle its doing the same thing, dropping rpms real low like its going to stall, but catching itself and going back to around 500 rpms. This happens every few minutes. I've always worked on cars myself, and have built a few performance vehicles and hate to go to a dealership because they'll really get you on cost. Any more help would be greatly appreciated.

 

My buddy plugged in the scanner, multiple misfire codes. It has botch plugs, and I've read on here that you should use the oem plugs. This is getting on my nerves. I've never had a problem on a GM or Ford vehicle that I couldn't figure out. The Rodeo runs fine while driving it, just idle's very rough and feels like its going to stall off and on. The check engine light goes on and off, and sometimes flashes when I'm giving it gas at around 2000 rpms. There's got to be an answer to whats wrong Please help!!!!

 

It's all about the sensors. Check your Haynes manual in the emissions section and you should see a list of which sensors you have and where they are. My nissan pick up had the same problem, and it was the throttle positioning sensor. I had checked for vacume leaks and tightened everything up like my manual had suggested, even looked into an EGR valve at 170 bucks. I put the new TPS on for 80 and it ran like a top.

 

My 1998 Rodeo 4x4 had exact same issue a couple of years ago. It was a vacum leak. O2 sensor was fine, but if you got a leak it drives teh sensor nuts!! Replaced intake manifold gasket and it ran great. Not an easy job, but parts are cheap. Also, don't trust that receipt; Replace spark plugs too. Cheap, easy, and can't hurt.

Check this or other boards on how to search for other possible vacum leaks besides manifold gasket if you're sure it's ok and to find an easier leak to fix before tackling the manifold.

 

Maybe this will help someone else with the same problem. If you have similiar problems to what I had, chances are its the intake manifold gasket. Their are actually two gaskets for the lower intake, and one for the upper, where the plenum connects. I changed all 3 since I had it apart. If you have the same problems, take it to get the codes at auto zone or some other place that will do it for free. If the codes say mulyiple engine misfire, chances are it the gasket. You could then take it to a shop for a diagnostic if your not sure, they will confirm for you, and usually most place will do it cheap if not for free. I know what other people wrote, but I would say for the ave. guy it will take 6 hours too do the job, faster if you have a better selection of tools then most. They originally used plastic gaskets which break apart at where the bolts are tightened, and thats where you get your leak. If you change em, don't use the plastic again, or if you have no choice don't tighten any more then 14 ft lbs of torque. All in all its a doable job, a couple bolts are hard to get too, but anyone can do it. Hopefully this will help someone in the future. Thanks.