I just got my 99 rodeo v6 back from the shop(second time it has been there in the past week). I took it in last Wednesday because of a CEL and a rough idle(felt like it was going to stall). I got it back and the next day the same thing, rough idle and CEL. When I had it there the first time the CEL was PO171 and they replaced the O2 sensor. Also they cleaned the ERG, changed the air filter, fuel filter and the spark plugs(NGK). It was a full blown tune-up. I got it back and as I stated it needed to go back. Today I took it back and they said a plug was bad causing a misfire(CEL on and blinking). I picked it up earlier and it was fine again. Just used my truck and the CEL is back on and the rough idle is back. It is very uncomfortable to drive. I spent $600 (money is real tight right now) last week and today it was free obviously, but it is still not running correctly. I was wondering if anybody has any ideas on what I need to look at. I am going back (I trust these mechanics I've been using them for years and I used to work for them as a parts deliverer) but I am at a loss I don't have a clue what is wrong or where to look. Anyone point me in the right direction as to what might be wrong. Could this be caused by a bad intake manifold gasket?

Thanks in advance
Marc

I would say a bad intake manifold gasket is not the only possible cause, but for that vintage of Isuzu, it is the most common cause.

Have you tried the flammable aerosol test? (engine running, spray carb cleaner or similar aerosol around the perimeter of the intake manifold, if the cleaner is drawn into the engine through a leak the rpm will change.) Not a foolproof test, but a cheap one...

The intake manifold gasket on my 2000 Rodeo went at about 40K. Sounds about right for the symptoms. Suprised the dealer didn't check for it as it is the most common cause of erratic idle. Also might want to check your plugs again - I went to NGK iridiums and my idle became pretty erratic and rough, so I went back to the original Champs and it runs as good as the day I drove it off the lot. Also check the gaps on the plugs again.

Rob

I took it to an independent shop and there are not too many Rodeos that they see. I asked if they thought it was the gasket, but they said they didn't think so becauase the codes it was giving were not related to that. I am taking it back tomorrow hopefully this time it will get fixed. I wish I was more mechanicaly inclined so I could do this myself.
Thanks again,
Marc

well I guess it is the intake manifold gasket giving me some trouble, guys said there was a big chunk missing and it is being replaced. Not bad the original lasted about 69,000 miles. Of course the additional $270 I have to spend hurts.

Ah, ain't it nice to finally know what the problem was?

Supposedly, the new gaskets have been reinforced to eliminate this problem...

Yes it is wonderful to finally know what is wrong. I spent a lot of money to fix it ($890) but it was worth it. I was gonna use that money for some mods. Oh well another time. Its just nice to have her purring again. Now I am ready for the winter and hopefully some fun in the Buffalo snow. After all that is why I went to a 4x4. I was pleased when I got the rodeo back and it did not sound sick anymore. It was a scary weak, my funds are tight and I was worrying about the mounting bills. Hopefully nothing but routine oil changes for a while. I still wish I had the know-how to do this work myself. Out of all my friends not one of them has mechanical skills. I think I need some new friends to teach me this stuff.
again thanks for the help,
Marc

Marcre,
You can do this yourself, you just need to buy a service manual, preferable Haynes and have some basic automotive knowledge. I have a 1991 Rodeo myself and really like the vehicle. It has 230,000 miles and keeps going strong. I do all of the maintenance myself and enjoy keeping it going. It's not gonna be long before people start calling it an antique but it still looks very nice, in fact I just installed a 2,000 watt audio system so I'm gonna keep it even longer. It's like the EverReady Battery, it just keeps going and going. I am very impressed with the quality of my Isuzu Rodeo, they built them well back in 91.
<img src="/forums/images/graemlins/cheers.gif" alt="" />
Cheers,

bbusbee,
I am always tempted to work on my truck myself, but I have no knowldge of what to do. I have a manual and have studied and think if I had time I could. Another problem is there is nowhere to do it where I live (apartment). I plan on keeping this truck for a long time so when I can get a second car and have a house of my own I will start taking it apart and doing everything myself. I wish there was someone to help me out though. But, yea it would save a lot of money.

Man if you lived here in Austin I would help you out in a heart beat. I like working with people that have the same appreciation for their cars. Good luck. <img src="/forums/images/graemlins/kewl.gif" alt="" />

bbusbee