99 Rodeo rough idle - IMG already replaced

mgeorge17 · 05-09-2005, 08:09 PM

99 Rodeo LS 3.2 Automatic, 78K miles

Sporadic idling problems - sometimes when I started it, it would idle at 2100, other times it would jump between 300-800, sometimes it was fine around 800. No check engine lights or anything.
I had a diagnostics run and it returned nothing, and it idled fine for the shop (ah - go figure).
I had them replace the IMG anyway, after reading a bunch of posts. It now idles around 1200 at cold start-up (fairly consistent). When coming to a stop, it will still occasionally jump around between the 300-800 range (20% of the time?). It does seem to run better, but the inconsistent idling is worrisome and I just don't feel like I can trust the vehicle (that and my wife occasionally drives it).
I've really done nothing but replace oil, air filters, and a fuel filter on this over the years. Any ideas considering it's not showing any error codes?
Thanks in advance!

Cat Fuzz · 05-09-2005, 09:36 PM

Next thing is to check your vacuum hoses for leaks. Check your PCV valve and the hose that it connects to and the grommet. The PCV valve should rattle freely, if not, replace it. Its what I would check next. Again, make sure all your vacuum hoses are tight and undamaged. Check them closly, its easy to miss a lateral split in the hoses.

amigo-2k · 05-09-2005, 10:21 PM

.... and clean up the EGR and EGR port.

superfret78 · 05-13-2005, 06:29 AM

Another thing you could try is to take the IAC valve off and clean off the pintle. Sometimes they get gunked up and that causes them to stick and gives you funny idling problems.

emt757911 · 05-14-2005, 11:50 AM

I'm new here so I'll just start talking. I have a 2000 Rodeo (4 cyl) with 66,000 miles that suddenly started vibrating and missing while at idle. At times you can feel the engine lug and surge while driving. Went to AutoZone for a read out and got the P0300 code (random multiple misfire. Yay) My friend, who is an automotive repair instructor, and myself went out and bought new plugs, wires, fuel filter, air filter was fine, cleaned the throttle body, EGR valve, fuel injectors, and anything else we could think of.

Unfortunately this did not fix the problem. Upon restart the CEL went off but later came back on with a flashing vengance. I returned to AutoZone and found that the engine was still giving me the P0300 code. I called a friend of mine and he told me that it sounded like I must have gotten ahold of some bad gas (this has happened to him before). He recommended that I put Gas Dry and Sea Foam in the tank to see if that will clear out this issue. It was hard to start this morning but seems to be running a bit better, however, the longer it idles the harder it vibrates. If this problem is still there when I am done with this tank of gas should I change the intake manifold gasket? I would take the truck in to have a diagnostic run but that is going to cost me 80.00 and if they have to change the gasket it is going to be more expensive than what I can afford. Besides, some of the Isuzu techs said that they have seen this problem come in before so they do a tune up, the truck comes back and they change the IMG...and it still idles rough! They said that it seems to be more of a problem with 6 cylinder trucks.

My friend asked one of his Isuzu tech friends about the problem just to find out that they have been having problems with the head gaskets needing to be repaired on the 4 cylinder engines (a 900.00 repair job). Anyone heard of head gasket failure with the 4 cyl.? I do have the 10year/100,000 mile warranty but don't know if it would be covered.

I do apologize for the long post but any suggestions will be appreciated.

mgeorge17 · 05-16-2005, 02:24 PM

Quote:

Originally Posted by Cat Fuzz

Next thing is to check your vacuum hoses for leaks. Check your PCV valve and the hose that it connects to and the grommet. The PCV valve should rattle freely, if not, replace it. Its what I would check next. Again, make sure all your vacuum hoses are tight and undamaged. Check them closly, its easy to miss a lateral split in the hoses.

--
Thanks. PCV valve was partially clogged and grommet a little worn. Replaced both and idles like a champ again. Truly appreciate all responses as this was my first post!

tim christopher · 10-03-2005, 09:23 PM

Quote:

Originally Posted by mgeorge17

--
Thanks. PCV valve was partially clogged and grommet a little worn. Replaced both and idles like a champ again. Truly appreciate all responses as this was my first post!

I have a 1996 Rodeo that was idling at about 2200 rpm in park at a stop light just 5 minutes after I had left my house this morning to go to work. I put it in park after it was idling at about 1500 rpm after i would let off the gas . Any ideas what is the problem??

tc

KevinSS · 05-07-2006, 02:59 PM

[quote=tim christopher]I have a 1996 Rodeo that was idling at about 2200 rpm in park at a stop light just 5 minutes after I had left my house this morning to go to work. I put it in park after it was idling at about 1500 rpm after i would let off the gas . Any ideas what is the problem??

tc[/

I also have a problem like this with my 97... Any ideas???

Runs/idles smooth, but after driving for around 10-15 minutes....idles very high at around 2200 rpm.

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