One long strange trip...

This is a story about my problems I had with my 94 Isuzu Rodeo(v6) on my way to vacation to Cape Hatteras from Columbus, Ohio which is a 750-800 mile trip...

It was running great until about 150 miles then my check engine light came on, I just figured it was something stupid so I ignored it and it got progressively worse, especially when I hit the mountains. It seemed to run better when the check engine light was on, when the light went off I would lose power and black smoke would pour out my exaust, I would even lose power going down mountains, by the time I was at 300 miles I could barely make it up mountain so I got a hotel at 4am.

Woke up the next morning and it was running better, still with black smoke, so I decided to try to make the rest of the trip. Got about 150 miles down the road and the check engine light never came back on, and the whole rest of the 300 miles I had to pump the gas slowly to keep at a even speed, holding the accelerator pedal steady would slow me down, I had to keep pumping until we got to our destination.

I stopped in Richmond, VA and talked with a Autozone employee and he thought my plugs were fouling out, he told me to try to get all the oil out from around my plugs and it should help, tried this and it didnt do any good.

When I finally got to the Outer Banks, the next morning I took it to a small private shop, the guy told me he had found a vacuum line off the transmission, and he also thought that the catalitic converter may be going bad, he told me to take my Rodeo out to the beach and 4x4 it in the sand for a while. It ran great, had lots of power, no black smoke, my problem was solved.... for now.

We took the Rodeo sight seeing and had no problems all week and the night we were headed back to Ohio at about 200 miles the dreaded check engine light came on, well dreading the mountains we stopped and got a hotel in Richmond, VA.

The next morning I took the Rodeo to a Midas shop since I figured it was my Catalitic convertor, they quoted me 250.00 over the phone so I figured this would be my ticket home. When the started looking at my car the tech called me back to the garage and showed me what a computer scan was showing, it showed a MAP sensor problem, and a lean problem. The tech said the if a catalitic converter goes bad it is usually discolored, he said mine LOOKED fine, but my muffler had a pinhole in it and was rattling. He said if he was me he would just replace the MAP sensor and I explained I had 3 children and a wife to take 500 miles in the mountains and I want anything fixed that could cause the problem, so he quoted me a price on a new exaust from cat back and a new MAP sensor, total would cost me 989.00 !!!!!!!!! Since I was pretty well stuck 500 miles from home I said what the hell if this gets me home, it took them about 5 hours to get parts and install them for me.

So I pick my wife and kids up at the hotel and head out happily towards home and 50 miles out of Richmond my check engine light comes back on !! almost ready for a nervous breakdown I called the midas shop and asked for the owner to plead for some help and he wasnt in, had to talk to the tech that worked on the car, I asked him what the hell could be the problem ? he said to bring it back and they could run it on the computer tomorrow and check codes again since it was 15 minutes till closing time. So I said hell with that and headed towards Ohio. The Rodeo seemed to get worse and worse, when check engine light would come on it would pick up power and get up mountains, when it went off poofs of black smoke would billow out my exaust. Eventually the check engine light never came back on and I had to pump the gas to keep the car going at 65, up mountains I could barely go 25-30 and thats with pumping the gas the whole time.

So now I am 1000.00 in the hole and my beautiful car is running like crap, Im about half scared to take it to a shop at this point, seen a few posts about this kind of problem and ill try to fix it myself this time, since I have tools to do so at my home... home sweet home :)

Any thoughts on what to try first, seen some people doing things from O2 sensor to valve cover gaskets, any help is greatly appreciated !

I cant tell you what your problem is but I would try to see if you can work something out with your local midas shop considering that you spent a grand at the other midas shop and your problem has not been fixed. Most people are reasonable and will understand that you arent going to drive back to richmond to have them look at your car again, especially since they already mis diagnosed it once.

I'm not sure if they would help me out or not but its worth a try I guess, what do you think my problem is exactly ?

It sounds like its running really rich but its wierd that it reacts differently at times. Wait till one of the isuzu pros show up, im sure they can give you a better idea of whats going on.

Have you ever replaced the oxygen sensor on your Rodeo? That turned out to be the problem on mine:

http://www.automotiveforums.com/vbulletin/showthread.php?t=258045

You may want to check the oxygen sensor's connector and wiring while you are at it, there could be an intermittent connection.

If you replace it yourself, be sure to clear the computer by disconnecting the battery or pulling the ECM fuse for 15 minutes.

I think when the check engine light comes on, the engine runs in "safe mode", that is why it ran better when it was lit.

I'm thinking on the 1994, you may be able to jump the diagnostic connector to flash the trouble codes to the check engine light. I am not certain about this though. Someone else may know for sure.

It sounds to me like you are ready for valve cover gaskets and spark plug tube seals. The parts are cheap, but the repair is labor intensive.

I'm sorry to hear about your experience with Midas, It is a shame to spend that kind of money and not get the problem solved.

As usual, just my two cents worth.

Let us know what you find.

Good luck,
Dale