how to check service engine light...

[94twacker]

I have a 1992 isuzu rodeo that I am having some problems with. It has started hesitating pretty badly, and when going up hill especially it will just suddenly lose all power and the check engine light will come on. After I get on flat land it seems to smooth out a little and the light goes off. Even when I am on flat land it still hesitates very bad about 3k rpm's, it just wont rev anymore. Sometimes when I turn it off I can smelll gas a little bit as well. Anyways I read in a haynes manual that there is a diagnostic plug under the dash on the drivers side, and its just like gm's obd1 plugs where you jump the two terminals. Well on the drivers side under the dash there are two plugs, one kind of big with two terminals on top and two on bottom, and the other really small with like 3 on top and 3 on bottom, nothing like what the book shows. I found another plug under the passengers side that looks closer, but once again not like the book shows and I tried jumping the terminals on it and I get nothing. I really need to figure out how to check this light so I can hopefully figure out what the problem is here and get it fixed. Can somebody PLEASE help me, I havent had any luck in any of my other posts. Thanks alot, by the way it is a 4x4 3.1tbi. Thanks.

[Ramblin Fever]

Sounds to me like an O2 sensor or perhaps the cat.

My CEL is on as well right now, on & steady, has not shut off since early last week. Have no symptoms of anything to report, yet, it's running perfectly normal. Did discover that I have an exhaust leak in/around the front passenger wheel-well.

[94twacker]

I was thinking that too, but its really bad, and I was reading a few posts on here that sounded simular and I saw escm "electronic spark control module" was mentioned a few times, what exactly is this, where is it, how expensive and hard to replace? Thanks guys...very frustrated.

[Ramblin Fever]

It's really hard to say, as most of the CEL's on this board are of the 98+ yrs.

I have heard that it's a bit harder to diagnose a CEL on a pre-96 OBDI versus an OBD II.

I'd personally try and find some assistance, specially if you have a trusty mechanic.

[94twacker]

well I found the port to check it, its under the kick panel right below the ecm. New problem is this....it was a code 44 oxygen sensor lean it says, check for vacuum leaks and manifold leaks then replace sensor, well I checked for leaks and when I sprayed carb cleaner in one spot it slightly effected the idle, but not much at all. The only problem is there is no way to tell which oxygen sensor it is, so that means I would have to buy both of them, and then what if that doesnt fix the problem? I am out of money, and still have to fix the problem and spend more money. What do you guys think I should do here? I really dont know...

[Ramblin Fever]

The way I looked at it is this - my CEL is putting out code P0401 (I believe, don't have it with me) but the code labeled the EGR as being the culprit.

However, the 1st night I went to Autozone, their scanner said that 1 or 2 of the O2 sensors (I have 4 O2's) were out.

However, I didn't feel comfortable with that, as the kid didn't sound "confident" in what he had to say. So I went back the night after, same store, but a different clerk came out and read the code, and that's when it came up to a P0401.

In the meantime, I had already bought 4 O2's, thru a website/company recommended by this forum. At that point, since the actual "problem" was uncertain - I called my mechanic, next morning, he said not to touch a thing, as he could guarantee that my CEL has nothing to do with either or problem that the Autozone scanner is reading.

I've known this mechanic a long long time, and aside from the fact that I've never had him guess wrong - even over the phone, his belief is those scanners that Autozone uses only give generic codes, they don't often give you the true culprit.

In which case, I've decided, I'm not going to just throw part after part at it, hoping "something" will shut it off. I'm sending the O2's back, and the truck will go in to my mechanic in 2-3 weeks.

Mind you, however, my truck is running good even with the CEL. If I were in your shoes, as it sounds like you've already covered a lot of ground in trying to eliminate the problem, I'd find a good mechanic and get the codes read, could end up being cheaper in the long run.

If anything, it could help with peace of mind.

[94twacker]

right, but I figure its 40 for both of them, and it definately cant hurt to replace them anyways, so maybe its worth a shot..also remember the light on these is just jumping two terminals and watching the flashes, not too specific really.

[94twacker]

turns out there is only one sensor on it, right at the y pipe before it goes into the converter.Anyways, I got it changed, and its still the same. I think I have a leak from the throttlebody base gasket, which is only 5.99 so Im going to change it and hope that is it, I will let you guys know.

[95.5 Rodeo]

Originally Posted by 94twacker

well I found the port to check it, its under the kick panel right below the ecm. New problem is this....it was a code 44 oxygen sensor lean it says, check for vacuum leaks and manifold leaks then replace sensor, well I checked for leaks and when I sprayed carb cleaner in one spot it slightly effected the idle, but not much at all. The only problem is there is no way to tell which oxygen sensor it is, so that means I would have to buy both of them, and then what if that doesnt fix the problem? I am out of money, and still have to fix the problem and spend more money. What do you guys think I should do here? I really dont know...

This sounds like a clogged fuel filter to me- Hesitation, no power going uphill then power returns when on flat land.

When was the last time you changed the fuel filter? When my fuel filter was clogged the computer set a code 44 because the filter could not pass enough fuel to the engine.

Look here:
http://www.automotiveforums.com/vbul...d.php?t=271850


Dale

[95.5 Rodeo]

Bump

[94twacker]

changed the gasket tonight, it was definately bad but still no change, tested the ignition coil and the secondary voltage is supposed to be between 5000-20000 and its at about 3, so tomorrow I am changing the coil and the cap and rotor, already did plugs on it. Fuel filter will come soon as well, I havent changed it yet because I just havent been looking forward to doing it because everything I have done with this thing it has fought me the whole way, and Im sure its probably never been changed so it will be just the same. Anyways I will keep you guys updated on what happens with it, thanks for the input.

[95.5 Rodeo]

When you change the fuel filter, be sure to pull the fuel pump relay and run the engine until it dies.

http://www.automotiveforums.com/vbul...d.php?t=471060

The filter is really easy to replace and may be the source of your problem.


Good luck,
Dale

[94twacker]

just a quick update, I got out of work the other day, changed the coil, cap and rotor. The cap and rotor were in really bad shape, Im surprised it even ran with those in there. Anyways, I changed those, took it for a ride, SAME THING, so I got pissed, went and bought the fuel filter and changed it in the parking lot, and the second I drive away it was like a new car, great power, NO hesitation at all, and it starts up alot better and quicker then ever before. Thanks for the suggestions guys!

[95.5 Rodeo]

It is good to hear your Rodeo is running right again.


Dale