1998 Isuzu Rodeo Poor Idle/Power loss/Serious backfiring

[FL 3.2L]

Sure sounds plausible.

[kellercars]

Ya that would be depressing. I hope a locaiting pin hasn't sheared. Well I'm going easy first. Removed EGR and valve seemed to open and close easy enough. Black soot and stuff but not excessive. Pulled plugs and the three on the right were wet while the ones on the left were dry with black carbon. O2 sensor?

Again... Midas says "no codes, mechanical". My diagnostic tool says my DTC is P0300 random/multiple misfire. I am thinking of tracking down a PCM since that is where all the timing and fuel/air information comes from. But that ain't gonna be cheap. Do PCM's often go bad...seems unlikely.

I can only find one fuse the O2 sensors but tommoro I will locate and unplug the two pre-cat sensors. That seems like a real good test since the other two don't feed info back to the PCM. Where are the little buggers?

thanks for you time guys

[kellercars]

Another frusterating day...

Let me start over, and tell you what I know.

Syptoms:

#1 Vehicle starts fine and idles fine for about two minutes then it begins to lope and the engine will VERY nearly die but usually catches itself.

#2 from 1800ish rpm through 2500rpm (basically when the engine is loaded while you are shifting through the gears) numerous backfires can be heard in the manifold and the car lurches lightly with the noise. above 2500rpm the backfiring quits but the car lacks power.

#3 Check engine light switches between steady and blinking.

What I know:

My diagnostic tool gives me a P0300 code "Random/multiple cylinder misfires detected"

When I erase the code and turn off the CEL it stays off for about two minutes of driving and then comes back on

I have good compression and spark.

A new timing belt and tensioner are installed and all the timing marks are aligned correctly double checked and verified by a second party.

Just today I installed correct AC delco plugs and the exact same syptoms persisted.

The EGR has been removed and cleaned (but it really wasn't that dirty) and the valve seemed to operate smoothly, reinstalled with new gasket.

Unplugging connectors to both pre-cat O2 sensors changed nothing.

After I run the engine and pull the plugs the ones on the drivers right are wet/black and the ones on the left are relatively clean. ALSO, THE RIGHT CAT IS WARM WHILE THE LEFT CAT IS HOT!

Lastly and most depressing is that everywhere I go on this car it appears someone has been there before me. remeber I got it at a dealers auction so I really do not know the history but it appears some other "mechanic" lost heart with this thing and gave up.

Questions:

Could it be a plugged Cat and why the heck would it be plugged.

How can I test to see if it is plugged.

Does the 3.2 liter have a locating pin on the cam and is it possible to shear one.

Could this be a bad ground somewhere in the PCM syestem or something awful like that...please say no

yehaw! This is fun.

Matt

[trooperbc]

well it seems you've made some real diagnostic progress here by going to the basics -- removing and inspecting the plugs. and by your observation of the plug conditions, AND the difference in temp of the two catalytic converters. cats do run hot. and an overly taxed cat (one that's getting alot of unburnt fuel, for example) will get very very hot. a cool cat is not at all normal under any condtion after the engine has been run for any time at all.

the easiest way for you to check it, would be to disconnect it and run it without that cat (and without the muffler if you can't rig a temp catreplacement pipe). since you are very aware of what happens and when, you should be able to tell pretty quick if that's the problem.

as been mentioned, these symptoms scream out 'timing', and the one side vs. the other could too. have you done a compression test?

...
look under there and see what it would take you to remove that one cat and see what happens.
what's the temperature of the exhaust pipes on the cool cat side? with a hose or other poorman'smechanic's stethoscope, do you *hear* a difference in the sounds of the exhaust pipes/manifolds one side to the other?

you're getting there....

//bc

[kellercars]

Thanks trooperbc

Compression tested good on all six. I was going to disconnect the cat today but I was chicken. Unfortunately there is a gas line right under the joint. If I get desperate I might just hack it off just upstream of the cat and then buy a new one but I hate to do that.

Would the 02 sensor downstream of the cat tell me if the cat was plugged?

Can I test a plugged cat by checking vaccum at the intake?

[Cat Fuzz]

Ok, are you saying right and left as if you're sitting in the drivers seat? Drivers side is left, passenger side is right. That is how you refer to the sides of a car. It really sounds like the hot cat is clogged and that it is dumping excess fuel into that side of the engine. That is what killed the cat. Try cutting out the suspected bad cat and replace with a length of flexible exhaust pipe and clamp the ends. Run it again and if it runs better, you have found your bad cat. The next step is finding out why it's dumping fuel on the one side. Then you can take it to a muffler shop to have a new cat welded in. Much cheaper than the direct fit.

If you leave the pipe in there, without replacing the cat, the check engine light will stay on.

[kellercars]

Yes Ive given left and right with respect to the drivers seat.

right side=unburnt gas on plugs, warm cat

Left side=normal plugs, hot cat

Would O2 sensor downstream of cat tell me if cat was plugged?

[cormech]

I have a 2000 Rodeo that started doing the same thing a week ago. I did have a code p0101 stored in memory indicating a problem with the MAF sensor. I replaced the MAF sensor and the vehicle has run fine ever since. There was also another code stored but I did not write it down and have forgoten what it was. When the cel lit up it was blinking when the throttle was applied and steady when my foot was off the gas.

[rflammia]

I've got a 2002 V6 3.2L. I am really starting to hate this car. My problem started about three months ago. I live in New England and fall approached. I noticed that it became more and more difficult to start it on cold mornings. CEL came on and stayed on. But then it gets worse. The colder it got i noticed that it started hard and when it finally kicked over, the Cruise control light comes on also. After warming up to 180 degres or so it would go off. I then noticed while driving at times the cruise control light and CEL would come on over a bump or while giving it gas. Now it's January and still having a problem. OBD II Scanner said Crankshaft poisitioning sensor and random misfiire. I've replaced a number of things in the past month. Throttle Positioning Sensor, O2 Sensor, Fuel Pressure Regulator, Plugs, Fuel Filter. Still no solution. I need help bad...... Rob