2001 Isuzu Rodeo Question 2 Questions - Check Engine Light &

2001 ISUZU RODEO
92,000 MILES • 6 CYL • 4WD • AUTOMATIC
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ZKILLOUGH
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My '01 Rodeo 4wd v6 with automatic transmission is displaying the check engine light sporadically. Each time the light turns on, I have it checked. The same code pops up - Random Misfire. I have tuned the engine up within the past 3000 miles and a new O2 sensor has been installed; yet, the problem persists. When the light is active, the engine seems to work very hard and inefficiently (almost to the point of guzzling fuel) and the power and performance is slightly off. I'm pulling my hair out trying to figure this one out. Help!

#2: Recently, while eating at a truck stop while on vacation, my rear windshield wiper was "vandalized". Someone grabbed it and twisted - unsetting the bolt and loosening the wiper arm. I have retightened the wiper arm, but it refuses to work consistently. I push the button and either nothing happens or I get one swipe then the wiper arm stops moving up on my hatch glass. As far as I am able to tell, the wiper motor is working fine as are the switches (without the wiper arm tightened to the motor shaft, and without wiper arm completely - works fine).
Aug 14, 2008 at 11:02 AM
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SERVICE WRITER
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Pull off the wiper arm and look at the post of the motor and where the arm seats onto it. The should be some kind of knurls or other gripping like marks. If they are smooth then it won't grip. Sometimes you can shim the nut with a washer to force the arm down further. Probably need an arm.

The misfire problem needs to be narrowed down to what is lacking...fuel... spark...timing/compression.

Start with fuel pressure, is it in spec?
Aug 14, 2008 at 11:17 AM
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ZKILLOUGH
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Thanks for the news on the wiper arm. That's exactly what I feared. I have already pulled it off, and it (the arm) has been slightly stripped out. The motor post still has good knurling.

As to the engine issue, I am getting good fuel pressure and everything seems to check out and be within spec. Could it be an issue with the EGR valve? When I purchased the vehicle, I had issues with the O2 sensor that was causing a Hard Misfire code, but since replacing the O2 sensor, I have had this new issue. I have also had the timing belt and water pump replaced (belt broke and nearly ruined the motor).

Thanks again.
Aug 14, 2008 at 12:20 PM
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SERVICE WRITER
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Do a compression test. the valves may have been weakened from the belt break.
Aug 14, 2008 at 3:38 PM
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ZKILLOUGH
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Alright. Compression test it is. Thanks.

Hopefully, I can get this running right without spending too much more money.
Aug 14, 2008 at 4:40 PM
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SERVICE WRITER
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You want good results on this...if it comes up bad, there may be valves blent, a timing issue etc...not cheap fixes. I hope it comes up good for you.
Aug 15, 2008 at 6:11 AM
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ZKILLOUGH
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Compression nominal. No bent valves & timing looks good. I'm stumped. Could I have missed something in my tune up? I've pulled the spark plugs and checked the gaps - normal & no signs of degradation.

There's a growing part of me that is thinking I should've stayed domestic (haven't had any issues out of my bowtie - except when I trashed the front end and suspension while offroading)
Aug 15, 2008 at 12:10 PM
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Don't stress, we'll get it. Troubleshooting is just a process. Be very happy the compression test was good. I read an article not too long ago about a honda that the timing belt broke and valves clashed with the heads. The valves were damaged, but because of the malluable valve over time it began to real....So at least yours didn't go south instead.

We still have plenty of potential ground to cover, so don't get too excited when the test is positive. Intake leak is the next area to focus on. You need to spray carb cleaner or use propane (un lit), around the rear of the engine at the intake manifold gasket. A change in idle will indicate that the intkae gasket is pulling in too much unmetered air and causing a lean condition that will misfire.

BTW..what brand spark plug, what gap and what number plug did you use?
Aug 15, 2008 at 7:31 PM
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ZKILLOUGH
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Ok. I'll check the manifold. I use Bosch Platinum Plus plugs with stock gap and stock numbers (i don't have that info in front of me right now).
Aug 16, 2008 at 1:49 PM
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Change the plugs. Put in NGK.... Isuzus do not like Bosch. I know it sounds goofy, but that is just a reality in many cases. Frankly I wouldn't use bosch plugs in any engine, but that is besides the point. the vast majority of the time I use autolite in engines, the few exceptions are some of the "imports".....(import is taking on a new meaning huh?)
Aug 16, 2008 at 3:43 PM